WorldWideScience

Sample records for underlying intraspecific variation

  1. Utilizing intraspecific variation in phenotypic plasticity to bolster agricultural and forest productivity under climate change.

    Science.gov (United States)

    Aspinwall, Michael J; Loik, Michael E; Resco de Dios, Victor; Tjoelker, Mark G; Payton, Paxton R; Tissue, David T

    2015-09-01

    Climate change threatens the ability of agriculture and forestry to meet growing global demands for food, fibre and wood products. Information gathered from genotype-by-environment interactions (G × E), which demonstrate intraspecific variation in phenotypic plasticity (the ability of a genotype to alter its phenotype in response to environmental change), may prove important for bolstering agricultural and forest productivity under climate change. Nonetheless, very few studies have explicitly quantified genotype plasticity-productivity relationships in agriculture or forestry. Here, we conceptualize the importance of intraspecific variation in agricultural and forest species plasticity, and discuss the physiological and genetic factors contributing to intraspecific variation in phenotypic plasticity. Our discussion highlights the need for an integrated understanding of the mechanisms of G × E, more extensive assessments of genotypic responses to climate change under field conditions, and explicit testing of genotype plasticity-productivity relationships. Ultimately, further investigation of intraspecific variation in phenotypic plasticity in agriculture and forestry may prove important for identifying genotypes capable of increasing or sustaining productivity under more extreme climatic conditions. © 2014 John Wiley & Sons Ltd.

  2. Species characteristics and intraspecific variation in growth and photosynthesis of Cryptomeria japonica under elevated O3 and CO2.

    Science.gov (United States)

    Hiraoka, Yuichiro; Iki, Taiichi; Nose, Mine; Tobita, Hiroyuki; Yazaki, Kenichi; Watanabe, Atsushi; Fujisawa, Yoshitake; Kitao, Mitsutoshi

    2017-06-01

    In order to predict the effects of future atmospheric conditions on forest productivity, it is necessary to clarify the physiological responses of major forest tree species to high concentrations of ozone (O3) and carbon dioxide (CO2). Furthermore, intraspecific variation of these responses should also be examined in order to predict productivity gains through tree improvements in the future. We investigated intraspecific variation in growth and photosynthesis of Cryptomeria japonica D. Don, a major silviculture species in Japan, in response to elevated concentrations of O3 (eO3) and CO2 (eCO2), separately and in combination. Cuttings of C. japonica were grown and exposed to two levels of O3 (ambient and twice-ambient levels) in combination with two levels of CO2 (ambient and 550 µmol mol-1 in the daytime) for two growing seasons in a free-air CO2 enrichment experiment. There was no obvious negative effect of eO3 on growth or photosynthetic traits of the C. japonica clones, but a positive effect was observed for annual height increments in the first growing season. Dry mass production and the photosynthetic rate increased under eCO2 conditions, while the maximum carboxylation rate decreased. Significant interaction effects of eO3 and eCO2 on growth and photosynthetic traits were not observed. Clonal effects on growth and photosynthetic traits were significant, but the interactions between clones and O3 and/or CO2 treatments were not. Spearman's rank correlation coefficients between growth traits under ambient conditions and for each treatment were significantly positive, implying that clonal ranking in growth abilities might not be affected by either eO3 or eCO2. The knowledge obtained from this study will be helpful for species selection in afforestation programs, to continue and to improve current programs involving this species, and to accurately predict the CO2 fixation capacity of Japanese forests. © The Author 2017. Published by Oxford University Press. All

  3. The ecological importance of intraspecific variation.

    Science.gov (United States)

    Des Roches, Simone; Post, David M; Turley, Nash E; Bailey, Joseph K; Hendry, Andrew P; Kinnison, Michael T; Schweitzer, Jennifer A; Palkovacs, Eric P

    2018-01-01

    Human activity is causing wild populations to experience rapid trait change and local extirpation. The resulting effects on intraspecific variation could have substantial consequences for ecological processes and ecosystem services. Although researchers have long acknowledged that variation among species influences the surrounding environment, only recently has evidence accumulated for the ecological importance of variation within species. We conducted a meta-analysis comparing the ecological effects of variation within a species (intraspecific effects) with the effects of replacement or removal of that species (species effects). We evaluated direct and indirect ecological responses, including changes in abundance (or biomass), rates of ecological processes and changes in community composition. Our results show that intraspecific effects are often comparable to, and sometimes stronger than, species effects. Species effects tend to be larger for direct ecological responses (for example, through consumption), whereas intraspecific effects and species effects tend to be similar for indirect responses (for example, through trophic cascades). Intraspecific effects are especially strong when indirect interactions alter community composition. Our results summarize data from the first generation of studies examining the relative ecological effects of intraspecific variation. Our conclusions can help inform the design of future experiments and the formulation of strategies to quantify and conserve biodiversity.

  4. Characterization and intraspecific variation of Fusarium semitectum ...

    African Journals Online (AJOL)

    A total of 79 isolates of Fusarium semitectum were characterized by morphological and IGS-RFLP analysis to assess its intraspecific variation. Based on morphological characteristics, the isolates of F. semitectum were classified into 2 distinct groups, morphotypes I and II. Morphotype I was characterized by longer ...

  5. Intraspecific variation in aerobic and anaerobic locomotion

    DEFF Research Database (Denmark)

    Svendsen, Jon Christian; Tirsgård, Bjørn; Cordero, Gerardo A.

    2015-01-01

    Intraspecific variation and trade-off in aerobic and anaerobic traits remain poorly understood in aquatic locomotion. Using gilthead sea bream (Sparus aurata) and Trinidadian guppy (Poecilia reticulata), both axial swimmers, this study tested four hypotheses: (1) gait transition from steady...... to unsteady (i.e., burst-assisted) swimming is associated with anaerobic metabolism evidenced as excess post exercise oxygen consumption (EPOC); (2) variation in swimming performance (critical swimming speed; U crit) correlates with metabolic scope (MS) or anaerobic capacity (i.e., maximum EPOC); (3...

  6. Variation in the relative magnitude of intraspecific and interspecific ...

    Indian Academy of Sciences (India)

    While there was considerable variation in the relative magnitude of intraspecific and interspecific competitive effects over generations, among both populations and environments, there was no clear evidence supporting the genetic feedback hypothesis. Intraspecific and interspecific competitive effects on population growth ...

  7. Inter- and intraspecific variations of cadmium accumulation of 13 leafy vegetable species in a greenhouse experiment.

    Science.gov (United States)

    Wang, Junli; Fang, Wei; Yang, Zhongyi; Yuan, Jiangang; Zhu, Yun; Yu, Hui

    2007-10-31

    Leafy vegetables are among the crop species that are most vulnerable to heavy metal pollution. This study investigated inter- and intraspecific variations of cadmium accumulation in 13 species with a total of 39 cultivars of leafy vegetables under two levels of soil Cd stress (1.5 and 7.7 mg kg (-1)). Intraspecific variations of shoot biomass and Cd concentration of the tested leafy vegetables were significantly larger than interspecific variations under both Cd treatments and were also more significantly correlated between two Cd stress levels when grouped by cultivar than grouped by species. These results indicate that cultivar is a more reliable taxa level for screening pollutant-safe leafy vegetables than species. Any screening for pollutant hypoaccumulator species, or other similar species-based concepts, without considering intraspecific variation should be avoided.

  8. Intraspecific genetic variation and species coexistence in plant communities.

    Science.gov (United States)

    Ehlers, Bodil K; Damgaard, Christian F; Laroche, Fabien

    2016-01-01

    Many studies report that intraspecific genetic variation in plants can affect community composition and coexistence. However, less is known about which traits are responsible and the mechanisms by which variation in these traits affect the associated community. Focusing on plant-plant interactions, we review empirical studies exemplifying how intraspecific genetic variation in functional traits impacts plant coexistence. Intraspecific variation in chemical and architectural traits promotes species coexistence, by both increasing habitat heterogeneity and altering competitive hierarchies. Decomposing species interactions into interactions between genotypes shows that genotype × genotype interactions are often intransitive. The outcome of plant-plant interactions varies with local adaptation to the environment and with dominant neighbour genotypes, and some plants can recognize the genetic identity of neighbour plants if they have a common history of coexistence. Taken together, this reveals a very dynamic nature of coexistence. We outline how more traits mediating plant-plant interactions may be identified, and how future studies could use population genetic surveys of genotype distribution in nature and methods from trait-based ecology to better quantify the impact of intraspecific genetic variation on plant coexistence. © 2016 The Author(s).

  9. Intraspecific genetic variation and competition interact to influence niche expansion.

    Science.gov (United States)

    Agashe, Deepa; Bolnick, Daniel I

    2010-10-07

    Theory and empirical evidence show that intraspecific competition can drive selection favouring the use of novel resources (i.e. niche expansion). The evolutionary response to such selection depends on genetic variation for resource use. However, while genetic variation might facilitate niche expansion, genetically diverse groups may also experience weaker competition, reducing density-dependent selection on resource use. Therefore, genetic variation for fitness on different resources could directly facilitate, or indirectly retard, niche expansion. To test these alternatives, we factorially manipulated both the degree of genetic variation and population density in flour beetles (Tribolium castaneum) exposed to both novel and familiar food resources. Using stable carbon isotope analysis, we measured temporal change and individual variation in beetle diet across eight generations. Intraspecific competition and genetic variation acted on different components of niche evolution: competition facilitated niche expansion, while genetic variation increased individual variation in niche use. In addition, genetic variation and competition together facilitated niche expansion, but all these impacts were temporally variable. Thus, we show that the interaction between genetic variation and competition can also determine niche evolution at different time scales.

  10. Y-Chromosome variation in hominids: intraspecific variation is limited to the polygamous chimpanzee.

    Directory of Open Access Journals (Sweden)

    Gabriele Greve

    Full Text Available BACKGROUND: We have previously demonstrated that the Y-specific ampliconic fertility genes DAZ (deleted in azoospermia and CDY (chromodomain protein Y varied with respect to copy number and position among chimpanzees (Pan troglodytes. In comparison, seven Y-chromosomal lineages of the bonobo (Pan paniscus, the chimpanzee's closest living relative, showed no variation. We extend our earlier comparative investigation to include an analysis of the intraspecific variation of these genes in gorillas (Gorilla gorilla and orangutans (Pongo pygmaeus, and examine the resulting patterns in the light of the species' markedly different social and mating behaviors. METHODOLOGY/PRINCIPAL FINDINGS: Fluorescence in situ hybridization analysis (FISH of DAZ and CDY in 12 Y-chromosomal lineages of western lowland gorilla (G. gorilla gorilla and a single lineage of the eastern lowland gorilla (G. beringei graueri showed no variation among lineages. Similar findings were noted for the 10 Y-chromosomal lineages examined in the Bornean orangutan (Pongo pygmaeus, and 11 Y-chromosomal lineages of the Sumatran orangutan (P. abelii. We validated the contrasting DAZ and CDY patterns using quantitative real-time polymerase chain reaction (qPCR in chimpanzee and bonobo. CONCLUSION/SIGNIFICANCE: High intraspecific variation in copy number and position of the DAZ and CDY genes is seen only in the chimpanzee. We hypothesize that this is best explained by sperm competition that results in the variant DAZ and CDY haplotypes detected in this species. In contrast, bonobos, gorillas and orangutans-species that are not subject to sperm competition-showed no intraspecific variation in DAZ and CDY suggesting that monoandry in gorillas, and preferential female mate choice in bonobos and orangutans, probably permitted the fixation of a single Y variant in each taxon. These data support the notion that the evolutionary history of a primate Y chromosome is not simply encrypted in its DNA

  11. Intraspecific variation in sperm length is negatively related to sperm competition in passerine birds.

    Science.gov (United States)

    Kleven, Oddmund; Laskemoen, Terje; Fossøy, Frode; Robertson, Raleigh J; Lifjeld, Jan T

    2008-02-01

    Spermatozoa are among the most diversified cells in the animal kingdom, but the underlying evolutionary forces affecting intraspecific variation in sperm morphology are poorly understood. It has been hypothesized that sperm competition is a potent selection pressure on sperm variation within species. Here, we examine intraspecific variation in total sperm length of 22 wild passerine bird species (21 genera, 11 families) in relation to the risk of sperm competition, as expressed by the frequency of extrapair paternity and relative testis size. We demonstrate, by using phylogenetic comparative methods, that between-male variation in sperm length within species is closely and negatively linked to the risk of sperm competition. This relationship was even stronger when only considering species in which data on sperm length and extrapair paternity originated from the same populations. Intramale variation in sperm length within species was also negatively, although nonsignificantly, related to sperm competition risk. Our findings suggest that postcopulatory sexual selection is a powerful evolutionary force reducing the intraspecific phenotypic variation in sperm-size traits, potentially driving the diversification of sperm morphology across populations and species.

  12. The role of intraspecific variation in the ecological and evolutionary success of diatoms in changing environments.

    Science.gov (United States)

    Godhe, Anna; Rynearson, Tatiana

    2017-09-05

    Intraspecific variation in diatoms has been shown to play a key role in species' responses to several important environmental factors such as light, salinity, temperature and nutrients. Furthermore, modelling efforts indicate that this variation within species extends bloom periods, and likely provides sufficient variability in competitive interactions between species under hydrographically variable conditions. The intraspecific variation most likely corresponds to optimal fitness in temporary microhabitats and may help to explain the paradox of the plankton. Here, we examine the implications of intraspecific variation for the ecology and success of diatoms in general and emphasize the potential implications for our understanding of carbon metabolism in these important organisms. Additionally, data from palaeoecological studies have the potential for evaluating genetic variation through past climate changes, going thousands of years back in time. We suggest pathways for future research including the adoption of multiple strains of individual species into studies of diatom carbon metabolism, to refine our understanding of the variation within and between species, and the inclusion of experimental evolution as a tool for understanding potential evolutionary responses of diatom carbon metabolism to climate change.This article is part of the themed issue 'The peculiar carbon metabolism in diatoms'. © 2017 The Author(s).

  13. Effects of intraspecific variation in white cabbage (Brassica oleracea var. Capitata) on soil ogranisms

    NARCIS (Netherlands)

    Kabouw, P.; Putten, van der W.H.; Dam, van N.M.; Biere, A.

    2010-01-01

    Intraspecific variation in plants can affect soil organisms. However, little is known about whether the magnitude of the effect depends on the degree of interaction with the roots. We analyzed effects of plant intraspecific variation on root herbivores and other soil organisms that interact directly

  14. Does intraspecific competition promote variation? A test via synthesis.

    Science.gov (United States)

    Jones, Andrew W; Post, David M

    2016-03-01

    Competitive diversification, that is, when increasing intraspecific competition promotes population niche expansion, is commonly invoked in evolutionary studies and currently plays a central role in how we conceptualize the process of adaptive diversification. Despite the frequency with which this idea is cited, the empirical evidence for the process is somewhat limited, and the findings of these studies have yet to be weighed objectively through synthesis. Here, we sought to fill this gap by reviewing the existing literature and collecting the data necessary to assess the evidence for competition as a diversifying force. Additionally, we sought to test a more recent hypothesis, which suggests that competition can act to both promote and inhibit dietary diversification depending on the degree to which a consumer depletes its resources. The surprising result of this synthesis was that increasing competition did not have a mean positive effect on population-level diet breadth or the degree of individual specialization. Instead, we found that increasing intraspecific competition had a restricting effect on population-level diet breadth in as many cases as it had a diversifying effect. This wide disparity in the effect of competition on consumer diet variation was negatively related to a metric for consumer resource depletion. Altogether, these findings call into question a long-standing assumption of basic evolutionary models and lend some support to recent theoretical predictions. Specifically, these findings support the idea that competition is primarily diversifying for species with a small effect (per unit biomass) on their resources and that resource depletion limits the diversifying effect of competition for consumers with larger ecological effects.

  15. The importance of intraspecific variation in tree responses to elevated [CO2]: breeding and management of future forests

    Science.gov (United States)

    One strategy for managing forests to sustain or increase productivity under global climate change is to initiate breeding programs which maximize responses to elevated [CO2] within species. The basis for any breeding program is intraspecific variation in the traits of interest, and for forests, grow...

  16. Intraspecific variation of the interparietal suture closure in Siberian roe deer Capreolus pygargus from Jeju Island.

    Science.gov (United States)

    Oh, Jinwoo; Oh, Hong-Shik; Kimura, Junpei; Koyabu, Daisuke

    2017-12-22

    The sequence of cranial suture closure among cervids is reported to be generally species-specific and highly conservative within species. On the other hand, it is known that intraspecific variation often exists to some extent in other mammalian taxa. Here we studied the cranial suture closures of Capreolus pygargus from Jeju Island and compared it with other cervid species. We found that the timing of the interparietal suture closure is highly variable within C. pygargus. Capreolus capreolus similarly shows intraspecific variation of the interparietal suture closure, whereas other cervid species studied to date do not show any intraspecific variation in the sequence of cranial suture closure. Such high intraspecific variation of the interparietal suture may be a derived character for Capreolus.

  17. Intraspecific variation in alkaline phosphatase activity in Phaeodactylum tricornutum (Bacillariophyceae, Bohlin

    Directory of Open Access Journals (Sweden)

    Domênica Teixeira de Lima

    2016-01-01

    Full Text Available ABSTRACT To describe potential intraspecific variation in phosphorus incorporation in two strains of Phaeodactylum tricornutum (Bohlin, Ub3 and Ub7, alkaline phosphatase (AP activity was evaluated via enzyme-labeled fluorescence assay. Analysis using the probe ELF-97(r provides individual evaluation, and therefore can determine the nutritional status of inorganic phosphorus in phytoplanktonic cells. Bioassays compared the control treatment to both phosphate-enriched and phosphate-depleted treatments by varying only the phosphate concentration in the media. The P. tricornutum strains exhibited differences in their development when incubated in the phosphate-enriched media. The development of the Ub7 strain differed by exhibiting "luxury uptake" and utilization of organic phosphorus, and the alkaline phosphatase analysis indicated limitations of this clone under such conditions. The Ub7 strain showed higher AP activity, when compared to Ub3, in the P-enriched condition. P. tricornutum presented increases in AP activity and low variation in Surface/Volume ratio, by increasing biovolume and its maximum linear dimension, as strategies for phosphate incorporation. Our results highlight intraspecific differences in alkaline phosphatase activity, and hence differences in the incorporation of organic phosphorus, as the tested species regulated enzymatic activity under different external phosphate concentrations.

  18. Variation in the relative magnitude of intraspecific and interspecific ...

    Indian Academy of Sciences (India)

    Administrator

    Models of competitor coevolution, especially the genetic feedback hypothesis, suggest that a negative correlation be- tween intraspecific and interspecific competitive effects may be important in sustaining competitor coexistence, and can give rise to oscillatory dynamics with repeated reversals of competitive superiority.

  19. Intra-specific pelage color variation in a South American small rodent species

    OpenAIRE

    Sandoval Salinas,M. L.; Barquez,R. M.; Colombo,E. M.; Sandoval,J. D.

    2017-01-01

    Abstract Intra-specific color variation is often underestimated by researchers, and among mammals, intra-specific differences in coloration are poorly documented for most species. The main goal of this study was to apply an objective color measurement methodology to the study of a specific problem: the detection, if any, of patterns of changes in the fur color of specimens of Akodon budini in relation to biological (i.e., sex) and environmental (i.e., season) variables. We hypothesize that co...

  20. Intra-specific pelage color variation in a South American small rodent species

    OpenAIRE

    Sandoval Salinas, M. L.; Barquez, R. M.; Colombo, E. M.; Sandoval, J. D.

    2016-01-01

    Abstract Intra-specific color variation is often underestimated by researchers, and among mammals, intra-specific differences in coloration are poorly documented for most species. The main goal of this study was to apply an objective color measurement methodology to the study of a specific problem: the detection, if any, of patterns of changes in the fur color of specimens of Akodon budini in relation to biological (i.e., sex) and environmental (i.e., season) variables. We hypothesize that co...

  1. Causes and Consequences of Intraspecific Variation in Nesting Behaviors: Insights from Blue Tits and Great Tits

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    Mark C. Mainwaring

    2017-05-01

    Full Text Available Nest building is an important and yet under-studied stage of the reproductive cycle in many taxa, including birds, and whilst we have a decent understanding of interspecific variation in avian nesting behaviors, our understanding of intraspecific variation in nesting behaviors is much less developed. This is largely because an insufficient number of studies have been performed on any one species to draw robust conclusions. Fortunately, though, the amount of research on the nesting behaviors of nestbox-breeding blue tits (Cyanistes caeruleus and great tits (Parus major has increased dramatically in recent years and their nesting behaviors are now sufficiently well-studied to offer useful insights into intraspecific variation in avian nesting behaviors. Studies show that individuals of both species select nest sites based on the presence and/or absence of conspecifics and heterospecifics and whilst neighbors were assumed to adversely affect focal individuals by competing for resources, they are now considered beneficial as they provide information about habitat quality and contribute to anti-predator defenses. Nest-building females accurately gauge local weather conditions and respond to predictable variation in environmental conditions by building nests with variable amounts of cup lining material to create suitable nest microclimates for nestlings. Meanwhile, both species vary the amount of aromatic plant materials in their nests in relation to the abundance of nest-dwelling parasites and pathogens and as aromatic plant materials also play a role in sexual selection then nest materials can have multiple functions. The height of nests is negatively correlated with the local risk of predation but whilst predator avoidance favors lower nests, sexual selection favors taller nests. In fact, higher quality females build taller nests that contain more green plant material which in turn influences the amount of care provided by males. This suggests

  2. The Orphan Gene dauerless Regulates Dauer Development and Intraspecific Competition in Nematodes by Copy Number Variation.

    Science.gov (United States)

    Mayer, Melanie G; Rödelsperger, Christian; Witte, Hanh; Riebesell, Metta; Sommer, Ralf J

    2015-06-01

    Many nematodes form dauer larvae when exposed to unfavorable conditions, representing an example of phenotypic plasticity and a major survival and dispersal strategy. In Caenorhabditis elegans, the regulation of dauer induction is a model for pheromone, insulin, and steroid-hormone signaling. Recent studies in Pristionchus pacificus revealed substantial natural variation in various aspects of dauer development, i.e. pheromone production and sensing and dauer longevity and fitness. One intriguing example is a strain from Ohio, having extremely long-lived dauers associated with very high fitness and often forming the most dauers in response to other strains' pheromones, including the reference strain from California. While such examples have been suggested to represent intraspecific competition among strains, the molecular mechanisms underlying these dauer-associated patterns are currently unknown. We generated recombinant-inbred-lines between the Californian and Ohioan strains and used quantitative-trait-loci analysis to investigate the molecular mechanism determining natural variation in dauer development. Surprisingly, we discovered that the orphan gene dauerless controls dauer formation by copy number variation. The Ohioan strain has one dauerless copy causing high dauer formation, whereas the Californian strain has two copies, resulting in strongly reduced dauer formation. Transgenic animals expressing multiple copies do not form dauers. dauerless is exclusively expressed in CAN neurons, and both CAN ablation and dauerless mutations increase dauer formation. Strikingly, dauerless underwent several duplications and acts in parallel or downstream of steroid-hormone signaling but upstream of the nuclear-hormone-receptor daf-12. We identified the novel or fast-evolving gene dauerless as inhibitor of dauer development. Our findings reveal the importance of gene duplications and copy number variations for orphan gene function and suggest daf-12 as major target for

  3. Determinants of intra-specific variation in basal metabolic rate.

    Science.gov (United States)

    Konarzewski, Marek; Książek, Aneta

    2013-01-01

    Basal metabolic rate (BMR) provides a widely accepted benchmark of metabolic expenditure for endotherms under laboratory and natural conditions. While most studies examining BMR have concentrated on inter-specific variation, relatively less attention has been paid to the determinants of within-species variation. Even fewer studies have analysed the determinants of within-species BMR variation corrected for the strong influence of body mass by appropriate means (e.g. ANCOVA). Here, we review recent advancements in studies on the quantitative genetics of BMR and organ mass variation, along with their molecular genetics. Next, we decompose BMR variation at the organ, tissue and molecular level. We conclude that within-species variation in BMR and its components have a clear genetic signature, and are functionally linked to key metabolic process at all levels of biological organization. We highlight the need to integrate molecular genetics with conventional metabolic field studies to reveal the adaptive significance of metabolic variation. Since comparing gene expressions inter-specifically is problematic, within-species studies are more likely to inform us about the genetic underpinnings of BMR. We also urge for better integration of animal and medical research on BMR; the latter is quickly advancing thanks to the application of imaging technologies and 'omics' studies. We also suggest that much insight on the biochemical and molecular underpinnings of BMR variation can be gained from integrating studies on the mammalian target of rapamycin (mTOR), which appears to be the major regulatory pathway influencing the key molecular components of BMR.

  4. Epigenetic variation predicts regional and local intraspecific functional diversity in a perennial herb.

    Science.gov (United States)

    Medrano, Mónica; Herrera, Carlos M; Bazaga, Pilar

    2014-10-01

    The ecological significance of epigenetic variation has been generally inferred from studies on model plants under artificial conditions, but the importance of epigenetic differences between individuals as a source of intraspecific diversity in natural plant populations remains essentially unknown. This study investigates the relationship between epigenetic variation and functional plant diversity by conducting epigenetic (methylation-sensitive amplified fragment length polymorphisms, MSAP) and genetic (amplified fragment length polymorphisms, AFLP) marker-trait association analyses for 20 whole-plant, leaf and regenerative functional traits in a large sample of wild-growing plants of the perennial herb Helleborus foetidus from ten sampling sites in south-eastern Spain. Plants differed widely in functional characteristics, and exhibited greater epigenetic than genetic diversity, as shown by per cent polymorphism of MSAP fragments (92%) or markers (69%) greatly exceeding that for AFLP ones (41%). After controlling for genetic structuring and possible cryptic relatedness, every functional trait considered exhibited a significant association with at least one AFLP or MSAP marker. A total of 27 MSAP (13.0% of total) and 12 AFLP (4.4%) markers were involved in significant associations, which explained on average 8.2% and 8.0% of trait variance, respectively. Individual MSAP markers were more likely to be associated with functional traits than AFLP markers. Between-site differences in multivariate functional diversity were directly related to variation in multilocus epigenetic diversity after multilocus genetic diversity was statistically accounted for. Results suggest that epigenetic variation can be an important source of intraspecific functional diversity in H. foetidus, possibly endowing this species with the capacity to exploit a broad range of ecological conditions despite its modest genetic diversity. © 2014 John Wiley & Sons Ltd.

  5. Consequences of intraspecific seed-size variation in Sparganium emersum for dispersal by fish

    NARCIS (Netherlands)

    Pollux, B.J.A.; Ouborg, J.; Van Groenendael, J.M.; Klaassen, M.R.J.

    2007-01-01

    The potential for seed dispersal by fish (ichthyochory) is likely to vary within aquatic plant species, depending on intraspecific variation in phenotypic seed traits. 2. We studied the effect of seed size variation within the unbranched burreed (Sparganium emersum) on the potential for internal

  6. The reciprocal relationship between competition and intraspecific trait variation

    DEFF Research Database (Denmark)

    A Bennett, Jonathan; Riibak, Kersti; Tamme, Riin

    2016-01-01

    with larger leaves and lower specific leaf area than their neighbours. Switching to more stress tolerant strategies by increasing root diameter and leaf tissue density also reduced competition. However, dissimilarity in root tissue density also minimized competition, consistent with limiting similarity...... outcomes, we grew 15 species alone, in monoculture, and in mixture. We measured traits relating to leaf and root tissue morphology as well as biomass allocation and related competition induced changes in these traits to intra- and interspecific competition using multi-model inference. Additionally, we...... to both intra- and interspecific competition, frequently affecting competitive hierarchies. Intraspecific competition was lower for species that limited competition-induced increases in root allocation and had less variability in this trait overall. Interspecific competition was lower for species...

  7. Assessing intraspecific variation in effective dispersal along an altitudinal gradient: a test in two Mediterranean high-mountain plants.

    Directory of Open Access Journals (Sweden)

    Carlos Lara-Romero

    Full Text Available Plant recruitment depends among other factors on environmental conditions and their variation at different spatial scales. Characterizing dispersal in contrasting environments may thus be necessary to understand natural intraspecific variation in the processes underlying recruitment. Silene ciliata and Armeria caespitosa are two representative species of cryophilic pastures above the tree line in Mediterranean high mountains. No explicit estimations of dispersal kernels have been made so far for these or other high-mountain plants. Such data could help to predict their dispersal and recruitment patterns in a context of changing environments under ongoing global warming.We used an inverse modelling approach to analyse effective seed dispersal patterns in five populations of both Silene ciliata and Armeria caespitosa along an altitudinal gradient in Sierra de Guadarrama (Madrid, Spain. We considered four commonly employed two-dimensional seedling dispersal kernels exponential-power, 2Dt, WALD and log-normal.No single kernel function provided the best fit across all populations, although estimated mean dispersal distances were short (<1 m in all cases. S. ciliata did not exhibit significant among-population variation in mean dispersal distance, whereas significant differences in mean dispersal distance were found in A. caespitosa. Both S. ciliata and A. caespitosa exhibited among-population variation in the fecundity parameter and lacked significant variation in kernel shape.This study illustrates the complexity of intraspecific variation in the processes underlying recruitment, showing that effective dispersal kernels can remain relatively invariant across populations within particular species, even if there are strong variations in demographic structure and/or physical environment among populations, while the invariant dispersal assumption may not hold for other species in the same environment. Our results call for a case-by-case analysis in a

  8. Inter- and intraspecific variation in leaf economic traits in wheat and maize.

    Science.gov (United States)

    Martin, Adam R; Hale, Christine E; Cerabolini, Bruno E L; Cornelissen, Johannes H C; Craine, Joseph; Gough, William A; Kattge, Jens; Tirona, Cairan K F

    2018-02-01

    Leaf Economics Spectrum (LES) trait variation underpins multiple agroecological processes and many prominent crop yield models. While there are numerous independent studies assessing trait variation in crops, to date there have been no comprehensive assessments of intraspecific trait variation (ITV) in LES traits for wheat and maize: the world's most widespread crops. Using trait databases and peer-reviewed literature, we compiled over 700 records of specific leaf area (SLA), maximum photosynthetic rates ( A max ) and leaf nitrogen (N) concentrations, for wheat and maize. We evaluated intraspecific LES trait variation, and intraspecific trait-environment relationships. While wheat and maize occupy the upper 90th percentile of LES trait values observed across a global species pool, ITV ranged widely across the LES in wheat and maize. Fertilization treatments had strong impacts on leaf N, while plant developmental stage (here standardized as the number of days since planting) had strong impacts on A max ; days since planting, N fertilization and irrigation all influenced SLA. When controlling for these factors, intraspecific responses to temperature and precipitation explained 39.4 and 43.7 % of the variation in A max and SLA, respectively, but only 5.4 % of the variation in leaf N. Despite a long history of domestication in these species, ITV in wheat and maize among and within cultivars remains large. Intraspecific trait variation is a critical consideration to refine regional to global models of agroecosystem structure, function and food security. Considerable opportunities and benefits exist for consolidating a crop trait database for a wider range of domesticated plant species.

  9. Intraspecific diversity among partners drives functional variation in coral symbioses.

    Science.gov (United States)

    Parkinson, John Everett; Banaszak, Anastazia T; Altman, Naomi S; LaJeunesse, Todd C; Baums, Iliana B

    2015-10-26

    The capacity of coral-dinoflagellate mutualisms to adapt to a changing climate relies in part on standing variation in host and symbiont populations, but rarely have the interactions between symbiotic partners been considered at the level of individuals. Here, we tested the importance of inter-individual variation with respect to the physiology of coral holobionts. We identified six genetically distinct Acropora palmata coral colonies that all shared the same isoclonal Symbiodinium 'fitti' dinoflagellate strain. No other Symbiodinium could be detected in host tissues. We exposed fragments of each colony to extreme cold and found that the stress-induced change in symbiont photochemical efficiency varied up to 3.6-fold depending on host genetic background. The S. 'fitti' strain was least stressed when associating with hosts that significantly altered the expression of 184 genes under cold shock; it was most stressed in hosts that only adjusted 14 genes. Key expression differences among hosts were related to redox signaling and iron availability pathways. Fine-scale interactions among unique host colonies and symbiont strains provide an underappreciated source of raw material for natural selection in coral symbioses.

  10. Intraspecific Trait Variation and Coordination: Root and Leaf Economics Spectra in Coffee across Environmental Gradients.

    Science.gov (United States)

    Isaac, Marney E; Martin, Adam R; de Melo Virginio Filho, Elias; Rapidel, Bruno; Roupsard, Olivier; Van den Meersche, Karel

    2017-01-01

    Hypotheses on the existence of a universal "Root Economics Spectrum" (RES) have received arguably the least attention of all trait spectra, despite the key role root trait variation plays in resource acquisition potential. There is growing interest in quantifying intraspecific trait variation (ITV) in plants, but there are few studies evaluating (i) the existence of an intraspecific RES within a plant species, or (ii) how a RES may be coordinated with other trait spectra within species, such as a leaf economics spectrum (LES). Using Coffea arabica (Rubiaceae) as a model species, we measured seven morphological and chemical traits of intact lateral roots, which were paired with information on four key LES traits. Field collections were completed across four nested levels of biological organization. The intraspecific trait coefficient of variation (cv) ranged from 25 to 87% with root diameter and specific root tip density showing the lowest and highest cv, respectively. Between 27 and 68% of root ITV was explained by site identity alone for five of the seven traits measured. A single principal component explained 56.2% of root trait covariation, with plants falling along a RES from resource acquiring to conserving traits. Multiple factor analysis revealed significant orthogonal relationships between root and leaf spectra. RES traits were strongly orthogonal with respect to LES traits, suggesting these traits vary independently from one another in response to environmental cues. This study provides among the first evidence that plants from the same species differentiate from one another along an intraspecific RES. We find that in one of the world's most widely cultivated crops, an intraspecific RES is orthogonal to an intraspecific LES, indicating that above and belowground responses of plants to managed (or natural) environmental gradients are likely to occur independently from one another.

  11. Isolation and identification of 4-a-rhamnosyloxy benzyl glucosinolate in Noccaea caerulescens showing intraspecific variation

    NARCIS (Netherlands)

    Graaf, de R.M.; Krosse, S.; Swolfs, A.E.M.; Brinke, te E.; Prill, N.; Leimu, R.; Galen, van P.M.; Wang, Y.; Aarts, M.G.M.; Dam, van N.M.

    2015-01-01

    Glucosinolates are secondary plant compounds typically found in members of the Brassicaceae and a few other plant families. Usually each plant species contains a specific subset of the ~130 different glucosinolates identified to date. However, intraspecific variation in glucosinolate profiles is

  12. Sizing ocean giants: patterns of intraspecific size variation in marine megafauna.

    Science.gov (United States)

    McClain, Craig R; Balk, Meghan A; Benfield, Mark C; Branch, Trevor A; Chen, Catherine; Cosgrove, James; Dove, Alistair D M; Gaskins, Lindsay C; Helm, Rebecca R; Hochberg, Frederick G; Lee, Frank B; Marshall, Andrea; McMurray, Steven E; Schanche, Caroline; Stone, Shane N; Thaler, Andrew D

    2015-01-01

    What are the greatest sizes that the largest marine megafauna obtain? This is a simple question with a difficult and complex answer. Many of the largest-sized species occur in the world's oceans. For many of these, rarity, remoteness, and quite simply the logistics of measuring these giants has made obtaining accurate size measurements difficult. Inaccurate reports of maximum sizes run rampant through the scientific literature and popular media. Moreover, how intraspecific variation in the body sizes of these animals relates to sex, population structure, the environment, and interactions with humans remains underappreciated. Here, we review and analyze body size for 25 ocean giants ranging across the animal kingdom. For each taxon we document body size for the largest known marine species of several clades. We also analyze intraspecific variation and identify the largest known individuals for each species. Where data allows, we analyze spatial and temporal intraspecific size variation. We also provide allometric scaling equations between different size measurements as resources to other researchers. In some cases, the lack of data prevents us from fully examining these topics and instead we specifically highlight these deficiencies and the barriers that exist for data collection. Overall, we found considerable variability in intraspecific size distributions from strongly left- to strongly right-skewed. We provide several allometric equations that allow for estimation of total lengths and weights from more easily obtained measurements. In several cases, we also quantify considerable geographic variation and decreases in size likely attributed to humans.

  13. Intraspecific variation of seed floating ability in Sparganium emersum suggests a bimodal dispersal strategy

    NARCIS (Netherlands)

    Pollux, B.J.A.; Verbruggen, E.; Van Groenendael, J.M.; Ouborg, N.J.

    2009-01-01

    Water-mediated spread of seeds (hydrochory) plays an important role in the dispersal of aquatic plants. In this study we investigate intraspecific variation in floating ability and germination capacity of Sparganium emersum seeds in relation to seed mass, within three natural populations along the

  14. Intraspecific variations in responses to ocean acidification in two branching coral species.

    Science.gov (United States)

    Sekizawa, Ayami; Uechi, Hikaru; Iguchi, Akira; Nakamura, Takashi; Kumagai, Naoki H; Suzuki, Atsushi; Sakai, Kazuhiko; Nojiri, Yukihiro

    2017-09-15

    Ocean acidification is widely recognised to have a negative impact on marine calcifying organisms by reducing calcifications, but controversy remains over whether such organisms could cope with ocean acidification within a range of phenotypic plasticity and/or adapt to future acidifying ocean. We performed a laboratory rearing experiment using clonal fragments of the common branching corals Montipora digitata and Porites cylindrica under control and acidified seawater (lower pH) conditions (approximately 400 and 900μatm pCO 2 , respectively) and evaluated the intraspecific variations in their responses to ocean acidification. Intra- and interspecific variations in calcification and photosynthetic efficiency were evident according to both pCO 2 conditions and colony, indicating that responses to acidification may be individually variable at the colony level. Our results suggest that some corals may cope with ocean acidification within their present genotypic composition by adaptation through phenotypic plasticity, while others may be placed under selective pressures resulting in population alteration. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Intraspecific trait variation and the leaf economics spectrum across resource gradients and levels of organization.

    Science.gov (United States)

    Fajardo, Alex; Siefert, Andrew

    2018-03-30

    Understanding patterns of functional trait variation across environmental gradients offers an opportunity to increase inference in the mechanistic causes of plant community assembly. The leaf economics spectrum (LES) predicts global tradeoffs in leaf traits and trait-environment relationships, but few studies have examined whether these predictions hold across different levels of organization, particularly within species. Here, we asked (1) whether the main assumptions of the LES (expected trait relationships and shifts in trait values across resource gradients) hold at the intraspecific level, and (2) how within-species trait correlations scale up to interspecific or among-community levels. We worked with leaf traits of saplings of woody species growing across light and soil N and P availability gradients in temperate rainforests of southern Chile. We found that ITV accounted for a large proportion of community-level variation in leaf traits (e.g., LMA and leaf P) and played an important role in driving community-level shifts in leaf traits across environmental gradients. Additionally, intraspecific leaf trait relationships were generally consistent with interspecific and community-level trait relationships and with LES predictions-e.g., a strong negative intraspecific LMA-leaf N correlation-although, most trait relationships varied significantly among species, suggesting idiosyncrasies in the LES at the intraspecific level. © 2018 by the Ecological Society of America.

  16. Hierarchical analysis of taxonomic variation in intraspecific competition across fish species.

    Science.gov (United States)

    Foss-Grant, Andrew P; Zipkin, Elise F; Thorson, James T; Jensen, Olaf P; Fagan, William F

    2016-07-01

    The nature and intensity of intraspecific competition can vary greatly among taxa, yet similarities in these interactions can lead to similar population dynamics among related organisms. Variation along the spectrum of intraspecific competition, with contest and scramble competition as endpoints, leads to vastly different responses to population density. Here we investigated the diversity of intraspecific competition among fish species, predicting that functional forms of density-dependent reproduction would be conserved in related taxa. Using a hierarchical model that links stock-recruitment parameters among populations, species, and orders, we found that the strength of overcompensation, and therefore the type of intraspecific competition, is tightly clustered within taxonomic groupings, as species within an order share similar degrees of compensation. Specifically, species within the orders Salmoniformes and Pleuronectiformes exhibited density dependence indicative of scramble competition (overcompensation) while the orders Clupeiformes, Gadiformes, Perciformes, and Scorpaeniformes exhibited dynamics consistent with contest competition (compensation). Maximum potential recruitment also varied among orders, but with less clustering across species. We also tested whether stock-recruitment parameters correlated with maximum body length among species, but found no strong relationship. Our results suggest that much of the variation in the form of density-dependent reproduction among fish species may be predicted taxonomically due to evolved life history traits and reproductive behaviors. © 2016 by the Ecological Society of America.

  17. Intraspecific Variation in Armillaria Species from Shrubs and Trees in Northwestern Spain

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    O. Aguín

    2004-08-01

    Full Text Available Until recently, the identification of Armillaria species relied upon morphological characteristics and mating tests, but now molecular techniques based on polymorphisms in the IGS region of the fungal rDNA are more commonly used, since these are more rapid and reliable. Differences found in RFLP patterns identifying Armillaria species have suggested the existence of intraspecific variation. In this work, 185 Armillaria isolates from different plant species (including fruit trees, broadleaf and coniferous trees, ornamental shrubs, kiwifruit and grapevine affected by white root rot were analyzed by RFLP-PCR, in order to study intraspecific variation in Armillaria and the relationship with the plant host. Armillaria mellea was found in the majority of samples (71%, and was the most frequent Armillaria species in symptomatic ornamental shrubs, kiwifruit, grapevine, fruit trees and broadleaf trees. In conifers however white root rot was generally caused by Armillaria ostoyae. Armillaria gallica was identified, although with low incidence, in ornamental, coniferous, broadleaf and fruit hosts. Intraspecies variation was recorded only in A. mellea, for which RFLP patterns mel 1 and mel 2 were found. Most plants infected with A. mellea showed the mel 2 pattern. Further research is needed to study whether Armillaria RFLP patterns are specific to certain plant hosts, and whether intraspecific variation is related to differences in pathogenicity.

  18. Planning tiger recovery: Understanding intraspecific variation for effective conservation

    Science.gov (United States)

    Wilting, Andreas; Courtiol, Alexandre; Christiansen, Per; Niedballa, Jürgen; Scharf, Anne K.; Orlando, Ludovic; Balkenhol, Niko; Hofer, Heribert; Kramer-Schadt, Stephanie; Fickel, Jörns; Kitchener, Andrew C.

    2015-01-01

    Although significantly more money is spent on the conservation of tigers than on any other threatened species, today only 3200 to 3600 tigers roam the forests of Asia, occupying only 7% of their historical range. Despite the global significance of and interest in tiger conservation, global approaches to plan tiger recovery are partly impeded by the lack of a consensus on the number of tiger subspecies or management units, because a comprehensive analysis of tiger variation is lacking. We analyzed variation among all nine putative tiger subspecies, using extensive data sets of several traits [morphological (craniodental and pelage), ecological, molecular]. Our analyses revealed little variation and large overlaps in each trait among putative subspecies, and molecular data showed extremely low diversity because of a severe Late Pleistocene population decline. Our results support recognition of only two subspecies: the Sunda tiger, Panthera tigris sondaica, and the continental tiger, Panthera tigris tigris, which consists of two (northern and southern) management units. Conservation management programs, such as captive breeding, reintroduction initiatives, or trans-boundary projects, rely on a durable, consistent characterization of subspecies as taxonomic units, defined by robust multiple lines of scientific evidence rather than single traits or ad hoc descriptions of one or few specimens. Our multiple-trait data set supports a fundamental rethinking of the conventional tiger taxonomy paradigm, which will have profound implications for the management of in situ and ex situ tiger populations and boost conservation efforts by facilitating a pragmatic approach to tiger conservation management worldwide. PMID:26601191

  19. Intraspecific Variation in Maximum Ingested Food Size and Body Mass in Varecia rubra and Propithecus coquereli.

    Science.gov (United States)

    Hartstone-Rose, Adam; Perry, Jonathan M G

    2011-01-01

    In a recent study, we quantified the scaling of ingested food size (V(b))-the maximum size at which an animal consistently ingests food whole-and found that V(b) scaled isometrically between species of captive strepsirrhines. The current study examines the relationship between V(b) and body size within species with a focus on the frugivorous Varecia rubra and the folivorous Propithecus coquereli. We found no overlap in V(b) between the species (all V. rubra ingested larger pieces of food relative to those eaten by P. coquereli), and least-squares regression of V(b) and three different measures of body mass showed no scaling relationship within each species. We believe that this lack of relationship results from the relatively narrow intraspecific body size variation and seemingly patternless individual variation in V(b) within species and take this study as further evidence that general scaling questions are best examined interspecifically rather than intraspecifically.

  20. Intraspecific variation of body size in a gamasid mite Laelaps clethrionomydis: environment, geography and host dependence.

    Science.gov (United States)

    Korallo-Vinarskaya, Natalia P; Vinarski, Maxim V; Khokhlova, Irina S; Shenbrot, Georgy I; Krasnov, Boris R

    2015-10-01

    We investigated intraspecific variation in body size of an ectoparasitic gamasid mite, Laelaps clethrionomydis, across 12 localities in the Palearctic. We asked whether mites collected from the same host species in different localities or from different host species in the same locality vary in body size. Within host species, mites collected in different localities differed significantly in body size, tending to be larger in northern than in southern localities. In addition, mite body size correlated negatively with mean annual temperature in a locality. Mites collected from different hosts in the same locality differed significantly in body size when hosts belonged to different genera but did not differ when collected from congeneric hosts. We conclude that intraspecific variation in mite body size is caused by interplay of environmental and host-related factors.

  1. Intraspecific Variation in Maximum Ingested Food Size and Body Mass in Varecia rubra and Propithecus coquereli

    Directory of Open Access Journals (Sweden)

    Adam Hartstone-Rose

    2011-01-01

    Full Text Available In a recent study, we quantified the scaling of ingested food size (Vb—the maximum size at which an animal consistently ingests food whole—and found that Vb scaled isometrically between species of captive strepsirrhines. The current study examines the relationship between Vb and body size within species with a focus on the frugivorous Varecia rubra and the folivorous Propithecus coquereli. We found no overlap in Vb between the species (all V. rubra ingested larger pieces of food relative to those eaten by P. coquereli, and least-squares regression of Vb and three different measures of body mass showed no scaling relationship within each species. We believe that this lack of relationship results from the relatively narrow intraspecific body size variation and seemingly patternless individual variation in Vb within species and take this study as further evidence that general scaling questions are best examined interspecifically rather than intraspecifically.

  2. [Intraspecific genetic and morphological variation of earthworm Eisenia foetida (Sav.)].

    Science.gov (United States)

    Bolotetskiĭ, N M; Kodolova, O P

    2005-01-01

    Polyacrylamide gel electrophoresis was used to study the allelic frequency distribution of four polymorphic loci (Pox, Lap, Pgm, and Odh) in 22 samples of Eisenia foetida (Sav.) from distant parts of the range: European Russia, Ukraine, Kazakhstan, and Kyrgyzstan. A hierarchical population structure was demonstrated for this species: local populations are integrated into spatial groups. Statistical analysis of morphological variation demonstrated that recognition of the spatial groups on the basis of biochemical and genetic characters as individual taxa of any rank is not justified.

  3. Intraspecific variation in fruit-frugivore interactions: effects of fruiting neighborhood and consequences for seed dispersal.

    Science.gov (United States)

    Guerra, Tadeu J; Dayrell, Roberta L C; Arruda, André J; Dáttilo, Wesley; Teixido, Alberto L; Messeder, João V S; Silveira, Fernando A O

    2017-10-01

    The extent of specialization/generalization continuum in fruit-frugivore interactions at the individual level remains poorly explored. Here, we investigated the interactions between the Neotropical treelet Miconia irwinii (Melastomataceae) and its avian seed dispersers in Brazilian campo rupestre. We built an individual-based network to derive plant degree of interaction specialization regarding disperser species. Then, we explored how intraspecific variation in interaction niche breadth relates to fruit availability on individual plants in varying densities of fruiting conspecific neighbors, and how these factors affect the quantity of viable seeds dispersed. We predicted broader interaction niche breadths for individuals with larger fruit crops in denser fruiting neighborhoods. The downscaled network included nine bird species and 15 plants, which varied nearly five-fold in their degree of interaction specialization. We found positive effects of crop size on visitation and fruit removal rates, but not on degree of interaction specialization. Conversely, we found that an increase in the density of conspecific fruiting neighbors both increased visitation rate and reduced plant degree of interaction specialization. We suggest that tracking fruit-rich patches by avian frugivore species is the main driver of density-dependent intraspecific variation in plants' interaction niche breadth. Our study shed some light on the overlooked fitness consequences of intraspecific variation in interaction niches by showing that individuals along the specialization/generalization continuum may have their seed dispersed with similar effectiveness. Our study exemplifies how individual-based networks linking plants to frugivore species that differ in their seed dispersal effectiveness can advance our understanding of intraspecific variation in the outcomes of fruit-frugivore interactions.

  4. Scandinavian Oncophorus (Bryopsida, Oncophoraceae: species, cryptic species, and intraspecific variation

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    Lars Hedenäs

    2017-05-01

    Full Text Available Scandinavian members of the acrocarpous moss genus Oncophorus were revised after field observations had suggested unrecognized diversity. Based on molecular (nuclear: internal transcribed spacers 1 and 2, ITS; plastid: trnGUCC G2 intron, trnG, rps4 gene + trnS-rps4 spacer, rps4 and morphological evidence, four morphologically distinguishable species are recognized, Oncophorus elongatus (I.Hagen Hedenäs, O. integerrimus Hedenäs sp. nov. (syn. O. virens var. elongatus Limpr., O. virens (Hedw. Brid., and O. wahlenbergii Brid. (O. sardous Herzog, syn. nov.. Oncophorus elongatus was earlier recognized, but much of its variation was hidden within O. wahlenbergii. Its circumscription is here expanded to include plants with long leaves having mostly denticulate or sharply denticulate upper margins and with long and narrow marginal cells in the basal portion of the sheathing leaf lamina. The new species O. integerrimus sp. nov. differs from O. virens in having more loosely incurved leaves and entire or almost entire upper leaf margins. Besides these characters, the species in the respective pairs differ in quantitative features of the leaf lamina cells. Several cryptic entities were found, in several cases as molecularly distinct as some of the morphologically recognizable species, and phylogeographic structure is present within O. elongatus and O. virens.

  5. Intraspecific Variation in Female Sex Pheromone of the Codling Moth Cydia pomonella.

    Science.gov (United States)

    Duménil, Claire; Judd, Gary J R; Bosch, Dolors; Baldessari, Mario; Gemeno, César; Groot, Astrid T

    2014-09-26

    The codling moth, Cydia pomonella L. (Lepidoptera, Tortricidae), is a major pest of apple, pear and walnut orchards worldwide. This pest is often controlled using the biologically friendly control method known as pheromone-based mating disruption. Mating disruption likely exerts selection on the sexual communication system of codling moth, as male and female moths will persist in their attempt to meet and mate. Surprisingly little is known on the intraspecific variation of sexual communication in this species. We started an investigation to determine the level of individual variation in the female sex pheromone composition of this moth and whether variation among different populations might be correlated with use of mating disruption against those populations. By extracting pheromone glands of individual females from a laboratory population in Canada and from populations from apple orchards in Spain and Italy, we found significant between- and within-population variation. Comparing females that had been exposed to mating disruption, or not, revealed a significant difference in sex pheromone composition for two of the minor components. Overall, the intraspecific variation observed shows the potential for a shift in female sexual signal when selection pressure is high, as is the case with continuous use of mating disruption.

  6. Intraspecific Variation in Female Sex Pheromone of the Codling Moth Cydia pomonella

    Directory of Open Access Journals (Sweden)

    Claire Duménil

    2014-09-01

    Full Text Available The codling moth, Cydia pomonella L. (Lepidoptera, Tortricidae, is a major pest of apple, pear and walnut orchards worldwide. This pest is often controlled using the biologically friendly control method known as pheromone-based mating disruption. Mating disruption likely exerts selection on the sexual communication system of codling moth, as male and female moths will persist in their attempt to meet and mate. Surprisingly little is known on the intraspecific variation of sexual communication in this species. We started an investigation to determine the level of individual variation in the female sex pheromone composition of this moth and whether variation among different populations might be correlated with use of mating disruption against those populations. By extracting pheromone glands of individual females from a laboratory population in Canada and from populations from apple orchards in Spain and Italy, we found significant between- and within-population variation. Comparing females that had been exposed to mating disruption, or not, revealed a significant difference in sex pheromone composition for two of the minor components. Overall, the intraspecific variation observed shows the potential for a shift in female sexual signal when selection pressure is high, as is the case with continuous use of mating disruption.

  7. Intraspecific morphological and genetic variation of common species predicts ranges of threatened ones

    Science.gov (United States)

    Fuller, Trevon L.; Thomassen, Henri A.; Peralvo, Manuel; Buermann, Wolfgang; Milá, Borja; Kieswetter, Charles M.; Jarrín-V, Pablo; Devitt, Susan E. Cameron; Mason, Eliza; Schweizer, Rena M.; Schlunegger, Jasmin; Chan, Janice; Wang, Ophelia; Schneider, Christopher J.; Pollinger, John P.; Saatchi, Sassan; Graham, Catherine H.; Wayne, Robert K.; Smith, Thomas B.

    2013-01-01

    Predicting where threatened species occur is useful for making informed conservation decisions. However, because they are usually rare, surveying threatened species is often expensive and time intensive. Here, we show how regions where common species exhibit high genetic and morphological divergence among populations can be used to predict the occurrence of species of conservation concern. Intraspecific variation of common species of birds, bats and frogs from Ecuador were found to be a significantly better predictor for the occurrence of threatened species than suites of environmental variables or the occurrence of amphibians and birds. Fully 93 per cent of the threatened species analysed had their range adequately represented by the geographical distribution of the morphological and genetic variation found in seven common species. Both higher numbers of threatened species and greater genetic and morphological variation of common species occurred along elevation gradients. Higher levels of intraspecific divergence may be the result of disruptive selection and/or introgression along gradients. We suggest that collecting data on genetic and morphological variation in common species can be a cost effective tool for conservation planning, and that future biodiversity inventories include surveying genetic and morphological data of common species whenever feasible. PMID:23595273

  8. Intraspecific variation in Trichogramma bruni Nagaraja, 1983 (Hymenoptera: Trichogrammatidae) associated with different hosts.

    Science.gov (United States)

    Querino, R B; Zucchi, R A

    2002-11-01

    Trichogramma bruni is an insufficiently studied South American species whose limits are still not well defined. Thus, the objective of the present study was to characterize T. bruni taxonomically and to determine the association between morphological variations as well as host and habitat, based on morphological and biological studies. Specimens from the Escola Superior de Agricultura "Luiz de Queiroz" (ESALQ) collection, and from the University of California Riverside (UCR) and specimens collected from the vegetation of forest parks with native areas planted with eucalyptus in Piracicaba and Itatinga, State of São Paulo, were also analyzed. The holotype deposited at Univeridade Federal de Minas Gerais (UFMG) collection was also examined. The variability in the genital capsule of T. bruni observed both among individuals of the same progeny and among specimens from different hosts is remarkable and is mainly related to the dorsal lamina. Therefore, an association of diagnostic characters rather than the dorsal lamina alone should be used for the identification of T. bruni and intraspecific variations should be considered. The intraspecific variation observed for T. bruni is a factor that should be considered for its identification, since the influence of the environment (habitat + host) and the variation among individuals itself is responsible for the plasticity observed in the genital capsule. Heliconius erato phyllis, Hamadryas feronia, Erosina hyberniata and Mechanitis lysiminia are new hosts of T. bruni.

  9. Traits underlying community consequences of plant intra-specific diversity.

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    Luis Abdala-Roberts

    Full Text Available A plant's performance and interactions with other trophic levels are recorgnized to be contingent upon plant diversity and underlying associational dynamics, but far less is known about the plant traits driving such phenomena. We manipulated diversity in plant traits using pairs of plant and a substitutive design to elucidate the mechanisms underlying diversity effects operating at a fine spatial scale. Specifically, we measured the effects of diversity in sex (sexual monocultures vs. male and female genotypes together and growth rate (growth rate monocultures vs. fast- and slow-growing genotypes together on growth of the shrub Baccharis salicifolia and on above- and belowground consumers associated with this plant. We compared effects on associate abundance (# associates per plant vs. density (# associates per kg plant biomass to elucidate the mechanisms underlying diversity effects; effects on abundance but not density suggest diversity effects are mediated by resource abundance (i.e. plant biomass alone, whereas effects on density suggest diversity effects are mediated by plant-based heterogeneity or quality. Sexual diversity increased root growth but reduced the density (but not abundance of the dietary generalist aphid Aphis gossypii and its associated aphid-tending ants, suggesting sex mixtures were of lower quality to this herbivore (e.g. via reduced plant quality, and that this effect indirectly influenced ants. Sexual diversity had no effect on the abundance or density of parasitoids attacking A. gossypii, the dietary specialist aphid Uroleucon macolai, or mycorrhizae. In contrast, growth rate diversity did not influence plant growth or any associates except for the dietary specialist aphid U. macolai, which increased in both abundance and density at high diversity, suggesting growth rate mixtures were of higher quality to this herbivore. These results highlight that plant associational and diversity effects on consumers are contingent

  10. Growth, inter- and intraspecific variation, palaeobiogeography, taphonomy and systematics of the Cenozoic ghost shrimp Glypturus

    Science.gov (United States)

    Klompmaker, Adiël A.; Hyžný, Matúš; Portell, Roger W.; Kowalewski, Michał

    2015-01-01

    Studies in systematic palaeontology are greatly aided when numerous, well-preserved specimens are available so that quantitative methods can be used to substantiate qualitative observations. This is often not the case for fossil decapod crustaceans due to their relatively low preservation potential. Here, we examined primarily two large collections of the well-preserved ghost shrimp Glypturus from the Holo-Pleistocene of Panama and the late Miocene of Florida. Using descriptive, bivariate, multivariate and geometric morphometric methods, two new species are described based on appendage material: Glypturus panamacanalensis sp. nov. and G. sikesi sp. nov. New characters are identified, and size-related and intraspecific variation are assessed for these taxa and modern G. acanthochirus. Taxonomic placement of single specimens from other localities was confirmed by multivariate methods. Furthermore, Glypturus is revised, especially with regard to Western Atlantic species that inhabited both carbonate and siliciclastic environments. Callianassa anguillensis, C. latidigata, and Neocallichirus? quisquellanus are referred to as Glypturus sp. until more material is available to determine the validity of these species. Diversity within Glypturus may thus be underestimated, thereby also impacting the assessment of phylogenetic relationships. Minor propodi appear under-represented relative to major propodi, suggesting a taphonomic bias. Single specimens of interest include a specimen of G. panamacanalensis sp. nov. exhibiting a peculiar swelling in the fixed finger and another showing damage on the propodal upper margin, suggesting failed predation or antagonistic behaviour. Glypturus is first found in the Oligocene in the Western Atlantic and may have expanded its palaeobiogeographical range since the Miocene. The genus was still present on the Pacific side of the Isthmus of Panama in the Holo-Pleistocene, but is only known from the Western Atlantic today, suggesting a

  11. Concordance between stabilizing sexual selection, intraspecific variation, and interspecific divergence inPhymata.

    Science.gov (United States)

    Punzalan, David; Rowe, Locke

    2016-11-01

    Empirical studies show that lineages typically exhibit long periods of evolutionary stasis and that relative levels of within-species trait covariance often correlate with the extent of between-species trait divergence. These observations have been interpreted by some as evidence of genetic constraints persisting for long periods of time. However, an alternative explanation is that both intra- and interspecific variation are shaped by the features of the adaptive landscape (e.g., stabilizing selection). Employing a genus of insects that are diverse with respect to a suite of secondary sex traits, we related data describing nonlinear phenotypic (sexual) selection to intraspecific trait covariances and macroevolutionary divergence. We found support for two key predictions (1) that intraspecific trait covariation would be aligned with stabilizing selection and (2) that there would be restricted macroevolutionary divergence in the direction of stabilizing selection. The observed alignment of all three matrices offers a point of caution in interpreting standing variability as metrics of evolutionary constraint. Our results also illustrate the power of sexual selection for determining variation observed at both short and long timescales and account for the apparently slow evolution of some secondary sex characters in this lineage.

  12. Intra-specific pelage color variation in a South American small rodent species

    Directory of Open Access Journals (Sweden)

    M. L. Sandoval Salinas

    Full Text Available Abstract Intra-specific color variation is often underestimated by researchers, and among mammals, intra-specific differences in coloration are poorly documented for most species. The main goal of this study was to apply an objective color measurement methodology to the study of a specific problem: the detection, if any, of patterns of changes in the fur color of specimens of Akodon budini in relation to biological (i.e., sex and environmental (i.e., season variables. We hypothesize that coat color will be more homogeneous in males than in females and that coat color will be darker in winter than in summer, the latter being orange. We measured the pelage color on five points over the dorsal surface of 26 A. budini museum specimens using a spectroradiometer and a diffuse illumination cabin. We used Principal Component Analysis to describe the association between the color variables, sex and season, and each of the observations. We then used general linear models of Analysis of Variance to examine relationships between color data, season, and sex. The results clearly confirm the hypothesis related to seasonal coat color change but do not directly confirm the hypothesis related to changes in coat color in relation to sex, and we show the complexity of the studied pattern. In conclusion, undoubtedly, the studied variables should accordingly be considered when studying the coloration of specimens for characterization, identification and discrimination of different taxonomic units based on color.

  13. Intra-specific pelage color variation in a South American small rodent species.

    Science.gov (United States)

    Sandoval Salinas, M L; Barquez, R M; Colombo, E M; Sandoval, J D

    2017-03-01

    Intra-specific color variation is often underestimated by researchers, and among mammals, intra-specific differences in coloration are poorly documented for most species. The main goal of this study was to apply an objective color measurement methodology to the study of a specific problem: the detection, if any, of patterns of changes in the fur color of specimens of Akodon budini in relation to biological (i.e., sex) and environmental (i.e., season) variables. We hypothesize that coat color will be more homogeneous in males than in females and that coat color will be darker in winter than in summer, the latter being orange. We measured the pelage color on five points over the dorsal surface of 26 A. budini museum specimens using a spectroradiometer and a diffuse illumination cabin. We used Principal Component Analysis to describe the association between the color variables, sex and season, and each of the observations. We then used general linear models of Analysis of Variance to examine relationships between color data, season, and sex. The results clearly confirm the hypothesis related to seasonal coat color change but do not directly confirm the hypothesis related to changes in coat color in relation to sex, and we show the complexity of the studied pattern. In conclusion, undoubtedly, the studied variables should accordingly be considered when studying the coloration of specimens for characterization, identification and discrimination of different taxonomic units based on color.

  14. The use and limits of ITS data in the analysis of intraspecific variation in Passiflora L. (Passifloraceae

    Directory of Open Access Journals (Sweden)

    Geraldo Mäder

    2010-01-01

    Full Text Available The discovery and characterization of informative intraspecific genetic markers is fundamental for evolutionary and conservation genetics studies. Here, we used nuclear ribosomal ITS sequences to access intraspecific genetic diversity in 23 species of the genus Passiflora L. Some degree of variation was detected in 21 of these. The Passiflora and Decaloba (DC. Rchb. subgenera showed significant differences in the sizes of the two ITS regions and in GC content, which can be related to reproductive characteristics of species in these subgenera. Furthermore, clear geographical patterns in the spatial distribution of sequence types were identified in six species. The results indicate that ITS may be a useful tool for the evaluation of intraspecific genetic variation in Passiflora.

  15. The use and limits of ITS data in the analysis of intraspecific variation in Passiflora L. (Passifloraceae).

    Science.gov (United States)

    Mäder, Geraldo; Zamberlan, Priscilla M; Fagundes, Nelson J R; Magnus, Tielli; Salzano, Francisco M; Bonatto, Sandro L; Freitas, Loreta B

    2010-01-01

    The discovery and characterization of informative intraspecific genetic markers is fundamental for evolutionary and conservation genetics studies. Here, we used nuclear ribosomal ITS sequences to access intraspecific genetic diversity in 23 species of the genus Passiflora L. Some degree of variation was detected in 21 of these. The Passiflora and Decaloba (DC.) Rchb. subgenera showed significant differences in the sizes of the two ITS regions and in GC content, which can be related to reproductive characteristics of species in these subgenera. Furthermore, clear geographical patterns in the spatial distribution of sequence types were identified in six species. The results indicate that ITS may be a useful tool for the evaluation of intraspecific genetic variation in Passiflora.

  16. Intraspecific variation in 137Cs activity concentration in sporocarps of Suillus variegatus in seven Swedish populations

    International Nuclear Information System (INIS)

    Dahlberg, Anders; Nikolova, Ivanka; Johanson, K.-J.

    1997-01-01

    Following the Chernobyl accident in 1986, sporocarps of Suillus variegatus in Sweden showed a large amount of individual variation in concentration of 137 Cs activity. Our aim was to determine the degrees to which this variability in sporocarp 137 Cs levels could be explained by differences between (i) local populations, (ii) fungal genets and (iii) locations within genets. Five populations in a 100-yr-old Scots pine forest, located within a 1 km 2 area, and two populations in Scots pine/Norway spruce forest, located 40 km north-west of Uppsala, were investigated. In total, 154 sporocarps were analysed to determine their 137 Cs content. Of these, the genetic affiliations of 86 were successfully characterized using somatic incompatibility reactions. Twenty-six genets were found which, on average, consisted of 6.5 sporocarps. The genets averaged 7.5 m in size, measured as the length between the most distant sporocarps. The mean sporocarp 137 Cs level was 67.1 ± 2.8 kBq kgsup(-1) D.W. (range between 13.6 and 182). According to analyses of variance, within-population variation accounted for 60% of the total variation in 137 Cs levels, while 40% was ascribed to variation among populations. Within a population, 137 Cs levels did not generally differ significantly between genets. Plausible reasons for intraspecific variation in radiocaesium content in sporocarps are discussed. (author)

  17. Intraspecific Variation in and Environment-Dependent Resource Allocation to Embryonic Development Time in Common Terns.

    Science.gov (United States)

    Vedder, Oscar; Kürten, Nathalie; Bouwhuis, Sandra

    Embryonic development time is thought to impact life histories through trade-offs against life-history traits later in life, yet the inference is based on interspecific comparative analyses only. It is largely unclear whether intraspecific variation in embryonic development time that is not caused by environmental differences occurs, which would be required to detect life-history trade-offs. Here we performed a classical common-garden experiment by incubating fresh eggs of free-living common terns (Sterna hirundo) in a controlled incubation environment at two different temperatures. Hatching success was high but was slightly lower at the lower temperature. While correcting for effects of year, incubation temperature, and laying order, we found significant variation in the incubation time embryos required until hatching and in their heart rate. Embryonic heart rate was significantly positively correlated within clutches, and a similar tendency was found for incubation time, suggesting that intrinsic differences in embryonic development rate between offspring of different parents exist. Incubation time and embryonic heart rate were strongly correlated: embryos with faster heart rates required shorter incubation time. However, after correction for heart rate, embryos still required more time for development at the lower incubation temperature. This suggests that processes other than development require a greater share of resources in a suboptimal environment and that relative resource allocation to development is, therefore, environment dependent. We conclude that there is opportunity to detect intraspecific life-history trade-offs with embryonic development time and that the resolution of trade-offs may differ between embryonic environments.

  18. Intraspecific variation in the diet of the Mexican garter snake Thamnophis eques

    Directory of Open Access Journals (Sweden)

    Javier Manjarrez

    2017-11-01

    Full Text Available The Mexican Garter Snake (Thamnophis eques is a terrestrial-aquatic generalist that feeds on both aquatic and terrestrial prey. We describe size-related variation and sexual variation in the diet of T. eques through analysis of 262 samples of identifiable stomach contents in snakes from 23 locations on the Mexican Plateau. The snake T. eques we studied consumed mostly fish, followed in lesser amounts by leeches, earthworms, frogs, and tadpoles. Correspondence analysis suggested that the frequency of consumption of various prey items differed between the categories of age but not between sex of snakes, and the general pattern was a reduction of prey item diversity with size of snake. Snake length was correlated positively with mass of ingested prey. Large snakes consumed large prey and continued to consume smaller prey. In general, no differences were found between the prey taxa of male and female snakes, although males ate two times more tadpoles than females. Males and females did not differ in the mass of leeches, earthworms, fishes, frogs and tadpoles that they ate, and males and females that ate each prey taxon were similar in length. We discuss proximate and functional determinants of diet and suggest that the observed intraspecific variation in T. eques could be explored by temporal variation in prey availability, proportions of snake size classes and possible sexual dimorphism in head traits and prey dimensions to assess the role of intersexual resource competition.

  19. Biomechanical implications of intraspecific shape variation in chimpanzee crania: moving towards an integration of geometric morphometrics and finite element analysis

    Science.gov (United States)

    Smith, Amanda L.; Benazzi, Stefano; Ledogar, Justin A.; Tamvada, Kelli; Smith, Leslie C. Pryor; Weber, Gerhard W.; Spencer, Mark A.; Dechow, Paul C.; Grosse, Ian R.; Ross, Callum F.; Richmond, Brian G.; Wright, Barth W.; Wang, Qian; Byron, Craig; Slice, Dennis E.; Strait, David S.

    2014-01-01

    In a broad range of evolutionary studies, an understanding of intraspecific variation is needed in order to contextualize and interpret the meaning of variation between species. However, mechanical analyses of primate crania using experimental or modeling methods typically encounter logistical constraints that force them to rely on data gathered from only one or a few individuals. This results in a lack of knowledge concerning the mechanical significance of intraspecific shape variation that limits our ability to infer the significance of interspecific differences. This study uses geometric morphometric methods (GM) and finite element analysis (FEA) to examine the biomechanical implications of shape variation in chimpanzee crania, thereby providing a comparative context in which to interpret shape-related mechanical variation between hominin species. Six finite element models (FEMs) of chimpanzee crania were constructed from CT scans following shape-space Principal Component Analysis (PCA) of a matrix of 709 Procrustes coordinates (digitized onto 21 specimens) to identify the individuals at the extremes of the first three principal components. The FEMs were assigned the material properties of bone and were loaded and constrained to simulate maximal bites on the P3 and M2. Resulting strains indicate that intraspecific cranial variation in morphology is associated with quantitatively high levels of variation in strain magnitudes, but qualitatively little variation in the distribution of strain concentrations. Thus, interspecific comparisons should include considerations of the spatial patterning of strains rather than focus only their magnitude. PMID:25529239

  20. Variation in Streptococcus pneumoniae susceptibility to human antimicrobial peptides may mediate intraspecific competition.

    Science.gov (United States)

    Habets, Michelle G J L; Rozen, Daniel E; Brockhurst, Michael A

    2012-09-22

    Streptococcus pneumoniae is a facultative pathogen inhabiting the nasopharynx of humans where it is exposed to a range of antimicrobial peptides (AMPs) of the innate immune response. It is possible therefore that the susceptibility of strains to AMPs plays a role in determining their ability to colonize, and furthermore, that AMPs could mediate competitive interactions between co-colonizing genotypes. However, little is known about patterns of natural variation in AMP susceptibility of S. pneumoniae, and it is unclear whether the susceptibilities of an isolate to multiple human AMPs are correlated. We tested this by characterizing the susceptibility of 31 S. pneumoniae natural isolates to human neutrophil peptide (HNP-1) (α-defensin) and LL-37 (cathelicidin). We observed significant variation in susceptibility between isolates to both AMPs, and in the majority of isolates, susceptibilities to HNP-1 and LL-37 were uncorrelated. Clinical isolates were more susceptible to AMPs than were carriage isolates. The polysaccharide capsule of S. pneumoniae is thought to protect cells against AMPs. However, serotype alone could not explain the observed variation in susceptibility suggesting that genetic background plays an equally important role. We tested directly whether AMPs could mediate competition between isolates using competition experiments in the presence and absence of AMPs. These experiments demonstrated that AMPs could indeed reverse the outcome of competition between selected isolates. AMP-mediated competition could therefore contribute to the maintenance of intraspecific genetic diversity in S. pneumoniae.

  1. Large intraspecific genetic variation within the Saffron-Crocus group (Crocus L., Series Crocus; Iridaceae)

    DEFF Research Database (Denmark)

    Larsen, Bjarne; Orabi, Jihad; Pedersen, Carsten

    2015-01-01

    generally were grouped with C. sativus samples. Pollination and maintenance of genetic variation are discussed. The large intraspecific variation found within the three specifically studied species reflects dynamic population structures with potential to meet future ecological fluctuations. It emphasises...

  2. Intraspecific variation in erythrocyte sizes among populations of Hypsiboas cordobas (Anura: Hylidae

    Directory of Open Access Journals (Sweden)

    Mariana Baraquet

    2013-12-01

    Full Text Available We studied the morphology and size of erythrocytes of H. cordobae, and analysed the geographic variation of this character along the distribution of the species, in relation to the latitudinal and altitudinal distances. Erythrocyte shape of the H. cordobae is ellipsoidal and the nuclei are also ellipsoidal and centrally oriented. Erythrocyte and nuclear size showed significant differences among populations, with the highest mean size corresponding to the population of Achiras (low altitude site and the lowest mean size to Los Linderos (high altitude site. There was no significant relationship between the latitude of each population and the both erythrocyte and nuclear size. The altitudinal variation in erythrocyte cell size may be attributable to the surface available for gas exchange; a small erythrocyte offers a possibility of greater rate of exchange than a larger one. Our results are consistent with studies of other amphibians, where intraspecific comparisons of populations at different altitudes show that individuals at higher altitudes are characterized by smaller erythrocytes.

  3. Intraspecific variation in thermal acclimation of photosynthesis across a range of temperatures in a perennial crop.

    Science.gov (United States)

    Zaka, Serge; Frak, Ela; Julier, Bernadette; Gastal, François; Louarn, Gaëtan

    2016-01-01

    Interest in the thermal acclimation of photosynthesis has been stimulated by the increasing relevance of climate change. However, little is known about intra-specific variations in thermal acclimation and its potential for breeding. In this article, we examined the difference in thermal acclimation between alfalfa (Medicago sativa) cultivars originating from contrasting origins, and sought to analyze the mechanisms in play. A series of experiments was carried out at seven growth temperatures between 5 and 35 °C using four cultivars from temperate and Mediterranean origin. Leaf traits, the photosynthetic rate at 25 °C (A400 (25)), the photosynthetic rate at optimal temperature (A400 (opt)), the thermal optimum of photosynthesis (Topt), and the photosynthetic parameters from the Farqhuar model were determined. Irrespective of cultivar origin, a clear shift in the temperature responses of photosynthesis was observed as a function of growth temperature, affecting thermal optimum of photosynthesis, photosynthetic rate at optimal temperature and photosynthetic rate at 25 °C. For both cultivars, Topt values increased linearly in leaves grown between 5 and 35 °C. Relative homeostasis of A400 (25) and A400 (opt) was found between 10 °C and 30 °C growth temperatures, but sharp declines were recorded at 5 and 35 °C. This homeostasis was achieved in part through modifications to leaf nitrogen content, which increased at extreme temperatures. Significant changes were also recorded regarding nitrogen partitioning in the photosynthetic apparatus and in the temperature dependence of photosynthetic parameters. The cultivars differed only in terms of the temperature response of photosynthetic parameters, with Mediterranean genotypes displaying a greater sensitivity of the maximum rate of Rubisco carboxylation to elevated temperatures. It was concluded that intra-specific variations in the temperature acclimation of photosynthesis exist among alfalfa cultivars

  4. Intraspecific variation in feeding strategies of Galapagos sea lions: A case of trophic specialization

    Science.gov (United States)

    Villegas-Amtmann, Stella; Costa, Daniel

    2017-01-01

    The trophic behavior of marine predators varies according to the level of competition to which they are exposed. In general, populations that inhabit lower productivity systems face a strong intraspecific competition, which contributes to the development of different foraging strategies to maximize nutritional efficiency. Given the high trophic flexibility of Zalophus wollebaeki, this species is considered appropriate for the analysis of such behavior. Furthermore, this trophic flexibility has allowed them to persist in a seemingly marginal ecosystem. In this study, we used a comparative analysis of variables (diet and dive behavior) related to Z. wollebaeki trophic niche plasticity to better understand their foraging ecology, using techniques such scat analysis, satellite telemetry and complementarily an isotopic analysis. Scat analysis revealed intra-population variation in their diet, represented by prey from different environments (epipelagic and benthic). These results are supported by the animals’ locations at sea and diving profiles. Global Positioning System (GPS) and time-depth recorder (TDR) records showed the existence of two groups, with differing feeding areas and diving behavior. Also the δ15N values showed differences in the trophic level at which the species fed. These results constitute a relevant finding in the evolutionary behavior of the species, showing that Z. wollebaeki has developed a high degree of foraging flexibility, thus increasing its survival rate in an ecosystem that is highly demanding in terms of resource availability. PMID:29059188

  5. Intraspecific variation in feeding strategies of Galapagos sea lions: A case of trophic specialization.

    Directory of Open Access Journals (Sweden)

    Diego Páez-Rosas

    Full Text Available The trophic behavior of marine predators varies according to the level of competition to which they are exposed. In general, populations that inhabit lower productivity systems face a strong intraspecific competition, which contributes to the development of different foraging strategies to maximize nutritional efficiency. Given the high trophic flexibility of Zalophus wollebaeki, this species is considered appropriate for the analysis of such behavior. Furthermore, this trophic flexibility has allowed them to persist in a seemingly marginal ecosystem. In this study, we used a comparative analysis of variables (diet and dive behavior related to Z. wollebaeki trophic niche plasticity to better understand their foraging ecology, using techniques such scat analysis, satellite telemetry and complementarily an isotopic analysis. Scat analysis revealed intra-population variation in their diet, represented by prey from different environments (epipelagic and benthic. These results are supported by the animals' locations at sea and diving profiles. Global Positioning System (GPS and time-depth recorder (TDR records showed the existence of two groups, with differing feeding areas and diving behavior. Also the δ15N values showed differences in the trophic level at which the species fed. These results constitute a relevant finding in the evolutionary behavior of the species, showing that Z. wollebaeki has developed a high degree of foraging flexibility, thus increasing its survival rate in an ecosystem that is highly demanding in terms of resource availability.

  6. Intraspecific variation in feeding strategies of Galapagos sea lions: A case of trophic specialization.

    Science.gov (United States)

    Páez-Rosas, Diego; Villegas-Amtmann, Stella; Costa, Daniel

    2017-01-01

    The trophic behavior of marine predators varies according to the level of competition to which they are exposed. In general, populations that inhabit lower productivity systems face a strong intraspecific competition, which contributes to the development of different foraging strategies to maximize nutritional efficiency. Given the high trophic flexibility of Zalophus wollebaeki, this species is considered appropriate for the analysis of such behavior. Furthermore, this trophic flexibility has allowed them to persist in a seemingly marginal ecosystem. In this study, we used a comparative analysis of variables (diet and dive behavior) related to Z. wollebaeki trophic niche plasticity to better understand their foraging ecology, using techniques such scat analysis, satellite telemetry and complementarily an isotopic analysis. Scat analysis revealed intra-population variation in their diet, represented by prey from different environments (epipelagic and benthic). These results are supported by the animals' locations at sea and diving profiles. Global Positioning System (GPS) and time-depth recorder (TDR) records showed the existence of two groups, with differing feeding areas and diving behavior. Also the δ15N values showed differences in the trophic level at which the species fed. These results constitute a relevant finding in the evolutionary behavior of the species, showing that Z. wollebaeki has developed a high degree of foraging flexibility, thus increasing its survival rate in an ecosystem that is highly demanding in terms of resource availability.

  7. Plant movements and climate warming: intraspecific variation in growth responses to nonlocal soils

    Czech Academy of Sciences Publication Activity Database

    De Frenne, P.; Coomes, D. A.; De Schrijver, A.; Staelens, J.; Alexander, J. M.; Bernhardt-Römermann, M.; Brunet, J.; Chabrerie, O.; Chiarucci, A.; den Ouden, J.; Eckstein, R. L.; Graae, B. J.; Gruwez, R.; Hédl, Radim; Hermy, M.; Kolb, A.; Marell, A.; Mullender, S. M.; Olsen, S. L.; Orczewska, A.; Peterken, G.; Petřík, Petr; Plue, J.; Simonson, W. D.; Tomescu, C. V.; Vangansbeke, P.; Verstraeten, G.; Vesterdal, L.; Wulf, M.; Verheyen, K.

    2014-01-01

    Roč. 202, č. 2 (2014), s. 431-441 ISSN 0028-646X Institutional support: RVO:67985939 Keywords : climate change * intraspecific variability * soil chemism Subject RIV: EF - Botanics Impact factor: 7.672, year: 2014

  8. Long-term evolution of polygenic traits under frequency-dependent intraspecific competition.

    Science.gov (United States)

    Schneider, Kristan A

    2007-05-01

    We analytically investigate the long-term evolution of a continuously varying quantitative character in a diploid population that is determined additively by a finite number of loci. The trait is under a mixture of frequency-dependent disruptive selection induced by intraspecific competition and frequency-independent stabilizing selection. Moreover, the trait is restricted to a finite range by constraints on the particular loci. Our investigations are based on explicit analytical results (provided by Bürger [2005. A multilocus analysis of intraspecific competition and stabilizing selection on a quantitative trait. J. Math. Biol. 50, 355-396]; Schneider [2006. A multilocus-multiallele analysis of frequency-dependent selection induced by intraspecific competition. J. Math. Biol. 52, 483-523]) on the short-term dynamics under the assumption of linkage equilibrium. We show that the population always reaches a long-term equilibrium (LTE), i.e., an equilibrium that is resistant against perturbations of mutations of sufficiently small effect. In general, several LTEs can coexist. They can be calculated explicitly, and we provide necessary and sufficient conditions for their existence. In the case that more than one LTE exists, we exemplify numerically that the evolutionary outcome depends crucially on the initial genetic architecture, on the joint distribution of mutational effects across loci, and on the particular realization of the mutation process. Therefore, long-term evolution cannot be predicted from the ecology alone. We further show that a partial order exists for the LTEs. The set of LTEs has a 'largest' element, an LTE which is reached during long-term evolution if the effects of the occurring mutant alleles are sufficiently large.

  9. Evolution of dominance under frequency-dependent intraspecific competition in an assortatively mating population.

    Science.gov (United States)

    Peischl, Stephan; Schneider, Kristan A

    2010-02-01

    We study the evolution of higher levels of dominance as a response to negative frequency-dependent selection. In contrast to previous studies, we focus on the effect of assortative mating on the evolution of dominance under frequency-dependent intraspecific competition. We analyze a two-locus two-allele model, in which the primary locus has a major effect on a quantitative trait that is under a mixture of frequency-independent stabilizing selection, density-dependent selection, and frequency-dependent selection caused by intraspecific competition for a continuum of resources. The second (modifier) locus determines the degree of dominance at the trait level. Additionally, the population mates assortatively with respect to similarities in the ecological trait. Our analysis shows that the parameter region in which dominance can be established decreases if small levels of assortment are introduced. In addition, the degree of dominance that can be established also decreases. In contrast, if assortment is intermediate, sexual selection for extreme types can be established, which leads to evolution of higher levels of dominance than under random mating. For modifiers with large effects, intermediate levels of assortative mating are most favorable for the evolution of dominance. For large modifiers, the speed of fixation can even be higher for intermediate levels of assortative mating than for random mating.

  10. Intraspecific variation in cellular and biochemical heat response strategies of Mediterranean Xeropicta derbentina [Pulmonata, Hygromiidae].

    Science.gov (United States)

    Troschinski, Sandra; Di Lellis, Maddalena A; Sereda, Sergej; Hauffe, Torsten; Wilke, Thomas; Triebskorn, Rita; Köhler, Heinz-R

    2014-01-01

    Dry and hot environments challenge the survival of terrestrial snails. To minimize overheating and desiccation, physiological and biochemical adaptations are of high importance for these animals. In the present study, seven populations of the Mediterranean land snail species Xeropicta derbentina were sampled from their natural habitat in order to investigate the intraspecific variation of cellular and biochemical mechanisms, which are assigned to contribute to heat resistance. Furthermore, we tested whether genetic parameters are correlated with these physiological heat stress response patterns. Specimens of each population were individually exposed to elevated temperatures (25 to 52°C) for 8 h in the laboratory. After exposure, the health condition of the snails' hepatopancreas was examined by means of qualitative description and semi-quantitative assessment of histopathological effects. In addition, the heat-shock protein 70 level (Hsp70) was determined. Generally, calcium cells of the hepatopancreas were more heat resistant than digestive cells - this phenomenon was associated with elevated Hsp70 levels at 40°C.We observed considerable variation in the snails' heat response strategy: Individuals from three populations invested much energy in producing a highly elevated Hsp70 level, whereas three other populations invested energy in moderate stress protein levels - both strategies were in association with cellular functionality. Furthermore, one population kept cellular condition stable despite a low Hsp70 level until 40°C exposure, whereas prominent cellular reactions were observed above this thermal limit. Genetic diversity (mitochondrial cytochrome c oxidase subunit I gene) within populations was low. Nevertheless, when using genetic indices as explanatory variables in a multivariate regression tree (MRT) analysis, population structure explained mean differences in cellular and biochemical heat stress responses, especially in the group exposed to 40°C. Our

  11. Intraspecific variation in cellular and biochemical heat response strategies of Mediterranean Xeropicta derbentina [Pulmonata, Hygromiidae].

    Directory of Open Access Journals (Sweden)

    Sandra Troschinski

    Full Text Available Dry and hot environments challenge the survival of terrestrial snails. To minimize overheating and desiccation, physiological and biochemical adaptations are of high importance for these animals. In the present study, seven populations of the Mediterranean land snail species Xeropicta derbentina were sampled from their natural habitat in order to investigate the intraspecific variation of cellular and biochemical mechanisms, which are assigned to contribute to heat resistance. Furthermore, we tested whether genetic parameters are correlated with these physiological heat stress response patterns. Specimens of each population were individually exposed to elevated temperatures (25 to 52°C for 8 h in the laboratory. After exposure, the health condition of the snails' hepatopancreas was examined by means of qualitative description and semi-quantitative assessment of histopathological effects. In addition, the heat-shock protein 70 level (Hsp70 was determined. Generally, calcium cells of the hepatopancreas were more heat resistant than digestive cells - this phenomenon was associated with elevated Hsp70 levels at 40°C.We observed considerable variation in the snails' heat response strategy: Individuals from three populations invested much energy in producing a highly elevated Hsp70 level, whereas three other populations invested energy in moderate stress protein levels - both strategies were in association with cellular functionality. Furthermore, one population kept cellular condition stable despite a low Hsp70 level until 40°C exposure, whereas prominent cellular reactions were observed above this thermal limit. Genetic diversity (mitochondrial cytochrome c oxidase subunit I gene within populations was low. Nevertheless, when using genetic indices as explanatory variables in a multivariate regression tree (MRT analysis, population structure explained mean differences in cellular and biochemical heat stress responses, especially in the group

  12. Does intraspecific behavioural variation of pollinator species influence pollination? A quantitative study with hummingbirds and a Neotropical shrub.

    Science.gov (United States)

    Maruyama, P K; Justino, D G; Oliveira, P E

    2016-11-01

    Floral visitors differ in their efficacy as pollinators, and the impact of different pollinator species on pollen flow and plant reproduction has been frequently evaluated. In contrast, the impact of intraspecific behavioural changes on their efficacy as pollinators has seldom been quantified. We studied a self-incompatible shrub Palicourea rigida (Rubiaceae) and its hummingbird pollinators, which adjust their behaviour according to floral resource availability. Fluorescence microscopy was used to access pollen tube growth and incompatibility reaction in pistils after a single visit of territorial or intruder hummingbirds in two populations. To characterise the plant populations and possible differences in resource availability between areas we used a three-term quadrat variance method to detect clusters of floral resources. Within-species variation in foraging behaviour, but not species identity, affected pollinator efficacy. Effectively, hummingbirds intruding into territories deposited more compatible pollen grains on P. rigida stigmas than territory holders in both study areas. Additionally, territory holders deposited more incompatible than compatible pollen grains. Our results imply that intraspecific foraging behaviour variation has consequences for pollination success. Quantifying such variation and addressing the implications of intraspecific variability contribute to a better understanding of the dynamics and consequences of plant-pollinator interactions. © 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.

  13. Extinction risks forced by climatic change and intraspecific variation in the thermal physiology of a tropical lizard.

    Science.gov (United States)

    Pontes-da-Silva, Emerson; Magnusson, William E; Sinervo, Barry; Caetano, Gabriel H; Miles, Donald B; Colli, Guarino R; Diele-Viegas, Luisa M; Fenker, Jessica; Santos, Juan C; Werneck, Fernanda P

    2018-04-01

    Temperature increases can impact biodiversity and predicting their effects is one of the main challenges facing global climate-change research. Ectotherms are sensitive to temperature change and, although predictions indicate that tropical species are highly vulnerable to global warming, they remain one of the least studied groups with respect to the extent of physiological variation and local extinction risks. We model the extinction risks for a tropical heliothermic teiid lizard (Kentropyx calcarata) integrating previously obtained information on intraspecific phylogeographic structure, eco-physiological traits and contemporary species distributions in the Amazon rainforest and its ecotone to the Cerrado savannah. We also investigated how thermal-biology traits vary throughout the species' geographic range and the consequences of such variation for lineage vulnerability. We show substantial variation in thermal tolerance of individuals among thermally distinct sites. Thermal critical limits were highly correlated with operative environmental temperatures. Our physiological/climatic model predicted relative extinction risks for local populations within clades of K. calcarata for 2050 ranging between 26.1% and 70.8%, while for 2070, extinction risks ranged from 52.8% to 92.8%. Our results support the hypothesis that tropical-lizard taxa are at high risk of local extinction caused by increasing temperatures. However, the thermo-physiological differences found across the species' distribution suggest that local adaptation may allow persistence of this tropical ectotherm in global warming scenarios. These results will serve as basis to further research to investigate the strength of local adaptation to climate change. Persistence of Kentropyx calcarata also depends on forest preservation, but the Amazon rainforest is currently under high deforestation rates. We argue that higher conservation priority is necessary so the Amazon rainforest can fulfill its capacity to

  14. Redescription of Atractus albuquerquei (Serpentes: Colubridae: Dipsadinae, with comments on geographical distribution and intraspecific variation

    Directory of Open Access Journals (Sweden)

    Hussam Zaher

    2005-01-01

    Full Text Available Atractus albuquerquei Cunha and Nascimento, 1983 was previously known from a holotype from eastern Pará, and 15 specimens from Rondônia and Acre, all in Brazil. We report on 23 additional specimens from the Brazilian states of Rondônia, Goiás, Mato Grosso, and Mato Grosso do Sul. These specimens extend the known range of A. albuquerquei substantially, and beyond the southern limits of the Amazon basin. The holotype of A. albuquerquei is redescribed and intraspecific variation in external morphology, hemipenes, and colour is documented. Sexual dimorphism exists in total length, and number of ventral (significantly greater in females and subcaudal scales (greater in males. There is a significant correlation between number of subcaudal scales and longitude (decreasing from East to West for both males and females.Atractus albuquerquei Cunha & Nascimento, 1983 era conhecida apenas do holótipo procedente do leste do estado do Pará e de 15 espécimes dos estados de Rondônia e Acre, no Brasil. Registramos aqui 23 espécimes adicionais provenientes dos estados de Rondônia, Goiás, Mato Grosso e Mato Grosso do Sul. Estes exemplares ampliam a área de distribuição conhecida de A. albuquerquei, para além do limite sul da bacia amazônica. O holótipo de A. albuquerquei é redescrito e a variação intraespecífica da morfologia externa, dos hemipenis e da coloração dos exemplares estudados é analizada. Foi detectado dimorfismo sexual no comprimento total do corpo bem como no número de ventrais (maior nas fêmeas e de subcaudais (maior nos machos. Foi notada uma correlação significativa entre o número de escamas subcaudais e a longitude (que diminuem de leste para oeste em ambos os sexos.

  15. Inter- and intra-specific competition of duckweed under multiple heavy metal contaminated water.

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    Zhao, Zhao; Shi, Huijuan; Kang, Xianjiang; Liu, Cunqi; Chen, Lingci; Liang, Xiaofei; Jin, Lei

    2017-11-01

    The influences of intra- and inter-species competition on ecosystems are poorly understood. Lemna aequinoctialis and Spirodela polyrhiza were used to assess the effects of exposure to different concentrations of multiple heavy metals (copper-cadmium-zinc), when the plants were grown in mixed- or mono-culture. Parameters assessed included relative growth rate (RGR), content of chlorophyll, glutathione (GSH), malondialdehyde (MDA), as well as the activity of catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD). Inter-specific competition was affected by metal concentration, with results indicating that inter-specific competition significantly affected duckweed growth and metal uptake in different heavy metal exposure conditions. Inter-specific competition increased growth rate of duckweed under high metal concentrations, although when compared with intra-specific competition, it caused no obvious differences under low metal concentrations. The growth of L. aequinoctialis was further increased in mixed culture when exposed to high metal concentrations, with inter-specific competition increasing the content of cadmium and zinc, while decreasing copper content of L. aequinoctialis compared with under intra-specific conditions. Conversely, inter-specific competition increased the content of copper and cadmium of S. polyrhiza, without causing obvious differences in zinc accumulation under high ambient concentrations. Under high metal conditions, inter-specific competition increased antioxidant enzyme activities in duckweed species, increasing resistance to heavy metals. Results show that inter-specific competition makes duckweed develop mechanisms to increase fitness and survival, such as enhancement of antioxidant enzyme activities, rather than limiting metal uptake when exposed to high concentrations of multiple metals. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Intra-specific variation in social organization of gorillas: implications for their social evolution.

    Science.gov (United States)

    Yamagiwa, Juichi; Kahekwa, John; Basabose, Augustin Kanyunyi

    2003-10-01

    We analysed intra-specific variation in the social organization of gorillas and ecological and social factors influencing them, based on recent data on diet, day journey length, home range size, group size and proportion of multi-male groups in three subspecies [western lowland gorillas (WLG); eastern lowland gorillas (ELG); mountain gorillas (MG)]. Median group size was similar across subspecies and across habitats, but the extraordinarily large group including >30 gorillas was only found in habitat with dense terrestrial herbaceous vegetation. Within-group competition may determine the upper limit of group size in frugivorous WLGs and ELGs in lowland habitats with scarce undergrowth. A frugivorous diet may be a causal factor of subgrouping in multi-male groups of WLGs and ELGs, while a folivorous diet may prevent subgrouping in multi-male groups of MGs. Social factors, rather than ecological factors, may play an important role in the formation of multi-male groups and their cohesiveness in MGs. High gregariousness of female gorillas and their prolonged association with a protector male are explained by their vulnerability to both infanticide (MGs) and predators (ELGs). Comparison of long-term changes in group composition and individual movements between ELGs in Kahuzi and MGs in the Virungas suggest that the occurrence of infanticide may promote kin-male association within a group. Threat of infanticide may stimulate MG females to transfer into multi-male groups to seek reliable protection and maturing MG males to stay in their natal groups after maturity. By contrast, the absence of infanticide may facilitate ELG females to associate with infants and other females at transfer and ELG males to establish large groups in a short period by taking females from their natal groups, by luring females from neighbouring groups, or by takeover of a widow group after the death of its leading male. These conditions may prevent ELG and WLG maturing males from remaining to

  17. Intraspecific non-sexual interactions of Grammostola schulzei (Araneae: Theraphosidae under laboratory conditions

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    Nelson E Ferretti

    2011-09-01

    Full Text Available Intraspecific interactions of araneomorph spiders have received considerable attention, but there are few detailed studies on intraspecific interactions of mygalomorph spiders. Moreover, a thorough understanding of theraphosid biology and ecology is necessary from a conservation standpoint because natural populations may be threatened by habitat disturbances and captures for pet commerce. We described the behavior of conspecific individuals of Grammostola schulzei during non-sexual interactions, under laboratory conditions. Pairs of individuals involving adult males, adult females and juveniles were confronted and observed in resident and intruder conditions, totalizing 115 trials. When confronted two adult females, they retreated or grappled, and performed gaping display with bite attempts, usually resulted in severe injury of the intruder spiders. When confronted females with large juveniles, we frequently observed cannibalism on juveniles. Juveniles exposed to females or to other juveniles retreated or made leg tapping with forelegs and palpal drumming, which are common displays of courting adult males. Adult males courted and clasped some juveniles, but juveniles avoided or reject clasping. The behaviors observed during intraspecific interactions could play an important role determining spatial distribution and could lead to behavioral adaptations of territoriality. Rev. Biol. Trop. 59 (3: 1173-1182. Epub 2011 September 01.Hay pocos estudios detallados sobre las interacciones intraespecíficas de arañas migalomorfas. Por lo tanto, se describe el comportamiento de individuos conspecíficos de Grammostola schulzei durante interacciones nosexuales en condiciones de laboratorio. Se confrontaron y observaron pares de individuos involucrando machos adultos, hembras adultas y juveniles en condiciones de locatarios y visitantes, totalizando 115 encuentros. Cuando dos hembras adultas se enfrentaron, retrocedieron o lucharon adoptando elevaciones

  18. Intraspecific variation in aerobic metabolic rate of fish: relations with organ size and enzyme activity in brown trout.

    Science.gov (United States)

    Norin, Tommy; Malte, Hans

    2012-01-01

    Highly active animals require a high aerobic capacity (i.e., a high maximum metabolic rate [MMR]) to sustain such activity, and it has been speculated that a greater capacity for aerobic performance is reflected in larger organs, which serve as energy processors but are also expensive to maintain and which increase the minimal cost of living (i.e., the basal or standard metabolic rate [SMR]). In this study, we assessed the extent of intraspecific variation in metabolic rate within a group of brown trout (Salmo trutta L.) and tested whether the observed variation in residual (body-mass-corrected) SMR, MMR, and absolute aerobic scope could be explained by variations in the residual size (mass) of metabolically active internal organs. Residual SMR was found to correlate positively with residual MMR, indicating a link between these two metabolic parameters, but no relationship between organ mass and metabolic rate was found for liver, heart, spleen, intestine, or stomach. Instead, activity in the liver of two aerobic mitochondrial enzymes, cytochrome c oxidase and, to a lesser extent, citrate synthase, was found to correlate with whole-animal metabolic rate, indicating that causes for intraspecific variation in the metabolic rate of fish can be found at a lower organizational level than organ size.

  19. Demographic History and Reproductive Output Correlates with Intraspecific Genetic Variation in Seven Species of Indo-Pacific Mangrove Crabs.

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    Sara Fratini

    Full Text Available The spatial distribution and the amount of intraspecific genetic variation of marine organisms are strongly influenced by many biotic and abiotic factors. Comparing biological and genetic data characterizing species living in the same habitat can help to elucidate the processes driving these variation patterns. Here, we present a comparative multispecies population genetic study on seven mangrove crabs co-occurring in the West Indian Ocean characterized by planktotrophic larvae with similar pelagic larval duration. Our main aim was to investigate whether a suite of biological, behavioural and ecological traits could affect genetic diversities of the study species in combination with historical demographic parameters. As possible current explanatory factors, we used the intertidal micro-habitat colonised by adult populations, various parameters of individual and population fecundity, and the timing of larval release. As the genetic marker, we used partial sequences of cytochrome oxidase subunit I gene. Genetic and ecological data were collected by the authors and/or gathered from primary literature. Permutational multiple regression models and ANOVA tests showed that species density and their reproductive output in combination with historical demographic parameters could explain the intraspecific genetic variation indexes across the seven species. In particular, species producing consistently less eggs per spawning event showed higher values of haplotype diversity. Moreover, Tajima's D parameters well explained the recorded values for haplotype diversity and average γst. We concluded that current intraspecific gene diversities in crabs inhabiting mangrove forests were affected by population fecundity as well as past demographic history. The results were also discussed in terms of management and conservation of fauna in the Western Indian Ocean mangroves.

  20. The genetic architecture of ecological adaptation: intraspecific variation in host plant use by the lepidopteran crop pest Chloridea virescens.

    Science.gov (United States)

    Oppenheim, Sara J; Gould, Fred; Hopper, Keith R

    2018-03-01

    Intraspecific variation in ecologically important traits is a cornerstone of Darwin's theory of evolution by natural selection. The evolution and maintenance of this variation depends on genetic architecture, which in turn determines responses to natural selection. Some models suggest that traits with complex architectures are less likely to respond to selection than those with simple architectures, yet rapid divergence has been observed in such traits. The simultaneous evolutionary lability and genetic complexity of host plant use in the Lepidopteran subfamily Heliothinae suggest that architecture may not constrain ecological adaptation in this group. Here we investigate the response of Chloridea virescens, a generalist that feeds on diverse plant species, to selection for performance on a novel host, Physalis angulata (Solanaceae). P. angulata is the preferred host of Chloridea subflexa, a narrow specialist on the genus Physalis. In previous experiments, we found that the performance of C. subflexa on P. angulata depends on many loci of small effect distributed throughout the genome, but whether the same architecture would be involved in the generalist's adoption of P. angulata was unknown. Here we report a rapid response to selection in C. virescens for performance on P. angulata, and establish that the genetic architecture of intraspecific variation is quite similar to that of the interspecific differences in terms of the number, distribution, and effect sizes of the QTL involved. We discuss the impact of genetic architecture on the ability of Heliothine moths to respond to varying ecological selection pressures.

  1. On the intraspecific variation in morphometry and shape of sagittal otoliths of common sardine, Strangomera bentincki, off central-southern Chile

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    Sandra Curin-Osorio

    2012-11-01

    Full Text Available Size and shape of fish otoliths are species-specific, but some species also display intraspecific variations. The common sardine, Strangomera bentincki, is a small pelagic fish inhabiting a seasonal upwelling ecosystem off central-southern Chile, having two discrete spawning sites along its latitudinal distribution. Otoliths of specimens were collected from commercial catches in Talcahuano and Corral, representing the central and south spawning zones. On the basis of otolith images, size-based shape descriptors were used to detect ontogenetic variation, and morphometric variables (length, breadth, area, perimeter and weight were used to detect geographical differences in size and shape of otoliths. Outline analysis was studied on the basis of elliptic Fourier descriptors through multivariate statistical procedures. Size-based shape descriptors showed that otolith shape starts to be stable for fish larger than 12 cm total length, which keep an elliptical form. Morphometric variables for fish larger than 12 cm revealed intraspecific variation between central and south zones, which were associated with otolith weight and breadth. Outline analysis did not reveal significant spatial differences, but extreme intraspecific variation was due to the antirostrum, excisure, and posterior part of otoliths. Intraspecific variation in otolith size could be linked to differences in each spawning habitat and related to geographical origin, whose differences are not clearly identified. It is concluded that intraspecific variability in morphometric variables of sardine otoliths revealed geographic differences in size that are not attributable to allometric effects, and that otolith shape was similar between specimens from different geographic origin.

  2. Intraspecific variation among clones of a naïve rare grass affects competition with a nonnative, invasive forb.

    Science.gov (United States)

    Gibson, David J; Dewey, Justin; Goossens, Hélène; Dodd, Misty M

    2014-01-01

    Intraspecific variation can have a major impact on plant community composition yet there is little information available on the extent that such variation by an already established species affects interspecific interactions of an invading species. The current research examined the competitiveness of clones of a globally rare but locally common native grass, Calamagrostis porteri ssp. insperata to invasion by Alliaria petiolata, a non-native invasive species. A greenhouse experiment was conducted twice over consecutive years in which 15 clones from three populations of Calamagrostis were paired with rosettes of Alliaria in pots containing native forest soil previously uninvaded by Alliaria. Both species showed a negative response to the presence of the other species, although Alliaria more so than Calamagrostis. Moreover, the effect of Calamagrostis depended upon population, and, to a lesser extent, the individual clone paired with Alliaria. Competitive effects were stronger in the first experiment compared with when the experiment was repeated in the second year. The influence of Calamagrostis clones on the outcome of the experiment varied among populations and among clones, but also between years. Clones from one of the three populations were more influential than clones from the other two populations. Only one of 15 clones, both from the same population, was influential in both experiments. This research supports a growing literature indicating that intraspecific variability among clones of a dominant species can affect interspecific interactions and that such variability in a native species can affect performance of an invading species.

  3. Inter-and intraspecific variation in fern mating systems after long-distance colonization: the importance of selfing

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    de Groot G Arjen

    2012-01-01

    Full Text Available Abstract Background Previous studies on the reproductive biology of ferns showed that mating strategies vary among species, and that polyploid species often show higher capacity for self-fertilization than diploid species. However, the amount of intraspecific variation in mating strategy and selfing capacity has only been assessed for a few species. Yet, such variation may have important consequences during colonization, as the establishment of any selfing genotypes may be favoured after long-distance dispersal (an idea known as Baker's law. Results We examined intra-and interspecific variation in potential for self-fertilization among four rare fern species, of which two were diploids and two were tetraploids: Asplenium scolopendrium (2n, Asplenium trichomanes subsp. quadrivalens (4n, Polystichum setiferum (2n and Polystichum aculeatum (4n. Sporophyte production was tested at different levels of inbreeding, by culturing gametophytes in isolation, as well as in paired cultures with a genetically different gametophyte. We tested gametophytes derived from various genetically different sporophytes from populations in a recently planted forest colonized through long-distance dispersal (Kuinderbos, the Netherlands, as well as from older, less disjunct populations. Sporophyte production in isolation was high for Kuinderbos genotypes of all four species. Selfing capacity did not differ significantly between diploids and polyploids, nor between species in general. Rather selfing capacity differed between genotypes within species. Intraspecific variation in mating system was found in all four species. In two species one genotype from the Kuinderbos showed enhanced sporophyte production in paired cultures. For the other species, including a renowned out crosser, selfing capacity was consistently high. Conclusions Our results for four different species suggest that intraspecific variation in mating system may be common, at least among temperate calcicole

  4. Intraspecific variation and influence of diet on the venom chemical profile of the Ectatomma brunneum Smith (Formicidae) ant evaluated by photoacoustic spectroscopy.

    Science.gov (United States)

    Bernardi, Rafaella Caroline; Firmino, Ellen Liciane Barbosa; Mendonça, Angelica; Sguarizi-Antonio, Denise; Pereira, Márlon César; da Cunha Andrade, Luis Humberto; Antonialli-Junior, William Fernando; Lima, Sandro Marcio

    2017-10-01

    Studies of venomous animals have shown that environmental and genetic factors contribute to determining the chemical composition of venom. It is well known that external effects cause differences in the toxicity, concentration, and prey specificity of venom. However, the influence of different factors on the chemical profile of Hymenoptera venom remains little explored. In view of this, the aim of this study was to evaluate intraspecific differences and the influence of diet on the chemical profile of Ectatomma brunneum venom using Fourier transform infrared photoacoustic spectroscopy. For the study of intraspecific variation of the venom, foragers were collected at locations with different environmental conditions, such as urban, intermediate, woodland and monoculture sites. To investigate the influence of diet on the venom, two colonies were sampled in the same area and were maintained in the laboratory under controlled diet conditions and at room temperature. The mid-infrared absorption spectra obtained were interpreted using discriminant function analysis. The results showed significant differences among the chemical profiles of the venoms of individuals from different environments and individuals exposed to a controlled diet in the laboratory, suggesting that venom composition was determined not only by genetic traits inherent to the species, but also by exogenous factors. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Natural variation in dauer pheromone production and sensing supports intraspecific competition in nematodes.

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    Bose, Neelanjan; Meyer, Jan M; Yim, Joshua J; Mayer, Melanie G; Markov, Gabriel V; Ogawa, Akira; Schroeder, Frank C; Sommer, Ralf J

    2014-07-07

    Dauer formation, a major nematode survival strategy, represents a model for small-molecule regulation of metazoan development [1-10]. Free-living nematodes excrete dauer-inducing pheromones that have been assumed to target conspecifics of the same genotype [9, 11]. However, recent studies in Pristionchus pacificus revealed that the dauer pheromone of some strains affects conspecifics of other genotypes more strongly than individuals of the same genotype [12]. To elucidate the mechanistic basis for this intriguing cross-preference, we compared six P. pacificus wild isolates to determine the chemical composition of their dauer-inducing metabolomes and responses to individual pheromone components. We found that these isolates produce dauer pheromone blends of different composition and respond differently to individual pheromone components. Strikingly, there is no correlation between production of and dauer response to a specific compound in individual strains. Specifically, pheromone components that are abundantly produced by one genotype induce dauer formation in other genotypes, but not necessarily in the abundant producer. Furthermore, some genotypes respond to pheromone components they do not produce themselves. These results support a model of intraspecific competition in nematode dauer formation. Indeed, we observed intraspecific competition among sympatric strains in a novel experimental assay, suggesting a new role of small molecules in nematode ecology. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Intraspecific variation in vertical habitat use by tiger sharks (Galeocerdo cuvier) in the western North Atlantic

    Science.gov (United States)

    Vaudo, Jeremy J; Wetherbee, Bradley M; Harvey, Guy; Nemeth, Richard S; Aming, Choy; Burnie, Neil; Howey-Jordan, Lucy A; Shivji, Mahmood S

    2014-01-01

    Tiger sharks (Galeocerdo cuvier) are a wide ranging, potentially keystone predator species that display a variety of horizontal movement patterns, making use of coastal and pelagic waters. Far less, however, is known about their vertical movements and use of the water column. We used pop-up satellite archival tags with two data sampling rates (high rate and standard rate tags) to investigate the vertical habitat use and diving behavior of tiger sharks tagged on the Puerto Rico–Virgin Islands platform and off Bermuda between 2008 and 2009. Useable data were received from nine of 14 sharks tagged, tracked over a total of 529 days. Sharks spent the majority of their time making yo-yo dives within the upper 50 m of the water column and considerable time within the upper 5 m of the water column. As a result, sharks typically occupied a narrow daily temperature range (∼2°C). Dives to greater than 200 m were common, and all sharks made dives to at least 250 m, with one shark reaching a depth of 828 m. Despite some similarities among individuals, a great deal of intraspecific variability in vertical habit use was observed. Four distinct depth distributions that were not related to tagging location, horizontal movements, sex, or size were detected. In addition, similar depth distributions did not necessitate similar dive patterns among sharks. Recognition of intraspecific variability in habitat use of top predators can be crucial for effective management of these species and for understanding their influence on ecosystem dynamics. PMID:24963376

  7. Species coexistence under resource competition with intraspecific and interspecific direct competition in a chemostat.

    Science.gov (United States)

    Saito, Yasuhisa; Miki, Takeshi

    2010-11-01

    Competition theory has developed separately for direct competition and for exploitative competition. However, the combined effects of the two types of competition on species coexistence remain unclear. To examine how intraspecific and interspecific direct competition contributes to the coexistence of species competing for a single resource, we constructed a chemostat-type resource competition model. With general functions for intraspecific and interspecific direct competition, we derived necessary and sufficient conditions (except for a critical case that rarely occurs in a biological sense) that determine the number of stably coexisting species. From these conditions, we found that the number of coexisting species is determined just by the invasibility of each species into subcommunities with a smaller number of species. In addition, using a combination of rigorous mathematical theory and a simple graphical method, we can demonstrate how the stronger intraspecific direct competition facilitates species invasion, leading to a larger number of coexisting species. Copyright 2010 Elsevier Inc. All rights reserved.

  8. Intraspecific variation in {sup 137}Cs activity concentration in sporocarps of Suillus variegatus in seven Swedish populations

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    Dahlberg, Anders [Swedish Univ. of Agricultural Sciences, Forest Mycology and Pathology Dept., Uppsala (Sweden); Nikolova, Ivanka; Johanson, K.-J. [Swedish Univ. of Agricultural Sciences, Radioecology Dept., Uppsala (Sweden)

    1997-05-01

    Following the Chernobyl accident in 1986, sporocarps of Suillus variegatus in Sweden showed a large amount of individual variation in concentration of {sup 137}Cs activity. Our aim was to determine the degrees to which this variability in sporocarp {sup 137}Cs levels could be explained by differences between (i) local populations, (ii) fungal genets and (iii) locations within genets. Five populations in a 100-yr-old Scots pine forest, located within a 1 km{sup 2} area, and two populations in Scots pine/Norway spruce forest, located 40 km north-west of Uppsala, were investigated. In total, 154 sporocarps were analysed to determine their {sup 137}Cs content. Of these, the genetic affiliations of 86 were successfully characterized using somatic incompatibility reactions. Twenty-six genets were found which, on average, consisted of 6.5 sporocarps. The genets averaged 7.5 m in size, measured as the length between the most distant sporocarps. The mean sporocarp {sup 137}Cs level was 67.1 {+-} 2.8 kBq kgsup(-1) D.W. (range between 13.6 and 182). According to analyses of variance, within-population variation accounted for 60% of the total variation in {sup 137}Cs levels, while 40% was ascribed to variation among populations. Within a population, {sup 137}Cs levels did not generally differ significantly between genets. Plausible reasons for intraspecific variation in radiocaesium content in sporocarps are discussed. (author).

  9. The Venom of the Spine-Bellied Sea Snake (Hydrophis curtus): Proteome, Toxin Diversity and Intraspecific Variation.

    Science.gov (United States)

    Neale, Vanessa; Sotillo, Javier; Seymour, Jamie E; Wilson, David

    2017-12-12

    The spine-bellied sea snake ( Hydrophis curtus ) is known to cause human deaths, yet its venom composition has not yet been proteomically characterised. An indepth proteomic analysis was performed on H. curtus venom from two different seasons, January and June, corresponding to adults and subadults, respectively. Venoms from adult and subadult H. curtus individuals were compared using reversedphase high-performance liquid chromatography (RP-HPLC), matrix-assisted laser desorption ionisation-time of flight (MALDI-TOF) mass spectrometry and liquid chromatography electrospray ionisation mass spectrometry (LC-ESI-MS) to detect intraspecific variation, and the molecular weight data obtained with ESIMS were used to assess toxin diversity. RPHPLC and LCESIMS/MS were used to characterise the venom proteome and estimate the relative abundances of protein families present. The most abundant protein family in January and June venoms is phospholipase A₂ (PLA₂: January 66.7%; June 54.5%), followed by threefinger toxins (3FTx: January 30.4%; June 40.4%) and a minor component of cysteine-rich secretory proteins (CRISP: January 2.5%; June 5%). Trace amounts of snake venom metalloproteinases (SVMP), C-type lectins and housekeeping and regulatory proteins were also found. Although the complexity of the venom is low by number of families present, each family contained a more diverse set of isoforms than previously reported, a finding that may have implications for the development of next-generation sea snake antivenoms. Intraspecific variability was shown to be minor with one obvious exception of a 14,157-Da protein that was present in some January (adult) venoms, but not at all in June (subadult) venoms. There is also a greater abundance of short-chain neurotoxins in June (subadult) venom compared with January (adult) venom. These differences potentially indicate the presence of seasonal, ontogenetic or sexual variation in H. curtus venom.

  10. Intraspecific variation in body size and shape in an andean highland anole species, Anolis ventrimaculatus (Squamata: Dactyloidae).

    Science.gov (United States)

    Calderón-Espinosa, Martha L; Ortega-León, Angela M; Zamora-Abrego, Joan G

    2013-03-01

    Variation in body characteristics related to lizard locomotion has been poorly studied at the intraspecific level in Anolis species. Local adaptation due to habitat heterogeneity has been reported in some island species. However, studies of mainland species are particularly scarce and suggest different patterns: high variability among highland lizards and poorly differentiated populations in one Amazonian species. We characterized inter population variation of body size and shape in the highland Andean Anolis ventrimaculatus, an endemic species from Western Colombia. A total of 15 morphometric variables were measured in specimens from the reptile collection of the Instituto de Ciencias Naturales, Universidad Nacional, Colombia. The study included individuals from seven different highland localities. We found size and shape sexual dimorphism, both of which varied among localities. Patterns of variation in body proportions among populations were different in both males and females, suggesting that either sexual or natural selective factors are different in each locality and between sexes. Since this species exhibits a fragmented distribution in highlands, genetic divergence may also be a causal factor of the observed variation. Ecological, behavioral, additional morphological as well as phylogenetic data, may help to understand the evolutionary processes behind the geographic patterns found in this species.

  11. Intraspecific variation in flight metabolic rate in the bumblebee Bombus impatiens: repeatability and functional determinants in workers and drones.

    Science.gov (United States)

    Darveau, Charles-A; Billardon, Fannie; Bélanger, Kasandra

    2014-02-15

    The evolution of flight energetics requires that phenotypes be variable, repeatable and heritable. We studied intraspecific variation in flight energetics in order to assess the repeatability of flight metabolic rate and wingbeat frequency, as well as the functional basis of phenotypic variation in workers and drones of the bumblebee species Bombus impatiens. We showed that flight metabolic rate and wingbeat frequency were highly repeatable in workers, even when controlling for body mass variation using residual analysis. We did not detect significant repeatability in drones, but a smaller range of variation might have prevented us from finding significant values in our sample. Based on our results and previous findings, we associated the high repeatability of flight phenotypes in workers to the functional links between body mass, thorax mass, wing size, wingbeat frequency and metabolic rate. Moreover, differences between workers and drones were as predicted from these functional associations, where drones had larger wings for their size, lower wingbeat frequency and lower flight metabolic rate. We also investigated thoracic muscle metabolic phenotypes by measuring the activity of carbohydrate metabolism enzymes, and we found positive correlations between mass-independent metabolic rate and the activity of all enzymes measured, but in workers only. When comparing workers and drones that differ in flight metabolic rate, only the activity of the enzymes hexokinase and trehalase showed the predicted differences. Overall, our study indicates that there should be correlated evolution among physiological phenotypes at multiple levels of organization and morphological traits associated with flight.

  12. Macroscale intraspecific variation and environmental heterogeneity: analysis of cold and warm zone abundance, mortality, and regeneration distributions of four eastern US tree species

    Science.gov (United States)

    Anantha M. Prasad

    2015-01-01

    I test for macroscale intraspecific variation of abundance, mortality, and regeneration of four eastern US tree species (Tsuga canadensis, Betula lenta, Liriodendron tulipifera, and Quercus prinus) by splitting them into three climatic zones based on plant hardiness zones (PHZs). The primary goals of the analysis are to assess the...

  13. Size does matter - Intraspecific variation of feeding mechanics in the crested newt Triturus dobrogicus (Kiritzescu, 1903)

    Science.gov (United States)

    Kucera, Florian; Beisser, Christian J.; Lemell, Patrick

    2018-03-01

    Many studies have yet been conducted on suction feeding in aquatic salamander species. Within the Salamandridae, the crested newt Triturus dobrogicus (Kiritzescu, 1903), occurring from the Austrian Danube floodplains to the Danube Delta, was not subject of investigations so far. The present study examines the kinematics of aquatic suction feeding in this species by means of high-speed videography. Recordings of five individuals of different size and sex while feeding on bloodworms were conducted, in order to identify potential discrepancies among individuals and sizes. Five coordinate points were digitized from recordings of prey capture and twelve time- and velocity-determined variables were evaluated. All specimens follow a typical inertial suction feeding process, where rapid hyoid depression expands the buccal cavity. Generated negative pressure within the buccal cavity causes influx of water along with the prey item into the mouth. Results demonstrate higher distance values and angles for gape in individuals with smaller size. In addition, hyoid depression is maximized in smaller individuals. While Triturus dobrogicus resembles a typical inertial suction feeder in its functional morphology, intraspecific differences could be found regarding the correlation of different feeding patterns and body size.

  14. Intraspecific evolution of the intercellular signaling network underlying a robust developmental system.

    Science.gov (United States)

    Milloz, Josselin; Duveau, Fabien; Nuez, Isabelle; Félix, Marie-Anne

    2008-11-01

    Many biological systems produce an invariant output when faced with stochastic or environmental variation. This robustness of system output to variation affecting the underlying process may allow for "cryptic" genetic evolution within the system without change in output. We studied variation of cell fate patterning of Caenorhabditis elegans vulva precursors, a developmental system that relies on a simple intercellular signaling network and yields an invariant output of cell fates and lineages among C. elegans wild isolates. We first investigated the system's genetic variation in C. elegans by means of genetic tools and cell ablation to break down its buffering mechanisms. We uncovered distinct architectures of quantitative variation along the Ras signaling cascade, including compensatory variation, and differences in cell sensitivity to induction along the anteroposterior axis. In the unperturbed system, we further found variation between isolates in spatio-temporal dynamics of Ras pathway activity, which can explain the phenotypic differences revealed upon perturbation. Finally, the variation mostly affects the signaling pathways in a tissue-specific manner. We thus demonstrate and characterize microevolution of a developmental signaling network. In addition, our results suggest that the vulva genetic screens would have yielded a different mutation spectrum, especially for Wnt pathway mutations, had they been performed in another C. elegans genetic background.

  15. Inter- and intraspecific genetic variation in Hippophae (Elaeagnaceae) investigated by RAPD markers

    Czech Academy of Sciences Publication Activity Database

    Bartish, Igor; Jeppsson, N.; Bartish, G.; Lu, R.; Nybom, H.

    2000-01-01

    Roč. 225, - (2000), s. 85-101 ISSN 0378-2697 Institutional research plan: CEZ:AV0Z6005908 Keywords : Elaeagnaceae * sea buckthorn * genetic variation Subject RIV: EF - Botanics Impact factor: 1.408, year: 2000

  16. Intraspecific phytochemical variation shapes community and population structure for specialist caterpillars

    OpenAIRE

    Glassmire, Andrea E.; Jeffrey, Christopher S.; Forister, Matthew L.; Parchman, Thomas L.; Nice, Chris C.; Jahner, Joshua P.; Wilson, Joseph S.; Walla, Thomas R.; Richards, Lora A.; Smilanich, Angela M.; Leonard, Michael D.; Morrison, Colin R.; Simba?a, Wilmer; Salagaje, Luis A.; Dodson, Craig D.

    2016-01-01

    Summary Chemically mediated plant?herbivore interactions contribute to the diversity of terrestrial communities and the diversification of plants and insects. While our understanding of the processes affecting community structure and evolutionary diversification has grown, few studies have investigated how trait variation shapes genetic and species diversity simultaneously in a tropical ecosystem. We investigated secondary metabolite variation among subpopulations of a single plant species, P...

  17. Intraspecific variation in the diet of the Mexican garter snake Thamnophis eques

    OpenAIRE

    Manjarrez, Javier; Pacheco-Tinoco, Martha; Venegas-Barrera, Crystian S.

    2017-01-01

    The Mexican Garter Snake (Thamnophis eques) is a terrestrial-aquatic generalist that feeds on both aquatic and terrestrial prey. We describe size-related variation and sexual variation in the diet of T. eques through analysis of 262 samples of identifiable stomach contents in snakes from 23 locations on the Mexican Plateau. The snake T. eques we studied consumed mostly fish, followed in lesser amounts by leeches, earthworms, frogs, and tadpoles. Correspondence analysis suggested that the freq...

  18. Intra-specific variation of sperm length in the malaria vector Anopheles gambiae: males with shorter sperm have higher reproductive success

    Directory of Open Access Journals (Sweden)

    Voordouw Maarten J

    2008-10-01

    Full Text Available Abstract Background Intra-specific variation in sperm length influences male reproductive success in several species of insects. In males of the malaria vector Anopheles gambiae, sperm length is highly variable but the significance of this variation is unknown. Understanding what determines the reproductive success of male mosquitoes is critical for controlling malaria, and in particular for replacing natural populations with transgenic, malaria-resistant mosquitoes. Methods A laboratory population of A. gambiae males was tested for intra-specific variation in sperm length. A full-sib quantitative genetic design was used to test for a genetic component of sperm length in A. gambiae males and estimate its heritability. This study also tested for a relationship between sperm length and male reproductive success in A. gambiae. Male reproductive success was measured as the proportions of inseminated and ovipositing females. Results There was intra-specific variation of sperm length in A. gambiae. There was no significant genetic variation in sperm length and its heritability was low (h2 = 0.18 compared to other insects. Sperm length was correlated with male body size (measured as wing length. Males with short sperm had significantly higher reproductive success than males with long sperm and this was independent of body size. Conclusion This is the first study to demonstrate intra-specific variation in sperm length in A. gambiae and that males with short sperm have higher reproductive success. That sperm length influences female oviposition is important for any strategy considering the release of transgenic males.

  19. INTRASPECIFIC VARIATION IN ACOUSTIC TRAITS AND BODY SIZE, AND NEW DISTRIBUTIONAL RECORDS FOR PSEUDOPALUDICOLA GIARETTAI CARVALHO, 2012 (ANURA, LEPTODACTYLIDAE, LEIUPERINAE: IMPLICATIONS FOR ITS CONGENERIC DIAGNOSIS

    Directory of Open Access Journals (Sweden)

    THIAGO RIBEIRO DE CARVALHO

    2015-01-01

    Full Text Available In this paper, we provide an updated diagnosis for Pseudopaludicola giarettai based on the morphometric and acoustic variation observed with the assessment of new populations, plus an expansion of its distribution range. Our results support that all acoustic variation observed might be attributed to intraspecific variation. The variation in body size and dorsal stripe patterns observed for Pseudopaludicola giarettai reinforces that the distinctive whistling advertisement call pattern is the most reliable evidence line to diagnose it from its congeners, whereas morphological (robust body, glandular dorsum and morphometric (body size features vary considerably within and among populations so that they should no longer be employed as diagnostic features of Pseudopaludicola giarettai.

  20. Intraspecific phytochemical variation shapes community and population structure for specialist caterpillars.

    Science.gov (United States)

    Glassmire, Andrea E; Jeffrey, Christopher S; Forister, Matthew L; Parchman, Thomas L; Nice, Chris C; Jahner, Joshua P; Wilson, Joseph S; Walla, Thomas R; Richards, Lora A; Smilanich, Angela M; Leonard, Michael D; Morrison, Colin R; Simbaña, Wilmer; Salagaje, Luis A; Dodson, Craig D; Miller, Jim S; Tepe, Eric J; Villamarin-Cortez, Santiago; Dyer, Lee A

    2016-10-01

    Chemically mediated plant-herbivore interactions contribute to the diversity of terrestrial communities and the diversification of plants and insects. While our understanding of the processes affecting community structure and evolutionary diversification has grown, few studies have investigated how trait variation shapes genetic and species diversity simultaneously in a tropical ecosystem. We investigated secondary metabolite variation among subpopulations of a single plant species, Piper kelleyi (Piperaceae), using high-performance liquid chromatography (HPLC), to understand associations between plant phytochemistry and host-specialized caterpillars in the genus Eois (Geometridae: Larentiinae) and associated parasitoid wasps and flies. In addition, we used a genotyping-by-sequencing approach to examine the genetic structure of one abundant caterpillar species, Eois encina, in relation to host phytochemical variation. We found substantive concentration differences among three major secondary metabolites, and these differences in chemistry predicted caterpillar and parasitoid community structure among host plant populations. Furthermore, E. encina populations located at high elevations were genetically different from other populations. They fed on plants containing high concentrations of prenylated benzoic acid. Thus, phytochemistry potentially shapes caterpillar and wasp community composition and geographic variation in species interactions, both of which can contribute to diversification of plants and insects. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  1. A global meta-analysis of the relative extent of intraspecific trait variation in plant communities

    Czech Academy of Sciences Publication Activity Database

    Siefert, A.; Violle, C.; Chalmandrier, L.; Albert, C. H.; Taudiere, A.; Fajardo, A.; Aarssen, L. W.; Baraloto, Ch.; Carlucci, M. B.; Cianciaruso, M. V.; de L. Dantas, V.; de Bello, Francesco; Duarte, L. D. S.; Fonseca, C. R.; Freschet, G. T.; Gaucherand, S.; Gross, N.; Hikosaka, K.; Jackson, B.; Jung, V.; Kamiyama, Ch.; Katabuchi, M.; Kembel, S. W.; Kichenin, E.; Kraft, N. J. B.; Lagerström, A.; Bagousse-Pinguet, Y. L.; Li, Y.; Mason, N.; Messier, J.; Nakashizuka, T.; Overton, J. McC.; Peltzer, D. A.; Pérez-Ramos, I. M.; Pillar, V. D.; Prentice, H. C.; Richardson, S.; Sasaki, T.; Schamp, B. S.; Schöb, C.; Shipley, B.; Sundqvist, M.; Sykes, M. T.; Vandewalle, M.; Wardle, D. A.

    2015-01-01

    Roč. 18, č. 12 (2015), s. 1406-1419 ISSN 1461-023X R&D Projects: GA ČR GAP505/12/1296 Institutional support: RVO:67985939 Keywords : community ecology * functional diversity * interspecific variation Subject RIV: EH - Ecology, Behaviour Impact factor: 10.772, year: 2015

  2. Intraspecific competition between ectomycorrhizal Pisolithus microcarpus isolates impacts plant and fungal performance under elevated CO2 and temperature.

    Science.gov (United States)

    Hortal, S; Powell, J R; Plett, J M; Simonin, A; Anderson, I C

    2016-08-01

    Root systems are simultaneously colonized by multiple individuals of mycorrhizal fungi. Intraspecific competitive interactions between fungal isolates are likely to affect both fungal and plant performance and be influenced by abiotic factors. Here, we assessed the impact of intraspecific competition between three Pisolithus microcarpus isolates on the establishment of, and benefit derived from, symbioses with Eucalyptus grandis seedlings. We investigated the outcomes of competition under ambient and elevated temperature and CO2 concentration ([CO2]) in a factorial design. We observed a reduction in mycelium growth, mycorrhiza formation and seedling mass when two P. microcarpus isolates were co-inoculated on a single E. grandis seedling. Isolates invested more in mycelium than in mycorrhizas in the presence of a competitor. All isolates responded negatively to elevated [CO2] and positively to elevated temperature, which led to no changes on the outcomes of the interactions with changing conditions. However, the presence of a competitor hindered the positive response of P. microcarpus isolates to warming, which resulted in larger negative effects of competition under elevated temperature than under ambient conditions. Our study highlights the need to consider how competition affects individual fungal responses as well as plant performance when trying to predict the impacts of climate change. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  3. Variation in ribosomal and mitochondrial DNA sequences demonstrates the existence of intraspecific groups in Paramecium multimicronucleatum (Ciliophora, Oligohymenophorea).

    Science.gov (United States)

    Tarcz, Sebastian; Potekhin, Alexey; Rautian, Maria; Przyboś, Ewa

    2012-05-01

    This is the first phylogenetic study of the intraspecific variability within Paramecium multimicronucleatum with the application of two-loci analysis (ITS1-5.8S-ITS2-5'LSU rDNA and COI mtDNA) carried out on numerous strains originated from different continents. The species has been shown to have a complex structure of several sibling species within taxonomic species. Our analysis revealed the existence of 10 haplotypes for the rDNA fragment and 15 haplotypes for the COI fragment in the studied material. The mean distance for all of the studied P. multimicronucleatum sequence pairs was p=0.025/0.082 (rDNA/COI). Despite the greater variation of the COI fragment, the COI-derived tree topology is similar to the tree topology constructed on the basis of the rDNA fragment. P. multimicronucleatum strains are divided into three main clades. The tree based on COI fragment analysis presents a greater resolution of the studied P. multimicronucleatum strains. Our results indicate that the strains of P. multimicronucleatum that appear in different clades on the trees could belong to different syngens. Copyright © 2012 Elsevier Inc. All rights reserved.

  4. Osteology of Physalaemus nattereri (Anura: Leptodactylidae) with comments on intraspecific variation.

    Science.gov (United States)

    Fratani, Jéssica; Woitovicz-Cardoso, Manoela; Lourenço, Ana Carolina Calijorne

    2017-02-02

    The cranium, postcranium, and osteological variation of Physalaemus nattereri (Steindachner) are described. The main sources of variation involve the degree of mineralization of the nasal capsule and the lengths of dermal skull bones (e.g., vomer, sphenethmoid, and neopalatine). Osteologically, P. nattereri differs from its congeners by the anterior placement of the jaw articulation (which lies anterior to the intersection between the alae and cultriform process of parasphenoid), and by the separation of the frontoparietals from the anterior margins of exoccipitals. Descriptions of the nasal capsule, the auditory apparatus, and the iliosacral articulation are presented for the first time for this species. One putative morphological synapomorphy is presented for the P. signifer Clade.

  5. Intraspecific variation between the ITS sequences of Toxocara canis, Toxocara cati and Toxascaris leonina from different host species in south-western Poland.

    Science.gov (United States)

    Fogt-Wyrwas, R; Mizgajska-Wiktor, H; Pacoń, J; Jarosz, W

    2013-12-01

    Some parasitic nematodes can inhabit different definitive hosts, which raises the question of the intraspecific variability of the nematode genotype affecting their preferences to choose particular species as hosts. Additionally, the issue of a possible intraspecific DNA microheterogeneity in specimens from different parts of the world seems to be interesting, especially from the evolutionary point of view. The problem was analysed in three related species - Toxocara canis, Toxocara cati and Toxascaris leonina - specimens originating from Central Europe (Poland). Using specific primers for species identification, internal transcribed spacer (ITS)-1 and ITS-2 regions were amplified and then sequenced. The sequences obtained were compared with sequences previously described for specimens originating from other geographical locations. No differences in nucleotide sequences were established in T. canis isolated from two different hosts (dogs and foxes). A comparison of ITS sequences of T. canis from Poland with sequences deposited in GenBank showed that the scope of intraspecific variability of the species did not exceed 0.4%, while in T. cati the differences did not exceed 2%. Significant differences were found in T. leonina, where ITS-1 differed by 3% and ITS-2 by as much as 7.4% in specimens collected from foxes in Poland and dogs in Australia. Such scope of differences in the nucleotide sequence seems to exceed the intraspecific variation of the species.

  6. Consequences of Intraspecific Competition and Environmental Variation for Selection in the Mustard Sinapsis arvensis: Contrasting Ecological and Evolutionary Perspectives.

    Science.gov (United States)

    Stanton, M L; Thiede, D A; Roy, B A

    2004-12-01

    Alternative models of plant life-history evolution differ in their views of how abiotic stress and competition interact to shape the evolution of plant life-history traits. To address this debate, which crosses traditional boundaries between community ecology and population biology, we grew wild turnip families from three selection histories in a field experiment in which we manipulated conspecific density and sun exposure. Hot spring conditions caused neutral shading to reduce drought stress, resulting in a greater mean and variance for lifetime fertility at low density and greater intensity of competition at high density. The variance in relative fitness among individuals or families was least in partial shade at low density. Prior selection under shade stress in the greenhouse reduced lifetime fitness in the less stressful partial-shade treatment under field conditions. Patterns of selection and predicted trait evolution were more similar between high and low densities than between the two light environments. Partial shade favored the proliferation of large leaves early in development, especially at high density. Selection in the stressful full-sun treatment favored reduced pathogen susceptibility at both densities and early flowering at low density. Because direct selection on traits changed principally in magnitude rather than in direction, genetic correlations for fitness were generally positive between light and density treatments. Greater intraspecific competition led to more rapid predicted trait evolution in the partial-shade environment but not in the stressful full-sun treatment.

  7. Illumina based whole mitochondrial genome of Junonia iphita reveals minor intraspecific variation

    Directory of Open Access Journals (Sweden)

    Catherine Vanlalruati

    2015-12-01

    Full Text Available In the present study, the near complete mitochondrial genome (mitogenome of Junonia iphita (Lepidoptera: Nymphalidae: Nymphalinae was determined to be 14,892 bp. The gene order and orientation are identical to those in other butterfly species. The phylogenetic tree constructed from the whole mitogenomes using the 13 protein coding genes (PCGs defines the genetic relatedness of the two J. iphita species collected from two different regions. All the Junonia species clustered together, and were further subdivided into clade one consisting of J. almana and J. orithya and clade two comprising of the two J. iphita which were collected from Indo and Indochinese subregions separated by river barrier. Comparison between the two J. iphita sequences revealed minor variations and Single Nucleotide Polymorphisms were identified at 51 sites amounting to 0.4% of the entire mitochondrial genome.

  8. Intraspecific variation in exploratory behavior and elevational affinity in a widely distributed songbird.

    Science.gov (United States)

    Poblete, Yanina; Gutiérrez, Víctor; Cid, Valeska; Newsome, Seth D; Sabat, Pablo; Vasquez, Rodrigo A

    2018-04-01

    Populations of the same species can vary substantially in their behavioral and morphometric traits when they are subject to different environmental pressures, which may lead to the development of different adaptive strategies. We quantified variation in exploratory behavior and morphometric traits among two rufous-collared sparrow populations that occur at low and high elevations in central Chile. Moreover, we used census and δ 2 H values of feather and blood to evaluate migration. We found that individual sparrows inhabiting high elevations were larger and showed more intense exploratory behavior in comparison with those that were captured at lower elevation. Moreover, we observed a steady decline in sparrow abundance during the winter and similar δ 2 H values for blood collected in the winter and summer at this site, which were significantly lower than blood δ 2 H values observed at low elevation. This pattern suggests that individuals do not move long distances during winter, and likely they remain at similar elevations in refuge habitats. As predicted, our results support the existent of different adaptive strategies among populations of the same species, and suggest that the combination of behavioral, morphometric, and stable isotope data is a novel and robust integrative approach to assess differences in adaptation across environmental gradients.

  9. Genetic Mapping and Phylogenetic Analysis Reveal Intraspecific Variation in Sex Chromosomes of the Virginian Strawberry.

    Science.gov (United States)

    Wei, Na; Govindarajulu, Rajanikanth; Tennessen, Jacob A; Liston, Aaron; Ashman, Tia-Lynn

    2017-10-30

    With their extraordinary diversity in sexual systems, flowering plants offer unparalleled opportunities to understand sex determination and to reveal generalities in the evolution of sex chromosomes. Comparative genetic mapping of related taxa with good phylogenetic resolution can delineate the extent of sex chromosome diversity within plant groups, and lead the way to understanding the evolutionary drivers of such diversity. The North American octoploid wild strawberries provide such an opportunity. We performed linkage mapping using targeted sequence capture for the subdioecious western Fragaria virginiana ssp. platypetala and compared the location of its sex-determining region (SDR) to those of 2 other (sub)dioecious species, the eastern subspecies, F. virginiana ssp. virginiana (whose SDR is at 0-5.5 Mb on chromosome VI of the B2 subgenome), and the sister species F. chiloensis (whose SDR is at 37 Mb on chromosome VI of the Av subgenome). Male sterility was dominant in F. virginiana ssp. platypetala and mapped to a chromosome also in homeologous group VI. Likewise, one major quantitative trait locus (QTL) for female fertility overlapped the male sterility region. However, the SDR mapped to yet another subgenome (B1), and to a different location (13 Mb), but similar to the location inferred in one population of the naturally occurring hybrid between F. chiloensis and F. virginiana (F. ×ananassa ssp. cuneifolia). Phylogenetic analysis of chromosomes across the octoploid taxa showed consistent subgenomic composition reflecting shared evolutionary history but also reinforced within-species variation in the SDR-carrying chromosome, suggesting either repeated evolution, or recent turnovers in SDR. © The American Genetic Association 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  10. Inter- and Intraspecific Variations of Bacterial Communities Associated with Marine Sponges from San Juan Island, Washington

    KAUST Repository

    Lee, O. O.

    2009-04-10

    This study attempted to assess whether conspecific or congeneric sponges around San Juan Island, Washington, harbor specific bacterial communities. We used a combination of culture-independent DNA fingerprinting techniques (terminal restriction fragment length polymorphism and denaturing gradient gel electrophoresis [DGGE]) and culture-dependent approaches. The results indicated that the bacterial communities in the water column consisted of more diverse bacterial ribotypes than and were drastically different from those associated with the sponges. High levels of similarity in sponge-associated bacterial communities were found only in Myxilla incrustans and Haliclona rufescens, while the bacterial communities in Halichondria panicea varied substantially among sites. Certain terminal restriction fragments or DGGE bands were consistently obtained for different individuals of M. incrustans and H. rufescens collected from different sites, suggesting that there are stable or even specific associations of certain bacteria in these two sponges. However, no specific bacterial associations were found for H. panicea or for any one sponge genus. Sequencing of nine DGGE bands resulted in recovery of seven sequences that best matched the sequences of uncultured Proteobacteria. Three of these sequences fell into the sponge-specific sequence clusters previously suggested. An uncultured alphaproteobacterium and a culturable Bacillus sp. were found exclusively in all M. incrustans sponges, while an uncultured gammaproteobacterium was unique to H. rufescens. In contrast, the cultivation approach indicated that sponges contained a large proportion of Firmicutes, especially Bacillus, and revealed large variations in the culturable bacterial communities associated with congeneric and conspecific sponges. This study revealed sponge species-specific but not genus- or site-specific associations between sponges and bacterial communities and emphasized the importance of using a combination

  11. Intraspecific variation in fine root respiration and morphology in response to in situ soil nitrogen fertility in a 100-year-old Chamaecyparis obtusa forest.

    Science.gov (United States)

    Makita, Naoki; Hirano, Yasuhiro; Sugimoto, Takanobu; Tanikawa, Toko; Ishii, Hiroaki

    2015-12-01

    Soil N fertility has an effect on belowground C allocation, but the physiological and morphological responses of individual fine root segments to variations in N availability under field conditions are still unclear. In this study, the direction and magnitude of the physiological and morphological function of fine roots in response to variable in situ soil N fertility in a forest site were determined. We measured the specific root respiration (Rr) rate, N concentration and morphology of fine root segments with 1-3 branching orders in a 100-year-old coniferous forest of Chamaecyparis obtusa. Higher soil N fertility induced higher Rr rates, root N concentration, and specific root length (SRL), and lower root tissue density (RTD). In all fertility levels, the Rr rates were significantly correlated positively with root N and SRL and negatively with RTD. The regression slopes of respiration with root N and RTD were significantly higher along the soil N fertility gradient. Although no differences in the slopes of Rr and SRL relationship were found across the levels, there were significant shifts in the intercept along the common slope. These results suggest that a contrasting pattern in intraspecific relationships between specific Rr and N, RTD, and SRL exists among soils with different N fertility. Consequently, substantial increases in soil N fertility would exert positive effects on organ-scale root performance by covarying the Rr, root N, and morphology for their potential nutrient and water uptake.

  12. Intraspecific variations of Dekkera/Brettanomyces bruxellensis genome studied by capillary electrophoresis separation of the intron splice site profiles.

    Science.gov (United States)

    Vigentini, Ileana; De Lorenzis, Gabriella; Picozzi, Claudia; Imazio, Serena; Merico, Annamaria; Galafassi, Silvia; Piškur, Jure; Foschino, Roberto

    2012-06-15

    In enology, "Brett" character refers to the wine spoilage caused by the yeast Dekkera/Brettanomyces bruxellensis and its production of volatile phenolic off-flavours. However, the spoilage potential of this yeast is strain-dependent. Therefore, a rapid and reliable recognition at the strain level is a key point to avoid serious economic losses. The present work provides an operative tool to assess the genetic intraspecific variation in this species through the use of introns as molecular targets. Firstly, the available partial D./B. bruxellensis genome sequence was investigated in order to build primers annealing to introns 5' splice site sequence (ISS). This analysis allowed the detection of a non-random vocabulary flanking the site and, exploiting this feature, the creation of specific probes for strain discrimination. Secondly, the separation of the intron splice site PCR fragments was obtained throughout the set up of a capillary electrophoresis protocol, giving a 94% repeatability threshold in our experimental conditions. The comparison of results obtained with ISS-PCR/CE versus the ones performed by mtDNA RFLP revealed that the former protocol is more discriminating and allowed a reliable identification at strain level. Actually sixty D./B. bruxellensis isolates were recognised as unique strains, showing a level of similarity below 79% and confirming the high genetic polymorphism existing within the species. Two main clusters were grouped at similarity levels of about 46% and 47%, respectively, showing a poor correlation with the geographic area of isolation. Moreover, from the evolutionary point of view, the proposed technique could determine the frequency of the genome rearrangements that can occur in D./B. bruxellesis populations. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Not all jellyfish are equal: isotopic evidence for inter- and intraspecific variation in jellyfish trophic ecology

    Directory of Open Access Journals (Sweden)

    Nicholas E.C. Fleming

    2015-07-01

    Full Text Available Jellyfish are highly topical within studies of pelagic food-webs and there is a growing realisation that their role is more complex than once thought. Efforts being made to include jellyfish within fisheries and ecosystem models are an important step forward, but our present understanding of their underlying trophic ecology can lead to their oversimplification in these models. Gelatinous zooplankton represent a polyphyletic assemblage spanning >2,000 species that inhabit coastal seas to the deep-ocean and employ a wide variety of foraging strategies. Despite this diversity, many contemporary modelling approaches include jellyfish as a single functional group feeding at one or two trophic levels at most. Recent reviews have drawn attention to this issue and highlighted the need for improved communication between biologists and theoreticians if this problem is to be overcome. We used stable isotopes to investigate the trophic ecology of three co-occurring scyphozoan jellyfish species (Aurelia aurita, Cyanea lamarckii and C. capillata within a temperate, coastal food-web in the NE Atlantic. Using information on individual size, time of year and δ13C and δ15N stable isotope values, we examined: (1 whether all jellyfish could be considered as a single functional group, or showed distinct inter-specific differences in trophic ecology; (2 Were size-based shifts in trophic position, found previously in A. aurita, a common trait across species?; (3 When considered collectively, did the trophic position of three sympatric species remain constant over time? Differences in δ15N (trophic position were evident between all three species, with size-based and temporal shifts in δ15N apparent in A. aurita and C. capillata. The isotopic niche width for all species combined increased throughout the season, reflecting temporal shifts in trophic position and seasonal succession in these gelatinous species. Taken together, these findings support previous

  14. Intraspecific Variation among Social Insect Colonies: Persistent Regional and Colony-Level Differences in Fire Ant Foraging Behavior.

    Directory of Open Access Journals (Sweden)

    Alison A Bockoven

    Full Text Available Individuals vary within a species in many ecologically important ways, but the causes and consequences of such variation are often poorly understood. Foraging behavior is among the most profitable and risky activities in which organisms engage and is expected to be under strong selection. Among social insects there is evidence that within-colony variation in traits such as foraging behavior can increase colony fitness, but variation between colonies and the potential consequences of such variation are poorly documented. In this study, we tested natural populations of the red imported fire ant, Solenopsis invicta, for the existence of colony and regional variation in foraging behavior and tested the persistence of this variation over time and across foraging habitats. We also reared single-lineage colonies in standardized environments to explore the contribution of colony lineage. Fire ants from natural populations exhibited significant and persistent colony and regional-level variation in foraging behaviors such as extra-nest activity, exploration, and discovery of and recruitment to resources. Moreover, colony-level variation in extra-nest activity was significantly correlated with colony growth, suggesting that this variation has fitness consequences. Lineage of the colony had a significant effect on extra-nest activity and exploratory activity and explained approximately half of the variation observed in foraging behaviors, suggesting a heritable component to colony-level variation in behavior.

  15. Consequences of the Allee effect and intraspecific competition on population persistence under adverse environmental conditions.

    Science.gov (United States)

    Petrovskii, Sergei; Blackshaw, Rod; Li, Bai-Lian

    2008-02-01

    The impact of intraspecific interactions on ecological stability and population persistence in terms of steady state(s) existence is considered theoretically based on a general competition model. We compare persistence of a structured population consisting of a few interacting (competitive) subpopulations, or groups, to persistence of the corresponding unstructured population. For a general case, we show that if the intra-group competition is stronger than the inter-group competition, then the structured population is less prone to extinction, i.e. it can persist in a parameter range where the unstructured population goes extinct. For a more specific case of a population with hierarchical competition, we show that relative viability of structured and unstructured populations depend on the type of density dependence in the population growth. Namely, while in the case of logistic growth, structured and unstructured populations exhibit equivalent persistence; in the case of Allee dynamics, the persistence of a hierarchically structured population is shown to be higher. We then apply these results to the case of behaviourally structured populations and demonstrate that an extreme form of individual aggression can be beneficial at the population level and enhance population persistence.

  16. Can we control the invasive cane toad using chemicals that have evolved under intraspecific competition?

    Science.gov (United States)

    Clarke, Gregory S; Crossland, Michael R; Shine, Richard

    2016-03-01

    Many invasive species experience intense intraspecific competition, because they are abundant in anthropogenically disturbed habitats where few native species persist. Species-specific competitive mechanisms that evolve in this context may offer novel, highly targeted means to control invasive taxa. We conducted laboratory experiments to evaluate the feasibility of this method of control, based on waterborne cues that are produced by tadpoles of the cane toad (Rhinella marina) to suppress the development of conspecific embryos. Our trials examined the nature and species-specificity of the effect, the robustness of the cue to freezing and storage, and the amounts required to suppress toad embryos. Our results were encouraging. The cue appears to be chemical rather than a biological organism, and may well be species-specific; the four species of native anurans that we tested were not influenced by toad larval cues. The cue retains its effectiveness after being frozen, but not after being dried, or after 7 d in water. It is effective at very low concentrations (the amount produced by three tadpoles within 750 L of water). Overall, the cane toad's suppressor pheromone may offer an effective new way to control invasive toads.

  17. Intraspecific variation in body size and shape in an Andean highland anole species, Anolis ventrimaculatus (Squamata: Dactyloidae

    Directory of Open Access Journals (Sweden)

    Martha L. Calderón-Espinosa

    2013-03-01

    Full Text Available Variation in body characteristics related to lizard locomotion has been poorly studied at the intraspecific level in Anolis species. Local adaptation due to habitat heterogeneity has been reported in some island species. However, studies of mainland species are particularly scarce and suggest different patterns: high variability among highland lizards and poorly differentiated populations in one Amazonian species. We characterized inter population variation of body size and shape in the highland Andean Anolis ventrimaculatus, an endemic species from Western Colombia. A total of 15 morphometric variables were measured in specimens from the reptile collection of the Instituto de Ciencias Naturales, Universidad Nacional, Colombia. The study included individuals from seven different highland localities. We found size and shape sexual dimorphism, both of which varied among localities. Patterns of variation in body proportions among populations were different in both males and females, suggesting that either sexual or natural selective factors are different in each locality and between sexes. Since this species exhibits a fragmented distribution in highlands, genetic divergence may also be a causal factor of the observed variation. Ecological, behavioral, additional morphological as well as phylogenetic data, may help to understand the evolutionary processes behind the geographic patterns found in this species.La diversificación fenotípica al interior de una especie en características de dimensiones corporales relacionadas con la locomoción de los lagartos, se ha estudiado poco en especies de Anolis. Los datos de algunas especies de isla revelan patrones distintos de variación geográfica y sugieren que la adaptación local, debida a la heterogeneidad del hábitat, ocurre a este nivel. Los estudios de especies de continente son particularmente escasos y sugieren patrones distintos: un lagarto altoandino altamente variable y poblaciones poco

  18. Intraspecific variation in the metabolic scaling exponent in ectotherms: testing the effect of latitudinal cline, ontogeny and transgenerational change in the land snail Cornu aspersum.

    Science.gov (United States)

    Gaitán-Espitia, Juan Diego; Bruning, Andrea; Mondaca, Fredy; Nespolo, Roberto F

    2013-06-01

    The strong dependence of metabolic rates on body mass has attracted the interest of ecological physiologists, as it has important implications to many aspects of biology including species variations in body size, the evolution of life history, and the structure and function of biological communities. The great diversity of observed scaling exponents has led some authors to conclude that there is no single universal scaling exponent, but instead it ranges from 2/3 to 1. Most of the telling evidence against the universality of power scaling exponents comes from ontogenetic changes. Nevertheless, there could be other sources of phenotypic variation that influence this allometric relationship at least at the intraspecific level. In order to explore the general concept of the metabolic scaling in terrestrial molluscs we tested the role of several biological and methodological sources of variation on the empirically estimated scaling exponent. Specifically, we measured a proxy of metabolic rate (CO(2) production) in 421 individuals, during three generations, in three different populations. Additionally, we measured this scaling relationship in 208 individuals at five developmental stages. Our results suggest that the metabolic scaling exponent at the intraspecific level does not have a single stationary value, but instead it shows some degree of variation across geographic distribution, transgenerational change and ontogenetic stages. The major differences in the metabolic scaling exponent that we found were at different developmental stages of snails, because ontogeny involves increases in size at different rates, which in turn, generate differential energy demands. Copyright © 2013 Elsevier Inc. All rights reserved.

  19. Emergence of intercolonial variation in termite shelter tube patterns and prediction of its underlying mechanism

    OpenAIRE

    Mizumoto, Nobuaki; Kobayashi, Kazuya; Matsuura, Kenji

    2015-01-01

    Building behaviours occur in various organisms from bacteria to humans. Social insects build various structures such as large nests and underground galleries, achieved by self-organization. Structures built by social insects have recently been demonstrated to vary widely in size and shape within a species, even under the same environmental conditions. However, little is known about how intraspecific variation in structures emerges from collective behaviours. Here we show that the colony varia...

  20. Stabilizing selection on genome size in a population of Festuca pallens under conditions of intensive intraspecific competition.

    Science.gov (United States)

    Smarda, Petr; Horová, Lucie; Bures, Petr; Hralová, Ivana; Marková, Michaela

    2010-09-01

    *Stabilizing selection is a key evolutionary mechanism for which there is relatively little experimental evidence. To date, stabilizing selection has never been observed at the whole-genome level. *We tested the effect of selection on genome size in a field experiment using seeds collected in a population of Festuca pallens with a highly variable genome size. Using flow cytometry, we measured the genome size in germinating seedlings and juvenile plants grown with or without high intraspecific competition (908 individuals). Above-ground biomass and leaf number were used as measurements of individual vegetative performance. The possible confounding effect of seed weight was controlled for in a separate experiment. *Growth under high competition had a significant stabilizing effect on genome size. Because no relationship was observed between genome size and vegetative performance, we assume that the elimination of plants with extreme genome sizes was the result of decreased survival as a consequence of some unrecognized stress. *Our results indicate that genome size may be under direct selection. The equal disadvantaging of either large or small genomes indicates that the selection for optimum genome size in species may be fully context dependent. This study demonstrates the power of competition experiments for the detection of weak selection processes.

  1. An updated description of the osteology of the pancake tortoise Malacochersus tornieri (Testudines: Testudinidae) with special focus on intraspecific variation.

    Science.gov (United States)

    Mautner, Anna-Katharina; Latimer, Ashley E; Fritz, Uwe; Scheyer, Torsten M

    2017-03-01

    Exceptional variability in the shell of the pancake tortoise Malacochersus tornieri, both in the keratinous surficial scutes and the underlying bones, in addition to its remarkably fenestrated bony shell are unique among tortoises. Based on 14 individuals of different sizes and ages, the observed variation in M. tornieri was described in detail, with additional notes on the typically testudinid skull, inner ear and brain endocast using microCT-scan data, as well as the limbs. Similar degrees of variation have not yet been described in any other extant turtle species and therefore seem notable in M. tornieri, and might be related to the species' unique lifestyle. Within the carapace, the peripherals and suprapygals are most variable in number. Furthermore, different combinations of peripherals are participating in the central plastral fontanelle and in some individuals additional bones take part in the formation of the plastron. J. Morphol. 278:321-333, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  2. Intraspecific differentiation of Paramecium novaurelia strains (Ciliophora, Protozoa) inferred from phylogenetic analysis of ribosomal and mitochondrial DNA variation.

    Science.gov (United States)

    Tarcz, Sebastian

    2013-01-01

    Paramecium novaurelia Beale and Schneller, 1954, was first found in Scotland and is known to occur mainly in Europe, where it is the most common species of the P. aurelia complex. In recent years, two non-European localities have been described: Turkey and the United States of America. This article presents the analysis of intraspecific variability among 25 strains of P. novaurelia with the application of ribosomal and mitochondrial loci (ITS1-5.8S-ITS2, 5' large subunit rDNA (5'LSU rDNA) and cytochrome c oxidase subunit 1 (COI) mtDNA). The mean distance observed for all of the studied P. novaurelia sequence pairs was p=0.008/0.016/0.092 (ITS1-5.8S-ITS2/5'LSU rDNA/COI). Phylogenetic trees (NJ/MP/BI) based on a comparison of all of the analysed sequences show that the studied strains of P. novaurelia form a distinct clade, separate from the P. caudatum outgroup, and are divided into two clusters (A and B) and two branches (C and D). The occurrence of substantial genetic differentiation within P. novaurelia, confirmed by the analysed DNA fragments, indicates a rapid evolution of particular species within the Paramecium genus. Copyright © 2012 Elsevier GmbH. All rights reserved.

  3. Inter- and intra-specific variation in drought sensitivity in Abies spec. and its relation to wood density and growth traits

    Science.gov (United States)

    George, Jan-Peter; Schueler, Silvio; Karanitsch-Ackerl, Sandra; Mayer, Konrad; Klumpp, Raphael T.; Grabner, Michael

    2016-01-01

    Understanding drought sensitivity of tree species and its intra-specific variation is required to estimate the effects of climate change on forest productivity, carbon sequestration and tree mortality as well as to develop adaptive forest management measures. Here, we studied the variation of drought reaction of six European Abies species and ten provenances of Abies alba planted in the drought prone eastern Austria. Tree-ring and X-ray densitometry data were used to generate early- and latewood measures for ring width and wood density. Moreover, the drought reaction of species and provenances within six distinct drought events between 1970 and 2011, as identified by the standardized precipitation index, was determined by four drought response measures. The mean reaction of species and provenances to drought events was strongly affected by the seasonal occurrence of the drought: a short, strong drought at the beginning of the growing season resulted in growth reductions up to 50%, while droughts at the end of the growing season did not affect annual increment. Wood properties and drought response measures showed significant variation among Abies species as well as among A. alba provenances. Whereas A. alba provenances explained significant parts in the variation of ring width measures, the Abies species explained significant parts in the variation of wood density parameters. A consistent pattern in drought response across the six drought events was observed only at the inter-specific level, where A. nordmanniana showed the highest resistance and A. cephalonica showed the best recovery after drought. In contrast, differences in drought reaction among provenances were only found for the milder drought events in 1986, 1990, 1993 and 2000 and the ranking of provenances varied at each drought event. This indicates that genetic variation in drought response within A. alba is more limited than among Abies species. Low correlations between wood density parameters and

  4. Inter- and intra-specific variation in drought sensitivity inAbies spec. and its relation to wood density and growth traits.

    Science.gov (United States)

    George, Jan-Peter; Schueler, Silvio; Karanitsch-Ackerl, Sandra; Mayer, Konrad; Klumpp, Raphael T; Grabner, Michael

    2015-12-15

    Understanding drought sensitivity of tree species and its intra-specific variation is required to estimate the effects of climate change on forest productivity, carbon sequestration and tree mortality as well as to develop adaptive forest management measures. Here, we studied the variation of drought reaction of six European Abies species and ten provenances of Abies alba planted in the drought prone eastern Austria. Tree-ring and X-ray densitometry data were used to generate early- and latewood measures for ring width and wood density. Moreover, the drought reaction of species and provenances within six distinct drought events between 1970 and 2011, as identified by the standardized precipitation index, was determined by four drought response measures. The mean reaction of species and provenances to drought events was strongly affected by the seasonal occurrence of the drought: a short, strong drought at the beginning of the growing season resulted in growth reductions up to 50%, while droughts at the end of the growing season did not affect annual increment. Wood properties and drought response measures showed significant variation among Abies species as well as among A. alba provenances. Whereas A. alba provenances explained significant parts in the variation of ring width measures, the Abies species explained significant parts in the variation of wood density parameters. A consistent pattern in drought response across the six drought events was observed only at the inter-specific level, where A. nordmanniana showed the highest resistance and A. cephalonica showed the best recovery after drought. In contrast, differences in drought reaction among provenances were only found for the milder drought events in 1986, 1990, 1993 and 2000 and the ranking of provenances varied at each drought event. This indicates that genetic variation in drought response within A. alba is more limited than among Abies species. Low correlations between wood density parameters and

  5. Intraspecific karyotypic polymorphism is highly concordant with allozyme variation in Lysimachia mauritiana (Primulaceae: Myrsinoideae) in Taiwan: implications for the colonization history and dispersal patterns of coastal plants.

    Science.gov (United States)

    Kono, Yoshiko; Chung, Kuo-Fang; Chen, Chih-Hui; Hoshi, Yoshikazu; Setoguchi, Hiroaki; Chou, Chang-Hung; Oginuma, Kazuo; Peng, Ching-I

    2012-11-01

    Investigating intraspecific karyotypic and genetic variations jointly can provide unique insights into how historical, ecological and cytogenetic factors influence microevolution. A coastal herb, Lysimachia mauritiana, exhibits extensive karyotypic polymorphism and displays a complex cytogeographic pattern across the Ryukyus. To explore whether a similar degree of chromosomal variation exists south of the Ryukyus, and in an attempt to ascertain the mechanisms that may have generated the patterns, comprehensive sampling was conducted in Taiwan. Karyotypes were analysed at mitotic metaphase for 550 individuals from 42 populations throughout Taiwan Proper and its adjacent islands. In addition, genetic variation was estimated using 12 allozymes (21 loci) of 314 individuals sampled from 12 localities. Four chromosome numbers and eight cytotypes, including four endemic cytotypes, were detected. Cytotype distributions were highly structured geographically, with single cytotypes present in most populations and four major cytotypes dominating the north, east and south of Taiwan and the Penghu Archipelago. Allozyme variation was very low and F-statistics indicated an extremely high level of population differentiation, implying limited gene flow among populations. Cluster analysis of allozyme variation uncovered four geographic groups, each corresponding perfectly to the four dominant cytotypes. The geographic structure of cytotype distribution and allozyme variation probably resulted from severe genetic drift triggered by genetic bottlenecks, suggesting that Taiwanese populations were likely to be derived from four independent founder events. In the few localities with multiple cytotypes, cytogeographic patterns and inferences of chromosomal evolution revealed a trend of northward dispersal, consistent with the course of the Kuroshio Current that has been influential in shaping the coastal biota of the region. The data elucidate the patterns of colonization and the effects

  6. Intraspecific variation in stomatal traits, leaf traits and physiology reflects adaptation along aridity gradients in a South African shrub.

    Science.gov (United States)

    Carlson, Jane E; Adams, Christopher A; Holsinger, Kent E

    2016-01-01

    Trait-environment relationships are commonly interpreted as evidence for local adaptation in plants. However, even when selection analyses support this interpretation, the mechanisms underlying differential benefits are often unknown. This study addresses this gap in knowledge using the broadly distributed South African shrub Protea repens. Specifically, the study examines whether broad-scale patterns of trait variation are consistent with spatial differences in selection and ecophysiology in the wild. In a common garden study of plants sourced from 19 populations, associations were measured between five morphological traits and three axes describing source climates. Trait-trait and trait-environment associations were analysed in a multi-response model. Within two focal populations in the wild, selection and path analyses were used to test associations between traits, fecundity and physiological performance. Across 19 populations in a common garden, stomatal density increased with the source population's mean annual temperature and decreased with its average amount of rainfall in midsummer. Concordantly, selection analysis in two natural populations revealed positive selection on stomatal density at the hotter, drier site, while failing to detect selection at the cooler, moister site. Dry-site plants with high stomatal density also had higher stomatal conductances, cooler leaf temperatures and higher light-saturated photosynthetic rates than those with low stomatal density, but no such relationships were present among wet-site plants. Leaf area, stomatal pore index and specific leaf area in the garden also co-varied with climate, but within-population differences were not associated with fitness in either wild population. The parallel patterns of broad-scale variation, differences in selection and differences in trait-ecophysiology relationships suggest a mechanism for adaptive differentiation in stomatal density. Densely packed stomata may improve performance by

  7. Intraspecific variation in body size and the rate of reproduction in female insects - adaptive allometry or biophysical constraint?

    Science.gov (United States)

    Berger, David; Olofsson, Martin; Friberg, Magne; Karlsson, Bengt; Wiklund, Christer; Gotthard, Karl

    2012-11-01

    1. A high rate of reproduction may be costly if ecological factors limit immediate reproductive output as a fast metabolism compromises own future survival. Individuals with more reserves need more time and opportunity to realize their reproductive potential. Theory therefore predicts that the reproductive rate, defined as the investment in early reproduction in proportion to total potential, should decrease with body size within species. 2. However, metabolic constraints on body size- and temperature-dependent biological rates may impede biophysical adaptation. Furthermore, the sequential manner resources that are allocated to somatic vs. reproductive tissue during ontogeny may, when juveniles develop in unpredictable environments, further contribute to non-adaptive variation in adult reproductive rates. 3. With a model on female egg laying in insects, we demonstrate how variation in body reserves is predicted to affect reproductive rate under different ecological scenarios. Small females always have higher reproductive rates but shorter lifespans. However, incorporation of female host selectivity leads to more similar reproductive rates among female size classes, and oviposition behaviour is predicted to co-evolve with reproductive rate, resulting in small females being more selective in their choice and gaining relatively more from it. 4. We fed simulations with data on the butterfly Pararge aegeria to compare model predictions with reproductive rates of wild butterflies. However, simulated reproductive allometry was a poor predictor of that observed. Instead, reproductive rates were better explained as a product of metabolic constraints on rates of egg maturation, and an empirically derived positive allometry between reproductive potential and size. However, fitness is insensitive to moderate deviations in reproductive rate when oviposition behaviour is allowed to co-evolve in the simulations, suggesting that behavioural compensation may mitigate putative

  8. Chloride and sulphate toxicity to Hydropsyche exocellata (Trichoptera, Hydropsychidae): Exploring intraspecific variation and sub-lethal endpoints

    Energy Technology Data Exchange (ETDEWEB)

    Sala, Miquel [Centre Tecnològic Forestal de Catalunya - CTFC, Solsona, Catalunya (Spain); Faria, Melissa [CESAM, Departamento de Biologia, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Sarasúa, Ignacio [Technische Universität München, Munich, Bayern (Germany); Barata, Carlos [Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Barcelona (Spain); Bonada, Núria [Grup de Recerca Freshwater Ecology and Management (FEM), Departament d' Ecologia, Facultat de Biologia, Universitat de Barcelona (UB), Diagonal 643, 08028 Barcelona, Catalonia (Spain); Grup de Recerca Freshwater Ecology and Management (FEM), Departament d' Ecologia, Facultat de Biologia, Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona - UB, Diagonal 643, 08028 Barcelona, Catalonia (Spain); Brucet, Sandra [Aquatic Ecology Group, BETA Tecnio Centre, University of Vic - Central University of Catalonia, Vic, Catalonia (Spain); Catalan Institution for Research and Advanced Studies, ICREA, Barcelona 08010 (Spain); Llenas, Laia; Ponsá, Sergio [Aquatic Ecology Group, BETA Tecnio Centre, University of Vic - Central University of Catalonia, Vic, Catalonia (Spain); Prat, Narcís [Grup de Recerca Freshwater Ecology and Management (FEM), Departament d' Ecologia, Facultat de Biologia, Universitat de Barcelona (UB), Diagonal 643, 08028 Barcelona, Catalonia (Spain); Soares, Amadeu M.V.M. [CESAM, Departamento de Biologia, Universidade de Aveiro, 3810-193 Aveiro (Portugal); and others

    2016-10-01

    The rivers and streams of the world are becoming saltier due to human activities. In spite of the potential damage that salt pollution can cause on freshwater ecosystems, this is an issue that is currently poorly managed. Here we explored intraspecific differences in the sensitivity of freshwater fauna to two major ions (Cl{sup −} and SO{sub 4}{sup 2−}) using the net-spinning caddisfly Hydropsyche exocellata Dufour 1841 (Trichoptera, Hydropsychidae) as a model organism. We exposed H. exocellata to saline solutions (reaching a conductivity of 2.5 mS cm{sup −1}) with Cl{sup −}:SO{sub 4}{sup 2−} ratios similar to those occurring in effluents coming from the meat, mining and paper industries, which release dissolved salts to rivers and streams in Spain. We used two different populations, coming from low and high conductivity streams. To assess toxicity, we measured sub-lethal endpoints: locomotion, symmetry of the food-capturing nets and oxidative stress biomarkers. According to biomarkers and net building, the population historically exposed to lower conductivities (B10) showed higher levels of stress than the population historically exposed to higher conductivities (L102). However, the differences between populations were not strong. For example, net symmetry was lower in the B10 than in the L102 only 48 h after treatment was applied, and biomarkers showed a variety of responses, with no discernable pattern. Also, treatment effects were rather weak, i.e. only some endpoints, and in most cases only in the B10 population, showed a significant response to treatment. The lack of consistent differences between populations and treatments could be related to the high salt tolerance of H. exocellata, since both populations were collected from streams with relatively high conductivities. The sub-lethal effects tested in this study can offer an interesting and promising tool to monitor freshwater salinization by combining physiological and behavioural bioindicators

  9. Intraspecific niche models for ponderosa pine (Pinus ponderosa) suggest potential variability in population-level response to climate change

    Science.gov (United States)

    Maguire, Kaitlin C.; Shinneman, Douglas; Potter, Kevin M.; Hipkins, Valerie D.

    2018-01-01

    Unique responses to climate change can occur across intraspecific levels, resulting in individualistic adaptation or movement patterns among populations within a given species. Thus, the need to model potential responses among genetically distinct populations within a species is increasingly recognized. However, predictive models of future distributions are regularly fit at the species level, often because intraspecific variation is unknown or is identified only within limited sample locations. In this study, we considered the role of intraspecific variation to shape the geographic distribution of ponderosa pine (Pinus ponderosa), an ecologically and economically important tree species in North America. Morphological and genetic variation across the distribution of ponderosa pine suggest the need to model intraspecific populations: the two varieties (var. ponderosa and var. scopulorum) and several haplotype groups within each variety have been shown to occupy unique climatic niches, suggesting populations have distinct evolutionary lineages adapted to different environmental conditions. We utilized a recently-available, geographically-widespread dataset of intraspecific variation (haplotypes) for ponderosa pine and a recently-devised lineage distance modeling approach to derive additional, likely intraspecific occurrence locations. We confirmed the relative uniqueness of each haplotype-climate relationship using a niche-overlap analysis, and developed ecological niche models (ENMs) to project the distribution for two varieties and eight haplotypes under future climate forecasts. Future projections of haplotype niche distributions generally revealed greater potential range loss than predicted for the varieties. This difference may reflect intraspecific responses of distinct evolutionary lineages. However, directional trends are generally consistent across intraspecific levels, and include a loss of distributional area and an upward shift in elevation. Our results

  10. Simulating the Interacting Effects of Intraspecific Variation, Disturbance, and Competition on Climate-Driven Range Shifts in Trees.

    Science.gov (United States)

    Moran, Emily V; Ormond, Rhys A

    2015-01-01

    Climate change is expected to favor shifts in plant distributions; some such shifts are already being observed along elevation gradients. However, the rate of such shifts may be limited by their ability to reach newly suitable areas and by competition from resident species. The degree of local adaptation and genetic variation may also play a role in the interaction between migrants and residents by affecting relative fitness. We used a simulation model to explore the interacting effects of dispersal, fecundity, disturbance, and genetic variation on range-edge dynamics between a pair of demographically similar tree species. Ideal climate for an individual is determined by genotype. The simulated landscape undergoes an 80-year period of climate change in which climate bands shift upslope; subsequently, climate is held constant for 300 years. The presence of a high-elevation competitor caused a significant lag in the range shift of the low-elevation species relative to competition-free scenarios. Increases in fecundity and dispersal distance both helped to speed up the replacement of the high-elevation species by the low-elevation species at their range boundary. While some disturbance scenarios facilitated this transition, frequent canopy disturbance inhibited colonization by removing reproductive adults and led to range contractions in both species. Differences between dispersal scenarios were more pronounced when disturbance was frequent (15 vs. 25 year return interval) and dispersal was limited. When the high-elevation species lacked genetic variation, its range was more-easily invaded by the low-elevation species, while a similar lack of variation in the low-elevation species inhibited colonization-but only when this lack of variation decreased the fitness of the affected species near the range boundary. Our model results support the importance of measuring and including dispersal/fecundity, disturbance type and frequency, and genetic variation when assessing the

  11. Intraspecific and Intracolonial Variation in the Profile of Venom Alkaloids and Cuticular Hydrocarbons of the Fire Ant Solenopsis saevissima Smith (Hymenoptera: Formicidae

    Directory of Open Access Journals (Sweden)

    Eduardo Gonçalves Paterson Fox

    2012-01-01

    Full Text Available Fire ants are aggressive Neotropical ants that are extensively similar in general biology and morphology, making species identification difficult. Some fire ant species are top-rated pests spreading throughout the world by trade vessels. Many researchers attempted to sort between invasive and native species by using chemical characters, including patterns of venom alkaloids. The present study is the first to report intraspecific variation in some chemical characters, namely, cuticular hydrocarbons and venom alkaloids, within the Brazilian fire ant species Solenopsis saevissima and also reports on within-nest variations among members of different castes. Two different haplotypes (cryptic species of S. saevissima were clearly identified, one presenting a predominant combination of the venom alkaloids cis- and trans-2-methyl-6-undecylpiperidine with the cuticular hydrocarbons C23, 3-Me-C23, 10-C25 : 1, C25, and 3-Me-C25, and the other a predominant combination of cis- and trans-2-methyl-6-tridecenylpiperidine with predominance of 12-C25 : 1, C25, 11-Me-C25, 3-Me-C25, 13-C27 : 1, C27, and 13-Me-C27. Intranest variations revealed that the proportions among these compounds varied sensibly among workers of different sizes, gynes, and males (no alkaloids were detected in the latter. Larva contained vestiges of the same compounds. The recorded chemical profiles are quite different from previous reports with S. saevissima samples from São Paulo. The finds thus support other recent claims that S. saevissima includes cryptic species; the study, moreover, adds the find that they can occur in the same geographical location.

  12. Intraspecific variation in a physiological thermoregulatory mechanism: the case of the lizard Liolaemus tenuis (Liolaeminae Variación intraespecífica en un mecanismo termorregulatorio fisiológico: el caso del lagarto Liolaemus tenuis (Liolaeminae

    Directory of Open Access Journals (Sweden)

    MARCELA A VIDAL

    2008-06-01

    Full Text Available The interspecific variation of heating rates in Liolaemus lizards, suggests an adaptive value of this physiological thermoregulatory mechanism, which would allow lizards to cope with the environmental thermal restrictions, imposed to behavioral thermoregulation. This trend has barely been tested at intraspecific level, and here we explore if intraspecific variation in heating rates occurs in Liolaemus tenuis, a relative widely distributed species from central Chile. We test the hypothesis that heating rates are related to the thermal environmental conditions at which populations are exposed, by comparing the heating rates of three populations (from a latitudinal range, which inhabit under different thermal conditions. Additionally, we explore if the intrinsic factor, sex, also modulates heating rates. There was a significant intraspecific variation in heating rates, at population and gender level. These rates however, showed only a partial relationship with the environmental thermal conditions. We found that the northern population, inhabiting at higher temperature, heated slower, which might reduce the risk of overheating. On the other hand, independent of the population, females heated slower than males. The meaning of this sexual variation is unclear, but may be consequence of the significant differences in genders' social behavior. Because males defend a territory with a harem, by heating faster, they can allocate extra time in behaviors associated to the defense and maintenance of the territory.La variación interespecífica en las tasas de calentamiento de Liolaemus pareciera ser un mecanismo fisiológico adaptativo que permitiría a los lagartos enfrentar restricciones térmicas ambientales impuestas a la termorregulación conductual. Esta tendencia ha sido raramente analizada a nivel intraespecífico y en este estudio exploramos si existe variación intraespecífica en las tasas de calentamiento de Liolaemus tenuis, una especie con rango

  13. FTIR-ATR-based prediction and modelling of lignin and energy contents reveals independent intra-specific variation of these traits in bioenergy poplars

    Directory of Open Access Journals (Sweden)

    Taylor Gail

    2011-04-01

    estimations in large data sets. Our study revealed that the intra-specific variations in lignin and energy contents were unrelated to each other and that the lignin content, therefore, was no predictor of the energy content. Employing principle component analyses we showed that factor loadings for the energy content were mainly associated with carbohydrate ring vibrations, whereas those for lignin were mainly related to aromatic compounds. Therefore, our analysis suggests that it may be possible to optimize the energy content of trees without concomitant increase in lignin.

  14. Inter and intra-specific variation in photosynthetic acclimation response to long term exposure of elevated carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Wilkinson, M. [Univ. of Essex, Colchester (United Kingdom)]|[Writtle Coll. (United Kingdom)

    1996-08-01

    The response of intra and interspecific variation in photosynthetic acclimation to growth at elevated atmospheric CO{sub 2} concentration (600{micro}mol mol-l) in six important grassland species was investigated. Plants were grown in a background sward of Lolium perenne and measurements were made after four years of growth at elevated C{sub a}. Elevated CO{sub 2} was maintained using a FACE (Free-Air Carbon Enrichment) system. Significant intra and interspecific variation in acclimation response was demonstrated. The response of adaxial and abaxial stomatal conductance to elevated CO{sub 2} was also investigated. The stomatal conductance of both the adaxial and abaxial leaf surfaces was found to be reduced by elevated C{sub a}. Significant asymmetric responses in stomatal conductance was demonstrated in D. glomerata and T. pratense. Analysis of stomatal indices and densities indicated that the observed reductions in stomatal conductance were probably the result of changes in stomatal aperture.

  15. Latitudinal variation in ecological opportunity and intraspecific competition indicates differences in niche variability and diet specialization of Arctic marine predators.

    Science.gov (United States)

    Yurkowski, David J; Ferguson, Steve; Choy, Emily S; Loseto, Lisa L; Brown, Tanya M; Muir, Derek C G; Semeniuk, Christina A D; Fisk, Aaron T

    2016-03-01

    Individual specialization (IS), where individuals within populations irrespective of age, sex, and body size are either specialized or generalized in terms of resource use, has implications on ecological niches and food web structure. Niche size and degree of IS of near-top trophic-level marine predators have been little studied in polar regions or with latitude. We quantified the large-scale latitudinal variation of population- and individual-level niche size and IS in ringed seals (Pusa hispida) and beluga whales (Delphinapterus leucas) using stable carbon and nitrogen isotope analysis on 379 paired ringed seal liver and muscle samples and 124 paired beluga skin and muscle samples from eight locations ranging from the low to high Arctic. We characterized both within- and between-individual variation in predator niche size at each location as well as accounting for spatial differences in the isotopic ranges of potential prey. Total isotopic niche width (TINW) for populations of ringed seals and beluga decreased with increasing latitude. Higher TINW values were associated with greater ecological opportunity (i.e., prey diversity) in the prey fish community which mainly consists of Capelin (Mallotus villosus) and Sand lance (Ammodytes sp.) at lower latitudes and Arctic cod (Boreogadus saida) at high latitudes. In beluga, their dietary consistency between tissues also known as the within-individual component (WIC) increased in a near 1:1 ratio with TINW (slope = 0.84), suggesting dietary generalization, whereas the slope (0.18) of WIC relative to TINW in ringed seals indicated a high degree of individual specialization in ringed seal populations with higher TINWs. Our findings highlight the differences in TINW and level of IS for ringed seals and beluga relative to latitude as a likely response to large-scale spatial variation in ecological opportunity, suggesting species-specific variation in dietary plasticity to spatial differences in prey resources and

  16. Intraspecific growth variation among rainbow trout and brook trout: Impact of initial body weight and feeding level

    DEFF Research Database (Denmark)

    Rasmussen, Richard Skøtt; Ostenfeld, T.

    2010-01-01

    larger body weight (BW) CVs compared to BT (0.257 vs. 0.206, P enhance size variations in terms...... for species (RT: 3.71, BT: 2.32, P > 0.05). The magnitude of slopes decreased over time (weeks 0–3:4.27, weeks 3–6:3.02 and weeks 6–9:1.74, P body growth. RT had...

  17. Intraspecific variation in seed dispersal of a Neotropical tree and its relationship to fruit and tree traits.

    Science.gov (United States)

    Augspurger, Carol K; Franson, Susan E; Cushman, Katherine C; Muller-Landau, Helene C

    2016-02-01

    The distribution of wind-dispersed seeds around a parent tree depends on diaspore and tree traits, as well as wind conditions and surrounding vegetation. This study of a neotropical canopy tree, Platypodium elegans, explored the extent to which parental variation in diaspore and tree traits explained (1) rate of diaspore descent in still air, (2) distributions of diaspores dispersed from a 40-m tower in the forest, and (3) natural diaspore distributions around the parent tree. The geometric mean rate of descent in still air among 20 parents was highly correlated with geometric mean wing loading(1/2) (r = 0.84). However, diaspore traits and rate of descent predicted less variation in dispersal distance from the tower, although descent rate(-1) consistently correlated with dispersal distance. Measured seed shadows, particularly their distribution edges, differed significantly among six parents (DBH range 62-181 cm) and were best fit by six separate anisotropic dispersal kernels and surveyed fecundities. Measured rate of descent and tree traits, combined in a mechanistic seed dispersal model, did not significantly explain variation among parents in natural seed dispersal distances, perhaps due to the limited power to detect effects with only six trees. Seedling and sapling distributions were at a greater mean distance from the parents than seed distributions; saplings were heavily concentrated at far distances. Variation among parents in the distribution tails so critical for recruitment could not be explained by measured diaspore or tree traits with this sample size, and may be determined more by wind patterns and the timing of abscission in relation to wind conditions. Studies of wind dispersal need to devote greater field efforts at recording the "rare" dispersal events that contribute to far dispersal distances, following their consequences, and in understanding the mechanisms that generate them.

  18. Patterns and drivers of intraspecific variation in avian life history along elevational gradients: a meta-analysis.

    Science.gov (United States)

    Alice Boyle, W; Sandercock, Brett K; Martin, Kathy

    2016-05-01

    Elevational gradients provide powerful natural systems for testing hypotheses regarding the role of environmental variation in the evolution of life-history strategies. Case studies have revealed shifts towards slower life histories in organisms living at high elevations yet no synthetic analyses exist of elevational variation in life-history traits for major vertebrate clades. We examined (i) how life-history traits change with elevation in paired populations of bird species worldwide, and (ii) which biotic and abiotic factors drive elevational shifts in life history. Using three analytical methods, we found that fecundity declined at higher elevations due to smaller clutches and fewer reproductive attempts per year. By contrast, elevational differences in traits associated with parental investment or survival varied among studies. High-elevation populations had shorter and later breeding seasons, but longer developmental periods implying that temporal constraints contribute to reduced fecundity. Analyses of clutch size data, the trait for which we had the largest number of population comparisons, indicated no evidence that phylogenetic history constrained species-level plasticity in trait variation associated with elevational gradients. The magnitude of elevational shifts in life-history traits were largely unrelated to geographic (altitude, latitude), intrinsic (body mass, migratory status), or habitat covariates. Meta-population structure, methodological issues associated with estimating survival, or processes shaping range boundaries could potentially explain the nature of elevational shifts in life-history traits evident in this data set. We identify a new risk factor for montane populations in changing climates: low fecundity will result in lower reproductive potential to recover from perturbations, especially as fewer than half of the species experienced higher survival at higher elevations. © 2015 Cambridge Philosophical Society.

  19. Heated communities: : large inter- and intraspecific variation in heat tolerance across trophic levels of a soil arthropod community

    NARCIS (Netherlands)

    Franken, Oscar; Huizinga, Milou; Ellers, Jacintha; Berg, Matty P

    Temperature extremes are predicted to increase in frequency, intensity and duration under global warming and are believed to significantly affect community composition and functioning. However, the effect of extreme climatic events on communities remains difficult to predict, especially because

  20. Intraspecific variation in root and leaf traits and leaf-root trait linkages in eight aspen demes (Populus tremula and P. tremuloides

    Directory of Open Access Journals (Sweden)

    Peter eHajek

    2013-10-01

    Full Text Available Leaf and fine root morphology and physiology have been found to vary considerably among tree species, but not much is known about intraspecific variation in root traits and their relatedness to leaf traits. Various aspen progenies (Populus tremula and P. tremuloides with different growth performance are used in short-rotation forestry. Hence, a better understanding of the link between root trait syndromes and the adaptation of a deme to a particular environment is essential in order to improve the match between planted varieties and their growth conditions. We examined the between-deme (genetic and within-deme (mostly environmental variation in important fine root traits [mean root diameter, specific root area (SRA and specific root length (SRL, root tissue density (RTD, root tip abundance, root N concentration] and their co-variation with leaf traits [specific leaf area (SLA, leaf size, leaf N concentration] in eight genetically distinct P. tremula and P. tremuloides demes. Five of the six root traits varied significantly between the demes with largest genotypic variation in root tip abundance and lowest in mean root diameter and RTD (no significant difference. Within-deme variation in root morphology was as large as between-deme variation suggesting a relatively low genetic control. Significant relationships existed neither between SLA and SRA nor between leaf N and root N concentration in a plant. Contrary to expectation, high aboveground relative growth rates (RGR were associated with large, and not small, fine root diameters with low SRA and SRL. Compared to leaf traits, the influence of root traits on RGR was generally low. We conclude that aspen exhibits large intraspecific variation in leaf and also in root morphological traits which is only partly explained by genetic distances. A root order-related analysis might give deeper insights into intraspecific root trait variation.

  1. Intraspecific competition increases toxicant effects in outdoor pond microcosms.

    Science.gov (United States)

    Knillmann, Saskia; Stampfli, Nathalie C; Beketov, Mikhail A; Liess, Matthias

    2012-10-01

    Competition is a ubiquitous factor in natural populations and has been reported to alter the ecological impact of xenobiotics. We investigated conditions that mirror the natural variation of environmental factors. For this, different treatments were applied to 96 outdoor pond microcosms by shading the ponds and harvesting the communities. Then, the effect of esfenvalerate (0.03, 0.3, and 3 μg/L) on populations of Daphnia spp. was investigated. The pesticide effect and the sensitivity of Daphnia spp. in the context of a zooplankton community was increased by intraspecific competition 11 days after contamination. This relationship was most pronounced at 0.03 and 0.3 μg/L esfenvalerate, which were the concentrations that led to partial mortality. In contrast, interspecific interaction did not significantly alter the effect of the toxicant on Daphnia spp. Modelled concentration-response curves showed that the negative effects of the pesticide differed by a factor of up to 100 depending on the strength of intraspecific competition. In addition, a wider range of concentrations led to negative effects at high levels of intraspecific competition than at low levels. We argue that increased intraspecific competition reduces the availability of resources at the individual level and thereby increases the effect of contaminants. This knowledge about the interaction between competition and the response to toxicants is important in assessing the effects of these factors under field conditions.

  2. Venom of Bothrops asper from Mexico and Costa Rica: intraspecific variation and cross-neutralization by antivenoms.

    Science.gov (United States)

    Segura, Alvaro; Herrera, María; Villalta, Mauren; Vargas, Mariángela; Uscanga-Reynell, Alfredo; de León-Rosales, Samuel Ponce; Jiménez-Corona, María Eugenia; Reta-Mares, José Francisco; Gutiérrez, José María; León, Guillermo

    2012-01-01

    Bothrops asper is the species that induces the highest incidence of snakebite envenomation in southern Mexico, Central America and parts of northern South America. The intraspecies variability in HPLC profile and toxicological activities between the venoms from specimens collected in Mexico (Veracruz) and Costa Rica (Caribbean and Pacific populations) was investigated, as well as the cross-neutralization by antivenoms manufactured in these countries. Venoms differ in their HPLC profiles and in their toxicity, since venom from Mexican population showed higher lethal and defibrinogenating activities, whereas those from Costa Rica showed higher hemorrhagic and in vitro coagulant activities. In general, antivenoms were more effective in the neutralization of homologous venoms. Overall, both antivenoms effectively neutralized the various toxic effects of venoms from the two populations of B. asper. However, antivenom raised against venom from Costa Rican specimens showed a higher efficacy in the neutralization of defibrinogenating and coagulant activities, thus highlighting immunochemical differences in the toxins responsible for these effects associated with hemostatic disturbances in snakebite envenoming. These observations illustrate how intraspecies venom variation may influence antivenom neutralizing profile. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. [RAPD analysis of the intraspecific and interspecific variation and phylogenetic relationships of Aegilops L. species with the U genome].

    Science.gov (United States)

    Goriunova, S V; Chikida, N N; Kochieva, E Z

    2010-07-01

    RAPD analysis was used to study the genetic variation and phylogenetic relationships of polyploid Aegilops species with the U genome. In total, 115 DNA samples of eight polyploid species containing the U genome and the diploid species Ae. umbellulata (U) were examined. Substantial interspecific polymorphism was observed for the majority of the polyploid species with the U genome (interspecific differences, 0.01-0,2; proportion of polymorphic loci, 56.6-88.2%). Aegilops triuncialis was identified as the only alloploid species with low interspecific polymorphism (interspecific differences, 0-0.01, P = 50%) in the U-genome group. The U-genome Aegilops species proved to be separated from other species of the genus. The phylogenetic relationships were established for the U-genome species. The greatest separation within the U-genome group was observed for the US-genome species Ae. kotschyi and Ae. variabilis. The tetraploid species Ae. triaristata and Ae. columnaris, which had the UX genome, and the hexaploid species Ae. recta (UXN) were found to be related to each other and separate from the UM-genome species. A similarity was observed between the U M-genome species Ae. ovata and Ae. biuncialis, which had the UM genome, and the ancestral diploid U-genome species Ae. umbellulata. The UC-genome species Ae. triuncialis was rather separate and slightly similar to the UX-genome species.

  4. Intraspecific variation in seed size and light intensity affect seed germination and initial seedling growth of a tropical shrub

    Directory of Open Access Journals (Sweden)

    Aniele C. R. Veloso

    2017-09-01

    Full Text Available ABSTRACT Seed germination and seedling performance are affected by environmental factors and seed traits. In this study we investigated the effects of seed size and light intensity on germinability and seedling development of Copaifera oblongifolia. A total of 225 seeds were individually weighed and sown in three germination trays composed of 75 cells each. Each tray was placed in a different germination chamber with controlled photoperiod, temperature and light intensity. Seed size showed a positive relationship with time required for seed germination, and seeds exposed to high light intensity required more time to germinate. Seed size did not affect germination percentage, but seeds sown under high light intensity had a lower germination percentage than seeds sown under low light intensity and darkness. Seedling shoot mass showed a positive relationship with seeds mass, and seedlings grown in high light intensity had greater shoot mass than seedling growth in low light intensity and darkness. Thus, seed germinability of C. oblongifolia was higher in darkness while seedlings exhibited greater development under light. Looking to explain the ability of C. oblongifolia to colonize open/disturbed sites, it seems possible that plowing soil can bury seeds, thereby stimulating the germination of seeds present in the seed bank.

  5. Molecular phylogeny of mangroves IV. nature and extent of intra-specific genetic variation and species diversity in mangroves

    International Nuclear Information System (INIS)

    Parida, A.; Parani, M.; Lakshmi, M.; Elango, S.; Ram, N.; Anuratha, C.S.

    1998-01-01

    Mangroves occupy estuarine ecosystems in the tropical regions of the world. Despite their highly productive nature and the protective roles they play in the coastal region, the ecosystem as a whole is under severe threat due to various climatic and anthropogenic factors. Therefore, the need for conservation of mangroves is widely emphasised. However, information on existing genetic diversity based on which a strategy for genetic conservation is to be drawn is not available for mangroves. This is primarily because conventional genetic analysis is difficult in these species for various reasons. Therefore, as an aid to our on-going conservation programme, efforts were made to assess the nature and extent of diversity in a number of mangrove species of the Indian coast using molecular markers. The nature and extent of intra-population diversity in sixteen mangrove species and detailed analysis of inter-population genetic polymorphism in four species, Acanthus ilicifolius, Excoecaria agallocha, Avicennia spp and Rhizophora (species and hybrid), is reported in the present communication. (author)

  6. Measuring Intraspecific Variation in Flight-Related Morphology of Monarch Butterflies (Danaus plexippus: Which Sex Has the Best Flying Gear?

    Directory of Open Access Journals (Sweden)

    Andrew K. Davis

    2015-01-01

    Full Text Available Optimal flight in butterflies depends on structural features of the wings and body, including wing size, flight muscle size, and wing loading. Arguably, there is no butterfly for which flight is more important than the monarch (Danaus plexippus, which undergoes long-distance migrations in North America. We examined morphological features of monarchs that would explain the apparent higher migratory success and flight ability of females over males. We examined 47 male and 45 female monarch specimens from a project where monarchs were reared under uniform conditions. We weighed individual body parts, including the thorax (flight muscle and wings, and computed wing loading and wing thickness for all specimens. When we compared each morphological trait between sexes, we found that females did not differ from males in terms of relative thorax (wing muscle size. Females were generally smaller than males, but females had relatively thicker wings than males for their size, which suggests greater mechanical strength. Importantly, females had significantly lower wing loading than males (7% lower. This would translate to more efficient flight, which may explain their higher migratory success. Results of this work should be useful for interpreting flight behavior and/or migration success in this and other Lepidopteran species.

  7. Intraspecific variation in essential oil composition of the medicinal plant Lippia integrifolia (Verbenaceae). Evidence for five chemotypes.

    Science.gov (United States)

    Marcial, Guillermo; de Lampasona, Marina P; Vega, Marta I; Lizarraga, Emilio; Viturro, Carmen I; Slanis, Alberto; Juárez, Miguel A; Elechosa, Miguel A; Catalán, César A N

    2016-02-01

    The aerial parts of Lippia integrifolia (incayuyo) are widely used in northwestern and central Argentina for their medicinal and aromatic properties. The essential oil composition of thirty-one wild populations of L. integrifolia covering most of its natural range was analyzed by GC and GC-MS. A total of one hundred and fifty two terpenoids were identified in the essential oils. Sesquiterpenoids were the dominant components in all but one of the collections analyzed, the only exception being a sample collected in San Juan province where monoterpenoids amounted to 51%. Five clearly defined chemotypes were observed. One possessed an exquisite and delicate sweet aroma with trans-davanone as dominant component (usually above 80%). Another with an exotic floral odour was rich in oxygenated sesquiterpenoids based on the rare lippifoliane and africanane skeletons. The trans-davanone chemotype is the first report of an essential oil containing that sesquiterpene ketone as the main constituent. The absolute configuration of trans-davanone from L. integrifolia was established as 6S, 7S, 10S, the enantiomer of trans-davanone from 'davana oil' (Artemisia pallens). Wild plants belonging to trans-davanone and lippifolienone chemotypes were propagated and cultivated in the same parcel of land in Santa Maria, Catamarca. The essential oil compositions of the cultivated plants were essentially identical to the original plants in the wild, indicating that the essential oil composition is largely under genetic control. Specimens collected near the Bolivian border that initially were identified as L. boliviana Rusby yielded an essential oil practically identical to the trans-davanone chemotype of L. integrifolia supporting the recent view that L. integrifolia (Gris.) Hieron. and L. boliviana Rusby are synonymous. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Untangling interacting mechanisms of see variation with elevation: insights from the comparison of interspecific and intraspecific studies on eastern Tibetan angiosperm species

    NARCIS (Netherlands)

    Qi, Wei; Bu, Haiyan; Cornelissen, J.H.C.; Zhang, Chunhui; Guo, Shuqing; Wang, Juhong; Zhou, Xianhui; Li, Wenjin; Du, Guozhen

    2015-01-01

    With increasing elevation, seed mass is expected to be either larger for its advantage during seedling establishment in stressful high-elevation environments (“stress-tolerance” mechanism) or smaller due to energy constraints. Based on the combination of inter- and intra-specific analyses on 4,023

  9. The conditions for speciation through intraspecific competition.

    Science.gov (United States)

    Bürger, Reinhard; Schneider, Kristan A; Willensdorfer, Martin

    2006-11-01

    It has been shown theoretically that sympatric speciation can occur if intraspecific competition is strong enough to induce disruptive selection. However, the plausibility of the involved processes is under debate, and many questions on the conditions for speciation remain unresolved. For instance, is strong disruptive selection sufficient for speciation? Which roles do genetic architecture and initial composition of the population play? How strong must assortative mating be before a population can split in two? These are some of the issues we address here. We investigate a diploid multilocus model of a quantitative trait that is under frequency-dependent selection caused by a balance of intraspecific competition and frequency-independent stabilizing selection. This trait also acts as mating character for assortment. It has been established previously that speciation can occur only if competition is strong enough to induce disruptive selection. We find that speciation becomes more difficult for very strong competition, because then extremely strong assortment is required. Thus, speciation is most likely for intermediate strengths of competition, where it requires strong, but not extremely strong, assortment. For this range of parameters, however, it is not obvious how assortment can evolve from low to high levels, because with moderately strong assortment less genetic variation is maintained than under weak or strong assortment-sometimes none at all. In addition to the strength of frequency-dependent competition and assortative mating, the roles of the number of loci, the distribution of allelic effects, the initial conditions, costs to being choosy, the strength of stabilizing selection, and the particular choice of the fitness function are explored. A multitude of possible evolutionary outcomes is observed, including loss of all genetic variation, splitting in two to five species, as well as very short and extremely long stable limit cycles. On the methodological

  10. Intraspecific plant-soil feedback and intraspecific overyielding in Arabidopsis thaliana.

    Science.gov (United States)

    Bukowski, Alexandra R; Petermann, Jana S

    2014-06-01

    -specific resource use based on genetic differences that are not expressed in morphological traits. Synthesis. Our results provide some of the first evidence for intraspecific plant-soil feedback and intraspecific overyielding. These findings may have wider implications for the maintenance of variation within species and the importance of this variation for ecosystem functioning. Our results highlight the need for an increased focus on intraspecific processes in plant diversity research to fully understand the mechanisms of coexistence and ecosystem functioning.

  11. Intraspecific variation in aerobic and anaerobic locomotion: gilthead sea bream (Sparus aurata) and Trinidadian guppy (Poecilia reticulata) do not exhibit a trade-off between maximum sustained swimming speed and minimum cost of transport

    Science.gov (United States)

    Svendsen, Jon C.; Tirsgaard, Bjørn; Cordero, Gerardo A.; Steffensen, John F.

    2015-01-01

    Intraspecific variation and trade-off in aerobic and anaerobic traits remain poorly understood in aquatic locomotion. Using gilthead sea bream (Sparus aurata) and Trinidadian guppy (Poecilia reticulata), both axial swimmers, this study tested four hypotheses: (1) gait transition from steady to unsteady (i.e., burst-assisted) swimming is associated with anaerobic metabolism evidenced as excess post exercise oxygen consumption (EPOC); (2) variation in swimming performance (critical swimming speed; Ucrit) correlates with metabolic scope (MS) or anaerobic capacity (i.e., maximum EPOC); (3) there is a trade-off between maximum sustained swimming speed (Usus) and minimum cost of transport (COTmin); and (4) variation in Usus correlates positively with optimum swimming speed (Uopt; i.e., the speed that minimizes energy expenditure per unit of distance traveled). Data collection involved swimming respirometry and video analysis. Results showed that anaerobic swimming costs (i.e., EPOC) increase linearly with the number of bursts in S. aurata, with each burst corresponding to 0.53 mg O2 kg−1. Data are consistent with a previous study on striped surfperch (Embiotoca lateralis), a labriform swimmer, suggesting that the metabolic cost of burst swimming is similar across various types of locomotion. There was no correlation between Ucrit and MS or anaerobic capacity in S. aurata indicating that other factors, including morphological or biomechanical traits, influenced Ucrit. We found no evidence of a trade-off between Usus and COTmin. In fact, data revealed significant negative correlations between Usus and COTmin, suggesting that individuals with high Usus also exhibit low COTmin. Finally, there were positive correlations between Usus and Uopt. Our study demonstrates the energetic importance of anaerobic metabolism during unsteady swimming, and provides intraspecific evidence that superior maximum sustained swimming speed is associated with superior swimming economy and

  12. Intraspecific variation in aerobic and anaerobic locomotion: gilthead sea bream (Sparus aurata) and Trinidadian guppy (Poecilia reticulata) do not exhibit a trade-off between maximum sustained swimming speed and minimum cost of transport.

    Science.gov (United States)

    Svendsen, Jon C; Tirsgaard, Bjørn; Cordero, Gerardo A; Steffensen, John F

    2015-01-01

    Intraspecific variation and trade-off in aerobic and anaerobic traits remain poorly understood in aquatic locomotion. Using gilthead sea bream (Sparus aurata) and Trinidadian guppy (Poecilia reticulata), both axial swimmers, this study tested four hypotheses: (1) gait transition from steady to unsteady (i.e., burst-assisted) swimming is associated with anaerobic metabolism evidenced as excess post exercise oxygen consumption (EPOC); (2) variation in swimming performance (critical swimming speed; U crit) correlates with metabolic scope (MS) or anaerobic capacity (i.e., maximum EPOC); (3) there is a trade-off between maximum sustained swimming speed (U sus) and minimum cost of transport (COTmin); and (4) variation in U sus correlates positively with optimum swimming speed (U opt; i.e., the speed that minimizes energy expenditure per unit of distance traveled). Data collection involved swimming respirometry and video analysis. Results showed that anaerobic swimming costs (i.e., EPOC) increase linearly with the number of bursts in S. aurata, with each burst corresponding to 0.53 mg O2 kg(-1). Data are consistent with a previous study on striped surfperch (Embiotoca lateralis), a labriform swimmer, suggesting that the metabolic cost of burst swimming is similar across various types of locomotion. There was no correlation between U crit and MS or anaerobic capacity in S. aurata indicating that other factors, including morphological or biomechanical traits, influenced U crit. We found no evidence of a trade-off between U sus and COTmin. In fact, data revealed significant negative correlations between U sus and COTmin, suggesting that individuals with high U sus also exhibit low COTmin. Finally, there were positive correlations between U sus and U opt. Our study demonstrates the energetic importance of anaerobic metabolism during unsteady swimming, and provides intraspecific evidence that superior maximum sustained swimming speed is associated with superior swimming

  13. Intraspecific variation in aerobic and anaerobic locomotion: gilthead sea bream (Sparus aurata and Trinidadian guppy (Poecilia reticulata do not exhibit a trade-off between maximum sustained swimming speed and minimum cost of transport.

    Directory of Open Access Journals (Sweden)

    Jon Christian Svendsen

    2015-02-01

    Full Text Available Intraspecific variation and trade-off in aerobic and anaerobic traits remain poorly understood in aquatic locomotion. Using gilthead sea bream (Sparus aurata and Trinidadian guppy (Poecilia reticulata, both axial swimmers, this study tested four hypotheses: 1 gait transition from steady to unsteady (i.e. burst-assisted swimming is associated with anaerobic metabolism evidenced as excess post exercise oxygen consumption (EPOC; 2 variation in swimming performance (critical swimming speed; Ucrit correlates with metabolic scope (MS or anaerobic capacity (i.e. maximum EPOC; 3 there is a trade-off between maximum sustained swimming speed (Usus and minimum cost of transport (COTmin; and 4 variation in Usus correlates positively with optimum swimming speed (Uopt; i.e. the speed that minimizes energy expenditure per unit of distance travelled. Data collection involved swimming respirometry and video analysis. Results showed that anaerobic swimming costs (i.e. EPOC increase linearly with the number of bursts in S. aurata, with each burst corresponding to 0.53 mg O2 kg-1. Data are consistent with a previous study on striped surfperch (Embiotoca lateralis, a labriform swimmer, suggesting that the metabolic cost of burst swimming is similar across various types of locomotion. There was no correlation between Ucrit and MS or anaerobic capacity in S. aurata indicating that other factors, including morphological or biomechanical traits, influenced Ucrit. We found no evidence of a trade-off between Usus and COTmin. In fact, data revealed significant negative correlations between Usus and COTmin, suggesting that individuals with high Usus also exhibit low COTmin. Finally, there were positive correlations between Usus and Uopt. Our study demonstrates the energetic importance of anaerobic metabolism during unsteady swimming, and provides intraspecific evidence that superior maximum sustained swimming speed is associated with superior swimming economy and optimum

  14. How variation between individuals affects species coexistence.

    Science.gov (United States)

    Hart, Simon P; Schreiber, Sebastian J; Levine, Jonathan M

    2016-08-01

    Although the effects of variation between individuals within species are traditionally ignored in studies of species coexistence, the magnitude of intraspecific variation in nature is forcing ecologists to reconsider. Compelling intuitive arguments suggest that individual variation may provide a previously unrecognised route to diversity maintenance by blurring species-level competitive differences or substituting for species-level niche differences. These arguments, which are motivating a large body of empirical work, have rarely been evaluated with quantitative theory. Here we incorporate intraspecific variation into a common model of competition and identify three pathways by which this variation affects coexistence: (1) changes in competitive dynamics because of nonlinear averaging, (2) changes in species' mean interaction strengths because of variation in underlying traits (also via nonlinear averaging) and (3) effects on stochastic demography. As a consequence of the first two mechanisms, we find that intraspecific variation in competitive ability increases the dominance of superior competitors, and intraspecific niche variation reduces species-level niche differentiation, both of which make coexistence more difficult. In addition, individual variation can exacerbate the effects of demographic stochasticity, and this further destabilises coexistence. Our work provides a theoretical foundation for emerging empirical interests in the effects of intraspecific variation on species diversity. © 2016 John Wiley & Sons Ltd/CNRS.

  15. Estimating intraspecific genetic diversity from community DNA metabarcoding data

    Directory of Open Access Journals (Sweden)

    Vasco Elbrecht

    2018-04-01

    Taeniopteryx nebulosa and the caddisfly Hydropsyche pellucidula showed a distinct north–south cline with respect to haplotype distribution, while the beetle Oulimnius tuberculatus and the isopod Asellus aquaticus displayed no clear population pattern but differed in genetic diversity. Discussion We developed a strategy to infer intraspecific genetic diversity from bulk invertebrate metabarcoding data. It needs to be stressed that at this point this metabarcoding-informed haplotyping is not capable of capturing the full diversity present in such samples, due to variation in specimen size, primer bias and loss of sequence variants with low abundance. Nevertheless, for a high number of species intraspecific diversity was recovered, identifying potentially isolated populations and taxa for further more detailed phylogeographic investigation. While we are currently lacking large-scale metabarcoding datasets to fully take advantage of our new approach, metabarcoding-informed haplotyping holds great promise for biomonitoring efforts that not only seek information about species diversity but also underlying genetic diversity.

  16. Field manipulations of resources mediate the transition from intraspecific competition to facilitation.

    Science.gov (United States)

    Svanfeldt, Karin; Monro, Keyne; Marshall, Dustin J

    2017-05-01

    Population density affects individual performance, though its effects are often mixed. For sessile species, increases in population density typically reduce performance. Still, cases of positive density-dependence do occur in sessile systems and demand explanation. The stress gradient hypothesis (SGH) predicts that under stressful conditions, positive effects of facilitation may outweigh the negative effects of competition. While some elements of the SGH are well studied, its potential to explain intraspecific facilitation has received little attention. Further, there have been questions regarding whether the SGH holds if the stressor is a resource. Most studies of interactions between the environment and intraspecific facilitation have relied on natural environmental gradients; manipulative studies are much rarer. To test the effects of intraspecific density and resources, we manipulated resource availability over natural population densities for the marine bryozoan Watersipora subtorquata. We found negative effects of density on colony performance in low resource environments, but mainly positive density-dependence in high resource environments. By adding resources, competition effects were reduced and the positive effects of facilitation were revealed. Our results suggest that resource availability mediates the relative strength of competition and facilitation in our system. We also suggest that intraspecific facilitation is more common than may be appreciated and that environmental variation may mediate the balance between negative and positive density-dependence. © 2017 The Authors. Journal of Animal Ecology © 2017 British Ecological Society.

  17. Intraspecific Variation and Phylogenetic Relationships Are Revealed by ITS1 Secondary Structure Analysis and Single-Nucleotide Polymorphism in Ganoderma lucidum.

    Directory of Open Access Journals (Sweden)

    Xiuqing Zhang

    Full Text Available Ganoderma lucidum is a typical polypore fungus used for traditional Chinese medical purposes. The taxonomic delimitation of Ganoderma lucidum is still debated. In this study, we sequenced seven internal transcribed spacer (ITS sequences of Ganoderma lucidum strains and annotated the ITS1 and ITS2 regions. Phylogenetic analysis of ITS1 differentiated the strains into three geographic groups. Groups 1-3 were originated from Europe, tropical Asia, and eastern Asia, respectively. While ITS2 could only differentiate the strains into two groups in which Group 2 originated from tropical Asia gathered with Groups 1 and 3 originated from Europe and eastern Asia. By determining the secondary structures of the ITS1 sequences, these three groups exhibited similar structures with a conserved central core and differed helices. While compared to Group 2, Groups 1 and 3 of ITS2 sequences shared similar structures with the difference in helix 4. Large-scale evaluation of ITS1 and ITS2 both exhibited that the majority of subgroups in the same group shared the similar structures. Further Weblogo analysis of ITS1 sequences revealed two main variable regions located in helix 2 in which C/T or A/G substitutions frequently occurred and ITS1 exhibited more nucleotide variances compared to ITS2. ITS1 multi-alignment of seven spawn strains and culture tests indicated that a single-nucleotide polymorphism (SNP site at position 180 correlated with strain antagonism. The HZ, TK and 203 fusion strains of Ganoderma lucidum had a T at position 180, whereas other strains exhibiting antagonism, including DB, RB, JQ, and YS, had a C. Taken together, compared to ITS2 region, ITS1 region could differentiated Ganoderma lucidum into three geographic originations based on phylogenetic analysis and secondary structure prediction. Besides, a SNP in ITS 1 could delineate Ganoderma lucidum strains at the intraspecific level. These findings will be implemented to improve species quality

  18. Intraspecific Variation and Phylogenetic Relationships Are Revealed by ITS1 Secondary Structure Analysis and Single-Nucleotide Polymorphism in Ganoderma lucidum

    Science.gov (United States)

    Pei, Haisheng; Chen, Zhou; Tan, Xiaoyan; Hu, Jing; Yang, Bin; Sun, Junshe

    2017-01-01

    Ganoderma lucidum is a typical polypore fungus used for traditional Chinese medical purposes. The taxonomic delimitation of Ganoderma lucidum is still debated. In this study, we sequenced seven internal transcribed spacer (ITS) sequences of Ganoderma lucidum strains and annotated the ITS1 and ITS2 regions. Phylogenetic analysis of ITS1 differentiated the strains into three geographic groups. Groups 1–3 were originated from Europe, tropical Asia, and eastern Asia, respectively. While ITS2 could only differentiate the strains into two groups in which Group 2 originated from tropical Asia gathered with Groups 1 and 3 originated from Europe and eastern Asia. By determining the secondary structures of the ITS1 sequences, these three groups exhibited similar structures with a conserved central core and differed helices. While compared to Group 2, Groups 1 and 3 of ITS2 sequences shared similar structures with the difference in helix 4. Large-scale evaluation of ITS1 and ITS2 both exhibited that the majority of subgroups in the same group shared the similar structures. Further Weblogo analysis of ITS1 sequences revealed two main variable regions located in helix 2 in which C/T or A/G substitutions frequently occurred and ITS1 exhibited more nucleotide variances compared to ITS2. ITS1 multi-alignment of seven spawn strains and culture tests indicated that a single-nucleotide polymorphism (SNP) site at position 180 correlated with strain antagonism. The HZ, TK and 203 fusion strains of Ganoderma lucidum had a T at position 180, whereas other strains exhibiting antagonism, including DB, RB, JQ, and YS, had a C. Taken together, compared to ITS2 region, ITS1 region could differentiated Ganoderma lucidum into three geographic originations based on phylogenetic analysis and secondary structure prediction. Besides, a SNP in ITS 1 could delineate Ganoderma lucidum strains at the intraspecific level. These findings will be implemented to improve species quality control in the

  19. Intraspecific Variation and Phylogenetic Relationships Are Revealed by ITS1 Secondary Structure Analysis and Single-Nucleotide Polymorphism in Ganoderma lucidum.

    Science.gov (United States)

    Zhang, Xiuqing; Xu, Zhangyang; Pei, Haisheng; Chen, Zhou; Tan, Xiaoyan; Hu, Jing; Yang, Bin; Sun, Junshe

    2017-01-01

    Ganoderma lucidum is a typical polypore fungus used for traditional Chinese medical purposes. The taxonomic delimitation of Ganoderma lucidum is still debated. In this study, we sequenced seven internal transcribed spacer (ITS) sequences of Ganoderma lucidum strains and annotated the ITS1 and ITS2 regions. Phylogenetic analysis of ITS1 differentiated the strains into three geographic groups. Groups 1-3 were originated from Europe, tropical Asia, and eastern Asia, respectively. While ITS2 could only differentiate the strains into two groups in which Group 2 originated from tropical Asia gathered with Groups 1 and 3 originated from Europe and eastern Asia. By determining the secondary structures of the ITS1 sequences, these three groups exhibited similar structures with a conserved central core and differed helices. While compared to Group 2, Groups 1 and 3 of ITS2 sequences shared similar structures with the difference in helix 4. Large-scale evaluation of ITS1 and ITS2 both exhibited that the majority of subgroups in the same group shared the similar structures. Further Weblogo analysis of ITS1 sequences revealed two main variable regions located in helix 2 in which C/T or A/G substitutions frequently occurred and ITS1 exhibited more nucleotide variances compared to ITS2. ITS1 multi-alignment of seven spawn strains and culture tests indicated that a single-nucleotide polymorphism (SNP) site at position 180 correlated with strain antagonism. The HZ, TK and 203 fusion strains of Ganoderma lucidum had a T at position 180, whereas other strains exhibiting antagonism, including DB, RB, JQ, and YS, had a C. Taken together, compared to ITS2 region, ITS1 region could differentiated Ganoderma lucidum into three geographic originations based on phylogenetic analysis and secondary structure prediction. Besides, a SNP in ITS 1 could delineate Ganoderma lucidum strains at the intraspecific level. These findings will be implemented to improve species quality control in the

  20. Intra-specific variations in expression of stress-related genes in beech progenies are stronger than drought-induced responses.

    Science.gov (United States)

    Carsjens, Caroline; Nguyen Ngoc, Quynh; Guzy, Jonas; Knutzen, Florian; Meier, Ina Christin; Müller, Markus; Finkeldey, Reiner; Leuschner, Christoph; Polle, Andrea

    2014-12-01

    Rapidly decreasing water availability as a consequence of climate change is likely to endanger the range of long-lived tree species. A pressing question is, therefore, whether adaptation to drought exists in important temperate tree species like European beech (Fagus sylvatica L.), a wide-spread, dominant forest tree in Central Europe. Here, five beech stands were selected along a precipitation gradient from moist to dry conditions. Neutral genetic markers revealed strong variation within and little differentiation between the populations. Natural regeneration from these stands was transferred to a common garden and used to investigate the expression of genes for abscisic acid (ABA)-related drought signaling [9-cis-epoxy-dioxygenase (NCED), protein phosphatase 2C (PP2C), early responsive to dehydration (ERD)] and stress protection [ascorbate peroxidase (APX), superoxide dismutase (SOD), aldehyde dehydrogenase (ALDH), glutamine amidotransferase (GAT)] that are involved in drought acclimation. We hypothesized that progenies from dry sites exhibit constitutively higher expression levels of ABA- and stress-related genes and are less drought responsive than progenies from moist sites. Transcript levels and stress responses (leaf area loss, membrane integrity) of well-irrigated and drought-stressed plants were measured during the early, mid- and late growing season. Principal component (PC) analysis ordered the beech progenies according to the mean annual precipitation at tree origin by the transcript levels of SOD, ALDH, GAT and ERD as major loadings along PC1. PC2 separated moist and drought treatments with PP2C levels as important loading. These results suggest that phosphatase-mediated signaling is flexibly acclimated to the current requirements, whereas stress compensatory measures exhibited genotypic variation, apparently underlying climate selection. In contrast to expectation, the drought responses were less pronounced than the progeny-related differences and the

  1. Genetic and molecular analyses of natural variation indicate CBF2 as a candidate gene for underlying a freezing tolerance quantitative trait locus in Arabidopsis

    NARCIS (Netherlands)

    Alonso-Blanco, C.; Gomez-Mena, C.; Llorente, F.; Koornneef, M.; Salinas, J.; Martinez-Zapater, J.M.

    2005-01-01

    Natural variation for freezing tolerance is a major component of adaptation and geographic distribution of plant species. However, little is known about the genes and molecular mechanisms that determine its naturally occurring diversity. We have analyzed the intraspecific freezing tolerance

  2. Intraspecific chemical communication in microalgae

    Czech Academy of Sciences Publication Activity Database

    Venuleo, M.; Raven, J. A.; Giordano, Mario

    2017-01-01

    Roč. 215, č. 2 (2017), s. 516-530 ISSN 1469-8137 Institutional support: RVO:61388971 Keywords : evolution * infochemicals * intraspecific communication Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology

  3. Intra-Specific Variation Reveals Potential for Adaptation to Ocean Acidification in a Cold-Water Coral from the Gulf of Mexico

    Directory of Open Access Journals (Sweden)

    Melissa D. Kurman

    2017-05-01

    Full Text Available Ocean acidification, the decrease in seawater pH due to the absorption of atmospheric CO2, profoundly threatens the survival of a large number of marine species. Cold-water corals are considered to be among the most vulnerable organisms to ocean acidification because they are already exposed to relatively low pH and corresponding low calcium carbonate saturation states (Ω. Lophelia pertusa is a globally distributed cold-water scleractinian coral that provides critical three-dimensional habitat for many ecologically and economically significant species. In this study, four different genotypes of L. pertusa were exposed to three pH treatments (pH = 7.60, 7.75, and 7.90 over a short (2-week experimental period, and six genotypes were exposed to two pH treatments (pH = 7.60 and 7.90 over a long (6-month experimental period. Their physiological response was measured as net calcification rate and the activity of carbonic anhydrase, a key enzyme in the calcification pathway. In the short-term experiment, net calcification rates did not significantly change with pH, although they were highly variable in the low pH treatment, including some genotypes that maintained positive net calcification in undersaturated conditions. In the 6-month experiment, average net calcification was significantly reduced at low pH, with corals exhibiting net dissolution of skeleton. However, one of the same genotypes that maintained positive net calcification (+0.04% day−1 under the low pH treatment in the short-term experiment also maintained positive net calcification longer than the other genotypes in the long-term experiment, although none of the corals maintained positive calcification for the entire 6 months. Average carbonic anhydrase activity was not affected by pH, although some genotypes exhibited small, insignificant, increases in activity after the sixth month. Our results suggest that while net calcification in L. pertusa is adversely affected by ocean

  4. A variational analysis for large deflection of skew plates under ...

    African Journals Online (AJOL)

    In the present paper, the static behaviour of thin isotropic skew plates under uniformly distributed load is analyzed with the geometric nonlinearity of the model properly handled. A variational method based on total potential energy has been implemented through assumed displacement field. The computational work has ...

  5. Characterization and intraspecific variation of Fusarium semitectum ...

    African Journals Online (AJOL)

    STORAGESEVER

    2010-01-18

    Jan 18, 2010 ... PCR was performed in a Peltier Thermal Cycler, PTC-100® (MJ. Research, Inc. USA) with the following conditions: an initial denaturation at 94°C for 2 min, followed by 35 cycles of denatu- ration at 94°C for 35 s, annealing at 59°C for 55 s, extension at. 72°C for 2 min and final extension at 72°C for 7 min.

  6. Intraspecific variation in pollen viability, germination and ...

    African Journals Online (AJOL)

    Oleaceae) cultivars 'Koroneiki', 'Mastoidis' and 'Kalamata' was studied with scanning electron microscopy to identify genotype- distinguishing characters that could be employed for morphological cultivar discrimination. Pollen viability and germination ...

  7. Intraspecific variation in Tsuga canadensis foliar chemistry

    Science.gov (United States)

    Laura Ingwell; Joseph Brady; Matthew Fitzpatrick; Brian Maynard; Richard Casagrande; Evan Preisser

    2009-01-01

    Three groups of eastern hemlock (Tsuga canadensis Carr.) trees were analyzed to compare their chemical composition and the potential for naturally occurring resistance to hemlock woolly adelgid (Adelges tsguae...

  8. Intraspecific competition between co-infecting parasite strains enhances host survival in African trypanosomes.

    Science.gov (United States)

    Balmer, Oliver; Stearns, Stephen Curtis; Schötzau, Andreas; Brun, Reto

    2009-12-01

    It is becoming increasingly clear that under natural conditions parasitic infections commonly consist of co-infections with multiple conspecific strains. Multiple-strain infections lead to intraspecific interactions and may have important ecological and evolutionary effects on both hosts and parasites. However, experimental evidence on intraspecific competition or facilitation in infections has been scarce because of the technical challenges of distinguishing and tracking individual co-infecting strains. To overcome this limitation, we engineered transgenic strains of the protozoan parasite Trypanosoma brucei, the causal agent of human African sleeping sickness. Different strains were transfected with fluorescence genes of different colors to make them visually distinguishable in order to investigate the effects of multiple-strain infections on parasite population dynamics and host fitness. We infected mice either with each strain alone or with mixes of two strains. Our results show a strong mutual competitive suppression of co-infecting T. brucei strains very early in infection. This mutual suppression changes within-host parasite dynamics and alleviates the effects of infection on the host. The strength of suppression depends on the density of the co-infecting strain, and differences in life-history traits between the strains determine the consequences of strain-strain competition for the host. Unexpectedly, co-infection with a less virulent strain significantly enhances host survival (+15%). Analysis of the strain dynamics reveals that this is due to the suppression of the density of the more virulent strain (-33%), whose degree of impact ultimately determines the physical condition of the host. The competitive suppression is likely caused by allelopathic interference or by apparent competition mediated by strain-specific immune responses. These findings highlight the importance of intraspecific variation for parasite-parasite and parasite-host interactions. To

  9. Consequences of intra-specific metabolic diversity in plants for soil organisms : a baseline approach for evaluating ecological effects of genetic modifications

    NARCIS (Netherlands)

    Kabouw, P.

    2012-01-01

    Plant intra-specific variation, i.e. variation within a plant species, is known to affect organisms that are directly associated to plants. These effects may be due to for example differences in nutritional quality or defensive metabolites. Plant intra-specific variation can also affect

  10. Parameter choice in Banach space regularization under variational inequalities

    International Nuclear Information System (INIS)

    Hofmann, Bernd; Mathé, Peter

    2012-01-01

    The authors study parameter choice strategies for the Tikhonov regularization of nonlinear ill-posed problems in Banach spaces. The effectiveness of any parameter choice for obtaining convergence rates depends on the interplay of the solution smoothness and the nonlinearity structure, and it can be expressed concisely in terms of variational inequalities. Such inequalities are link conditions between the penalty term, the norm misfit and the corresponding error measure. The parameter choices under consideration include an a priori choice, the discrepancy principle as well as the Lepskii principle. For the convenience of the reader, the authors review in an appendix a few instances where the validity of a variational inequality can be established. (paper)

  11. Intraspecific chromosome variability

    Directory of Open Access Journals (Sweden)

    N Dubinin

    2010-12-01

    Full Text Available (Editorial preface. The publication is presented in order to remind us of one of dramatic pages of the history of genetics. It re-opens for the contemporary reader a comprehensive work marking the priority change from plant cytogenetics to animal cytogenetics led by wide population studies which were conducted on Drosophila polytene chromosomes. The year of the publication (1937 became the point of irretrievable branching between the directions of Old World and New World genetics connected with the problems of chromosome variability and its significance for the evolution of the species. The famous book of T. Dobzhansky (1937 was published by Columbia University in the US under the title “Genetics and the origin of species”, and in the shadow of this American ‘skybuilding’ all other works grew dim. It is remarkable that both Dobzhansky and Dubinin come to similar conclusions about the role of chromosomes in speciation. This is not surprising given that they both might be considered as representatives of the Russian genetic school, by their birth and education. Interestingly, Dobzhansky had never referred to the full paper of Dubinin et al. (1937, though a previous short communication in Nature (1936 was included together with all former papers on the related subject. In full, the volume of the original publication printed in the Biological Journal in Moscow comprised 47 pages, in that number 41 pages of the Russian text accompanied by 16 Figs, a table and reference list, and, above all, 6 pages of the English summary. This final part in English is now reproduced in the authors’ version with the only addition being the reference list in the originally printed form.

  12. Specialist-generalist model of body temperature regulation can be applied at the intraspecific level.

    Science.gov (United States)

    Przybylska, Anna S; Boratyński, Jan S; Wojciechowski, Michał S; Jefimow, Małgorzata

    2017-07-01

    According to theoretical predictions, endothermic homeotherms can be classified as either thermal specialists or thermal generalists. In high cost environments, thermal specialists are supposed to be more prone to using facultative heterothermy than generalists. We tested this hypothesis at the intraspecific level using male laboratory mice (C57BL/cmdb) fasted under different thermal conditions (20 and 10°C) and for different time periods (12-48 h). We predicted that variability of body temperature ( T b ) and time spent with T b below normothermy would increase with the increase of environmental demands (duration of fasting and cold). To verify the above prediction, we measured T b and energy expenditure of fasted mice. We did not record torpor bouts but we found that variations in T b and time spent in hypothermia increased with environmental demands. In response to fasting, mice also decreased their energy expenditure. Moreover, animals that showed more precise thermoregulation when fed had more variable T b when fasted. We postulate that the prediction of the thermoregulatory generalist-specialist trade-off can be applied at the intraspecific level, offering a valid tool for identifying mechanistic explanations of the differences in animal responses to variations in energy supply. © 2017. Published by The Company of Biologists Ltd.

  13. Revisiting Darwin's hypothesis: Does greater intraspecific variability increase species' ecological breadth?

    Science.gov (United States)

    Sides, Colby B; Enquist, Brian J; Ebersole, James J; Smith, Marielle N; Henderson, Amanda N; Sloat, Lindsey L

    2014-01-01

    Darwin first proposed that species with larger ecological breadth have greater phenotypic variation. We tested this hypothesis by comparing intraspecific variation in specific leaf area (SLA) to species' local elevational range and by assessing how external (abiotic) filters may influence observed differences in ecological breadth among species. Understanding the patterns of individual variation within and between populations will help evaluate differing hypotheses for structuring of communities and distribution of species. We selected 21 species with varying elevational ranges and compared the coefficient of variation of SLA for each species against its local elevational range. We examined the influence of external filters on local trait composition by determining if intraspecific changes in SLA with elevation have the same direction and similar rates of change as the change in community mean SLA value. In support of Darwin's hypothesis, we found a positive relationship between species' coefficient of variation for SLA with species' local elevational range. Intraspecific changes in SLA had the same sign, but generally lower magnitude than the community mean SLA. The results indicate that wide-ranging species are indeed characterized by greater intraspecific variation and that species' phenotypes shift along environmental gradients in the same direction as the community phenotypes. However, across species, the rate of intraspecific trait change, reflecting plastic and/or adaptive changes across populations, is limited and prevents species from adjusting to environmental gradients as quickly as interspecific changes resulting from community assembly.

  14. Sound velocity variations and melting of vanadium under shock compression

    International Nuclear Information System (INIS)

    Dai Chengda; Jin Xiaogang; Zhou Xianming; Liu Jianjun; Hu Jinbiao

    2001-01-01

    The sound velocities of vanadium at shock pressure ranging from 154 to 250 GPa were determined using transparent-window optical analyser techniques. A discontinuity in sound velocities at about 225 GPa may mark the partial melting under shock compression. The comparison between the measured sound velocity data sets above ∼225 GPa and calculated values yields γ 0 ∼2.0 and the empirical expression γρ=γ 0 ρ 0 is basically tenable. Additionally, shock temperatures along the principal Hugoniot of vanadium were also determined from interfacial radiation intensities according to Grover's ideal interface model. Thus the temperature at this solid-liquid phase transition was constrained to be round about 7800(±800) K on the basis of the measured Hugoniot temperatures, melting temperatures, and high-pressure sound velocity variations with pressure. (author)

  15. Experimental Evidence for an Eco-Evolutionary Coupling between Local Adaptation and Intraspecific Competition.

    Science.gov (United States)

    Siepielski, Adam M; Nemirov, Alex; Cattivera, Matthew; Nickerson, Avery

    2016-04-01

    Determining how adaptive evolution can be coupled to ecological processes is key for developing a more integrative understanding of the demographic factors that regulate populations. Intraspecific competition is an especially important ecological process because it generates negative density dependence in demographic rates. Although ecological factors are most often investigated to determine the strength of density dependence, evolutionary processes such as local adaptation could also feed back to shape variation in the strength of density dependence among populations. Using an experimental approach with damselflies, a predaceous aquatic insect, we find evidence that both density-dependent intraspecific competition and local adaptation can reduce per capita growth rates. In some cases, the effects of local adaptation on reducing per capita growth rates exceeded the ecological competitive effects of a doubling of density. However, we also found that these ecological and evolutionary properties of populations are coupled, and we offer two interpretations of the causes underlying this pattern: (1) the strength of density-dependent competition depends on the extent of local adaptation, or (2) the extent of local adaptation is shaped by the strength of density-dependent competition. Regardless of the underlying causal pathway, these results show how eco-evolutionary dynamics can affect a key demographic process regulating populations.

  16. Intraspecific Genetic dynamics under Climate Change

    DEFF Research Database (Denmark)

    Florez Rodriguez, Alexander

    Climate change has a deep influence on the maintenance and generation of global biodiversity. Past contractions, expansions and shifts in species’ ranges drove to changes in species genetic diversity. Noteworthy, the interaction among: climate change, range, population size and extinction is ofte...

  17. Intra-specific Differences in Root and Shoot Glucosinolate Profiles among White Cabbage (Brassica oleracea var capitata)

    NARCIS (Netherlands)

    Kabouw, P.; Biere, A.; Putten, van der W.H.; Dam, van N.M.

    2010-01-01

    Shoot glucosinolate profiles of Brassicaceae are known to vary within species, across environmental conditions, and between developmental stages. Here we study whether root profiles follow the intra-specific, environmental, and developmental variation observed for aerial parts in white cabbage

  18. Strain Identity of the Ectomycorrhizal Fungus Laccaria bicolor Is More Important than Richness in Regulating Plant and Fungal Performance under Nutrient Rich Conditions

    Directory of Open Access Journals (Sweden)

    Christina Hazard

    2017-09-01

    Full Text Available Effects of biodiversity on productivity are more likely to be expressed when there is greater potential for niche complementarity. In soil, chemically complex pools of nutrient resources should provide more opportunities for niche complementarity than chemically simple pools. Ectomycorrhizal (ECM fungal genotypes can exhibit substantial variation in nutrient acquisition traits and are key components of soil biodiversity. Here, we tested the hypothesis that increasing the chemical complexity and forms of soil nutrients would enhance the effects of intraspecific ECM diversity on host plant and fungal productivity. In pure culture, we found substantial variation in growth of strains of the ECM fungus Laccaria bicolor on a range of inorganic and organic forms of nutrients. Subsequent experiments examined the effects of intraspecific identity and richness using Scots pine (Pinus sylvestris seedlings colonized with different strains of L. bicolor growing on substrates supplemented with either inorganic or organic forms of nitrogen and phosphorus. Intraspecific identity effects on plant productivity were only found under the inorganic nutrient amendment, whereas intraspecific identity affected fungal productivity to a similar extent under both nutrient treatments. Overall, there were no significant effects of intraspecific richness on plant and fungal productivity. Our findings suggest soil nutrient composition does not interact strongly with ECM intraspecific richness, at least under experimental conditions where mineral nutrients were not limiting. Under these conditions, intraspecific identity of ECM fungi becomes more important than richness in modulating plant and fungal performance.

  19. Catenary Variation of Soil Properties under Oil Palm Plantation in ...

    African Journals Online (AJOL)

    Topographic position and ground slope are the main factors accounting for variations in soil properties along the catena. There is the need to manage parts of oil palm plantation on different topographic positions differently, taking cognizance of variations in soil properties along the catena, in order to ensure long term ...

  20. Variations in morphological and life-history traits under extreme ...

    Indian Academy of Sciences (India)

    C than at 32°C in D. ananassae. The genetic variations for all the quantitative and life-history traits were higher at low temperature. Variation in sexual traits was more pronounced as compared with other morphometric traits, which shows that ...

  1. A role for gene duplication and natural variation of gene expression in the evolution of metabolism.

    Directory of Open Access Journals (Sweden)

    Daniel J Kliebenstein

    Full Text Available BACKGROUND: Most eukaryotic genomes have undergone whole genome duplications during their evolutionary history. Recent studies have shown that the function of these duplicated genes can diverge from the ancestral gene via neo- or sub-functionalization within single genotypes. An additional possibility is that gene duplicates may also undergo partitioning of function among different genotypes of a species leading to genetic differentiation. Finally, the ability of gene duplicates to diverge may be limited by their biological function. METHODOLOGY/PRINCIPAL FINDINGS: To test these hypotheses, I estimated the impact of gene duplication and metabolic function upon intraspecific gene expression variation of segmental and tandem duplicated genes within Arabidopsis thaliana. In all instances, the younger tandem duplicated genes showed higher intraspecific gene expression variation than the average Arabidopsis gene. Surprisingly, the older segmental duplicates also showed evidence of elevated intraspecific gene expression variation albeit typically lower than for the tandem duplicates. The specific biological function of the gene as defined by metabolic pathway also modulated the level of intraspecific gene expression variation. The major energy metabolism and biosynthetic pathways showed decreased variation, suggesting that they are constrained in their ability to accumulate gene expression variation. In contrast, a major herbivory defense pathway showed significantly elevated intraspecific variation suggesting that it may be under pressure to maintain and/or generate diversity in response to fluctuating insect herbivory pressures. CONCLUSION: These data show that intraspecific variation in gene expression is facilitated by an interaction of gene duplication and biological activity. Further, this plays a role in controlling diversity of plant metabolism.

  2. Variations in morphological and life-history traits under extreme ...

    Indian Academy of Sciences (India)

    Madhsudhan

    The genetic variations for all the quantitative and life-history traits were higher at ... variation in quantitative traits has important evolutionary ..... Mean ± SE and phenotypic variance (s2) of morphometric and life-history traits in D. ananassae reared at different temperatures. 18°C. 25°C. 32°C. Trait. Sex. Mean ± SE s2. Mean ± ...

  3. Empirical analysis of skin friction under variations of temperature

    International Nuclear Information System (INIS)

    Parra Alvarez, A. R. de la; Groot Viana, M. de

    2014-01-01

    In soil geotechnical characterization, strength parameters, cohesion (c) and internal friction angle (Φ) has been traditional measured without taking into account temperature, been a very important issue in energy geostructures. The present document analyzes the variation of these parameters in soil-concrete interface at different temperatures. A traditional shear strength case with a forced plane of failure was used. Several tests were carried out to determine the variation of skin friction in granular and cohesive oils with temperature. (Author)

  4. Intraspecific maternal competition induces summer diapause in insect parasitoids.

    Science.gov (United States)

    Tougeron, Kévin; Hraoui, George; Le Lann, Cécile; van Baaren, Joan; Brodeur, Jacques

    2017-06-15

    Organisms often live in unpredictable environments and have to adopt life history strategies that optimize their fitness under these conditions. According to bet-hedging theory, individuals can reduce variation in fitness outcomes by investing in different strategies at the same time. For arthropods, facultative summer diapause enables survival during dry and hot periods of the year, and can be triggered by a decrease in resource abundance. However, the effect of resource depletion on diapause induction has never been disentangled from the effect of the perception of the presence of competitors. Using two solitary parasitoid species of cereal aphids as a model system, Aphidius avenae (Haliday) and Aphidius rhopalosiphi (De Stefani-Perez) (Hymenoptera: Braconidae), we tested whether (i) low absolute host density and/or (ii) high levels of parasitoid females' competition lead to maternal-induced summer diapause in parasitoid offspring. Under summer-like climatic conditions, emerging parasitoid females were (i) reared alone and exposed to different host densities (from 5 to 130 aphids), or (ii) reared together with competing females (from 2 to 20 females) and then exposed individually to 50 aphids. For both parasitoid species, low aphid densities did not induce summer diapause. However, the incidence of summer diapause increased up to a maximum of 11% with increasing levels of competition experienced by female parasitoids. More than 60% of the females produced both diapausing and nondiapausing offspring after being kept at the two highest competition densities. Such a "spreading-the-risk" strategy has likely evolved to optimize parasitoid fitness by preventing the following generation from exposure to low populations of suitable hosts and high mortality from superparasitism. These results provide the first experimental evidence of direct maternal competition-induced diapause in insects, and may change the way we apprehend the evolution of arthropod seasonal ecology

  5. Intraspecific diversity regulates fungal productivity and respiration.

    Directory of Open Access Journals (Sweden)

    Anna Wilkinson

    2010-09-01

    Full Text Available Individuals and not just species are key components of biodiversity, yet the relationship between intraspecific diversity and ecosystem functioning in microbial systems remains largely untested. This limits our ability to understand and predict the effects of altered genetic diversity in regulating key ecosystem processes and functions. Here, we use a model fungal system to test the hypothesis that intraspecific genotypic richness of Paxillus obscurosporus stimulates biomass and CO(2 efflux, but that this is dependent on nitrogen supply. Using controlled experimental microcosms, we show that populations containing several genotypes (maximum 8 of the fungus had greater productivity and produced significantly more CO(2 than those with fewer genotypes. Moreover, intraspecific diversity had a much stronger effect than a four-fold manipulation of the carbon:nitrogen ratio of the growth medium. The effects of intraspecific diversity were underpinned by strong roles of individuals, but overall intraspecific diversity increased the propensity of populations to over-yield, indicating that both complementarity and selection effects can operate within species. Our data demonstrate the importance of intraspecific diversity over a range of nitrogen concentrations, and the need to consider fine scale phylogenetic information of microbial communities in understanding their contribution to ecosystem processes.

  6. 3D Facial Landmarking under Expression, Pose, and Occlusion Variations

    NARCIS (Netherlands)

    H. Dibeklioğ lu; A.A. Salah (Albert Ali); L. Akarun

    2008-01-01

    htmlabstractAutomatic localization of 3D facial features is important for face recognition, tracking, modeling and expression analysis. Methods developed for 2D images were shown to have problems working across databases acquired with different illumination conditions. Expression variations, pose

  7. A simple genetic architecture underlies morphological variation in dogs.

    Directory of Open Access Journals (Sweden)

    Adam R Boyko

    2010-08-01

    Full Text Available Domestic dogs exhibit tremendous phenotypic diversity, including a greater variation in body size than any other terrestrial mammal. Here, we generate a high density map of canine genetic variation by genotyping 915 dogs from 80 domestic dog breeds, 83 wild canids, and 10 outbred African shelter dogs across 60,968 single-nucleotide polymorphisms (SNPs. Coupling this genomic resource with external measurements from breed standards and individuals as well as skeletal measurements from museum specimens, we identify 51 regions of the dog genome associated with phenotypic variation among breeds in 57 traits. The complex traits include average breed body size and external body dimensions and cranial, dental, and long bone shape and size with and without allometric scaling. In contrast to the results from association mapping of quantitative traits in humans and domesticated plants, we find that across dog breeds, a small number of quantitative trait loci (< or = 3 explain the majority of phenotypic variation for most of the traits we studied. In addition, many genomic regions show signatures of recent selection, with most of the highly differentiated regions being associated with breed-defining traits such as body size, coat characteristics, and ear floppiness. Our results demonstrate the efficacy of mapping multiple traits in the domestic dog using a database of genotyped individuals and highlight the important role human-directed selection has played in altering the genetic architecture of key traits in this important species.

  8. Intraspecific competition in Tridacna crocea, a burrowing bivalve.

    Science.gov (United States)

    Hamner, W M

    1978-01-01

    Intraspecific competition for space and light occurred when Tridacna crocea burrowed into coralline substratum of boulders on leeward coral reefs in the central Great Barrier Reef near Townsville, Australia. Intensity of competition was linearly related to clam density. Above about 200 clams/m 2 , all clams physically contacted one another and all shells sustained damage. Mortality in isolated populations due to intraspecific competition was estimated at 40%. Principles of intraspecific competition in plants were tested for applicability to T. crocea populations. Juvenile mortality due to competitive stress was density dependent. Aggregated distributions of one year old clams changed to random or regular distribution of adults. Normal size-frequency distribution for juveniles became skewed for older groups. A bimodal size-frequency distribution of the population was related to selective mortality in 1-3 year old clams. Adult mortality due to crowding was less severe but significant. Growth rates were inhibited by competition. Deformations in morphology resulted from crowding. Intraspecific competition for space and light by adults inhibited recruitment of young. Animal adaptations to reduce mortality under crowded conditions were also important. Larvae aggregated on settling and oriented with posterior ends pointed away from nearest neighbors. Positional alignment within the substratum was selectively advantageous. Burrowing posteriorly was preferential, but anterior and sideways burrowing as well as twisting within the burrow were also observed. Movement within substratum served to reduce local damage to the shell. Proteinaceous deposits secreted through perforations in the shell reduced subsequent damage. T. crocea populations exhibited many animal adaptations that reduced mortality during the first years of life, but as cohorts matured, plant-like patterns of competitive interaction became more significant.

  9. Intraspecific functional diversity of common species enhances community stability.

    Science.gov (United States)

    Wood, Connor M; McKinney, Shawn T; Loftin, Cynthia S

    2017-03-01

    Common species are fundamental to the structure and function of their communities and may enhance community stability through intraspecific functional diversity (iFD). We measured among-habitat and within-habitat iFD (i.e., among- and within-plant community types) of two common small mammal species using stable isotopes and functional trait dendrograms, determined whether iFD was related to short-term population stability and small mammal community stability, and tested whether spatially explicit trait filters helped explain observed patterns of iFD. Southern red-backed voles ( Myodes gapperi ) had greater iFD than deer mice ( Peromyscus maniculatus ), both among habitats, and within the plant community in which they were most abundant (their "primary habitat"). Peromyscus maniculatus populations across habitats differed significantly between years and declined 78% in deciduous forests, their primary habitat, as did the overall deciduous forest small mammal community. Myodes gapperi populations were stable across habitats and within coniferous forest, their primary habitat, as was the coniferous forest small mammal community. Generalized linear models representing internal trait filters (e.g., competition), which increase within-habitat type iFD, best explained variation in M. gapperi diet, while models representing internal filters and external filters (e.g., climate), which suppress within-habitat iFD, best explained P. maniculatus diet. This supports the finding that M. gapperi had higher iFD than P. maniculatus and is consistent with the theory that internal trait filters are associated with higher iFD than external filters. Common species with high iFD can impart a stabilizing influence on their communities, information that can be important for conserving biodiversity under environmental change.

  10. Intraspecific functional diversity of common species enhances community stability

    Science.gov (United States)

    Wood, Connor M.; McKinney, Shawn T.; Loftin, Cynthia S.

    2017-01-01

    Common species are fundamental to the structure and function of their communities and may enhance community stability through intraspecific functional diversity (iFD). We measured among-habitat and within-habitat iFD (i.e., among- and within-plant community types) of two common small mammal species using stable isotopes and functional trait dendrograms, determined whether iFD was related to short-term population stability and small mammal community stability, and tested whether spatially explicit trait filters helped explain observed patterns of iFD. Southern red-backed voles (Myodes gapperi) had greater iFD than deer mice (Peromyscus maniculatus), both among habitats, and within the plant community in which they were most abundant (their “primary habitat”). Peromyscus maniculatus populations across habitats differed significantly between years and declined 78% in deciduous forests, their primary habitat, as did the overall deciduous forest small mammal community. Myodes gapperi populations were stable across habitats and within coniferous forest, their primary habitat, as was the coniferous forest small mammal community. Generalized linear models representing internal trait filters (e.g., competition), which increase within-habitat type iFD, best explained variation in M. gapperidiet, while models representing internal filters and external filters (e.g., climate), which suppress within-habitat iFD, best explained P. maniculatus diet. This supports the finding that M. gapperi had higher iFD than P. maniculatus and is consistent with the theory that internal trait filters are associated with higher iFD than external filters. Common species with high iFD can impart a stabilizing influence on their communities, information that can be important for conserving biodiversity under environmental change.

  11. The diverse effects of intraspecific competition on the selective advantage to resistance: A model and its predictions

    NARCIS (Netherlands)

    Weis, A.E.; Hochberg, M.E.

    2000-01-01

    We constructed a model to investigate conditions under which intraspecific competition amplifies or diminishes the selective advantage to resistance. The growth trajectories of competing individual plants were depicted by logistic difference equations that incorporated basic costs (lowered growth

  12. Variations in morphological and life-history traits under extreme ...

    Indian Academy of Sciences (India)

    Madhsudhan

    increases in ecologically extreme environments, thus promoting more rapid evolutionary change. An alternative hypothesis (Johnson and Frey 1967; Blum 1988) assumes that heritability decreases under stress, which may lead to deceleration of the evolutionary process. At present, it seems that neither of these hypotheses ...

  13. Managing variations in dairy cow nutrient supply under grazing.

    Science.gov (United States)

    Peyraud, J L; Delagarde, R

    2013-03-01

    Grazed pasture, which is the cheapest source of nutrients for dairy cows, should form the basis of profitable and low-input animal production systems. Management of high-producing dairy cows at pasture is thus a major challenge in most countries. The objective of the present paper is to review the factors that can affect nutrient supply for grazing dairy cows in order to point out areas with scope for improvement on managing variations in nutrient supply to achieve high animal performance while maintaining efficient pasture utilisation per hectare (ha). Reviewing the range in animal requirements, intake capacity and pasture nutritive values shows that high-producing cows cannot satisfy their energy requirements from grazing alone and favourable to unfavourable situations for grazing dairy cows may be classified according to pasture quality and availability. Predictive models also enable calculation of supplementation levels required to meet energy requirements in all situations. Solutions to maintain acceptable level of production per cow and high output per ha are discussed. Strategies of concentrate supplementation and increasing use of legumes in mixed swards are the most promising. It is concluded that although high-producing cow cannot express their potential milk production at grazing, there is scope to improve animal performance at grazing given recent developments in our understanding of factors influencing forage intake and digestion of grazed forages.

  14. Wind power variations under humid and arid meteorological conditions

    International Nuclear Information System (INIS)

    Şen, Zekâi

    2013-01-01

    Highlights: • It indicates the role of weather parameters’ roles in the wind energy calculation. • Meteorological variables are more significant in arid regions for wind power. • It provides opportunity to take into consideration air density variability. • Wind power is presented in terms of the wind speed, temperature and pressure. - Abstract: The classical wind power per rotor area per time is given as the half product of the air density by third power of the wind velocity. This approach adopts the standard air density as constant (1.23 g/cm 3 ), which ignores the density dependence on air temperature and pressure. Weather conditions are not taken into consideration except the variations in wind velocity. In general, increase in pressure and decrease in temperature cause increase in the wind power generation. The rate of increase in the pressure has less effect on the wind power as compared with the temperature rate. This paper provides the wind power formulation based on three meteorological variables as the wind velocity, air temperature and air pressure. Furthermore, from the meteorology point of view any change in the wind power is expressed as a function of partial changes in these meteorological variables. Additionally, weather conditions in humid and arid regions differ from each other, and it is interesting to see possible differences between the two regions. The application of the methodology is presented for two meteorology stations in Istanbul, Turkey, as representative of the humid regions and Al-Madinah Al-Monawwarah, Kingdom of Saudi Arabia, for arid region, both on daily record bases for 2010. It is found that consideration of air temperature and pressure in the average wind power calculation gives about 1.3% decrease in Istanbul, whereas it is about 13.7% in Al-Madinah Al-Monawwarah. Hence, consideration of meteorological variables in wind power calculations becomes more significant in arid regions

  15. SOILS AGROCHEMICAL PROPERTIES VARIATION UNDER MEDICINAL HERBS ECOLOGICAL CROPS

    Directory of Open Access Journals (Sweden)

    Mihaela Lungu

    2012-12-01

    Full Text Available Researches have been carried out with medicinal herbs in the frame of a National project financed by CNCSIS through the Partnership Program. Ecologic and conventional technologies were applied. The project aimed to implement a standardization system of the vegetal raw materials which can be used in the cosmetic industry. Sage, basilicum, and savory were subject of the experiments, at Jucu, Cluj County, Ungureni – Butimanu, Dâmboviţa County, and Secuieni, Neamţ County. The dominant soils in these areas are Fluvisols and Haplic Chernozems in the Jucu area, Chromic Luvisol in the Ungureni – Butimanu area, and Calcic Chernozem in the Secuieni area. The agrochemical analysis of the soils from the experimental fields highlighted soil fertility properties conservation both under ecologic and conventional growing technologies.

  16. Intraspecific chromosomal and genetic polymorphism in Brassica ...

    Indian Academy of Sciences (India)

    2014-04-16

    Apr 16, 2014 ... A. V., Lemesh V. A. and Muravenko O. V. 2014 Intraspecific chromosomal and genetic polymorphism in Brassica napus L. detected by cytogenetic and molecular markers. J. Genet. ...... Howell E. C., Kearsey M. J., Jones G. H., King G. J. and Armstrong. S. J. 2008 A and C genome distinction and ...

  17. Molecular markers unravel intraspecific and interspecific genetic ...

    Indian Academy of Sciences (India)

    Molecular markers unravel intraspecific and interspecific genetic variability in Plantago ovata and some of its wild allies. Shivanjali Kotwal, Manoj K. Dhar, Balbir Kour, Kuldeep Raj and Sanjana Kaul. J. Genet. 92, 293–298. Table 1. Jaccard's similarity matrix of AFLP analysis of Plantago species. P. coronopus P. lanceolata ...

  18. 1 Catenary Variation of Soil Properties under Oil Palm Plantation in ...

    African Journals Online (AJOL)

    `123456789jkl''''#

    Department of Geography ... This study characterizes variations in soil properties in a catena under a 30-year oil palm (Elaeis guineesis) plantation established on ... gmelina, pines, eucalyptus, cocoa and para rubber grown in plantations in ...

  19. Melanic variation underlies aposematic color variation in two hymenopteran mimicry systems.

    Directory of Open Access Journals (Sweden)

    Heather M Hines

    Full Text Available The stinging hymenopteran velvet ants (Mutillidae and bumble bees (Apidae: Bombus spp. have both undergone extensive diversification in aposematic color patterns, including yellow-red hues and contrasting dark-light body coloration, as a result of Müllerian mimicry. Understanding the genetic and developmental mechanisms underlying shifts in these mimetic colors requires characterization of their pigmentation. In this study, a combination of solubility, spectrophotometry, and melanin degradation analysis are applied to several color forms and species of these lineages to determine that orange-red colors in both lineages are comprised of primarily dopamine-derived pheomelanins. Until a few recent studies, pheomelanins were thought not to occur in insects. These results support their potential to occur across insects and particularly among the Hymenoptera. Shifts between black and orange-red colors, such as between mimetic color forms of bumble bee Bombus melanopygus, are inferred to involve modification of the ratios of dark eumelanins to red pheomelanins, thus implicating the melanin pathway in mimetic diversification. This discovery highlights the need to focus on how pheomelanins are synthesized in the insect melanin pathway and the potential for new pigments to be found even in some of our most well-known insect systems.

  20. Effects of temperature on intraspecific competition in ectotherms.

    Science.gov (United States)

    Amarasekare, Priyanga; Coutinho, Renato M

    2014-09-01

    Understanding how temperature influences population regulation through its effects on intraspecific competition is an important question for which there is currently little theory or data. Here we develop a theoretical framework for elucidating temperature effects on competition that integrates mechanistic descriptions of life-history trait responses to temperature with population models that realistically capture the variable developmental delays that characterize ectotherm life cycles. This framework yields testable comparative predictions about how intraspecific competition affects reproduction, development, and mortality under alternative hypotheses about the temperature dependence of competition. The key finding is that ectotherm population regulation in seasonal environments depends crucially on the mechanisms by which temperature affects competition. When competition is strongest at temperatures optimal for reproduction, effects of temperature and competition act antagonistically, leading to more complex dynamics than when competition is temperature independent. When the strength of competition increases with temperature past the optimal temperature for reproduction, effects of temperature and competition act synergistically, leading to dynamics qualitatively similar to those when competition is temperature independent. Paradoxically, antagonistic effects yield a higher population floor despite greater fluctuations. These findings have important implications for predicting effects of climate warming on population regulation. Synergistic effects of temperature and competition can predispose populations to stochastic extinction by lowering minimum population sizes, while antagonistic effects can increase the potential for population outbreaks through greater fluctuations in abundance.

  1. Can we predict diatoms herbicide sensitivities with phylogeny? Influence of intraspecific and interspecific variability.

    Science.gov (United States)

    Esteves, Sara M; Keck, François; Almeida, Salomé F P; Figueira, Etelvina; Bouchez, Agnès; Rimet, Frédéric

    2017-10-01

    Diatoms are used as indicators of freshwater ecosystems integrity. Developing diatom-based tools to assess impact of herbicide pollution is expected by water managers. But, defining sensitivities of all species to multiple herbicides would be unattainable. The existence of a phylogenetic signal of herbicide sensitivity was shown among diatoms and should enable prediction of new species sensitivity. However, diatoms present a cryptic diversity that may lead to variation in their sensitivity to herbicides that would need to be taken into account. Using bioassays, the sensitivity to four herbicides (Atrazine, Terbutryn, Diuron, Isoproturon) was evaluated for 11 freshwater diatom taxa and intraspecific variability was assessed for two of them (Nitzschia palea and Achnanthidium spp.). Intraspecific variability of herbicide sensitivity was always smaller than interspecific variability, but intraspecific variability was more important in N. palea than in Achnanthidium spp. Indeed, one species showed no intraspecific phylogenetic signal (N. palea) whereas the other did (Achnanthidium spp.). On one hand, species boundaries are not set properly for Achnanthidium spp. which encompass several taxa. On the other hand, there is a higher phenotypic plasticity for N. palea. Finally, a phylogenetic signal of herbicide sensitivity was measured at the interspecific level, opening up prospects for setting up reliable biomonitoring tools based on sensitivity prediction, insofar as species boundaries are correctly defined.

  2. Trait-Based Community Assembly along an Elevational Gradient in Subalpine Forests: Quantifying the Roles of Environmental Factors in Inter- and Intraspecific Variability.

    Directory of Open Access Journals (Sweden)

    Ya-Huang Luo

    Full Text Available Understanding how communities respond to environmental variation is a central goal in ecology. Plant communities respond to environmental gradients via intraspecific and/or interspecific variation in plant functional traits. However, the relative contribution of these two responses to environmental factors remains poorly tested. We measured six functional traits (height, leaf thickness, specific leaf area (SLA, leaf carbon concentration (LCC, leaf nitrogen concentration (LNC and leaf phosphorus concentration (LPC for 55 tree species occurring at five elevations across a 1200 m elevational gradient of subalpine forests in Yulong Mountain, Southwest China. We examined the relative contribution of interspecific and intraspecific traits variability based on community weighted mean trait values and functional diversity, and tested how different components of trait variation respond to different environmental axes (climate and soil variables. Species turnover explained the largest amount of variation in leaf morphological traits (leaf thickness and SLA across the elevational gradient. However, intraspecific variability explained a large amount of variation (49.3%-76.3% in three other traits (height, LNC and LPC despite high levels of species turnover. The detection of limiting similarity in community assembly was improved when accounting for both intraspecific and interspecific variability. Different components of trait variation respond to different environmental axes, especially soil water content and climatic variables. Our results indicate that intraspecific variation is critical for understanding community assembly and evaluating community response to environmental change.

  3. Trait-Based Community Assembly along an Elevational Gradient in Subalpine Forests: Quantifying the Roles of Environmental Factors in Inter- and Intraspecific Variability.

    Science.gov (United States)

    Luo, Ya-Huang; Liu, Jie; Tan, Shao-Lin; Cadotte, Marc William; Wang, Yue-Hua; Xu, Kun; Li, De-Zhu; Gao, Lian-Ming

    2016-01-01

    Understanding how communities respond to environmental variation is a central goal in ecology. Plant communities respond to environmental gradients via intraspecific and/or interspecific variation in plant functional traits. However, the relative contribution of these two responses to environmental factors remains poorly tested. We measured six functional traits (height, leaf thickness, specific leaf area (SLA), leaf carbon concentration (LCC), leaf nitrogen concentration (LNC) and leaf phosphorus concentration (LPC)) for 55 tree species occurring at five elevations across a 1200 m elevational gradient of subalpine forests in Yulong Mountain, Southwest China. We examined the relative contribution of interspecific and intraspecific traits variability based on community weighted mean trait values and functional diversity, and tested how different components of trait variation respond to different environmental axes (climate and soil variables). Species turnover explained the largest amount of variation in leaf morphological traits (leaf thickness and SLA) across the elevational gradient. However, intraspecific variability explained a large amount of variation (49.3%-76.3%) in three other traits (height, LNC and LPC) despite high levels of species turnover. The detection of limiting similarity in community assembly was improved when accounting for both intraspecific and interspecific variability. Different components of trait variation respond to different environmental axes, especially soil water content and climatic variables. Our results indicate that intraspecific variation is critical for understanding community assembly and evaluating community response to environmental change.

  4. Repeated intraspecific divergence in life span and aging of African annual fishes along an aridity gradient

    Czech Academy of Sciences Publication Activity Database

    Blažek, Radim; Polačik, Matej; Kačer, P.; Cellerino, A.; Řežucha, Radomil; Methling, Caroline; Tomášek, Oldřich; Syslová, K.; Terzibasi Tozzini, E.; Albrecht, Tomáš; Vrtílek, Milan; Reichard, Martin

    2017-01-01

    Roč. 71, č. 2 (2017), s. 386-402 ISSN 0014-3820 R&D Projects: GA ČR GA13-05872S; GA ČR(CZ) GA16-00291S Institutional support: RVO:68081766 Keywords : Intraspecific variation * life span * neoplasia * pace-of-life syndrome * parallel evolution * reproductive senescence Subject RIV: EG - Zoology OBOR OECD: Ecology Impact factor: 4.201, year: 2016

  5. Terrestrial carbon and intraspecific size-variation shape lake ecosystems

    NARCIS (Netherlands)

    Jansson, M.; Persson, L.; de Roos, A.M.; I. Jones, R.; Tranvik, L.J.

    2007-01-01

    Conceptual models of lake ecosystem structure and function have generally assumed that energy in pelagic systems is derived from in situ photosynthesis and that its use by higher trophic levels depends on the average properties of individuals in consumer populations. These views are challenged by

  6. Intra-specific variations in Silene: Morphometry and ...

    African Journals Online (AJOL)

    MRT

    2013-08-14

    Aug 14, 2013 ... Silene conica L. and Silene lacera (Steven) Sims. (Sopova and Sekovski, 1982), and 2n = 46 for Silene firma Siebold and Zucc (Zhang, 1994). .... Fully mature and undamaged seeds were selected. The seeds were thoroughly vacuum-coated with gold to provide conductivity for the SEM images at Tehran ...

  7. Reactive power control methods for improved reliability of wind power inverters under wind speed variations

    DEFF Research Database (Denmark)

    Ma, Ke; Liserre, Marco; Blaabjerg, Frede

    2012-01-01

    temperature fluctuation in the most stressed devices of 3L-NPC wind power inverter under severe wind speed variations can be significantly stabilized, and the reliability of the power converter can thereby be improved while the increased stress of the other devices in the same power converter......The thermal cycling of power switching devices may lead to failures that compromise the reliability of power converters. Wind Turbine Systems (WTS) are especially subject to severe thermal cycling which may be caused by the wind speed variations or power grid faults. This paper proposes a control...... method to relieve the thermal cycling of power switching devices under severe wind speed variations, by circulating reactive power among the parallel power converters in a WTS or among the WTS's in a wind park. The amount of reactive power is adjusted to limit the junction temperature fluctuation...

  8. Dynamical role of the degree of intraspecific cooperation: A simple model for prebiotic replicators and ecosystems

    Science.gov (United States)

    Fontich, Ernest; Sardanyés, Josep

    2009-05-01

    We present a simple mean field model to analyze the dynamics of competition between two populations of replicators in terms of the degree of intraspecific cooperation (i.e., autocatalysis) in one of these populations. The first population can only replicate with Malthusian kinetics while the second one can reproduce with Malthusian or autocatalytic replication or with a combination of both reproducing strategies. The model consists of two coupled, nonlinear, autonomous ordinary differential equations. We investigate analytically and numerically the phase plane dynamics and the bifurcation scenarios of this ecologically coupled system, focusing on the outcome of competition for several degrees of intraspecific cooperation, σ, in the second population of replicators. We demonstrate that the dynamics of both populations can not be governed by a limit cycle, and also that once cooperation is considered, the topology of phase space does not allow for coexistence. Even for low values of the degree of intraspecific cooperation, for large enough autocatalytic replication rates, the second population of replicators is able to outcompete the first one, having a wide basin of attraction in state space. We characterize the same power law dependence between the outcompetition extinction times, τ, and the degree of intraspecific cooperation for both populations, given by τ˜ciσ-1. Our results suggest that, under some kinetic conditions, the appearance of autocatalysis might be favorable in a population of replicators growing with Malthusian kinetics competing with another population also reproducing exponentially.

  9. The good, the bad, and the ugly: the influence of skull reconstructions and intraspecific variability in studies of cranial morphometrics in theropods and Basal saurischians.

    Directory of Open Access Journals (Sweden)

    Christian Foth

    Full Text Available Several studies investigating macroevolutionary skull shape variation in fossil reptiles were published recently, often using skull reconstructions taken from the scientific literature. However, this approach could be potentially problematic, because skull reconstructions might differ notably due to incompleteness and/or deformation of the material. Furthermore, the influence of intraspecific variation has usually not been explored in these studies. Both points could influence the results of morphometric analyses by affecting the relative position of species to each other within the morphospace. The aim of the current study is to investigate the variation in morphometric data between skull reconstructions based on the same specimen, and to compare the results to shape variation occurring in skull reconstructions based on different specimens of the same species (intraspecific variation and skulls of closely related species (intraspecific variation. Based on the current results, shape variation of different skull reconstructions based on the same specimen seems to have generally little influence on the results of a geometric morphometric analysis, although it cannot be excluded that some erroneous reconstructions of poorly preserved specimens might cause problems occasionally. In contrast, for different specimens of the same species the variation is generally higher than between different reconstructions based on the same specimen. For closely related species, at least with similar ecological preferences in respect to the dietary spectrum, the degree of interspecific variation can overlap with that of intraspecific variation, most probably due to similar biomechanical constraints.

  10. Spatio-temporal variations of vegetation indicators in Eastern Siberia under global warming

    Science.gov (United States)

    Varlamova, Eugenia V.; Solovyev, Vladimir S.

    2017-11-01

    Study of spatio-temporal variations of NDVI (Normalized Difference Vegetation Index) and phenological parameters of Eastern Siberia vegetation cover under global warming was carried out on AVHRR/NOAA data (1982-2014). Trend maps of NDVI and annual variations of phenological parameters and NDVI are analyzed. A method based on stable transition of air temperature through +5°C was used to estimate the beginning, end and the length of the growing season. Correlation between NDVI and phenological parameters, surface air temperature and precipitation are discussed.

  11. Effects of intraspecific competition on the life cycle of the stonefly, Nemurella pictetii (Plecoptera: Nemouridae).

    Science.gov (United States)

    Lieske, Reimo; Zwick, Peter

    2008-04-16

    Considerable variation of life cycle duration in given insect species has been frequently recorded. Splitting of populations into cohorts with different life cycle lengths may occur, sometimes even between siblings from the same batch. Larval populations of the stonefly Nemurella pictetii in central Europe regularly split into a very fast developing and a normal univoltine cohort, leading to partial multivoltinism. The causes for such variation remain unknown but presumably act on the larval stage in which most of the life cycle is spent. We therefore studied possible effects of intraspecific competition on growth and development of larvae in the laboratory. Intraspecific competition had important influence on growth and development of the larvae. High larval densities led to reduced growth and retarded development through interference, not through exploitative competition. All specimens were negatively affected by frequent encounters and the resulting disturbance. There were no dominant individuals able to grow and develop faster than the rest, at the expense of the others. Differences in life cycle length of Nemurella pictetii may result from different larval densities in different microhabitats and resultant different degrees of interference competition. Although competition alone probably does not cause splitting of populations into cohorts with different life cycle duration differences in size and development caused by other factors are certainly enhanced by intraspecific competition.

  12. Antagonism between phytohormone signalling underlies the variation in disease susceptibility of tomato plants under elevated CO2.

    Science.gov (United States)

    Zhang, Shuai; Li, Xin; Sun, Zenghui; Shao, Shujun; Hu, Lingfei; Ye, Meng; Zhou, Yanhong; Xia, Xiaojian; Yu, Jingquan; Shi, Kai

    2015-04-01

    Increasing CO2 concentrations ([CO2]) have the potential to disrupt plant-pathogen interactions in natural and agricultural ecosystems, but the research in this area has often produced conflicting results. Variations in phytohormone salicylic acid (SA) and jasmonic acid (JA) signalling could be associated with variations in the responses of pathogens to plants grown under elevated [CO2]. In this study, interactions between tomato plants and three pathogens with different infection strategies were compared. Elevated [CO2] generally favoured SA biosynthesis and signalling but repressed the JA pathway. The exposure of plants to elevated [CO2] revealed a lower incidence and severity of disease caused by tobacco mosaic virus (TMV) and by Pseudomonas syringae, whereas plant susceptibility to necrotrophic Botrytis cinerea increased. The elevated [CO2]-induced and basal resistance to TMV and P. syringae were completely abolished in plants in which the SA signalling pathway nonexpressor of pathogenesis-related genes 1 (NPR1) had been silenced or in transgenic plants defective in SA biosynthesis. In contrast, under both ambient and elevated [CO2], the susceptibility to B. cinerea highly increased in plants in which the JA signalling pathway proteinase inhibitors (PI) gene had been silenced or in a mutant affected in JA biosynthesis. However, plants affected in SA signalling remained less susceptible to this disease. These findings highlight the modulated antagonistic relationship between SA and JA that contributes to the variation in disease susceptibility under elevated [CO2]. This information will be critical for investigating how elevated CO2 may affect plant defence and the dynamics between plants and pathogens in both agricultural and natural ecosystems. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  13. Antagonism between phytohormone signalling underlies the variation in disease susceptibility of tomato plants under elevated CO2

    Science.gov (United States)

    Zhang, Shuai; Li, Xin; Sun, Zenghui; Shao, Shujun; Hu, Lingfei; Ye, Meng; Zhou, Yanhong; Xia, Xiaojian; Yu, Jingquan; Shi, Kai

    2015-01-01

    Increasing CO2 concentrations ([CO2]) have the potential to disrupt plant–pathogen interactions in natural and agricultural ecosystems, but the research in this area has often produced conflicting results. Variations in phytohormone salicylic acid (SA) and jasmonic acid (JA) signalling could be associated with variations in the responses of pathogens to plants grown under elevated [CO2]. In this study, interactions between tomato plants and three pathogens with different infection strategies were compared. Elevated [CO2] generally favoured SA biosynthesis and signalling but repressed the JA pathway. The exposure of plants to elevated [CO2] revealed a lower incidence and severity of disease caused by tobacco mosaic virus (TMV) and by Pseudomonas syringae, whereas plant susceptibility to necrotrophic Botrytis cinerea increased. The elevated [CO2]-induced and basal resistance to TMV and P. syringae were completely abolished in plants in which the SA signalling pathway nonexpressor of pathogenesis-related genes 1 (NPR1) had been silenced or in transgenic plants defective in SA biosynthesis. In contrast, under both ambient and elevated [CO2], the susceptibility to B. cinerea highly increased in plants in which the JA signalling pathway proteinase inhibitors (PI) gene had been silenced or in a mutant affected in JA biosynthesis. However, plants affected in SA signalling remained less susceptible to this disease. These findings highlight the modulated antagonistic relationship between SA and JA that contributes to the variation in disease susceptibility under elevated [CO2]. This information will be critical for investigating how elevated CO2 may affect plant defence and the dynamics between plants and pathogens in both agricultural and natural ecosystems. PMID:25657213

  14. Microfluidic-Based Measurement Method of Red Blood Cell Aggregation under Hematocrit Variations.

    Science.gov (United States)

    Kang, Yang Jun

    2017-09-06

    Red blood cell (RBC) aggregation and erythrocyte sedimentation rate (ESR) are considered to be promising biomarkers for effectively monitoring blood rheology at extremely low shear rates. In this study, a microfluidic-based measurement technique is suggested to evaluate RBC aggregation under hematocrit variations due to the continuous ESR. After the pipette tip is tightly fitted into an inlet port, a disposable suction pump is connected to the outlet port through a polyethylene tube. After dropping blood (approximately 0.2 mL) into the pipette tip, the blood flow can be started and stopped by periodically operating a pinch valve. To evaluate variations in RBC aggregation due to the continuous ESR, an EAI (Erythrocyte-sedimentation-rate Aggregation Index) is newly suggested, which uses temporal variations of image intensity. To demonstrate the proposed method, the dynamic characterization of the disposable suction pump is first quantitatively measured by varying the hematocrit levels and cavity volume of the suction pump. Next, variations in RBC aggregation and ESR are quantified by varying the hematocrit levels. The conventional aggregation index (AI) is maintained constant, unrelated to the hematocrit values. However, the EAI significantly decreased with respect to the hematocrit values. Thus, the EAI is more effective than the AI for monitoring variations in RBC aggregation due to the ESR. Lastly, the proposed method is employed to detect aggregated blood and thermally-induced blood. The EAI gradually increased as the concentration of a dextran solution increased. In addition, the EAI significantly decreased for thermally-induced blood. From this experimental demonstration, the proposed method is able to effectively measure variations in RBC aggregation due to continuous hematocrit variations, especially by quantifying the EAI.

  15. Microfluidic-Based Measurement Method of Red Blood Cell Aggregation under Hematocrit Variations

    Science.gov (United States)

    2017-01-01

    Red blood cell (RBC) aggregation and erythrocyte sedimentation rate (ESR) are considered to be promising biomarkers for effectively monitoring blood rheology at extremely low shear rates. In this study, a microfluidic-based measurement technique is suggested to evaluate RBC aggregation under hematocrit variations due to the continuous ESR. After the pipette tip is tightly fitted into an inlet port, a disposable suction pump is connected to the outlet port through a polyethylene tube. After dropping blood (approximately 0.2 mL) into the pipette tip, the blood flow can be started and stopped by periodically operating a pinch valve. To evaluate variations in RBC aggregation due to the continuous ESR, an EAI (Erythrocyte-sedimentation-rate Aggregation Index) is newly suggested, which uses temporal variations of image intensity. To demonstrate the proposed method, the dynamic characterization of the disposable suction pump is first quantitatively measured by varying the hematocrit levels and cavity volume of the suction pump. Next, variations in RBC aggregation and ESR are quantified by varying the hematocrit levels. The conventional aggregation index (AI) is maintained constant, unrelated to the hematocrit values. However, the EAI significantly decreased with respect to the hematocrit values. Thus, the EAI is more effective than the AI for monitoring variations in RBC aggregation due to the ESR. Lastly, the proposed method is employed to detect aggregated blood and thermally-induced blood. The EAI gradually increased as the concentration of a dextran solution increased. In addition, the EAI significantly decreased for thermally-induced blood. From this experimental demonstration, the proposed method is able to effectively measure variations in RBC aggregation due to continuous hematocrit variations, especially by quantifying the EAI. PMID:28878199

  16. The effect of subdivision on variation at multi-allelic loci under balancing selection

    DEFF Research Database (Denmark)

    Schierup, M H; Vekemans, X; Charlesworth, D

    2000-01-01

    Simulations are used to investigate the expected pattern of variation at loci under different forms of multi-allelic balancing selection in a finite island model of a subdivided population. The objective is to evaluate the effect of restricted migration among demes on the distribution of polymorp......Simulations are used to investigate the expected pattern of variation at loci under different forms of multi-allelic balancing selection in a finite island model of a subdivided population. The objective is to evaluate the effect of restricted migration among demes on the distribution......, and to the possibility of inferring ancient population genetic events and processes. In addition, it is shown that, for sporophytic self-incompatibility systems, it is not necessarily true in a subdivided population that recessive alleles are more frequent than dominant ones. Udgivelsesdato: 2000-Aug...

  17. Identification of genotypic variation for nitrogen response in potato (Solanum tuberosum) under low nitrogen input circumstances

    OpenAIRE

    Tiemens-Hulscher, M.; Lammerts Van Bueren, E.; Struik, P.C.

    2009-01-01

    Nitrogen is an essential nutrient for crop growth. The demand for nitrogen in the potato crop is relatively high. However, in organic farming nitrogen input is rather limited, compared with conventional farming. In this research nine potato varieties were tested at three nitrogen levels. Genotypic variation for yield, leaf area index, period of maximum soil cover, sensitivity for N-shortage and nitrogen efficiency under low input circumstances was found. However, in these experiments varietie...

  18. The structural variation of phytoplankton in the Gulf of Riga under the influence of environmental factors

    OpenAIRE

    Jurgensone, Iveta

    2011-01-01

    „The structural variation of phytoplankton in the Gulf of Riga under the influence of environmental factors.” Trends of phytoplankton (1976-2008) from the Gulf of Riga and the related environmental factors are investigated. Phytoplankton response to riverine DOM and nutrient increase was tested and the effect on the pelagic food web assessed. Changes in the winter-spring DIN/DIP ratio cause shift from diatoms to cyanobacteria. Dinoflagellate biomass remains constant after temperature excee...

  19. Wall thickness variation effect on tank’s shape behaviour under critical harmonic settlement

    Directory of Open Access Journals (Sweden)

    Ahmed Shamel Fahmy

    2016-12-01

    Full Text Available The purpose of this study was to investigate the effect of wall thickness variation on tank’s wall buckling mode under the effect of critical harmonic settlement for open top tanks. The study was performed on four tanks which have the same geometric and material properties except wall thickness, for each case the tank was subjected to several settlement waves which has the same settlement amplitude, and the buckling mode and critical vertical settlement results were compared. For buckling mode, the results show that tanks with wall thickness at a close range have similar buckling mode behaviour and in case using too thick wall the buckling mode starts to change. And for the effect on critical vertical settlement, the results show that vertical settlement is sensitive to any variation in wall thickness beside that settlement value changes with the effected wave number and this variation could change the whole behaviour of the tanks. The study recommended that in case of performing analysis for a tank with neglecting the variation in wall thickness values, the value of chosen wall thickness should be the average of wall thickness values obtained from the designed equation.

  20. Comparative mapping in intraspecific populations uncovers a high degree of macrosynteny between A- and B-genome diploid species of peanut

    Directory of Open Access Journals (Sweden)

    Guo Yufang

    2012-11-01

    Full Text Available Abstract Background Cultivated peanut or groundnut (Arachis hypogaea L. is an important oilseed crop with an allotetraploid genome (AABB, 2n = 4x = 40. Both the low level of genetic variation within the cultivated gene pool and its polyploid nature limit the utilization of molecular markers to explore genome structure and facilitate genetic improvement. Nevertheless, a wealth of genetic diversity exists in diploid Arachis species (2n = 2x = 20, which represent a valuable gene pool for cultivated peanut improvement. Interspecific populations have been used widely for genetic mapping in diploid species of Arachis. However, an intraspecific mapping strategy was essential to detect chromosomal rearrangements among species that could be obscured by mapping in interspecific populations. To develop intraspecific reference linkage maps and gain insights into karyotypic evolution within the genus, we comparatively mapped the A- and B-genome diploid species using intraspecific F2 populations. Exploring genome organization among diploid peanut species by comparative mapping will enhance our understanding of the cultivated tetraploid peanut genome. Moreover, new sources of molecular markers that are highly transferable between species and developed from expressed genes will be required to construct saturated genetic maps for peanut. Results A total of 2,138 EST-SSR (expressed sequence tag-simple sequence repeat markers were developed by mining a tetraploid peanut EST assembly including 101,132 unigenes (37,916 contigs and 63,216 singletons derived from 70,771 long-read (Sanger and 270,957 short-read (454 sequences. A set of 97 SSR markers were also developed by mining 9,517 genomic survey sequences of Arachis. An SSR-based intraspecific linkage map was constructed using an F2 population derived from a cross between K 9484 (PI 298639 and GKBSPSc 30081 (PI 468327 in the B-genome species A. batizocoi. A high degree of macrosynteny was observed

  1. Variations in cardiovascular disease under-diagnosis in England: national cross-sectional spatial analysis

    Directory of Open Access Journals (Sweden)

    Walford Hannah

    2011-03-01

    Full Text Available Abstract Background There is under-diagnosis of cardiovascular disease (CVD in the English population, despite financial incentives to encourage general practices to register new cases. We compared the modelled (expected and diagnosed (observed prevalence of three cardiovascular conditions- coronary heart disease (CHD, hypertension and stroke- at local level, their geographical variation, and population and healthcare predictors which might influence diagnosis. Methods Cross-sectional observational study in all English local authorities (351 and general practices (8,372 comparing model-based expected prevalence with diagnosed prevalence on practice disease registers. Spatial analyses were used to identify geographic clusters and variation in regression relationships. Results A total of 9,682,176 patients were on practice CHD, stroke and transient ischaemic attack, and hypertension registers. There was wide spatial variation in observed: expected prevalence ratios for all three diseases, with less than five per cent of expected cases diagnosed in some areas. London and the surrounding area showed statistically significant discrepancies in observed: expected prevalence ratios, with observed prevalence much lower than the epidemiological models predicted. The addition of general practitioner supply as a variable yielded stronger regression results for all three conditions. Conclusions Despite almost universal access to free primary healthcare, there may be significant and highly variable under-diagnosis of CVD across England, which can be partially explained by persistent inequity in GP supply. Disease management studies should consider the possible impact of under-diagnosis on population health outcomes. Compared to classical regression modelling, spatial analytic techniques can provide additional information on risk factors for under-diagnosis, and can suggest where healthcare resources may be most needed.

  2. Intraspecific diet shift in Talitrus saltator inhabiting exposed sandy beaches

    Science.gov (United States)

    Olabarria, Celia; Incera, Mónica; Garrido, Josefina; Rodil, Iván F.; Rossi, Francesca

    2009-09-01

    Talitrid amphipods are the most abundant herbivores on exposed sandy beaches. Despite their important role as trophic intermediates between macrophytes and higher levels (i.e. insect and bird) of beach food webs, very little information is available on their feeding patterns. The main aim of this study was to investigate intraspecific differences in the feeding behaviour of Talitrus saltator. We tested the hypotheses that: (1) adult females and males showed different isotope signatures and therefore relied on different sources of food; and (2) patterns of variation of isotope signatures of juveniles differed from those of adult specimens, evidencing a diet shift during the development. We used stable isotope signatures and tested for differences upon the level on the shore, times of the year and beaches experiencing similar morpho-dynamic and environmental conditions. Finally, we investigated the trophic significance of macrophyte detritus in the diet of males, females and juveniles. Results showed that adult males had a more variable diet than females and juveniles (inferred from δ 13C and δ 15N values). Dual-isotope graphs suggested that Sargassum muticum and Cystoseira baccata wrack could be among the main food sources for both juvenile and adult stage.

  3. Which species will successfully track climate change? The influence of intraspecific competition and density dependent dispersal on range shifting dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Best, A.S.; Johst, K.; Muenkemueller, T.; Travis, J.M.J.

    2007-09-15

    Understanding the ability of species to shift their geographic range is of considerable importance given the current period of rapid climate change. Furthermore, a greater understanding of the spatial population dynamics underlying range shifting is required to complement the advances made in climate niche modelling. A simulation model is developed which incorporates three key features that have been largely overlooked in studies of range shifting dynamics: the form of intraspecific competition, density dependent dispersal and the transient dynamics of habitat patches. The results show that the exact shape of the response depends critically on both local and patch dynamics. Species whose intraspecific competition is contest based are more vulnerable than those whose competition is scramble based. Contesters are especially sensitive when combined with density dependent dispersal. Species living in patches whose carrying capacity grows slowly are also susceptible to rapid shifts of environmental conditions. A complementary analytic approach further highlights the importance of intraspecific competition. (au)

  4. Intraspecific adaptive radiation: Competition, ecological opportunity, and phenotypic diversification within species.

    Science.gov (United States)

    Levis, Nicholas A; Martin, Ryan A; O'Donnell, Kerry A; Pfennig, David W

    2017-10-01

    Intraspecific variation in resource-use traits can have profound ecological and evolutionary implications. Among the most striking examples are resource polymorphisms, where alternative morphs that utilize different resources evolve within a population. An underappreciated aspect of their evolution is that the same conditions that favor resource polymorphism-competition and ecological opportunity-might foster additional rounds of diversification within already existing morphs. We examined these issues in spadefoot toad tadpoles that develop into either a generalist "omnivore" or a specialist "carnivore" morph. Specifically, we assessed the morphological diversity of tadpoles from natural ponds and experimentally induced carnivores reared on alternative diets. We also surveyed natural ponds to determine if the strength of intramorph competition and the diversity and abundance of dietary resources (measures of ecological opportunity) influenced the diversity of within-morph variation. We found that five omnivore and four carnivore types were present in natural ponds; alternative diets led to shape differences, some of which mirrored variation in the wild; and both competition and ecological opportunity were associated with enhanced morphological diversity in natural ponds. Such fine-scale intraspecific variation might represent an underappreciated form of biodiversity and might constitute a crucible of evolutionary innovation and diversification. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

  5. Intraspecific competition facilitates the evolution of tolerance to insect damage in the perennial plant Solanum carolinense.

    Science.gov (United States)

    McNutt, David W; Halpern, Stacey L; Barrows, Kahaili; Underwood, Nora

    2012-12-01

    Tolerance to herbivory (the degree to which plants maintain fitness after damage) is a key component of plant defense, so understanding how natural selection and evolutionary constraints act on tolerance traits is important to general theories of plant-herbivore interactions. These factors may be affected by plant competition, which often interacts with damage to influence trait expression and fitness. However, few studies have manipulated competitor density to examine the evolutionary effects of competition on tolerance. In this study, we tested whether intraspecific competition affects four aspects of the evolution of tolerance to herbivory in the perennial plant Solanum carolinense: phenotypic expression, expression of genetic variation, the adaptive value of tolerance, and costs of tolerance. We manipulated insect damage and intraspecific competition for clonal lines of S. carolinense in a greenhouse experiment, and measured tolerance in terms of sexual and asexual fitness components. Compared to plants growing at low density, plants growing at high density had greater expression of and genetic variation in tolerance, and experienced greater fitness benefits from tolerance when damaged. Tolerance was not costly for plants growing at either density, and only plants growing at low density benefited from tolerance when undamaged, perhaps due to greater intrinsic growth rates of more tolerant genotypes. These results suggest that competition is likely to facilitate the evolution of tolerance in S. carolinense, and perhaps in other plants that regularly experience competition, while spatio-temporal variation in density may maintain genetic variation in tolerance.

  6. Egg size matching by an intraspecific brood parasite

    OpenAIRE

    Patrick R. Lemons; James S. Sedinger

    2011-01-01

    Avian brood parasitism provides an ideal system with which to understand animal recognition and its affect on fitness. This phenomenon of laying eggs in the nests of other individuals has classically been framed from the perspective of interspecific brood parasitism and host recognition of parasitic eggs. Few examples exist of strategies adopted by intraspecific brood parasites to maximize success of parasitic eggs. Intraspecific brood parasitism within precocial birds can be a risky strategy...

  7. Sources of variation in under-5 mortality across sub-Saharan Africa: a spatial analysis.

    Science.gov (United States)

    Burke, Marshall; Heft-Neal, Sam; Bendavid, Eran

    2016-12-01

    Detailed spatial understanding of levels and trends in under-5 mortality is needed to improve the targeting of interventions to the areas of highest need, and to understand the sources of variation in mortality. To improve this understanding, we analysed local-level information on child mortality across sub-Saharan Africa between 1980-2010. We used data from 82 Demographic and Health Surveys in 28 sub-Saharan African countries, including the location and timing of 3·24 million childbirths and 393 685 deaths, to develop high-resolution spatial maps of under-5 mortality in the 1980s, 1990s, and 2000s. These estimates were at a resolution of 0·1 degree latitude by 0·1 degree longitude (roughly 10 km × 10 km). We then analysed this spatial information to distinguish within-country versus between-country sources of variation in mortality, to examine the extent to which declines in mortality have been accompanied by convergence in the distribution of mortality, and to study localised drivers of mortality differences, including temperature, malaria burden, and conflict. In our sample of sub-Saharan African countries from the 1980s to the 2000s, within-country differences in under-5 mortality accounted for 74-78% of overall variation in under-5 mortality across space and over time. Mortality differed significantly across only 8-15% of country borders, supporting the role of local, rather than national, factors in driving mortality patterns. We found that by the end of the study period, 23% of the eligible children in the study countries continue to live in mortality hotspots-areas where, if current trends continue, the Sustainable Developent Goals mortality targets will not be met. In multivariate analysis, within-country mortality levels at each pixel were significantly related to local temperature, malaria burden, and recent history of conflict. Our findings suggest that sub-national determinants explain a greater portion of under-5 mortality than do country

  8. Diurnal variation in soil respiration under different land uses on Taihang Mountain, North China

    Science.gov (United States)

    Liu, Xiuping; Zhang, Wanjun; Zhang, Bin; Yang, Qihong; Chang, Jianguo; Hou, Ke

    2016-01-01

    The aim of this paper is to evaluate the diurnal variation in soil respiration under different land use types on Taihang Mountain, North China, and to understand its response to environmental factors (e.g., soil temperature and moisture) and forest management. Diurnal variations in soil respiration from plantations (Robinia pseudoacacia, Punica granatum, and Ziziphus jujuba), naturally regenerated forests (Vitex negundo var. heterophylla), grasslands (Bothriochloa ischaemum), and farmlands (winter wheat/summer maize) were measured using an LI-8100 automated soil CO2 flux system from May 2012 to April 2013. The results indicated that land use type had a significant effect on the diurnal variation of soil respiration. The diurnal soil respiration from farmlands was highest, followed by Ziziphus jujube, R. pseudoacacia, P. granatum, the lower soil CO2 efflux was found from B. ischaemum and V. negundo var. heterophylla. The diurnal soil respiration across different land use types was significantly affected by soil temperature and moisture, and their interaction. Precipitation-stimulated soil respiration increased more in soil with low water content and less in soil with high water content. The lower diurnal soil respiration from naturally regenerated forests suggests that naturally regenerated vegetation is the optimal vegetation type for reducing global warming.

  9. Transcriptomes Reveal Genetic Signatures Underlying Physiological Variations Imposed by Different Fermentation Conditions in Lactobacillus plantarum

    Science.gov (United States)

    Bongers, Roger S.; van Bokhorst-van de Veen, Hermien; Wiersma, Anne; Overmars, Lex; Marco, Maria L.; Kleerebezem, Michiel

    2012-01-01

    Lactic acid bacteria (LAB) are utilized widely for the fermentation of foods. In the current post-genomic era, tools have been developed that explore genetic diversity among LAB strains aiming to link these variations to differential phenotypes observed in the strains investigated. However, these genotype-phenotype matching approaches fail to assess the role of conserved genes in the determination of physiological characteristics of cultures by environmental conditions. This manuscript describes a complementary approach in which Lactobacillus plantarum WCFS1 was fermented under a variety of conditions that differ in temperature, pH, as well as NaCl, amino acid, and O2 levels. Samples derived from these fermentations were analyzed by full-genome transcriptomics, paralleled by the assessment of physiological characteristics, e.g., maximum growth rate, yield, and organic acid profiles. A data-storage and -mining suite designated FermDB was constructed and exploited to identify correlations between fermentation conditions and industrially relevant physiological characteristics of L. plantarum, as well as the associated transcriptome signatures. Finally, integration of the specific fermentation variables with the transcriptomes enabled the reconstruction of the gene-regulatory networks involved. The fermentation-genomics platform presented here is a valuable complementary approach to earlier described genotype-phenotype matching strategies which allows the identification of transcriptome signatures underlying physiological variations imposed by different fermentation conditions. PMID:22802930

  10. A trans-Amazonian screening of mtDNA reveals deep intraspecific divergence in forest birds and suggests a vast underestimation of species diversity.

    Directory of Open Access Journals (Sweden)

    Borja Milá

    Full Text Available The Amazonian avifauna remains severely understudied relative to that of the temperate zone, and its species richness is thought to be underestimated by current taxonomy. Recent molecular systematic studies using mtDNA sequence reveal that traditionally accepted species-level taxa often conceal genetically divergent subspecific lineages found to represent new species upon close taxonomic scrutiny, suggesting that intraspecific mtDNA variation could be useful in species discovery. Surveys of mtDNA variation in Holarctic species have revealed patterns of variation that are largely congruent with species boundaries. However, little information exists on intraspecific divergence in most Amazonian species. Here we screen intraspecific mtDNA genetic variation in 41 Amazonian forest understory species belonging to 36 genera and 17 families in 6 orders, using 758 individual samples from Ecuador and French Guiana. For 13 of these species, we also analyzed trans-Andean populations from the Ecuadorian Chocó. A consistent pattern of deep intraspecific divergence among trans-Amazonian haplogroups was found for 33 of the 41 taxa, and genetic differentiation and genetic diversity among them was highly variable, suggesting a complex range of evolutionary histories. Mean sequence divergence within families was the same as that found in North American birds (13%, yet mean intraspecific divergence in Neotropical species was an order of magnitude larger (2.13% vs. 0.23%, with mean distance between intraspecific lineages reaching 3.56%. We found no clear relationship between genetic distances and differentiation in plumage color. Our results identify numerous genetically and phenotypically divergent lineages which may result in new species-level designations upon closer taxonomic scrutiny and thorough sampling, although lineages in the tropical region could be older than those in the temperate zone without necessarily representing separate species. In

  11. Intraspecific competition delays recovery of population structure.

    Science.gov (United States)

    Liess, Matthias; Foit, Kaarina

    2010-04-01

    Ecotoxicological field studies have shown that total abundance and biomass often recover shortly after pulsed toxicant stress. In contrast, population structure showed comparatively long-term alterations before reaching pre-treatment conditions. We investigated two mechanisms that may explain the prolonged recovery of population structure: latent toxicant effects on life-history traits on the individual level and competition on the population level. To test these hypotheses we exposed populations of Daphnia magna to a pulse of the pyrethroid Fenvalerate. For several generations the populations were kept at two different degrees of competition: strong competition at carrying capacity and reduced competition maintained by simulated predation. After disturbance due to Fenvalerate exposure, biomass recovered after 14-17 days. In contrast, size structure characterised by a lack of large and dominance of small organisms recovered after 43 days in populations with strong competition. Size structure recovered twice faster in populations with reduced competition. We explain this as follows: due to toxicant induced mortality, food availability and consequently birth rate increased and populations were dominated by small individuals. In populations without predation, these cohorts grew and eventually exerted high intraspecific competition that (i) stopped further growth of juveniles and (ii) increased mortality of adults. These demographic processes were mainly responsible for the prolonged recovery of size structure. In contrast, for populations with predation, the regular harvest of individuals reduced competition. Juveniles developed continuously, allowing a fast recovery of size structure in these dynamic populations. In risk assessment the duration for populations to recover from (toxicant) stress, is crucial for the determination of ecological acceptable effects. We conclude that competition needs to be considered in order to understand and predict recovery of size

  12. Multiple dimensions of intraspecific diversity affect biomass of eelgrass and its associated community.

    Science.gov (United States)

    Abbott, Jessica M; Grosberg, Richard K; Williams, Susan L; Stachowicz, John J

    2017-12-01

    Genetic diversity within key species can play an important role in the functioning of entire communities. However, the extent to which different dimensions of diversity (e.g., the number of genotypes vs. the extent of genetic differentiation among those genotypes) best predicts functioning is unknown and may yield clues into the different mechanisms underlying diversity effects. We explicitly test the relative influence of genotypic richness and genetic relatedness on eelgrass productivity, biomass, and the diversity of associated invertebrate grazers in a factorial field experiment using the seagrass species, Zostera marina (eelgrass). Genotypic richness had the strongest effect on eelgrass biomass accumulation, such that plots with more genotypes at the end of the experiment attained a higher biomass. Genotypic diversity (richness + evenness) was a stronger predictor of biomass than richness alone, and both genotype richness and diversity were positively correlated with trait diversity. The relatedness of genotypes in a plot reduced eelgrass biomass independently of richness. Plots containing eelgrass with greater trait diversity also had a higher abundance of invertebrate grazers, while the diversity and relatedness of eelgrass genotypes had little effect on invertebrate abundance or richness. Our work extends previous findings by explicitly relating genotypic diversity to trait diversity, thus mechanistically connecting genotypic diversity to plot-level yields. We also show that other dimensions of diversity, namely relatedness, influence eelgrass performance independent of trait differentiation. Ultimately, richness and relatedness captured fundamentally different components of intraspecific variation and should be treated as complementary rather than competing dimensions of biodiversity affecting ecosystem functioning. © 2017 by the Ecological Society of America.

  13. [Spatiotemporal variations of natural wetland CH4 emissions over China under future climate change].

    Science.gov (United States)

    Liu, Jian-gong; Zhu, Qiu-an; Shen, Yan; Yang, Yan-zheng; Luo, Yun-peng; Peng, Chang-hui

    2015-11-01

    Based on a new process-based model, TRIPLEX-GHG, this paper analyzed the spatio-temporal variations of natural wetland CH4 emissions over China under different future climate change scenarios. When natural wetland distributions were fixed, the amount of CH4 emissions from natural wetland ecosystem over China would increase by 32.0%, 55.3% and 90.8% by the end of 21st century under three representative concentration pathways (RCPs) scenarios, RCP2. 6, RCP4.5 and RCP8.5, respectively, compared with the current level. Southern China would have higher CH4 emissions compared to that from central and northern China. Besides, there would be relatively low emission fluxes in western China while relatively high emission fluxes in eastern China. Spatially, the areas with relatively high CH4 emission fluxes would be concentrated in the middle-lower reaches of the Yangtze River, the Northeast and the coasts of the Pearl River. In the future, most natural wetlands would emit more CH4 for RCP4.5 and RCP8.5 than that of 2005. However, under RCP2.6 scenario, the increasing trend would be curbed and CH4 emissions (especially from the Qinghai-Tibet Plateau) begin to decrease in the late 21st century.

  14. Study on the Variation of Groundwater Level under Time-varying Recharge

    Science.gov (United States)

    Wu, Ming-Chang; Hsieh, Ping-Cheng

    2017-04-01

    The slopes of the suburbs come to important areas by focusing on the work of soil and water conservation in recent years. The water table inside the aquifer is affected by rainfall, geology and topography, which will result in the change of groundwater discharge and water level. Currently, the way to obtain water table information is to set up the observation wells; however, owing to that the cost of equipment and the wells excavated is too expensive, we develop a mathematical model instead, which might help us to simulate the groundwater level variation. In this study, we will discuss the groundwater level change in a sloping unconfined aquifer with impermeable bottom under time-varying rainfall events. Referring to Child (1971), we employ the Boussinesq equation as the governing equation, and apply the General Integral Transforms Method (GITM) to analyzing the groundwater level after linearizing the Boussinesq equation. After comparing the solution with Verhoest & Troch (2000) and Bansal & Das (2010), we get satisfactory results. To sum up, we have presented an alternative approach to solve the linearized Boussinesq equation for the response of groundwater level in a sloping unconfined aquifer. The present analytical results combine the effect of bottom slope and the time-varying recharge pattern on the water table fluctuations. Owing to the limitation and difficulty of measuring the groundwater level directly, we develop such a mathematical model that we can predict or simulate the variation of groundwater level affected by any rainfall events in advance.

  15. Robust group fused lasso for multisample copy number variation detection under uncertainty.

    Science.gov (United States)

    Sharifi Noghabi, Hossein; Mohammadi, Majid; Tan, Yao-Hua

    2016-12-01

    One of the most important needs in the post-genome era is providing the researchers with reliable and efficient computational tools to extract and analyse this huge amount of biological data, in which DNA copy number variation (CNV) is a vitally important one. Array-based comparative genomic hybridisation (aCGH) is a common approach in order to detect CNVs. Most of methods for this purpose were proposed for one-dimensional profiles. However, slightly this focus has moved from one- to multi-dimensional signals. In addition, since contamination of these profiles with noise is always an issue, it is highly important to have a robust method for analysing multi-sample aCGH profiles. In this study, the authors propose robust group fused lasso which utilises the robust group total variations. Instead of l 2,1 norm, the l 1 - l 2 M-estimator is used which is more robust in dealing with non-Gaussian noise and high corruption. More importantly, Correntropy (Welsch M-estimator) is also applied for fitting error. Extensive experiments indicate that the proposed method outperforms the state-of-the art algorithms and techniques under a wide range of scenarios with diverse noises.

  16. Acoustic Emission and Modal Frequency Variation in Concrete Specimens under Four-Point Bending

    Directory of Open Access Journals (Sweden)

    Giuseppe Lacidogna

    2017-03-01

    Full Text Available The Acoustic Emission (AE and Dynamic Identification (DI techniques were applied simultaneously, in an original way, to examine the stress dependent damage progress in pre-notched concrete beams tested in four-point bending. The damage mechanisms were characterized by analyzing the AE signals registered during the tests, conducted by increasing the specimen’s vertical deflection. In particular, the dominant fracture mode was identified, and correlations between dissipated and emitted energies were investigated. Moreover, variations in the natural bending frequencies, produced by the crack advancement under loading, were detected and put in relation with the cumulated AE energy. Two different types of piezoelectric (PZT sensors, operating in well distinct frequency ranges, were used to measure AE and modal signals. This study may be of interest with an outlook on possible correlations between a multi-parameter structural monitoring and the solution of inverse problems by numerical models.

  17. Intra-specific diversity of Serratia marcescens in Anopheles mosquito midgut defines Plasmodium transmission capacity

    Science.gov (United States)

    Bando, Hironori; Okado, Kiyoshi; Guelbeogo, Wamdaogo M.; Badolo, Athanase; Aonuma, Hiroka; Nelson, Bryce; Fukumoto, Shinya; Xuan, Xuenan; Sagnon, N'Fale; Kanuka, Hirotaka

    2013-01-01

    A critical stage in malaria transmission occurs in the Anopheles mosquito midgut, when the malaria parasite, Plasmodium, ingested with blood, first makes contact with the gut epithelial surface. To understand the response mechanisms within the midgut environment, including those influenced by resident microbiota against Plasmodium, we focus on a midgut bacteria species' intra-specific variation that confers diversity to the mosquito's competency for malaria transmission. Serratia marcescens isolated from either laboratory-reared mosquitoes or wild populations in Burkina Faso shows great phenotypic variation in its cellular and structural features. Importantly, this variation is directly correlated with its ability to inhibit Plasmodium development within the mosquito midgut. Furthermore, this anti-Plasmodium function conferred by Serratia marcescens requires increased expression of the flagellum biosynthetic pathway that is modulated by the motility master regulatory operon, flhDC. These findings point to new strategies for controlling malaria through genetic manipulation of midgut bacteria within the mosquito. PMID:23571408

  18. On the possibility of a decay ratio jump under continuous parameter variation in a BWR

    Energy Technology Data Exchange (ETDEWEB)

    Lange, Carsten; Hennig, Dieter; Hurtado, Antonio [Technische Univ. Dresden (Germany). Professur fuer Wasserstoff- und Kernenergietechnik

    2012-11-01

    The objective of this paper is to demonstrate that specific methods of the nonlinear dynamics like bifurcation analysis are helpful to understand the temporal behavior of the nonlinear dynamical system BWR in many details. So, the stability state of the system changes discontinuously if a nonlinear dynamical system encountered a Hopf bifurcation under parameter variation. BWR stability analysis is performed in the most cases by application of system codes which provide the time evolution of the neutron flux or thermal power at a defined operational point (OP) after imposing a system parameter perturbation (like a control rod sinusoidal movement). However, in general, we are not able to understand the real stability state of the BWR at a specific OP by application of system code analysis alone. We have shown in the paper that complex dynamical states with coexisting stability modes (fixed points, stable and unstable limit cycles) could spontaneously emerge under selected system parameter variations. Hence, even in the relative simple case where stable fixed points and unstable limit cycles coexist, in the framework of a stability test the unstable dynamical mode could be overlooked because the simple stability linear indicator ''decay ratio'' does not indicate an unstable state for small amplitude perturbations. Or, e.g., both, the in-phase and the out-of-phase oscillation mode can encounter a Hopf bifurcation (everyone for itself) resulting in a change of the stability characteristics which cannot be ''detected'' by the asymptotic decay ratio. (orig.)

  19. Isotopic variation in five species of stream fishes under the influence of different land uses.

    Science.gov (United States)

    Carvalho, D R; Castro, D; Callisto, M; Moreira, M Z; Pompeu, P S

    2015-09-01

    The aim of this study was to test if changes in land use alter the isotopic signature of fish species, promoting changes in the trophic position and food resource partitioning between these consumers. Three different systems were investigated: pasture streams (n = 3), streams in sugar cane plantations (n = 3) and reference streams (n = 3). Fish species Aspidoras fuscoguttatus, Astyanax altiparanae, Characidium zebra, Hisonotus piracanjuba and Knodus moenkhausii were selected, and their nitrogen and carbon isotopic compositions were estimated to assess changes in the trophic level and partitioning of food items consumed. The composition of δ(13) C (‰) only differed among the land use categories for A. altiparanae, H. piracanjuba and K. moenkhausii. Resource partitioning was different for all species, with changes in the sources or proportions they consumed in each land use category, but only A. altiparanae introduced new food sources in large quantity in altered land uses. It is important to note, however, that the results from the resource partitioning analysis are limited due to large overlapping of isotopic signatures between the analysed food resources. All fish species exhibited variation in δ(15) N (‰), with the highest values found in streams under sugar cane or pasture influence. Despite the variation in nitrogen isotopic values, only C. zebra and H. piracanjuba displayed changes in trophic level. Therefore, it is believed that the increase in the δ(15) N (‰) value of the individuals collected in streams under the influence of sugar cane or pasture was due to the greater influence of livestock dung and chemical and organic fertilizers. The results also highlight the importance of studying consumer species along with all forms of resources available at each location separately, because the signatures of these resources also vary within different land uses. © 2015 The Fisheries Society of the British Isles.

  20. Intraspecific variability and systematics in South American Syrotrigoniinae (Trigoniida, Bivalvia)

    Science.gov (United States)

    Echevarría, Javier; Damborenea, Susana E.; Manceñido, Miguel O.

    2015-04-01

    The systematics of the genus Syrotrigonia is revised in the light of the intraspecific variability of a large sample of Syrotrigonia sigeli from the Valanginian from Neuquén Basin, Argentina. The genus can be recognized by the presence of concentric or subconcentric costae surrounding the umbo, later on developing an inflection and finally resulting in a set of anterior horizontal to commarginal costae and another set of posterior sub-vertical costae. The anterior part of the area bears transverse, usually anteriorly concave, costae which direct towards the umbo on the escutcheon; initially they are continuous with those on the flank, but later on they usually alternate. General shell shape, the presence of an antecarinal sulcus, the junction pattern between both sets of costae and the number of horizontal costae relative to vertical costae are variable among species, while costae width or density and the development of horizontal vs. commarginal costae may vary highly within species. The presence of commarginal rugae developed on the whole surface of the shell is interpreted as a result of environmental perturbations. A brief biogeographical interpretation of the family Buchotrigoniidae is also outlined. Syrotrigonia probably originated in North America in the Tithonian, being widespread in the Pacific coast of South America by Early Cretaceous times; at least six (probably seven) South American species could be recognized. By Aptian times the taxon reached the Tethyan realm, its last record being Aptian or Albian in age. The frequent presence of different species in marginal marine deposits suggests a euryhaline lineage adapted to salinity variations, this may also be the cause of the frequent presence of commarginal rugae. Considering the high variability displayed in the analyzed material, large samples are needed to characterize new species within the group.

  1. Genotypic Variation for N2-FIXATION in Voandzou (vigna Subterranea) Under P Deficiency and P Sufficiency

    Science.gov (United States)

    Andry, A.; Mahamadou, M.; Lilia, R.; Laurie, A.; Hélène, V.; Dominique, M.; Christian, M.; Jean-Jacques, D.

    2011-12-01

    Genetic variation associated with N2 fixation exists in numerous legume species (Graham, 2004). High symbiotic N2 fixation under P deficiency is related closely to nodulation which was used in legume selection for N2 fixation (Herridge and Rose, 2000). Until now, study of genetic potential of neglected crops like Vigna subterranea (bambara groundnut or voandzou) is often limited while its agronomic properties is interesting for the farmers of Africa. In order to assess the genotypic variation of voandzou for tolerance to phosphorus deficiency, a physiological approach of cultivar selection was performed with 54 cultivars from Madagascar, Niger and Mali in hydroponic culture under P deficiency and P sufficiency and inoculated with the reference strain of Bradyrhizobium sp. Vigna CB756. The results of nodulation and plant biomass, which are closely related, showed a large dispersion between cultivars (0.05-0.43 g nodule dry weight per plant and 0.50-5.51 g shoot dry weight per plant). The cultivars which presented the maximum growth during the experiment presented a high efficiency in use of the rhizobial symbiosis calculated as the slope of plant biomass regression as a function of nodulation. A large increase in nodulated-root O2 consumption under P deficiency was observed for the two most tolerant cultivars. The microscopic analysis with in situ RT-PCR of the nodule sections showed an increase of a phytase gene expression with tolerance of cultivars to P deficiency. From two most contrasting cultivars, an isotopic exchange method 32P was carried out on rhizosphere soil in rhizotron culture in order to assess the direct effect induced by the roots in terms of phosphorus mobilization. The rhizospheric effect was observed under P deficiency marked by a strong re-supplying capacity of soil solution in the diffusive phosphate ion between solid phase and soil solution leading to great phosphorus nutrition. These results highlight the genotypic variability among voandzou

  2. The variation of root exudates from the hyperaccumulator Sedum alfredii under cadmium stress: metabonomics analysis.

    Directory of Open Access Journals (Sweden)

    Qing Luo

    Full Text Available Hydroponic experiments were conducted to investigate the variation of root exudates from the hyperaccumulator Sedum alfredii under the stress of cadmium (Cd. S. alfredii was cultured for 4 days in the nutrient solution spiked with CdCl2 at concentrations of 0, 5, 10, 40, and 400 µM Cd after the pre-culture. The root exudates were collected and analyzed by GC-MS, and 62 compounds were identified. Of these compounds, the orthogonal partial least-squares discrimination analysis (OPLS-DA showed that there were a distinct difference among the root exudates with different Cd treatments and 20 compounds resulting in this difference were found out. Changing tendencies in the relative content of these 20 compounds under the different Cd treatments were analyzed. These results indicated that trehalose, erythritol, naphthalene, d-pinitol and n-octacosane might be closely related to the Cd stabilization, phosphoric acid, tetradecanoic acid, oxalic acid, threonic acid and glycine could be attributed to the Cd mobilization, and mannitol, oleic acid, 3-hydroxybutanoic acid, fructose, octacosanol and ribitol could copy well with the Cd stress.

  3. Assessment of seasonal variation for air pollutant accumulation by Zizyphus tree under washing treatment.

    Science.gov (United States)

    Shaheen, Mohamed Abdulraheem; El-Nakhlawy, Fathy Saad; Almehmadi, Fahd Mosallam; Ihsan, Muhammad Zahid; Al-Shareef, Abdulmohsin Rajeh

    2016-06-01

    A field study was carried out near Jeddah Industrial Zone to estimate the leaf impairment, physiological disorders, and air pollutant accumulation potential of Ziziphus tree. The experiment was triplicated in RCBD design with factorial arrangement having seasonality as the main plot and washing as subplot treatments along with the control. Accumulation of heavy metals and micronutrients in plant foliage varied significantly under the influence of seasons and washing treatments. The maximum accumulation of cadmium, chromium, nickel, and lead were perceived in summer season while the minimum was observed in winter. Contrarily, a greater acquisition of iron, copper, zinc, and manganese was observed in autumn. Washing significantly reduced the accumulation of Cd, Cr, Ni, and Pb by 58, 90, 80, and 96 %, while Fe, Cu, Zn, and Mn by 89, 37, 60, and 93 %, respectively. Leaf protein and nitrogen content illustrated a greater adjustment for pollutants by presenting a minimum variation (14-18 % and 2-3 %) to seasonality. In contrast, leaf area and stomatal aperture were significantly disturbed and resulted in minimum recovery under washing. Correlation analysis revealed a stronger negative interaction of heavy metal accumulation to leaf features while non-significant interaction was perceived for microelements. In conclusion, planting of Ziziphus trees along industrial areas may impede potential threats of toxic pollutants to human and ecosystem.

  4. Proximity of signallers can maintain sexual signal variation under stabilizing selection.

    Science.gov (United States)

    van Wijk, Michiel; Heath, Jeremy; Lievers, Rik; Schal, Coby; Groot, Astrid T

    2017-12-22

    How sexual communication systems can evolve under stabilizing selection is still a paradox in evolutionary biology. In moths, females emit a species-specific sex pheromone, consisting of a blend of biochemically related components, to which males are attracted. Although males appear to exert strong stabilizing selection on female pheromone, these blends seem to have evolved rapidly, as evidenced by ~120,000 moth species. Here we propose and test a "proximity model" wherein two females that vary in their relative attractiveness to males, can both benefit from calling in close proximity to each other. In a field study, we show that (1) artificially selected unattractive females can achieve mating rates comparable to attractive females if they signal in close proximity to attractive females, and (2) attractive females benefit from higher mating rates when signalling in close proximity to unattractive females. We propose that frequency-dependent behavioural and spatial interactions can sustain signal variation within populations even when these signals are under stabilizing selection.

  5. Variations of melatonin and stress hormones under extended shifts and radiofrequency electromagnetic radiation.

    Science.gov (United States)

    Vangelova, Katia Koicheva; Israel, Mishel Salvador

    2005-01-01

    We studied the time-of-day variations in urinary levels of 6-sulphatoxy-melatonin and three stress hormones in operators working fast-rotating extended shifts under radiofrequency electromagnetic radiation (EMR). The excretion rate of the hormones was monitored by radioimmunoassay and spectrofluorimetry at 4-hour intervals in a group of 36 male operators comprising 12 broadcasting station operators, 12 TV station operators, and a control group of 12 satellite station operators. Measuring the time-weighted average (TWA) of EMR exposure revealed a high-level of exposure in broadcasting station operators (TWAmean= 3.10 microW/ cm2, TWAmax = 137.00 microW/cm2), a low-level in TV station operators (TWAmean = 1.89 microW/cm2, TWAmax = 5.24 microW/cm2), and a very low level in satellite station operators. The differences among the groups remained the same after confounding factors were taken into account. Radiofrequency EMR had no effect on the typical diurnal pattern of 6-sulphatoxymelatonin. High-level radiofrequency EMR exposure significantly increased the excretion rates of cortisol (p cortisol and noradrenaline correlated with TWAmean and TWAmax. In conclusion, the excretion of 6-sulphatoxymelatonin retained a typical diurnal pattern under fast-rotating extended shifts and radiofrequency EMR, but showed an exposure-effect relation with stress hormones.

  6. Genetic variation underlying psychosis-inducing effects of cannabis: critical review and future directions.

    Science.gov (United States)

    Decoster, Jeroen; van Os, Jim; Myin-Germeys, Inez; De Hert, Marc; van Winkel, Ruud

    2012-01-01

    Cannabis use is associated with an increased risk for psychotic disorder, yet most cannabis users do not develop psychosis, suggesting that other factors are also involved. This paper reviews the available evidence suggesting that differential sensitivity to the psychosis-inducing effects of cannabis may be related to underlying genetic liability. There is robust evidence that persons at psychometric risk for psychosis are most vulnerable to display psychotic symptoms subsequent to the use of cannabis. Multiple studies have also found that persons at familial risk for psychosis have an increased sensitivity to the effects of cannabis. Together, these findings support the concept of a biological interaction between cannabis use and one's underlying genetic vulnerability. At the molecular-genetic level, however, few (if any) interactions have been consistently replicated, although a reported interaction with variation in AKT1 is promising and deserves further follow-up. The apparent lack of consistent replication can be ascribed to problems of initial gene selection, statistical power, a bias towards positive results and insufficient attempts at true replication, leading to the conclusion that increased sample sizes, greater density of genetic markers and a stronger focus on true replication are necessary. The major challenge for molecular-genetic gene-environment interaction research will be to combine the agnostic detection of disorder-associated genetic variants from genome-wide studies with the hypothesis-based approach from epidemiological and neurobiological studies. Possible strategies for future cannabis interaction studies are discussed.

  7. Intraspecific relationship within the genus convolvulus l. inferred by rbcl gene using different phylogenetic approaches

    International Nuclear Information System (INIS)

    Kausar, S.; Qamarunnisa, S.

    2016-01-01

    A molecular systematics analysis was conducted using sequence data of chloroplast rbcL gene for the genus Convolvulus L., by distance and character based phylogenetic methods. Fifteen representative members from genus Convolvulus L., were included as in group whereas two members from a sister family Solanaceae were taken as out group to root the tree. Intraspecific relationships within Convolvulus were inferred by distance matrix, maximum parsimony and bayesian analysis. Transition/transversion ratio was also calculated and it was revealed that in the investigated Convolvulus species, transitional changes were more prevalent in rbcL gene. The nature of rbcL gene in the present study was observed to be conserved, as it does not show major variations between examined species. Distance matrix represented the minimal genetic variations between some species (C. glomeratus and C. pyrrhotrichus), thus exhibiting them as close relatives. The result of parsimonious and bayesian analysis revealed almost similar clades however maximum parsimony based tree was unable to establish relationship between some Convolvulus species. The bayesian inference method was found to be the method of choice for establishing intraspecific associations between Convolvulus species using rbcL data as it clearly defined the connections supported by posterior probability values. (author)

  8. Ecological opportunities and intraspecific competition alter trophic niche specialization in an opportunistic stream predator.

    Science.gov (United States)

    Evangelista, Charlotte; Boiche, Anatole; Lecerf, Antoine; Cucherousset, Julien

    2014-09-01

    Many generalist populations are composed of specialized individuals that use a narrow part of the population's niche. Ecological theories predict that individual specialization and population trophic niche are determined by biotic interactions and resource diversity emerging from environmental variations (i.e. ecological opportunities). However, due to the paucity of empirical and experimental demonstrations, the genuine importance of each of these drivers in determining trophic niche attributes is not fully appreciated. The present study aimed at determining the population level and individual responses of brown trout (Salmo trutta) to variations in ecological opportunities (terrestrial prey inputs) and autochthonous prey communities among 10 stream reaches along a riparian condition gradient using individual longitudinal monitoring and stable isotope analyses. Our results suggested that trophic niche diversity varied along the environmental gradient, while individual trophic specialization was indirectly driven by ecological opportunities through strengthened intraspecific competition. Individual diet was repeatable over the study period, and the growth rate of juvenile brown trout increased with their specialization for aquatic predatory invertebrates. Our findings highlight the dual influences of intraspecific competition and ecological opportunities on individual trophic specialization and population trophic niche. © 2014 The Authors. Journal of Animal Ecology © 2014 British Ecological Society.

  9. Natural variation in rosette size under salt stress conditions corresponds to developmental differences between Arabidopsis accessions and allelic variation in the LRR-KISS gene

    KAUST Repository

    Julkowska, Magdalena

    2016-02-11

    Natural variation among Arabidopsis accessions is an important genetic resource to identify mechanisms underlying plant development and stress tolerance. To evaluate the natural variation in salinity stress tolerance, two large-scale experiments were performed on two populations consisting of 160 Arabidopsis accessions each. Multiple traits, including projected rosette area, and fresh and dry weight were collected as an estimate for salinity tolerance. Our results reveal a correlation between rosette size under salt stress conditions and developmental differences between the accessions grown in control conditions, suggesting that in general larger plants were more salt tolerant. This correlation was less pronounced when plants were grown under severe salt stress conditions. Subsequent genome wide association study (GWAS) revealed associations with novel candidate genes for salinity tolerance such as LRR-KISS (At4g08850), flowering locus KH-domain containing protein and a DUF1639-containing protein. Accessions with high LRR-KISS expression developed larger rosettes under salt stress conditions. Further characterization of allelic variation in candidate genes identified in this study will provide more insight into mechanisms of salt stress tolerance due to enhanced shoot growth.

  10. Variação intraspecífica do lenho de Pseudopiptadenia contorta (DC. G.P. Lewis & M.P. Lima (Leguminosae - Mimosoideae de populações ocorrentes em dois remanescentes de Floresta Atlântica Intraspecific variation in wood anatomy of Pseudopiptadenia contorta (DC G.P. Lewis & M.P. Lima (Leguminosae -Mimosoidae in two Atlantic rain forest remnants

    Directory of Open Access Journals (Sweden)

    Maria Luiza R. da Costa Ribeiro

    2006-12-01

    Full Text Available O presente trabalho compara populações distintas de Pseudopiptadenia contorta (DC. G.P. Lewis & M.P. Lima ocorrentes em dois remanescentes de Floresta Atlântica no Estado do Rio de Janeiro. Foram amostradas árvores de diâmetro semelhante retas e sem defeitos aparentes. Os resultados obtidos comprovam estatisticamente a ocorrência de variação intraspecífica na estrutura anatômica da madeira. Os caracteres qualitativos mantiveram-se constantes, enquanto os quantitativos variaram, sendo os significativos, de acordo com o teste t de Student, a freqüencia, comprimento e diâmetro dos elementos vasos, o comprimento e espessura da parede das fibras, a freqüência e largura dos raios. A análise dos componentes principais, utilizando características anatômicas quantitativas ordenou as duas populações separadamente. O eixo I responde por 33% da variância total principalmente pela relação positiva do diâmetro do elemento de vaso, enquanto o eixo II responde por 20% da variância total, principalmente pelo comprimento das fibras.This study compares distinct populations of Pseudopiptadenia contorta (DC G.P. Lewis & M.P. Lima occurring in two remnants of Atlantic rain forest in Rio de Janeiro state. Trees with similar diameters and with no apparent defects were selected. The results confirm intraspecific variation in wood anatomy. Qualitative features do not change, while according to the Student t test quantitative features showed significant differences in vessel-element frequency, width, and length, fiber length and wall thickness, and ray frequency and width. Principal component analysis showed two separate populations. Factor 1 explains 33% of the total variance, mainly due to the positive relationship of vessel-element tangential diameter; factor 2 explains 20% of the total variance, mainly due to fiber length.

  11. Intraspecific competition reveals conditional fitness effects of single gene polymorphism at the Arabidopsis root growth regulator BRX.

    Science.gov (United States)

    Shindo, Chikako; Bernasconi, Giorgina; Hardtke, Christian S

    2008-01-01

    Intraspecific genetic variation for morphological traits is observed in many organisms. In Arabidopsis thaliana, alleles responsible for intraspecific morphological variation are increasingly being identified. However, the fitness consequences remain unclear in most cases. Here, the fitness effects of alleles of the BRX gene are investigated. A brx loss-of-function allele, which was found in a natural accession, results in a highly branched but poorly elongated root system. Comparison between the control accession Sav-0 and an introgression of brx into this background (brxS) indicated that, surprisingly, brx loss of function did not negatively affect fitness in pure stands. However, in mixed, well-watered stands brxS performance and reproductive output decreased significantly, as the proportion of Sav-0 neighbors increased. Additional comparisons between brxS and a brxS line that was complemented by a BRX transgene confirmed a direct effect of the loss-of-function allele on plant performance, as indicated by restored competitive ability of the transgenic genotype. Further, because plant height was very similar across genotypes and because the experimental setup largely excluded shading effects, the impaired competitiveness of the brx loss-of-function genotype likely reflects below-ground competition. In summary, these data reveal conditional fitness effects of a single gene polymorphism in response to intraspecific competition in Arabidopsis.

  12. Sampling intraspecific variability in leaf functional traits: Practical suggestions to maximize collected information.

    Science.gov (United States)

    Petruzzellis, Francesco; Palandrani, Chiara; Savi, Tadeja; Alberti, Roberto; Nardini, Andrea; Bacaro, Giovanni

    2017-12-01

    The choice of the best sampling strategy to capture mean values of functional traits for a species/population, while maintaining information about traits' variability and minimizing the sampling size and effort, is an open issue in functional trait ecology. Intraspecific variability (ITV) of functional traits strongly influences sampling size and effort. However, while adequate information is available about intraspecific variability between individuals (ITV BI ) and among populations (ITV POP ), relatively few studies have analyzed intraspecific variability within individuals (ITV WI ). Here, we provide an analysis of ITV WI of two foliar traits, namely specific leaf area (SLA) and osmotic potential (π), in a population of Quercus ilex L. We assessed the baseline ITV WI level of variation between the two traits and provided the minimum and optimal sampling size in order to take into account ITV WI , comparing sampling optimization outputs with those previously proposed in the literature. Different factors accounted for different amount of variance of the two traits. SLA variance was mostly spread within individuals (43.4% of the total variance), while π variance was mainly spread between individuals (43.2%). Strategies that did not account for all the canopy strata produced mean values not representative of the sampled population. The minimum size to adequately capture the studied functional traits corresponded to 5 leaves taken randomly from 5 individuals, while the most accurate and feasible sampling size was 4 leaves taken randomly from 10 individuals. We demonstrate that the spatial structure of the canopy could significantly affect traits variability. Moreover, different strategies for different traits could be implemented during sampling surveys. We partially confirm sampling sizes previously proposed in the recent literature and encourage future analysis involving different traits.

  13. Methods for quantifying the influences of pressure and temperature variation on metal hydride reaction rates measured under isochoric conditions.

    Science.gov (United States)

    Voskuilen, Tyler G; Pourpoint, Timothée L

    2013-11-01

    Analysis techniques for determining gas-solid reaction rates from gas sorption measurements obtained under non-constant pressure and temperature conditions often neglect temporal variations in these quantities. Depending on the materials in question, this can lead to significant variations in the measured reaction rates. In this work, we present two new analysis techniques for comparison between various kinetic models and isochoric gas measurement data obtained under varying temperature and pressure conditions in a high pressure Sievert system. We introduce the integral pressure dependence method and the temperature dependence factor as means of correcting for experimental variations, improving model-measurement fidelity, and quantifying the effect that such variations can have on measured reaction rates. We use measurements of hydrogen absorption in LaNi5 and TiCrMn to demonstrate the effect of each of these methods and show that their use can provide quantitative improvements in interpretation of kinetics measurements.

  14. [Variations of soil fertility level in red soil region under long-term fertilization].

    Science.gov (United States)

    Yu, Han-qing; Xu, Ming-gang; Lü, Jia-long; Bao, Yao-xian; Sun, Nan; Gao, Ju-sheng

    2010-07-01

    Based on the long-term (1982-2007) field experiment of "anthropogenic mellowing of raw soil" at the Qiyang red soil experimental station under Chinese Academy of Agricultural Sciences, and by using numerical theory, this paper studied the variations of the fertility level of granite red soil, quaternary red soil, and purple sandy shale soil under six fertilization patterns. The fertilization patterns included non-fertilization (CK), straw-returning without fertilizers (CKR), chemical fertilization (NPK), NPK plus straw-return (NPKR), rice straw application (M), and M plus straw-return (MR). The soil integrated fertility index (IFI) was significantly positively correlated with relative crop yield, and could better indicate soil fertility level. The IFI values of the three soils all were in the order of NPK, NPKR > M, MR > CK, CKR, with the highest value in treatment NPKR (0.77, 0.71, and 0.71 for granite red soil, quaternary red soil, and purple sandy shale soil, respectively). Comparing with that in the treatments of no straw-return, the IFI value in the treatments of straw return was increased by 6.72%-18.83%. A turning point of the IFI for all the three soils was observed at about 7 years of anthropogenic mellowing, and the annual increasing rate of the IFI was in the sequence of purple sandy shale soil (0.016 a(-1)) > quaternary red clay soil (0.011 a(-1)) > granite red soil (0.006 a(-1)). It was suggested that a combined application of organic and chemical fertilizers and/or straw return could be an effective and fast measure to enhance the soil fertility level in red soil region.

  15. Diurnal variations in blood phenylalanine of PKU infants under different feeding regimes.

    Science.gov (United States)

    van Rijn, Margreet; Hoeksma, Marieke; Sauer, Pieter J J; Modderman, Pim; Reijngoud, Dirk-Jan; van Spronsen, Francjan J

    2011-01-01

    In phenylketonuria (PKU) patients, diurnal fluctuations of blood phenylalanine (Phe) are different from healthy individuals. Until now this pattern has been studied in PKU patients over one year of age. The aim of this observational study was to investigate diurnal patterns in PKU infants under one year of age receiving both the natural protein and Phe-free formula at the same time or in an alternating feeding scheme. In 7 PKU infants (aged 3-8 months), diurnal variations in blood Phe concentrations were recorded: on day A they received natural protein and Phe-free formula combined in each feeding; on day B they received these in an alternating feeding scheme. The number of feedings, total protein, and energy intake was similar on both study days. Blood samples were taken before each feeding. The means (± SD) of the difference between the individual minimum and maximum blood Phe concentrations were 81(± 50) μmol/L and 104(± 26) μmol/L on days A and B, respectively (n.s.). Fifty and 30% of the samples were below target range for age (120 μmol/L), while only 3% and 6% were above target range (360 μmol/L) on days A and B respectively (n.s.). Both feeding regimes, i.e. the natural protein and Phe-free formula combined in each feeding or alternating, resulted in comparable diurnal fluctuations of blood Phe concentrations. Copyright © 2011 Elsevier Inc. All rights reserved.

  16. ARHGEF9 mutations in epileptic encephalopathy/intellectual disability: toward understanding the mechanism underlying phenotypic variation.

    Science.gov (United States)

    Wang, Jing-Yang; Zhou, Peng; Wang, Jie; Tang, Bin; Su, Tao; Liu, Xiao-Rong; Li, Bing-Mei; Meng, Heng; Shi, Yi-Wu; Yi, Yong-Hong; He, Na; Liao, Wei-Ping

    2018-01-01

    ARHGEF9 resides on Xq11.1 and encodes collybistin, which is crucial in gephyrin clustering and GABA A receptor localization. ARHGEF9 mutations have been identified in patients with heterogeneous phenotypes, including epilepsy of variable severity and intellectual disability. However, the mechanism underlying phenotype variation is unknown. Using next-generation sequencing, we identified a novel mutation, c.868C > T/p.R290C, which co-segregated with epileptic encephalopathy, and validated its association with epileptic encephalopathy. Further analysis revealed that all ARHGEF9 mutations were associated with intellectual disability, suggesting its critical role in psychomotor development. Three missense mutations in the PH domain were not associated with epilepsy, suggesting that the co-occurrence of epilepsy depends on the affected functional domains. Missense mutations with severe molecular alteration in the DH domain, or located in the DH-gephyrin binding region, or adjacent to the SH3-NL2 binding site were associated with severe epilepsy, implying that the clinical severity was potentially determined by alteration of molecular structure and location of mutations. Male patients with ARHGEF9 mutations presented more severe phenotypes than female patients, which suggests a gene-dose effect and supports the pathogenic role of ARHGEF9 mutations. This study highlights the role of molecular alteration in phenotype expression and facilitates evaluation of the pathogenicity of ARHGEF9 mutations in clinical practice.

  17. Plasticity in variation of xylem and phloem cell characteristics of Norway spruce under different local conditions

    Directory of Open Access Journals (Sweden)

    Jozica eGricar

    2015-09-01

    Full Text Available There is limited information on intra-annual plasticity of secondary tissues of tree species growing under different environmental conditions. To increase the knowledge about the plasticity of secondary growth, which allows trees to adapt to specific local climatic regimes, we examined climate–radial growth relationships of Norway spruce (Picea abies (L. H. Karst. from three contrasting locations in the temperate climatic zone by analyzing tree-ring widths for the period 1932–2010, and cell characteristics in xylem and phloem increments formed in the years 2009–2011. Variation in the structure of xylem and phloem increments clearly shows that plasticity in seasonal dynamics of cambial cell production and cell differentiation exists on xylem and phloem sides. Anatomical characteristics of xylem and phloem cells are predominantly site-specific characteristics, because they varied among sites but were fairly uniform among years in trees from the same site. Xylem and phloem tissues formed in the first part of the growing season seemed to be more stable in structure, indicating their priority over latewood and late phloem for tree performance. Long-term climate and radial growth analyses revealed that growth was in general less dependent on precipitation than on temperature; however, growth sensitivity to local conditions differed among the sites. Only partial dependence of radial growth of spruce on climatic factors on the selected sites confirms its strategy to adapt the structure of wood and phloem increments to function optimally in local conditions.

  18. Morphogenic and biochemical variations under different spectral lights in callus cultures of Artemisia absinthium L.

    Science.gov (United States)

    Tariq, Umayya; Ali, Mohammad; Abbasi, Bilal Haider

    2014-01-05

    Through its impact on morphogenesis, light is the key environmental factor that alters plant architectural development; however, the understanding that how light controls plant growth and developmental processes is still poor and needs further research. In this study, we monitored the effect of various monochromatic lights and plant growth regulators (PGRs) combinations on morphogenic and biochemical variation in wild grown-leaf derived callus cultures of Artemisia absinthium L. Combination of α-naphthalene acetic acid (NAA 1.0mg/l) and Thidiazuron (TDZ 2.0mg/l) resulted in optimum callogenic frequency (90%) when kept under fluorescent light for 4weeks (16/8h). In contrast to the control (white spectrum), red spectrum enhanced peroxidase activity, protease activity, total protein content and chlorophyll a/b ratio. Green spectrum was found to be more supportive for total phenolics, total flavonoids and antioxidant activity. Yellow light enhanced MDA content while white and green light improved total chlorophyll content and carotenoid content. A positive correlation among callogenic response, antioxidant activities and set of antioxidative enzyme activities was also observed in the current report. This study will help in understanding the influence of light on production of commercially important secondary metabolites and their optimization in the in vitro cultures of A. absinthium L. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Growth dynamics variation of different larch provenances under the mountain conditions in Poland

    Energy Technology Data Exchange (ETDEWEB)

    Kulej, M. [Univ. of Agriculture, Cracow (Poland). Section of Seed Production and Selection

    1995-12-31

    The results of 25-year investigations based on measurements and statistical analysis concerning the growth dynamics variation of larch provenances from the entire area of Poland are reported in this paper. This is the first larch provenance experiment in Poland under mountain conditions. The results obtained showed a significant variability among the provenances tested as regards the basic growth characters (height, d.b.h., growth index) at the age of 5, 8, 11, 15, 20 and 25 years. The larch from Klodzko and Proszkow turned out to be the best in respect of growth during the entire 25-years period. Decidedly bad were provenances from Marcule, Grojec, Rawa mazowiecka and Kroscienko. We cannot forecast the future growth of larch when trees are 5-years old since such prognosis may carry an error. However, on the basis of the results obtained it may be concluded that when trees are about 8 years old the stabilization of the position of individual provenances as regards growth takes place. The height growth curves for the individual provenances during the 25-years period (with exception of the provenance from Marcule) fall within the interval {+-} 0,5S from the compensated curve for the entire population studied. All larch provenances in the experiment had reached the height growth culmination. A greatest differentiation in respect of this character occurred in case of the provenances from Sudetes. 27 refs, 4 figs, 8 tabs

  20. From phenotypic to molecular polymorphisms involved in naturally occurring variation for plant development

    NARCIS (Netherlands)

    Alonso-Blanco, C.; Mendez-Vigo, B.; Koornneef, M.

    2005-01-01

    An enormous amount of naturally occurring genetic variation affecting development is found within wild and domesticated plant species. This diversity is presumably involved in plant adaptation to different natural environments or in human preferences. In addition, such intraspecific variation

  1. Testing the niche variation hypothesis with a measure of body condition

    Science.gov (United States)

    Individual variation and fitness are cornerstones of evolution by natural selection. The niche variation hypothesis (NVH) posits that when interspecific competition is relaxed, intraspecific competition should drive niche expansion by selection favoring use of novel resources. Po...

  2. Intraspecific hybridization studies in three wild strains of ...

    African Journals Online (AJOL)

    There were no significant (P > 0.05) differences in the weight of the three parental strains and the six intraspecific hybrids at hatching and six weeks of rearing indoor aquaria and outdoor concrete tanks. The best survival value of 96% was recorded for the Jos strain followed by that of the hybrid cross involving female Jos ...

  3. Hypothalamically Induced Intraspecific Aggressive Behaviour in the Rat

    NARCIS (Netherlands)

    Koolhaas, J.M.

    1978-01-01

    The effects of electrical stimulation of the lateral hypothalamus (LH) of rats on intraspecific aggressive behaviour were studied. In order to investigate the specificity of the stimulation effects, each experimental animal was stimulated in a number of different social situations. Stimulation of

  4. Intraspecific prey choice of bushmeat hunters outside the Serengeti ...

    African Journals Online (AJOL)

    In this study we investigated intraspecific prey choice of illegal bushmeat hunters outside the Serengeti National Park, Tanzania. During the study 151 animals belonging to 12 species were reported killed. The majority, 76%, of prey species were migratory herbivores. Night hunting with dogs was the most common hunting ...

  5. Lateral, radial and temporal variations in upper mantle viscosity and rheology under Scandinavia

    NARCIS (Netherlands)

    Barnhoorn, A.; Wal, W. van der; Vermeersen, L.L.A.; Drury, M.R.

    2011-01-01

    The viscosity of the upper mantle has a large control on the dynamics of plate tectonic processes or the response of the Earth's crust after a period of glaciation. Temperature variations within the upper mantle, time-dependent stress changes due to glaciations, and/or variations in the

  6. Light induced intraspecific variability in response to thermal stress in the hard coral Stylophora pistillata

    Directory of Open Access Journals (Sweden)

    Arjen Tilstra

    2017-10-01

    Full Text Available Recent research suggests that prior exposure of several months to elevated irradiance induces enhanced thermal tolerance in scleractinian corals. While this tolerance has been reported at the species level, individual coral colonies may react differently due to individual variability in thermal tolerance. As thermal anomalies are predicted to become common in the upcoming future, intraspecific variation may be key to the survival of coral populations. In order to study light-history based thermal stress responses on individual colonies, we developed a preliminary microcosm experiment where three randomly chosen, aquacultured colonies of the model coral Stylophora pistillata were exposed to two irradiance treatments (200 and 400 μmol photons m−2 s−1 for 31 days, followed by artificially induced heat stress (∼33.4 °C. We found different responses to occur at both the intraspecific and the intracolonial levels, as indicated by either equal, less severe, delayed, and/or even non-necrotic responses of corals previously exposed to the irradiance of 400 compared to 200 μmol photons m−2 s−1. In addition, all individual colonies revealed light-enhanced calcification. Finally, elevated irradiance resulted in a lower chlorophyll a concentration in one colony compared to the control treatment, and the same colony displayed more rapid bleaching compared to the other ones. Taken together, this study highlights the potential importance of intra-individual variability in physiological responses of scleractinian corals and provides recommendations for improving methodological designs for future studies.

  7. Solid-phase microextraction-based cuticular hydrocarbon profiling for intraspecific delimitation in Acyrthosiphon pisum.

    Directory of Open Access Journals (Sweden)

    Nan Chen

    Full Text Available Insect cuticular hydrocarbons (CHCs play critical roles in reducing water loss and chemical communication. Species-specific CHC profiles have been used increasingly as an excellent character for species classification. However, considerably less is known about their potential for population delimitation within species. The aims of this study were to develop a solid-phase microextraction (SPME-based CHC collection method and to investigate whether CHC profiles could serve as potential chemotaxonomic tools for intraspecific delimitation in Acyrthosiphon pisum. Optimization of fibers for SPME sampling revealed that 7 μm polydimethylsiloxane (PDMS demonstrated the most efficient adsorption of CHCs among five different tested fibers. SPME sampling showed good reproducibility with repeated collections of CHCs from a single aphid. Validation of SPME was performed by comparing CHC profiles with those from conventional hexane extractions. The two methods showed no qualitative differences in CHCs, although SPME appeared to extract relatively fewer short-chained CHCs. While CHC profiles of a given population differed among developmental stages, wing dimorphism types, and host plants, wingless adult aphids showed very low variance in relative proportions of individual CHC components. Reproducibility of CHC profiles was explored further to classify wingless adult morphs of A. pisum from five different geographic regions that showed no variation in mitochondrial COI gene sequences. Our results demonstrate that CHC profiles are useful in intraspecific delimitation in the field of insect chemotaxonomy.

  8. Solid-phase microextraction-based cuticular hydrocarbon profiling for intraspecific delimitation in Acyrthosiphon pisum

    Science.gov (United States)

    Chen, Nan; Bai, Yu; Fan, Yong-Liang

    2017-01-01

    Insect cuticular hydrocarbons (CHCs) play critical roles in reducing water loss and chemical communication. Species-specific CHC profiles have been used increasingly as an excellent character for species classification. However, considerably less is known about their potential for population delimitation within species. The aims of this study were to develop a solid-phase microextraction (SPME)-based CHC collection method and to investigate whether CHC profiles could serve as potential chemotaxonomic tools for intraspecific delimitation in Acyrthosiphon pisum. Optimization of fibers for SPME sampling revealed that 7 μm polydimethylsiloxane (PDMS) demonstrated the most efficient adsorption of CHCs among five different tested fibers. SPME sampling showed good reproducibility with repeated collections of CHCs from a single aphid. Validation of SPME was performed by comparing CHC profiles with those from conventional hexane extractions. The two methods showed no qualitative differences in CHCs, although SPME appeared to extract relatively fewer short-chained CHCs. While CHC profiles of a given population differed among developmental stages, wing dimorphism types, and host plants, wingless adult aphids showed very low variance in relative proportions of individual CHC components. Reproducibility of CHC profiles was explored further to classify wingless adult morphs of A. pisum from five different geographic regions that showed no variation in mitochondrial COI gene sequences. Our results demonstrate that CHC profiles are useful in intraspecific delimitation in the field of insect chemotaxonomy. PMID:28859151

  9. Spatiotemporal Variations of Extreme Precipitation under a Changing Climate in the Three Gorges Reservoir Area (TGRA

    Directory of Open Access Journals (Sweden)

    Mingquan Lü

    2018-01-01

    Full Text Available The Three Gorges Dam (TGD is one of the largest hydroelectric projects in the world. Monitoring the spatiotemporal distribution of extreme precipitation offers valuable information for adaptation and mitigation strategies and reservoir management schemes. This study examined variations in extreme precipitation over the Three Gorges Reservoir area (TGRA in China to investigate the potential role of climate warming and Three Gorges Reservoir (TGR. The trends in extreme precipitation over the TGRA were investigated using the iterative-based Mann–Kendall (MK test and Sen’s slope estimator, based on weather station daily data series and TRMM (Tropical Rainfall Measuring Mission data series. The mean and density distribution of extreme precipitation indices between pre-dam and post-dam, pre-1985 and post-1985, and near and distant reservoir area were assessed by the Mann–Whitney test and the Kolmogorov–Smirnov test. The ratio of extreme precipitation to non-extreme precipitation became larger. The precipitation was characterized by increases in heavy precipitation as well as decreases in light and moderate rain. Comparing extreme precipitation indices between pre-1985 (cooling and post-1985 (warming indicated extreme precipitation has changed to become heavier. Under climate warming, the precipitation amount corresponding to more than the 95th percentile increased at the rate of 6.48%/°C. Results from comparing extreme precipitation for the pre- and post-dam, near reservoir area (NRA and away from the reservoir area (ARA imply an insignificant role of the TGR on rainfall extremes over the TGRA. Moreover, the impoundment of TGR did not exert detectable impacts on the surface relative humidity (RH and water vapor pressure (WP.

  10. Consumer interaction strength may limit the diversifying effect of intraspecific competition: a test in alewife (Alosa pseudoharengus).

    Science.gov (United States)

    Jones, Andrew W; Post, David M

    2013-06-01

    Intraspecific competition is considered a principal driver of dietary variation, but empirical studies provide mixed support for this mechanism. Here we link comparative and experimental work testing the effects of competition and resource availability on the dietary variation of the alewife (Alosa pseudoharengus). The alewife, a consumer with extreme effects on its resources, was specifically utilized to additionally test the idea that strong interactions between a consumer and its resources can diminish the diversifying effect of competition. First, we compared the short- and long-term diet measures of wild populations across a wide range of densities. Second, in a pair of large-scale field mesocosm experiments, we explored the influence of competition and interaction strength on alewife dietary variation. Results from a whole-lake comparison and field experiments indicated that increasing competition was negatively correlated with population dietary variation. Further, altering the strength of the interaction between the alewife and its prey via prey supplementation eliminated this negative relationship. Collectively, our results suggest that competitive interactions may not drive dietary diversification in the alewife and, potentially, in other highly effective consumers. Our results also indicate that further consideration of the strength of species interactions (and the consumer traits that underlie them) would improve our understanding of the link between intraspecific competition and variation.

  11. Intraspecific relationships among wood density, leaf structural traits and environment in four co-occurring species of Nothofagus in New Zealand.

    Directory of Open Access Journals (Sweden)

    Sarah J Richardson

    Full Text Available Plant functional traits capture important variation in plant strategy and function. Recent literature has revealed that within-species variation in traits is greater than previously supposed. However, we still have a poor understanding of how intraspecific variation is coordinated among different traits, and how it is driven by environment. We quantified intraspecific variation in wood density and five leaf traits underpinning the leaf economics spectrum (leaf dry matter content, leaf mass per unit area, size, thickness and density within and among four widespread Nothofagus tree species in southern New Zealand. We tested whether intraspecific relationships between wood density and leaf traits followed widely reported interspecific relationships, and whether variation in these traits was coordinated through shared responses to environmental factors. Sample sites varied widely in environmental variables, including soil fertility (25-900 mg kg(-1 total P, precipitation (668-4875 mm yr(-1, temperature (5.2-12.4 °C mean annual temperature and latitude (41-46 °S. Leaf traits were strongly correlated with one another within species, but not with wood density. There was some evidence for a positive relationship between wood density and leaf tissue density and dry matter content, but no evidence that leaf mass or leaf size were correlated with wood density; this highlights that leaf mass per unit area cannot be used as a surrogate for component leaf traits such as tissue density. Trait variation was predicted by environmental factors, but not consistently among different traits; e.g., only leaf thickness and leaf density responded to the same environmental cues as wood density. We conclude that although intraspecific variation in wood density and leaf traits is strongly driven by environmental factors, these responses are not strongly coordinated among functional traits even across co-occurring, closely-related plant species.

  12. Novel approach to evaluate the dynamic variation of wind drift and evaporation losses under moving irrigation systems

    Science.gov (United States)

    Sayed-Hossein Sadeghi; Troy R. Peters; Mohammad Z. Amini; Sparkle L. Malone; Hank W. Loescher

    2015-01-01

    The increased need for water and food security requires the development of new approaches to save water through irrigation management strategies, particularly for center pivot irrigation. To do so entails monitoring of the dynamic variation in wind drift and evaporation losses (WDELs) of irrigation systems under different weather conditions and for relatively long time...

  13. MDA and GSH-Px activity in transition dairy cows under seasonal variations and their relationship with reproductive performance

    Directory of Open Access Journals (Sweden)

    Colakoglu Hatice Esra

    2017-12-01

    Full Text Available Introduction: The purpose of the current study was to evaluate the blood glutathione peroxidase (GSH-Px and malondialdehyde (MDA levels under seasonal variations in dairy cows during transition period, and to assess the relationship between chosen reproductive parameters, GSH-Px, and MDA.

  14. Developmental plasticity in Tenebrio molitor (Coleoptera: Tenebrionidae): Analysis of Instar Variation in Number and Development Time under Different Diets

    Science.gov (United States)

    The variation in instar number and the pattern of sequential instar development time of Tenebrio molitor L. (Coleoptera: Tenebrionidae) was studied under 4 different diet regimes. Addition of dietary supplements consisting of dry potato or a mix of dry potato and dry egg whites significantly reduced...

  15. Intramale variation in sperm size: functional significance in a polygynous mammal

    Directory of Open Access Journals (Sweden)

    José Luis Ros-Santaella

    2015-12-01

    Full Text Available Studies concerning the relationships between sperm size and velocity at the intraspecific level are quite limited and often yielded contradictory results across the animal kingdom. Intramale variation in sperm size may represent a meaningful factor to predict sperm velocity, due to its relationship with the level of sperm competition among related taxa. Because sperm phenotype is under post-copulatory sexual selection, we hypothesized that a reduced intramale variation in sperm size is associated with sperm competitiveness in red deer. Our results show that low variation in sperm size is strongly related to high sperm velocity and normal sperm morphology, which in turn are good predictors of male fertility in this species. Furthermore, it is well known that the red deer show high variability in testicular mass but there is limited knowledge concerning the significance of this phenomenon at intraspecific level, even though it may reveal interesting processes of sexual selection. Thereby, as a preliminary result, we found that absolute testes mass is negatively associated with intramale variation in sperm size. Our findings suggest that sperm size variation in red deer is under a strong selective force leading to increase sperm function efficiency, and reveal new insights into sexual selection mechanisms.

  16. Image registration under illumination variations using region-based confidence weighted M-estimators.

    Science.gov (United States)

    Fouad, Mohamed M; Dansereau, Richard M; Whitehead, Anthony D

    2012-03-01

    We present an image registration model for image sets with arbitrarily shaped local illumination variations between images. Any nongeometric variations tend to degrade the geometric registration precision and impact subsequent processing. Traditional image registration approaches do not typically account for changes and movement of light sources, which result in interimage illumination differences with arbitrary shape. In addition, these approaches typically use a least-square estimator that is sensitive to outliers, where interimage illumination variations are often large enough to act as outliers. In this paper, we propose an image registration approach that compensates for arbitrarily shaped interimage illumination variations, which are processed using robust M -estimators tuned to that region. Each M-estimator for each illumination region has a distinct cost function by which small and large interimage residuals are unevenly penalized. Since the segmentation of the interimage illumination variations may not be perfect, a segmentation confidence weighting is also imposed to reduce the negative effect of mis-segmentation around illumination region boundaries. The proposed approach is cast in an iterative coarse-to-fine framework, which allows a convergence rate similar to competing intensity-based image registration approaches. The overall proposed approach is presented in a general framework, but experimental results use the bisquare M-estimator with region segmentation confidence weighting. A nearly tenfold improvement in subpixel registration precision is seen with the proposed technique when convergence is attained, as compared with competing techniques using both simulated and real data sets with interimage illumination variations.

  17. Genetic Architecture of Natural Variation Underlying Adult Foraging Behavior That Is Essential for Survival of Drosophila melanogaster.

    Science.gov (United States)

    Lee, Yuh Chwen G; Yang, Qian; Chi, Wanhao; Turkson, Susie A; Du, Wei A; Kemkemer, Claus; Zeng, Zhao-Bang; Long, Manyuan; Zhuang, Xiaoxi

    2017-05-01

    Foraging behavior is critical for the fitness of individuals. However, the genetic basis of variation in foraging behavior and the evolutionary forces underlying such natural variation have rarely been investigated. We developed a systematic approach to assay the variation in survival rate in a foraging environment for adult flies derived from a wild Drosophila melanogaster population. Despite being such an essential trait, there is substantial variation of foraging behavior among D. melanogaster strains. Importantly, we provided the first evaluation of the potential caveats of using inbred Drosophila strains to perform genome-wide association studies on life-history traits, and concluded that inbreeding depression is unlikely a major contributor for the observed large variation in adult foraging behavior. We found that adult foraging behavior has a strong genetic component and, unlike larval foraging behavior, depends on multiple loci. Identified candidate genes are enriched in those with high expression in adult heads and, demonstrated by expression knock down assay, are involved in maintaining normal functions of the nervous system. Our study not only identified candidate genes for foraging behavior that is relevant to individual fitness, but also shed light on the initial stage underlying the evolution of the behavior. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  18. Loss of variation of state detected in soybean metabolic and human myelomonocytic leukaemia cell transcriptional networks under external stimuli

    KAUST Repository

    Sakata, Katsumi

    2016-10-24

    Soybean (Glycine max) is sensitive to flooding stress, and flood damage at the seedling stage is a barrier to growth. We constructed two mathematical models of the soybean metabolic network, a control model and a flooded model, from metabolic profiles in soybean plants. We simulated the metabolic profiles with perturbations before and after the flooding stimulus using the two models. We measured the variation of state that the system could maintain from a state–space description of the simulated profiles. The results showed a loss of variation of state during the flooding response in the soybean plants. Loss of variation of state was also observed in a human myelomonocytic leukaemia cell transcriptional network in response to a phorbol-ester stimulus. Thus, we detected a loss of variation of state under external stimuli in two biological systems, regardless of the regulation and stimulus types. Our results suggest that a loss of robustness may occur concurrently with the loss of variation of state in biological systems. We describe the possible applications of the quantity of variation of state in plant genetic engineering and cell biology. Finally, we present a hypothetical “external stimulus-induced information loss” model of biological systems.

  19. Variation in Gas Exchange Characteristics in Clones of Eucalyptus сamaldulensis Under Varying Conditions of CO2

    Directory of Open Access Journals (Sweden)

    Rekha R. Warrier

    2013-08-01

    Full Text Available he Institute of Forest Genetics and Tree Breeding, Coimbatore, India has a long term systematic tree improvement programme for Eucalyptus species aimed at enhancing productivity and breeding for trait specific clones. In the process, thirty high yielding clones of Eucalyptus camaldulensis Dehnh. were identified. Carbondioxide enrichment studies in special chambers help in understanding the changes at individual level, and also at physiological, biochemical and genetic level. It also provides valuable information for establishing plantations at different geographic locations. Considerable variations were observed when the selected 30 clones of E. camaldulensis were subjected to physiological studies under elevated CO2 conditions (600 mol mol-1. Ten clones exhibited superior growth coupled with favourable physiological characteristics including high photosynthetic rate, carboxylation and water use efficiency under elevated carbon di oxide levels. Clones with minimal variation in physiological characteristics under elevated levels of CO2 suggest their ability to overcome physiological stresses and adapt to varying climatic conditions.

  20. Intraspecific Competition and Population Dynamics of Aedes aegypti

    Science.gov (United States)

    Paixão, C. A.; Charret, I. C.; Lima, R. R.

    2012-04-01

    We report computational simulations for the evolution of the population of the dengue vector, Aedes aegypti mosquitoes. The results suggest that controlling the mosquito population, on the basis of intraspecific competition at the larval stage, can be an efficient mechanism for controlling the spread of the epidemic. The results also show the presence of a kind of genetic evolution in vector population, which results mainly in increasing the average lifespan of individuals in adulthood.

  1. Intraspecific hybridization, developmental stability and fitness in Drosophila mercatorum

    DEFF Research Database (Denmark)

    Andersen, DH; Pertoldi, C; Scali, V

    2002-01-01

    One of the possible effects of intraspecific hybridization is outbreeding depression, due to a breakdown of coadapted gene complexes, which can lead to reduced fitness and decreased developmental stability in hybrids. Alternatively, increased fitness and increased developmental stability in hybrids...... (hybrid vigour) may be a result of hybridization, probably due to increased heterozygosity. Developmental stability is assumed to be correlated with fitness and is commonly measured as fluctuating asymmetry or phenotypic variance. Drosophila mercatorum is capable of reproducing sexually, but also...

  2. Quality standards for DNA sequence variation databases to improve clinical management under development in Australia

    Directory of Open Access Journals (Sweden)

    B. Bennetts

    2014-09-01

    Full Text Available Despite the routine nature of comparing sequence variations identified during clinical testing to database records, few databases meet quality requirements for clinical diagnostics. To address this issue, The Royal College of Pathologists of Australasia (RCPA in collaboration with the Human Genetics Society of Australasia (HGSA, and the Human Variome Project (HVP is developing standards for DNA sequence variation databases intended for use in the Australian clinical environment. The outputs of this project will be promoted to other health systems and accreditation bodies by the Human Variome Project to support the development of similar frameworks in other jurisdictions.

  3. Egg size matching by an intraspecific brood parasite

    Science.gov (United States)

    Lemons, Patrick R.; Sedinger, James S.

    2011-01-01

    Avian brood parasitism provides an ideal system with which to understand animal recognition and its affect on fitness. This phenomenon of laying eggs in the nests of other individuals has classically been framed from the perspective of interspecific brood parasitism and host recognition of parasitic eggs. Few examples exist of strategies adopted by intraspecific brood parasites to maximize success of parasitic eggs. Intraspecific brood parasitism within precocial birds can be a risky strategy in that hatch synchrony is essential to reproductive success. Given that egg size is positively correlated with incubation time, parasitic birds would benefit by recognizing and selecting hosts with a similar egg size. Intraspecific brood parasitism is an alternative reproductive strategy in black brant (Branta bernicla nigricans), a colonial nesting goose with precocial young. Based on a randomization test, parasitic eggs in this study differed less in size from eggs in their host's nests than did random eggs placed in random nests. Parasitic eggs were remarkably similar in size to hosts’ eggs, differing by parasitic brant match the egg size of hosts in our study supports our hypothesis that brant match egg size of hosts, thereby maximizing hatching success of their parasitic eggs.

  4. Intraspecific competition, not predation, drives lizard tail loss on islands.

    Science.gov (United States)

    Itescu, Yuval; Schwarz, Rachel; Meiri, Shai; Pafilis, Panayiotis

    2017-01-01

    Tail autotomy is mainly considered an antipredator mechanism. Theory suggests that predation pressure relaxes on islands, subsequently reducing autotomy rates. Intraspecific aggression, which may also cause tail loss, probably intensifies on islands due to the higher abundance. We studied whether tail autotomy is mostly affected by predation pressure or by intraspecific competition. We further studied whether predator abundance or predator richness is more important in this context. To test our predictions, we examined multiple populations of two gecko species: Kotschy's gecko (Mediodactylus kotschyi; mainland and 41 islands) and the Mediterranean house gecko (Hemidactylus turcicus; mainland and 17 islands), and estimated their abundance together with five indices of predation. In both species, autotomy rates are higher on islands and decline with most predation indices, in contrast with common wisdom, and increase with gecko abundance. In M. kotschyi, tail-loss rates are higher on predator and viper-free islands, but increase with viper abundance. We suggest that autotomy is not simply, or maybe even mainly, an antipredatory mechanism. Rather, such defence mechanisms are a response to complex direct and indirect biotic interactions and perhaps, in the case of tail autotomy in insular populations, chiefly to intraspecific aggression. © 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological Society.

  5. Segregating YKU80 and TLC1 alleles underlying natural variation in telomere properties in wild yeast.

    Directory of Open Access Journals (Sweden)

    Gianni Liti

    2009-09-01

    Full Text Available In yeast, as in humans, telomere length varies among individuals and is controlled by multiple loci. In a quest to define the extent of variation in telomere length, we screened 112 wild-type Saccharomyces sensu stricto isolates. We found extensive telomere length variation in S. paradoxus isolates. This phenotype correlated with their geographic origin: European strains were observed to have extremely short telomeres (400 bp. Insertions of a URA3 gene near telomeres allowed accurate analysis of individual telomere lengths and telomere position effect (TPE. Crossing the American and European strains resulted in F1 spores with a continuum of telomere lengths consistent with what would be predicted if many quantitative trait loci (QTLs were involved in length maintenance. Variation in TPE is similarly quantitative but only weakly correlated with telomere length. Genotyping F1 segregants indicated several QTLs associated with telomere length and silencing variation. These QTLs include likely candidate genes but also map to regions where there are no known genes involved in telomeric properties. We detected transgressive segregation for both phenotypes. We validated by reciprocal hemizygosity that YKU80 and TLC1 are telomere-length QTLs in the two S. paradoxus subpopulations. Furthermore, we propose that sequence divergence within the Ku heterodimer generates negative epistasis within one of the allelic combinations (American-YKU70 and European-YKU80 resulting in very short telomeres.

  6. A non-convex variational approach to photometric stereo under inaccurate lighting

    DEFF Research Database (Denmark)

    Quéau, Yvain; Wu, Tao; Lauze, Francois Bernard

    2017-01-01

    This paper tackles the photometric stereo problem in the presence of inaccurate lighting, obtained either by calibration or by an uncalibrated photometric stereo method. Based on a precise modeling of noise and outliers, a robust variational approach is introduced. It explicitly accounts for self...

  7. Response to recharge variation of thin rainwater lenses and their mixing zone with underlying saline groundwater

    Directory of Open Access Journals (Sweden)

    S. Eeman

    2012-10-01

    Full Text Available In coastal zones with saline groundwater, fresh groundwater lenses may form due to infiltration of rain water. The thickness of both the lens and the mixing zone, determines fresh water availability for plant growth. Due to recharge variation, the thickness of the lens and the mixing zone are not constant, which may adversely affect agricultural and natural vegetation if saline water reaches the root zone during the growing season. In this paper, we study the response of thin lenses and their mixing zone to variation of recharge. The recharge is varied using sinusoids with a range of amplitudes and frequencies. We vary lens characteristics by varying the Rayleigh number and Mass flux ratio of saline and fresh water, as these dominantly influence the thickness of thin lenses and their mixing zone. Numerical results show a linear relation between the normalised lens volume and the main lens and recharge characteristics, enabling an empirical approximation of the variation of lens thickness. Increase of the recharge amplitude causes increase and the increase of recharge frequency causes a decrease in the variation of lens thickness. The average lens thickness is not significantly influenced by these variations in recharge, contrary to the mixing zone thickness. The mixing zone thickness is compared to that of a Fickian mixing regime. A simple relation between the travelled distance of the centre of the mixing zone position due to variations in recharge and the mixing zone thickness is shown to be valid for both a sinusoidal recharge variation and actual records of daily recharge data. Starting from a step response function, convolution can be used to determine the effect of variable recharge in time. For a sinusoidal curve, we can determine delay of lens movement compared to the recharge curve as well as the lens amplitude, derived from the convolution integral. Together the proposed equations provide us with a first order approximation of lens

  8. Network analysis reveals contrasting effects of intraspecific competition on individual vs. population diets.

    Science.gov (United States)

    Araújo, Márcio S; Guimarães, Paulo R; Svanbäck, Richard; Pinheiro, Aluisio; Guimarães, Paulo; Dos Reis, Sérgio F; Bolnick, Daniel I

    2008-07-01

    Optimal foraging theory predicts that individuals should become more opportunistic when intraspecific competition is high and preferred resources are scarce. This density-dependent diet shift should result in increased diet breadth for individuals as they add previously unused prey to their repertoire. As a result, the niche breadth of the population as a whole should increase. In a recent study, R. Svanbäck and D. I. Bolnick confirmed that intraspecific competition led to increased population diet breadth in threespine stickleback (Gasterosteus aculeatus). However, individual diet breadth did not expand as resource levels declined. Here, we present a new method based on complex network theory that moves beyond a simple measure of diet breadth, and we use the method to reexamine the stickleback experiment. This method reveals that the population as a whole added new types of prey as stickleback density was increased. However, whereas foraging theory predicts that niche expansion is achieved by individuals accepting new prey in addition to previously preferred prey, we found that a subset of individuals ceased to use their previously preferred prey, even though other members of their population continued to specialize on the original prey types. As a result, populations were subdivided into groups of ecologically similar individuals, with diet variation among groups reflecting phenotype-dependent changes in foraging behavior as prey density declined. These results are consistent with foraging theory if we assume that quantitative trait variation among consumers affects prey preferences, and if cognitive constraints prevent individuals from continuing to use their formerly preferred prey while adding new prey.

  9. Differential sulphur assimilation mechanism regulates response of Arabidopsis thaliana natural variation towards arsenic stress under limiting sulphur condition.

    Science.gov (United States)

    Khare, Ria; Kumar, Smita; Shukla, Tapsi; Ranjan, Avriti; Trivedi, Prabodh Kumar

    2017-09-05

    Arsenic (As) is a ubiquitous element, which imposes threat to crops productivity and human health through contaminated food chain. As a part of detoxification mechanism, As is chelated and sequestered into the vacuoles via sulphur containing compounds glutathione (GSH) and phytochelatins (PCs). Under limiting sulphur (LS) conditions, exposure of As leads to enhanced toxic effects in plants. Therefore, it is a prerequisite to understand molecular mechanisms involved in As stress response under sulphur deficiency conditions in plants. In recent years, natural variation has been utilized to explore the genetic determinants linked to plant development and stress response. In this study, natural variation in Arabidopsis has been utilized to understand the molecular mechanisms underlying LS and As(III) stress response. Analysis of different accession of Arabidopsis led to the identification of Koz2-2 and Ri-0 as the most tolerant and sensitive accessions, respectively, towards As(III) and LS+As(III) stress. Biochemical analysis and expression profiling of the genes responsible for sulphur transport and assimilation as well as metal detoxification and accumulation revealed significantly enhanced sulphur assimilation mechanism in Koz2-2 as compared to Ri-0. Analyses suggest that genetic variation regulates differential response of accessions towards As(III) under LS condition. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Cultivar mixtures: a meta-analysis of the effect of intraspecific diversity on crop yield.

    Science.gov (United States)

    Reiss, Emily R; Drinkwater, Laurie E

    2018-01-01

    Extensive research has shown that greater plant community diversity leads to higher levels of productivity and other ecosystem services, and such increased diversity has been suggested as a way to improve yield and agricultural sustainability. Increasing intraspecific diversity with cultivar mixtures is one way to increase diversity in agricultural systems. We examined the relationship between intraspecific diversity and yield in cultivar mixtures using a meta-analysis of 91 studies and >3,600 observations. Additionally, we investigated how environmental and management factors might influence this relationship, and if the yield stability of cultivar mixtures differed from that of monocultures. We found that the yield increased by 2.2% overall in cultivar mixtures relative to their monoculture components. Mixtures with more cultivars and those with more functional trait diversity showed higher relative yields. Under biotic stressors, such as disease pressure, and abiotic stressors, such as low levels of soil organic matter and nutrient availability, this diversity effect was stronger, resulting in higher relative yields. Finally, cultivar mixtures generally showed higher yield stability compared to monocultures, especially in response to annual weather variability at a site over time. This practice of mixing cultivars can be integrated into intensified cropping systems where species monocultures dominate, as well as in smallholder cropping systems where low-cost improvements are in demand. Overall, these results suggest that cultivar mixtures are a viable strategy to increase diversity in agroecosystems, promoting increased yield and yield stability, with minimal environmental impact. © 2017 by the Ecological Society of America.

  11. Effect of intraspecific competition and substrate type on terpene emissions from some Mediterranean plant species.

    Science.gov (United States)

    Ormeño, Elena; Bousquet-Mélou, Anne; Mévy, Jean-Philippe; Greff, Stéphane; Robles, Christine; Bonin, Gilles; Fernandez, Catherine

    2007-02-01

    Competition is an important factor that has been extensively reported in the Mediterranean area. There is evidence that leaf terpene accumulation may vary between plants growing on calcareous and siliceous soils. In the present study, leaf terpene emissions from potted seedlings of Pinus halepensis, Cistus albidus, and Quercus coccifera, growing under natural environmental conditions on calcareous and siliceous substrates, were studied by using a bag enclosure method. In both substrates, seedlings were potted alone and in intraspecific competition, to examine the effect of substrate type and that of intraspecific competition on terpene emissions. The results showed that competition favored: (i) overall monoterpene and sesquiterpene emissions from Q. coccifera; (ii) overall monoterpene emissions from P. halepensis; (iii) overall sesquiterpene emissions from C. albidus. Substrate type affected terpene emissions to a limited extent and in a species-specific way. Whereas for Q. coccifera, the overall monoterpene emissions and that of Allo-aromadendrene were favored on siliceous substrate, no significant changes were found in emissions from P. halepensis. Only the release of AR-curcumene from C. albidus was higher on siliceous substrate. We also found high variability in terpene emission composition from the study species, particularly for P. halepensis and Q. coccifera. These two species released both monoterpenes and sesquiterpenes, instead of monoterpenes only, as shown in previous studies.

  12. Potential energy savings using dynamically optimizing control in refrigeration systems under daily variations in ambient temperature

    DEFF Research Database (Denmark)

    Larsen, Lars Finn Sloth; Thybo, Claus; Wisniewski, Rafal

    2007-01-01

    The objective of this study is to investigate the energy saving potential for refrigeration systems by refrigeration more at the colder night time than at the warmer day time. The potential is evaluated using an optimal control policy and illustrated on a simulation example. The results show...... that the significant potential savings depends on two system parameters and the variation of the outdoor temperature. The system dependency is illustrated in a parameter study....

  13. Postcopulatory sexual selection is associated with reduced variation in sperm morphology.

    Science.gov (United States)

    Calhim, Sara; Immler, Simone; Birkhead, Tim R

    2007-05-02

    The evolutionary role of postcopulatory sexual selection in shaping male reproductive traits, including sperm morphology, is well documented in several taxa. However, previous studies have focused almost exclusively on the influence of sperm competition on variation among species. In this study we tested the hypothesis that intraspecific variation in sperm morphology is driven by the level of postcopulatory sexual selection in passerine birds. Using two proxy measures of sperm competition level, (i) relative testes size and (ii) extrapair paternity level, we found strong evidence that intermale variation in sperm morphology is negatively associated with the degree of postcopulatory sexual selection, independently of phylogeny. Our results show that the role of postcopulatory sexual selection in the evolution of sperm morphology extends to an intraspecific level, reducing the variation towards what might be a species-specific 'optimum' sperm phenotype. This finding suggests that while postcopulatory selection is generally directional (e.g., favouring longer sperm) across avian species, it also acts as a stabilising evolutionary force within species under intense selection, resulting in reduced variation in sperm morphology traits. We discuss some potential evolutionary mechanisms for this pattern.

  14. Postcopulatory sexual selection is associated with reduced variation in sperm morphology.

    Directory of Open Access Journals (Sweden)

    Sara Calhim

    2007-05-01

    Full Text Available The evolutionary role of postcopulatory sexual selection in shaping male reproductive traits, including sperm morphology, is well documented in several taxa. However, previous studies have focused almost exclusively on the influence of sperm competition on variation among species. In this study we tested the hypothesis that intraspecific variation in sperm morphology is driven by the level of postcopulatory sexual selection in passerine birds.Using two proxy measures of sperm competition level, (i relative testes size and (ii extrapair paternity level, we found strong evidence that intermale variation in sperm morphology is negatively associated with the degree of postcopulatory sexual selection, independently of phylogeny.Our results show that the role of postcopulatory sexual selection in the evolution of sperm morphology extends to an intraspecific level, reducing the variation towards what might be a species-specific 'optimum' sperm phenotype. This finding suggests that while postcopulatory selection is generally directional (e.g., favouring longer sperm across avian species, it also acts as a stabilising evolutionary force within species under intense selection, resulting in reduced variation in sperm morphology traits. We discuss some potential evolutionary mechanisms for this pattern.

  15. Time resolved FTIR study of the catalytic CO oxidation under periodic variation of the reactant concentration

    Energy Technology Data Exchange (ETDEWEB)

    Kritzenberger, J.; Wokaun, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    Oxidation of CO over palladium/zirconia catalyst obtained from an amorphous Pd{sub 25}Zr{sub 75} precursor was investigated by time resolved FTIR spectroscopy. Sine wave shaped modulation of the reactant concentration, i.e. variation of CO or O{sub 2} partial pressure, was used to induce variations of the IR signals of product (CO{sub 2}) and unconverted reactant (CO), which were detected in a multi-pass absorption cell. The phase shift {phi} between external perturbation and variation of the CO{sub 2} signal was examined in dependence on temperature (100{sup o}C{<=}T{<=}350{sup o}C) and modulation frequency (1.39x10{sup -4}Hz{<=}{omega}{<=}6.67x10{sup -2}Hz). From the phase shift values, a simple Eley-Rideal mechanism is excluded, and the rate limiting step of the Langmuir-Hinshelwood mechanism for the CO oxidation may be identified. Adsorption and possible surface movement of CO to the actual reaction site determine the rate of the CO oxidation on the palladium/zirconia catalyst used in our study. The introduction of an external perturbation is a first step towards the application of two-dimensional infrared spectroscopy to heterogeneous catalyzed reactions. (author) 3 figs., 4 refs.

  16. Evaluating groundwater recharge variations under climate change in an endorheic basin of the Andean plateau

    Science.gov (United States)

    Blin, N.; Hausner, M. B.; Suarez, F. I.

    2017-12-01

    In arid and semi-arid regions, where surface water and precipitations are scarce, groundwater is the main source of drinking water that sustains human and natural ecosystems. Therefore, it is very important to consider the potential impacts of climate change that threaten the availability of this resource. The purpose of this study is to investigate the variations caused by climate change on the recharge of the regional groundwater aquifer at the Huasco salt flat, located in the Chilean Andean plateau. The Huasco salt flat basin has ecosystems sustained by wetlands that depend on the groundwater levels of this aquifer. Due to this reason, the Chilean government has declared this zone as protected. Hence, the assurance of the future availability of the groundwater resource becomes extremely important. The sustainable management of this resource requires reasonable estimates of recharge and evapotranspiration, which are highly dependent on the characteristics and processes occurring in the vadose zone, i.e., topography, soil type and land use, and their temporal and spatial variations are significant in arid regions. With this aim, a three-dimensional groundwater model, implemented in SWAT-MODFLOW, was developed to couple the saturated system with the vadose zone. The model was calibrated and validated using historic data. General circulation models (GCMs) were used as scenarios inputs of recharge to the groundwater model. Future simulations were run by applying an offset to the historic air temperatures and to the precipitation. These offsets were determined using a delta hybrid approach based on the Coupled Model Intercomparison Project Phase 5 (CMIP5) multi-model ensemble archive. The obtained results were downscaled to the 0.125º latitude x 0.125º longitude grid cell containing the basin of the Huasco salt flat. The hybrid approach considered the 10th, 50th and 90th percentiles of the projected temperature and precipitation output as three scenarios of climate

  17. Vibration and damping characteristics of beams with active constrained layer treatments under parametric variations

    International Nuclear Information System (INIS)

    Kumar, Navin; Singh, S.P.

    2009-01-01

    Hybrid damping designs with active piezoelectric materials and passive viscoelastic materials (VEMs) combine the advantages of both active and passive constrained layer damping (ACLD/PCLD) treatments. Researchers have established the standards for the extent and placement of the PCLD treatment for common structures. However for ACLD treatment, such detailed studies are not available. This study is aimed to examine, the effect of parametric variation of active constrained layer on the vibration control of the beams treated with optimally placed active or passive constrained layer damping patches. Finite element model is developed to model the open-loop and close-loop dynamics of active/passive constrained layer damping treated beam. The placement strategies of ACLD patches are devised using the modal strain energy (MSE) approach. Extensive experimentation studies are conducted by making twenty one separate samples of ACLD/PCLD treated beams with variations in viscoelastic material layer thickness, ACLD/PCLD patch coverage and location of the patch. Effects of key parameters, such as control gain, viscoelastic material thickness, coverage and location variation of ACLD patch on the system loss factor have been investigated. The careful analysis of results from partially covered ACLD treated beam suggests that the maximum damping of the first mode can be achieved by attaching the ACLD patch only up to 50% coverage. It also reveals that with proper choice of the control voltage and thickness, the effective loss factor can be almost doubled. The present study suggests the potential use of parametric studies that establish some guide lines for the extent and placement of the ACLD patches on the cantilevered beam.

  18. Respiratory variation in peak aortic velocity accurately predicts fluid responsiveness in children undergoing neurosurgery under general anesthesia.

    Science.gov (United States)

    Morparia, Kavita G; Reddy, Srijaya K; Olivieri, Laura J; Spaeder, Michael C; Schuette, Jennifer J

    2018-04-01

    The determination of fluid responsiveness in the critically ill child is of vital importance, more so as fluid overload becomes increasingly associated with worse outcomes. Dynamic markers of volume responsiveness have shown some promise in the pediatric population, but more research is needed before they can be adopted for widespread use. Our aim was to investigate effectiveness of respiratory variation in peak aortic velocity and pulse pressure variation to predict fluid responsiveness, and determine their optimal cutoff values. We performed a prospective, observational study at a single tertiary care pediatric center. Twenty-one children with normal cardiorespiratory status undergoing general anesthesia for neurosurgery were enrolled. Respiratory variation in peak aortic velocity (ΔVpeak ao) was measured both before and after volume expansion using a bedside ultrasound device. Pulse pressure variation (PPV) value was obtained from the bedside monitor. All patients received a 10 ml/kg fluid bolus as volume expansion, and were qualified as responders if stroke volume increased >15% as a result. Utility of ΔVpeak ao and PPV and to predict responsiveness to volume expansion was investigated. A baseline ΔVpeak ao value of greater than or equal to 12.3% best predicted a positive response to volume expansion, with a sensitivity of 77%, specificity of 89% and area under receiver operating characteristic curve of 0.90. PPV failed to demonstrate utility in this patient population. Respiratory variation in peak aortic velocity is a promising marker for optimization of perioperative fluid therapy in the pediatric population and can be accurately measured using bedside ultrasonography. More research is needed to evaluate the lack of effectiveness of pulse pressure variation for this purpose.

  19. Niche separation in Varecia variegata rubra and Eulemur fulvus albifrons: II. Intraspecific patterns.

    Science.gov (United States)

    Vasey, Natalie

    2002-06-01

    Based on a year-long field study in northeastern Madagascar, I summarize annual patterns of niche use (food patch size, diet, forest height, and forest site) in two sympatric lemurs, Varecia variegata rubra and Eulemur fulvus albifrons. Furthermore, I examine intraspecific patterns of niche use according to sex, season, and reproductive stage in these two lemurs that differ in terms of energetic investment in reproduction. Lemurs as a group provide a special opportunity to test hypotheses concerning sex differences in niche use. Due to their body size monomorphism and seasonal, synchronous pattern of breeding, it is possible to directly evaluate whether sex differences in diet reflect high energetic investment in reproduction by females. Results confirm the hypothesis that intraspecific variation in niche use (e.g., sex differences, seasonal differences) would be more pronounced in V. v. rubra than in E. f. albifrons, due in large measure to the former's relatively high energetic investment in reproduction: 1a) Dietary sex differences in V. v. rubra are most pronounced during costly reproductive stages and involve acquisition of low-fiber, high-protein plant foods. Females of both species consume more seasonally available low-fiber protein (young leaves, flowers) relative to conspecific males during the hot dry season, but only in V. v. rubra females is this pattern also evident during gestation and lactation. 1b) The diets of female V. v. rubra and female E. f. albifrons are more similar to each other than are the diets of conspecific males and females in the case of V. v. rubra. This is not uniformly the case for female E. f. albifrons. This finding confirms a hypothesis put forward in Vasey ([2000] Am J Phys Anthropol 112:411-431) that energetic requirements of reproductive females drive niche separation more than do the energetic requirements of males. 1c) Both species synchronize most or all of lactation with seasonal food abundance and diversity. E. f

  20. Seasonal variations in phosphorus fractions in semiarid sandy soils under different vegetation types

    Science.gov (United States)

    Qiong Zhao; Dehui Zeng; Zhiping Fan; Zhanyuan Yu; Yalin Hu; Jianwei Zhang

    2009-01-01

    We investigated the seasonal patterns of soil phosphorus (P) fractions under five vegetation types – Ulmus macrocarpa savanna, grassland, Pinus sylvestris var. mongolica plantation, Pinus tabulaeformis plantation, and Populus simonii plantation ...

  1. Evaluating the change in fingerprint directional patterns under variation of rotation and number of regions

    CSIR Research Space (South Africa)

    Dorasamy, K

    2015-09-01

    Full Text Available Directional Patterns, which are formed by grouping regions of orientation fields falling within a specific range, vary under rotation and the number of regions. For fingerprint classification schemes, this can result in missclassification due...

  2. Theoretical Analysis and Experimental Study of Subgrade Moisture Variation and Underground Antidrainage Technique under Groundwater Fluctuations

    Directory of Open Access Journals (Sweden)

    Liu Jie

    2013-01-01

    Full Text Available Groundwater is a main natural factor impacting the subgrade structure, and it plays a significant role in the stability of the subgrade. In this paper, the analytical solution of the subgrade moisture variations considering groundwater fluctuations is derived based on Richards’ equation. Laboratory subgrade model is built, and three working cases are performed in the model to study the capillary action of groundwater at different water tables. Two types of antidrainage materials are employed in the subgrade model, and their anti-drainage effects are discussed. Moreover, numerical calculation is conducted on the basis of subgrade model, and the calculate results are compared with the experimental measurements. The study results are shown. The agreement between the numerical and the experimental results is good. Capillary action is obvious when the groundwater table is rising. As the groundwater table is falling, the moisture decreases in the position of the subgrade near the water table and has no variations in the subgrade where far above the table. The anti-drainage effect of the sand cushion is associated with its thickness and material properties. New waterproofing and drainage material can prevent groundwater entering the subgrade effectively, and its anti-drainage effect is good.

  3. THE VARIATIONS OF WATER IN HUMAN TISSUE UNDER CERTAIN COMPRESSION: STUDIED WITH DIFFUSE REFLECTANCE SPECTROSCOPY

    Directory of Open Access Journals (Sweden)

    CHENXI LI

    2013-01-01

    Full Text Available The reflectance spectrum has been widely adopted to extract diagnosis information of human tissue because it possesses the advantages of noninvasive and rapidity. The external pressure brought by fiber optic probe may influence the accuracy of measurement. In this paper, a systematic study is focused on the effects of probe pressure on intrinsic changes of water and scattering particles in tissue. According to the biphasic nonlinear mixture model, the pressure modulated reflectance spectrum of both in vitro and in vivo tissue is measured and processed with second-derivation. The results indicate that the variations of bulk and bonded water in tissue have a nonlinear relationship with the pressure. Differences in tissue structure and morphology contribute to site-specific probe pressure effects. Then the finite element (FEM and Monte Carlo (MC method is employed to simulate the deformation and reflectance spectrum variations of tissue before and after compression. The simulation results show that as the pressure of fiber optic probe applied to the detected skin increased to 80 kPa, the effective photon proportion form dermis decreases significantly from 86% to 76%. Future designs might benefit from the research of change of water volume inside the tissue to mitigate the pressure applied to skin.

  4. Variation with age of anisotropy under oceans, from great circle surface waves

    International Nuclear Information System (INIS)

    Journet, B.; Jobert, N.

    1982-01-01

    Global great circle measurements of regionalized mantle Love wave phase velocities are interpreted in terms of regional models. The same study had been made by J. J. Leveque (1980) for Rayleigh waves, and the resulting models for the two oceanic regions of different ages are used as a basis for comparison: the observed Love wave dispersion cannot be explained with these models if isotropic. The models obtained by inversion of Love wave data are compared with the models mentioned; the discrepancy appearing in the 250 km depth range between the velocities β/sub H/ and β/sub V/ of respectively SH and SV waves is indicative of polarization anisotropy. Moreover, we put forward a significant variation from young to old oceans: the difference between β/sub H/, and β/sub V/ is of the order of 1% for the former, compared to 3% for the latter. This variation can bring information about the behaviour of upper mantle materials in connection with the motion of oceanic plates

  5. Spatial Variation of Soil Respiration in a Cropland under Winter Wheat and Summer Maize Rotation in the North China Plain.

    Directory of Open Access Journals (Sweden)

    Ni Huang

    Full Text Available Spatial variation of soil respiration (Rs in cropland ecosystems must be assessed to evaluate the global terrestrial carbon budget. This study aims to explore the spatial characteristics and controlling factors of Rs in a cropland under winter wheat and summer maize rotation in the North China Plain. We collected Rs data from 23 sample plots in the cropland. At the late jointing stage, the daily mean Rs of summer maize (4.74 μmol CO2 m-2 s-1 was significantly higher than that of winter wheat (3.77μmol CO2 m-2 s-1. However, the spatial variation of Rs in summer maize (coefficient of variation, CV = 12.2% was lower than that in winter wheat (CV = 18.5%. A similar trend in CV was also observed for environmental factors but not for biotic factors, such as leaf area index, aboveground biomass, and canopy chlorophyll content. Pearson's correlation analyses based on the sampling data revealed that the spatial variation of Rs was poorly explained by the spatial variations of biotic factors, environmental factors, or soil properties alone for winter wheat and summer maize. The similarly non-significant relationship was observed between Rs and the enhanced vegetation index (EVI, which was used as surrogate for plant photosynthesis. EVI was better correlated with field-measured leaf area index than the normalized difference vegetation index and red edge chlorophyll index. All the data from the 23 sample plots were categorized into three clusters based on the cluster analysis of soil carbon/nitrogen and soil organic carbon content. An apparent improvement was observed in the relationship between Rs and EVI in each cluster for both winter wheat and summer maize. The spatial variation of Rs in the cropland under winter wheat and summer maize rotation could be attributed to the differences in spatial variations of soil properties and biotic factors. The results indicate that applying cluster analysis to minimize differences in soil properties among different

  6. The physiological variations of adaptation mechaniam in Glycine soja seedlings under saline and alkaline stresses

    International Nuclear Information System (INIS)

    Shao, S.; Li, M.; Yang, D.

    2016-01-01

    The seedlings of Glycine soja were treated with varying saline stress and alkaline stress. The growth, photosynthesis and concentrations of inorganic ions in tissue sap of stressed seedlings were measured to elucidate the mechanism of saline and alkaline stress (high pH) damage to G. soja, and the differences between physiological adaptive mechanism to alkaline stress and saline stress. Our experimental data showed alkalinity had a more severe effects on G. soja seedlings than salinity in the similar concentration, severely inhibited shoot and root growth, and photosynthesis. Diurnal change of pN showed the bimodal curves getting less obvious and transformed to be single peak with increasing stress intensity which might be an efficient energy-conserving strategy for G. soja to adapt to saline and alkaline stress. Na+/K+ were all increased, with greater degrees of increasing under alkaline than under saline stress, cations and anions were almost not accumulated under high alkaline stress, while the influx of superfluous Na+ can be balanced by the accumulation of Cl-, SO42-, H2PO4- in root under saline stress. This indicated that the roots of G. soja were injured so severely that couldn't absorb Na+ and keep ion balance under high alkaline stress including high-pH stress, which might lead to greater accumulation of Na+ in leaves under alkaline stress than that under saline stress, and then sharply reduced the growth and photosynthesis. pN of G. soja seedlings was promoted under low concentration saline and alkaline stresses. Na+/K+ were significant lower in leaves compare with that in roots, and a large amount of Na+ was accumulated in stems of G. soja seedlings under both stresses. Under alkaline stress, the K+, NO3-, Mg2+ and Ca2+ contents in leaves were increased with increasing Na+, and maintain high water content in root. Our results showed obvious differences between physiological adaptive mechanisms to saline stress and alkaline stress. This study would

  7. Elemental stoichiometry and compositions of weevil larvae and two acorn hosts under natural phosphorus variation

    Science.gov (United States)

    Ji, Huawei; Du, Baoming; Liu, Chunjiang

    2017-04-01

    To understand how different trophic organisms in a parasite food chain adapt to the differences in soil nutrient conditions, we investigated stoichiometric variation and homeostasis of multiple elements in two acorn trees, Quercus variabilis and Quercus acutissima, and their parasite weevil larvae (Curculio davidi Fairmaire) at phosphorus (P)-deficient and P-rich sites in subtropical China where P-rich ores are scattered among dominant P-deficient soils. Results showed that elemental stoichiometry and compositions of both acorns and weevil larvae differed significantly between P-deficient and P-rich sites (p plants and animals to P loading, a worldwide issue from excess release of P into the environment.

  8. Sewage-treatment under substantial load variations in winter tourism areas--a full case study.

    Science.gov (United States)

    Winkler, S; Matsché, N; Gamperer, T; Dum, M

    2004-01-01

    The sewage-load variations in winter tourism areas are characterized by sudden increases--in the range of a factor two to three--within only a few days at the start and the end of the tourist season, especially at Christmas. The sudden load increases occur during periods of low wastewater temperatures, which is an additional demanding factor with respect to nitrogen removal. A full case study was carried out at WWTP Saalfelden, which is located near one of Austria's largest skiing resorts. The plant is designed for 80,000 PE and built according to the HYBRID-concept, which is a special two stage activated sludge process for extensive nutrient removal.

  9. Interannual variations in needle and sapwood traits of Pinus edulis branches under an experimental drought

    DEFF Research Database (Denmark)

    Guerin, Marceau; Martin-Benito, Dario; von Arx, Georg

    2018-01-01

    the drop of leaf water potential in branches from year to year through needle morphological adjustments. We tested our hypothesis using a 7-year experiment in central New Mexico with three watering treatments (irrigated, normal, and rain exclusion). We analyzed how variation in evaporative structure...... (d), defining the yearly ratios SA:LA and SA:LA/d. Needle length (l) increased with increasing winter and monsoon water supply, and showed more interannual variability when the soil was drier. Stomatal density increased with dryness, while stomatal diameter was reduced. As a result, anatomical...... maximal stomatal conductance was relatively invariant across treatments. SA:LA and SA:LA/d showed significant differences across treatments and contrary to our expectation were lower with reduced water input. Within average precipitation ranges, the response of these ratios to soil moisture was similar...

  10. Frequency of mononuclear diploid cardiomyocytes underlies natural variation in heart regeneration.

    Science.gov (United States)

    Patterson, Michaela; Barske, Lindsey; Van Handel, Ben; Rau, Christoph D; Gan, Peiheng; Sharma, Avneesh; Parikh, Shan; Denholtz, Matt; Huang, Ying; Yamaguchi, Yukiko; Shen, Hua; Allayee, Hooman; Crump, J Gage; Force, Thomas I; Lien, Ching-Ling; Makita, Takako; Lusis, Aldons J; Kumar, S Ram; Sucov, Henry M

    2017-09-01

    Adult mammalian cardiomyocyte regeneration after injury is thought to be minimal. Mononuclear diploid cardiomyocytes (MNDCMs), a relatively small subpopulation in the adult heart, may account for the observed degree of regeneration, but this has not been tested. We surveyed 120 inbred mouse strains and found that the frequency of adult mononuclear cardiomyocytes was surprisingly variable (>7-fold). Cardiomyocyte proliferation and heart functional recovery after coronary artery ligation both correlated with pre-injury MNDCM content. Using genome-wide association, we identified Tnni3k as one gene that influences variation in this composition and demonstrated that Tnni3k knockout resulted in elevated MNDCM content and increased cardiomyocyte proliferation after injury. Reciprocally, overexpression of Tnni3k in zebrafish promoted cardiomyocyte polyploidization and compromised heart regeneration. Our results corroborate the relevance of MNDCMs in heart regeneration. Moreover, they imply that intrinsic heart regeneration is not limited nor uniform in all individuals, but rather is a variable trait influenced by multiple genes.

  11. Phylogeny and intraspecific variability of holoparasitic Orobanche (Orobanchaceae) inferred from plastid rbcL sequences.

    Science.gov (United States)

    Manen, Jean-François; Habashi, Christine; Jeanmonod, Daniel; Park, Jeong-Mi; Schneeweiss, Gerald M

    2004-11-01

    The rbcL sequences of 106 specimens representing 28 species of the four recognized sections of Orobanche were analyzed and compared. Most sequences represent pseudogenes with premature stop codons. This study confirms that the American lineage (sects. Gymnocaulis and Myzorrhiza) contains potentially functional rbcL-copies with intact open reading frames and low rates of non-synonymous substitutions. For the first time, this is also shown for a member of the Eurasian lineage, O. coerulescens of sect. Orobanche, while all other investigated species of sects. Orobanche and Trionychon contain pseudogenes with distorted reading frames and significantly higher rates of non-synonymous substitutions. Phylogenetic analyses of the rbcL sequences give equivocal results concerning the monophyly of Orobanche, and the American lineage might be more closely related to Boschniakia and Cistanche than to the other sections of Orobanche. Additionally, species of sect. Trionychon phylogenetically nest in sect. Orobanche. This is in concordance with results from other plastid markers (rps2 and matK), but in disagreement with other molecular (nuclear ITS), morphological, and karyological data. This might indicate that the ancestor of sect. Trionychon has captured the plastid genome, or parts of it, of a member of sect. Orobanche. Apart from the phylogenetically problematic position of sect. Trionychon, the phylogenetic relationships within sect. Orobanche are similar to those inferred from nuclear ITS data and are close to the traditional groupings traditionally recognized based on morphology. The intraspecific variation of rbcL is low and is neither correlated with intraspecific morphological variability nor with host range. Ancestral character reconstruction using parsimony suggests that the ancestor of O. sect. Orobanche had a narrow host range.

  12. Intraspecific hybridization, developmental stability and fitness in Drosophila mercatorum

    DEFF Research Database (Denmark)

    Andersen, DH; Pertoldi, C; Scali, V

    2002-01-01

    (hybrid vigour) may be a result of hybridization, probably due to increased heterozygosity. Developmental stability is assumed to be correlated with fitness and is commonly measured as fluctuating asymmetry or phenotypic variance. Drosophila mercatorum is capable of reproducing sexually, but also....... Intraspecific hybridization between a parthenogenetic and a sexually reproducing strain of Drosophila mercatorum resulted in significant changes in fecundity as well as fluctuating asymmetry and phenotypic variance for the number of sternopleural bristles and in the length of two wing traits over three...

  13. Compliance variations in the fatigue thresold regime of a low alloy ferritic steel under closure-free testing conditions

    International Nuclear Information System (INIS)

    Vaidya, W.V.

    1991-01-01

    Compliance variations in the threshold regime of a high strength ferritic steel tested under closure-free conditions at room temperature and in air are reported. In contrast to the Paris regime, and irrespective of whether the data during load shedding, at threshold or after postthreshold load increase are considered, it is found that comparatively compliance varies inconsistently in the threshold regime. Therefore, a 1:1 correlation between the averaged optical crack length and that inferred from compliance was not observed. This discrepancy is analyzed. The variations in compliance are utilized to infer the crack front behavior, and the results are discussed in terms of the microstructural impedance. (orig.) With 22 figs., 2 appendices [de

  14. Variation in total sugars and reductive sugars in the moss Pleurozium schreberi (hylocomiaceae) under water deficit conditions

    International Nuclear Information System (INIS)

    Montenegro Ruiz, Luis Carlos; Melgarejo Munoz, Luz Marina.

    2012-01-01

    The structural simplicity of the bryophytes exposed them easily to water stress, forcing them to have physiological and biochemical mechanisms that enable them to survive. This study evaluated the variation of total soluble sugars and reducing sugars in relation to relative water content, in Pleurozium schreberi when faced with low water content in the Paramo de Chingaza (Colombia) and under simulated conditions of water deficit in the laboratory. we found that total sugars increase when the plant is dehydrated and returned to their normal content when re-hydrated moss, this could be interpreted as a possible mechanism of osmotic adjustment and osmoprotection of the cell content and cellular structure. Reducing sugars showed no significant variation, showing that monosaccharides do not have a protective role during dehydration.

  15. Performance Evaluation of Type-3 PLLs Under Wide Variation in Input Voltage and Frequency

    DEFF Research Database (Denmark)

    Aravind, C. K.; Rani, B.Indu; Chakkarapani, M.

    2017-01-01

    bandwidth, both the single loop and dual loop Type-3 PLL exhibit similar dynamics provided the supply voltage is balanced. However, under voltage sag conditions, dual loop PLL shows improved dynamic response without affecting its stability. Further, the tracking time is reduced as the feed forward frequency...

  16. Compositional sorting dynamics in coexisting lipid bilayer phases with variations in underlying e-beam formed curvature pattern.

    Science.gov (United States)

    Ogunyankin, Maria O; Longo, Marjorie L

    2013-07-07

    Nanometer-scale curvature patterns of an underlying substrate are imposed on lipid multibilayers with each pattern imparting distinctly different sorting dynamics to a metastable pixelation pattern of coexisting liquid ordered (Lo)-liquid disordered (Ld) lipid phases. Therefore, this work provides pathways toward mechanical energy-based separations for analysis of biomembrane-associate species. The central design concept of the patterned sections of the silica substrate is a square lattice pattern of 100 nm projected radius poly(methyl methacrylate) (PMMA) hemispherical features formed by electron beam lithography which pixelates the coexisting phases in order to balance membrane bending and line energy. In one variation, we surround this pattern with three PMMA walls/fences 100 nm in height which substantially slows the loss of the high line energy pixelated Lo phase by altering the balance of two competing mechanism (Ostwald ripening vs. vesiculation). In another walled variation, we form a gradient of the spacing of the 100 nm features which forces partitioning of the Lo phase toward the end of the gradient with the most open (400 nm spacing) lattice pattern where a single vesicle could grow from the Lo phase. We show that two other variations distinctly impact the dynamics, demonstrating locally slowed loss of the high line energy pixelated Lo phase and spontaneous switching of the pixel location on the unit cell, respectively. Moreover, we show that the pixelation patterns can be regenerated and sharpened by a heating and cooling cycle. We argue that localized variations in the underlying curvature pattern have rather complex consequences because of the coupling and/or competition of dynamic processes to optimize mechanical energy such as lipid diffusion, vesiculation and growth, and phase/compositional partitioning.

  17. [Variation of soil organic carbon under different vegetation types in Karst Mountain areas of Guizhou Province, southwest China].

    Science.gov (United States)

    Liao, Hong-kai; Long, Jian

    2011-09-01

    This paper studied the variation characteristics of soil organic carbon (SOC) and different particle sizes soil particulate organic carbon (POC) in normal soil and in micro-habitats under different vegetation types in typical Karst mountain areas of southwest Guizhou. Under different vegetation types, the SOC content in normal soil and in micro-habitats was all in the order of bare land forest, with the variation range being 7.18-43.42 g x kg(-1) in normal soil and being 6.62-46.47 g x kg(-1) and 9.01-52.07 g x kg(-1) in earth surface and stone pit, respectively. The POC/MOC (mineral-associated organic carbon) ratio under different vegetation types was in the order of bare land forest stone pit was the highest, as compared to that in normal soil and in earth surface. In the process of bare land-grass-shrub-forest, the contents of different particle sizes soil POC increased, while the SOC mainly existed in the forms of sand- and silt organic carbon, indicating that in Karst region, soil carbon sequestration and SOC stability were weak, soil was easily subjected to outside interference and led to organic carbon running off, and thus, soil quality had the risk of decline or degradation.

  18. DGAT1 underlies large genetic variation in milk-fat composition of dairy cows.

    Science.gov (United States)

    Schennink, A; Stoop, W M; Visker, M H P W; Heck, J M L; Bovenhuis, H; van der Poel, J J; van Valenberg, H J F; van Arendonk, J A M

    2007-10-01

    Dietary fat may play a role in the aetiology of many chronic diseases. Milk and milk-derived foods contribute substantially to dietary fat, but have a fat composition that is not optimal for human health. We measured the fat composition of milk samples in 1918 Dutch Holstein Friesian cows in their first lactation and estimated genetic parameters for fatty acids. Substantial genetic variation in milk-fat composition was found: heritabilities were high for short- and medium-chain fatty acids (C4:0-C16:0) and moderate for long-chain fatty acids (saturated and unsaturated C18). We genotyped 1762 cows for the DGAT1 K232A polymorphism, which is known to affect milk-fat percentage, to study the effect of the polymorphism on milk-fat composition. We found that the DGAT1 K232A polymorphism has a clear influence on milk-fat composition. The DGAT1 allele that encodes lysine (K) at position 232 (232K) is associated with more saturated fat; a larger fraction of C16:0; and smaller fractions of C14:0, unsaturated C18 and conjugated linoleic acid (P < 0.001). We conclude that selective breeding can make a significant contribution to change the fat composition of cow's milk.

  19. Seed Bank Variation under Contrasting Site Quality Conditions in Mixed Oak Forests of Southeastern Ohio, USA

    Directory of Open Access Journals (Sweden)

    Christine J. Small

    2010-01-01

    Full Text Available Seed bank composition was sampled in 192–2.5 m2 quadrats, established in six regenerating clearcut (∼7 years and six second-growth (∼125 years mixed-oak forest stands in southeastern Ohio. Seed bank and aboveground composition diverged markedly (Sørensen's coefficient <10%, emphasizing the importance of fast-growing, early-successional germinants to early ecosystem recovery. Seed richness was significantly (P<.01 higher in clearcut stands, suggesting declining richness with stand age. Richness estimations 28%–60% higher than observed values demonstrated high seed bank heterogeneity, emphasizing the need for intensive sampling to assess temperate forest seed bank variation. Site quality (topographic aspect strongly influenced seed bank composition, with greater importance of early-successional trees, thicket-forming shrubs, and nonnative species on mesic sites. Thus, forest seed banks are likely to play an important, site-dependent role in shaping competitive environments for commercially important timber species after harvesting and soil disturbance and have the potential for marked influence on postharvest forest development.

  20. Seed Bank Variation under Contrasting Site Quality Conditions in Mixed Oak Forests of Southeastern Ohio, USA

    International Nuclear Information System (INIS)

    Small, Ch.J.; McCarthy, B.C.

    2010-01-01

    Seed bank composition was sampled in 192-2.5 m 2 quadrats, established in six regenerating clearcut (∼7 years) and six second-growth ((∼125 years) mixed-oak forest stands in southeastern Ohio. Seed bank and aboveground composition diverged markedly (Sorensen's coefficient <10%), emphasizing the importance of fast-growing, early-successional germinants to early ecosystem recovery. Seed richness was significantly (ρ<.01) higher in clearcut stands, suggesting declining richness with stand age. Richness estimations 28%-60% higher than observed values demonstrated high seed bank heterogeneity, emphasizing the need for intensive sampling to assess temperate forest seed bank variation. Site quality (topographic aspect) strongly influenced seed bank composition, with greater importance of early-successional trees, thicket-forming shrubs, and nonnative species on mesic sites. Thus, forest seed banks are likely to play an important, site-dependent role in shaping competitive environments for commercially important timber species after harvesting and soil disturbance and have the potential for marked influence on post harvest forest development.

  1. VARIATION IN GRAIN YIELD, BIOMASS AND GRAIN NUMBER OF BARLEY UNDER DROUGHT

    Directory of Open Access Journals (Sweden)

    Cándido López-Castañeda

    2011-08-01

    Full Text Available Variability in grain yield (GY, aerial biomass (BM and number of grains m-2 (G M-2 in F6 lines and commercial varieties of barley was studied, and the relationship among these characters in full-irrigation (FI, drought (D and rain-fed (RF conditions was determined. Variation in GY, BM and G M-2 among all genotypes, between F6 lines and varieties, and among genotypes of F6 lines and varieties was significant in all the three soil moisture environments. GY, BM and G M-2 in FI were 23, 14 and 21 % greater than the average of the three soil moisture environments; GY, BM and G M-2 in RF were 21, 16 y 24 % lower than this average. F6 lines produced greater GY (380 g m-2, BM (1027 g m-2 and G M-2 (8641 than the commercial varieties (GY=290 g m-2; BM=726 g m-2 y G M-2=7463 in average of the three environments. GY was positive and significantly associated with BM and G M-2; BM and G M-2 were also associated. GY could be improved in either FI, D or RF environments by selecting genotypes with a greater BM and G M-2 or both of them.

  2. Adaptive Sliding Mode Control Design of a SCARA Robot Manipulator System Under Parametric Variations

    Directory of Open Access Journals (Sweden)

    F. Adelhed

    2015-12-01

    Full Text Available – The sliding mode control (SMC has yet proven its efficiency through several theoretical researches. Indeed, the robotic field is recognized as one of the main SMC portals on practical implementations. The interest of this work consists in testing the SMC robustness and its reliability versus the parameters variation and model uncertainties. In this paper, an algorithm for trajectory tracking task of robot manipulators based on a SMC has been proposed. Then, aiming to deal with the presence of disturbances and parametric modeling uncertainties, the adopted control law has been extended to an adaptive SMC version based integral sliding surface, where the selection of the parameters adaptation law has been detailed. It has been proven that the adaptive control design can stabilize both position and velocity of the system, where the explicit use of the system dynamic model becomes no longer required. Simulation results performed on a SCARA robot manipulator reveal improving control acting clearly denoted by the introduction of the adaptive control design

  3. Natural variation in a single amino acid substitution underlies physiological responses to topoisomerase II poisons.

    Science.gov (United States)

    Zdraljevic, Stefan; Strand, Christine; Seidel, Hannah S; Cook, Daniel E; Doench, John G; Andersen, Erik C

    2017-07-01

    Many chemotherapeutic drugs are differentially effective from one patient to the next. Understanding the causes of this variability is a critical step towards the development of personalized treatments and improvements to existing medications. Here, we investigate sensitivity to a group of anti-neoplastic drugs that target topoisomerase II using the model organism Caenorhabditis elegans. We show that wild strains of C. elegans vary in their sensitivity to these drugs, and we use an unbiased genetic approach to demonstrate that this natural variation is explained by a methionine-to-glutamine substitution in topoisomerase II (TOP-2). The presence of a non-polar methionine at this residue increases hydrophobic interactions between TOP-2 and its poison etoposide, as compared to a polar glutamine. We hypothesize that this stabilizing interaction results in increased genomic instability in strains that contain a methionine residue. The residue affected by this substitution is conserved from yeast to humans and is one of the few differences between the two human topoisomerase II isoforms (methionine in hTOPIIα and glutamine in hTOPIIβ). We go on to show that this amino acid difference between the two human topoisomerase isoforms influences cytotoxicity of topoisomerase II poisons in human cell lines. These results explain why hTOPIIα and hTOPIIβ are differentially affected by various poisons and demonstrate the utility of C. elegans in understanding the genetics of drug responses.

  4. A comparative analysis between FinFET Semi-Dynamic Flip-Flop topologies under process variations

    KAUST Repository

    Rabie, Mohamed A.

    2011-11-01

    Semi-Dynamic Flip-Flops are widely used in state-of-art microprocessors. Moreover, scaling down traditional CMOS technology faces major challenges which rises the need for new devices for replacement. FinFET technology is a potential replacement due to similarity in both fabrication process and theory of operation to current CMOS technology. Hence, this paper presents the study of Semi Dynamic Flip Flops using both Independent gate and Tied gate FinFET devices in 32nm technology node. Furthermore, it studies the performance of these new circuits under process variations. © 2011 IEEE.

  5. Intraspecific larval competition in the olive fruit fly (Diptera: tephritidae).

    Science.gov (United States)

    Burrack, Hannah Joy; Fornell, Angela M; Connell, Joseph H; O'Connell, Neil V; Phillips, Phil A; Vossen, Paul M; Zalom, Frank G

    2009-10-01

    Olive fruit flies [Bactrocera oleae (Gmelin)] occur at densities in California that can result in intraspecific larval competition within infested fruit. Larval B. oleae densities tracked in the field at six location were found to be highly variable and related to the proportion of fruit infested and adult densities. Egg and larval distribution within the field was generally aggregated early in the season and trended toward random and uniform as the season progressed. To determine whether B. oleae experienced fitness consequences at a range of larval densities observed in the field, olive fruits were infested with one, two, four, and six eggs, and larval and pupal developmental time, pupal weight, and pupal yield were compared. At the highest egg density, all measures of performance were negatively impacted, resulting in fewer and lighter pupae that took longer to pupate and emerge as adults, and even when only two larvae was present per olive, resulting pupae were significantly smaller. Density did not impact the sex ratio of the resulting flies or survive to adults. As field surveys showed, larval densities ranged from 1 to 11 B. oleae per fruit at some sites, and our results suggest that, at high densities, B. oleae do experience competition for larval resources. The impact of intraspecific larval competition North American in field populations of B. oleae is unknown, but the potential for competition is present.

  6. Spatio-temporal variation in soil derived nitrous oxide emissions under sugarcane.

    Science.gov (United States)

    Huang, Xiaodong; Grace, Peter; Mengersen, Kerrie; Weier, Keith

    2011-10-01

    Nitrous oxide (N(2)O) is a significant greenhouse gas with a global warming potential that is 300 times than that of carbon dioxide. Soil derived N(2)O emissions usually display a high degree of spatial and temporal variability because of their dependence on soil chemical and physical properties, and climate dependent environmental factors. However, there is little research that incorporates spatial dependence in the estimation of N(2)O emissions allowing for environmental factors in the same model. This study aims to examine the impact of two environmental factors (soil temperature and soil moisture) on N(2)O emissions and explore the spatial structure of N(2)O in the sub-tropical South East Queensland region of Australia. The replicated data on N(2)O emissions and soil properties were collected at a typical sugarcane land site covering 25 uniform grid points across 3600 m(2) between October 2007 and September 2008. A Bayesian conditional autoregressive (CAR) model was used to model spatial dependence. Results showed that soil moisture and soil temperature appeared to have substantially different effects on N(2)O emissions after taking spatial dependence into account in the four seasons. There was a substantial variation in the spatial distribution of N(2)O emission in the different seasons. The high N(2)O emission regions were accompanied by high uncertainty and changed in varying seasons in this study site. Spatial CAR models might be more plausible to elucidate and account for the uncertainty arising from unclear variables and spatial variability in the assessment of N(2)O emissions in soils, and more accurately identify relationships with key environmental factors and help to reduce the uncertainty of the soil parameters. Copyright © 2011 Elsevier B.V. All rights reserved.

  7. Transposable Element-Mediated Balancing Selection at Hsp90 Underlies Embryo Developmental Variation.

    Science.gov (United States)

    Chen, Bing; Zhang, Bo; Xu, Lingling; Li, Qing; Jiang, Feng; Yang, Pengcheng; Xu, Yanan; Kang, Le

    2017-05-01

    Understanding the roles of transposable elements (TEs) in the evolution of genome and adaptation is a long-sought goal. Here, we present a new model of TE co-option, in which a TE is harnessed by an essential gene and confers local adaptation through heterozygote advantage. We characterized a human Alu-like TE family, the Lm1 elements, in the genome of the migratory locust Locusta migratoria that harbors 0.7 million copies of the elements. Scanning Lm1 insertions in the natural locust populations revealed the widespread high polymorphism of Lm1. An Lm1 was recruited into the coding region of Heat-shock protein 90 (Hsp90), an important molecular chaperone for diverse signal transduction and developmental pathways. Only heterozygotes of the allele are present in natural populations. Allele frequency increases with decreased latitudes in east coastal China, even increasing up to 76% in southern populations. Regions flanking the Lm1 insertion display clear signatures of a selective sweep linked to Lm1. The Lm1-mediated Hsp90 mutation is consequential for the embryonic development of locust. Heterozygous embryos develop faster than the wild type, particularly when cued by long-day parental photoperiod. The heterozygotes also present a reduced within-population variation in embryonic development, i.e., high developmental synchrony of embryos. The naturally occurring Hsp90 mutation could facilitate multivoltinism and developmental synchronization of the locust in southern tropical region. These results revealed a genetic mechanism behind microevolutionary changes in which balancing selection may have acted to maintain the heterozygote advantage through TE co-option in essential genes. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  8. Genetic variation underlying resistance to infectious hematopoietic necrosis virus in a steelhead trout (Oncorhynchus mykiss) population

    Science.gov (United States)

    Brieuc, Marine S. O.; Purcell, Maureen K.; Palmer, Alexander D.; Naish, Kerry A.

    2015-01-01

    Understanding the mechanisms of host resistance to pathogens will allow insights into the response of wild populations to the emergence of new pathogens. Infectious hematopoietic necrosis virus (IHNV) is endemic to the Pacific Northwest and infectious to Pacific salmon and trout (Oncorhynchus spp.). Emergence of the M genogroup of IHNV in steelhead trout O. mykiss in the coastal streams of Washington State, between 2007 and 2011, was geographically heterogeneous. Differences in host resistance due to genetic change were hypothesized to be a factor influencing the IHNV emergence patterns. For example, juvenile steelhead trout losses at the Quinault National Fish Hatchery (QNFH) were much lower than those at a nearby facility that cultures a stock originally derived from the same source population. Using a classical quantitative genetic approach, we determined the potential for the QNFH steelhead trout population to respond to selection caused by the pathogen, by estimating the heritability for 2 traits indicative of IHNV resistance, mortality (h2 = 0.377 (0.226 - 0.550)) and days to death (h2 = 0.093 (0.018 - 0.203)). These results confirm that there is a genetic basis for resistance and that this population has the potential to adapt to IHNV. Additionally, genetic correlation between days to death and fish length suggests a correlated response in these traits to selection. Reduction of genetic variation, as well as the presence or absence of resistant alleles, could affect the ability of populations to adapt to the pathogen. Identification of the genetic basis for IHNV resistance could allow the assessment of the susceptibility of other steelhead populations.

  9. [Variation characteristics of soil carbon sequestration under long-term different fertilization in red paddy soil].

    Science.gov (United States)

    Huang, Jing; Zhang, Yang-zhu; Gao, Ju-sheng; Zhang, Wen-ju; Liu, Shu-jun

    2015-11-01

    The objective of this study was to clarify the changes of soil organic carbon (SOC) content, the saturation capacity of soil carbon sequestration and its cooperation with carbon input (crop source and organic fertilizer source carbon) under long-term (1982-2012) different fertilization in red paddy soil. The results showed that fertilization could increase SOC content. The SOC content of all the fertilization treatments demonstrated a trend of stabilization after applying fertilizer for 30 years. The SOC content in the treatments applying organic manure with mineral fertilizers was between 21.02 and 21.24 g · kg(-1), and the increase rate ranged from 0.41 to 0.59 g · kg(-1) · a(-1). The SOC content in the treatments applying mineral fertilizers only was 15.48 g · kg(-1). The average soil carbon sequestration in the treatments that applied organic manure with mineral fertilizers ranged from 43.61 to 48.43 t C · hm(-2), and the average SOC storage over the years in these treatments was significantly greater than those applying mineral fertilizers only. There was an exponentially positive correlation between C sequestration efficiency and annual average organic C input. It must input exogenous organic carbon at least at 0. 12 t C · hm(-2) · a(-1) to maintain the balance of soil organic carbon under the experimental conditions.

  10. Genotypic Variation of Early Maturing Soybean Genotypes for Phosphorus Utilization Efficiency under Field Grown Conditions

    International Nuclear Information System (INIS)

    Abaidoo, R.C.; Opoku, A.; Boahen, S.; Dare, M.O.

    2013-01-01

    Variability in the utilization of phosphorus (P) by 64 early-maturing soybean (Glycine max L. Merr.) genotypes under low-P soil conditions were evaluated in 2009 and 2010 at Shika, Nigeria. Fifteen phenotypic variables; number of nodules, nodule dry weight, grain yield, plant biomass, total biomass, biomass N and P content, Phosphorus Utilization Index (PUI), shoot P Utilization efficiency (PUIS), grain P Utilization efficiency (PUIG), Harvest Index (HI), Biological N fixed (BNF), total N fixed and N and P uptake were measured. The four clusters revealed by cluster analysis were basically divided along (1) plant biomass and uptake, (2) nutrient acquisition and utilization and (3) nodulation components. Three early maturing genotypes, TGx1842-14E, TGx1912-11F and TGx1913-5F, were identified as having high P utilization index and low P uptake. These genotypes could be a potential source for breeding for P use efficiency in early maturing soybean genotypes. (author)

  11. Detection of structural damage using novelty detection algorithm under variational environmental and operational conditions

    Science.gov (United States)

    El Mountassir, M.; Yaacoubi, S.; Dahmene, F.

    2015-07-01

    Novelty detection is a widely used algorithm in different fields of study due to its capabilities to recognize any kind of abnormalities in a specific process in order to ensure better working in normal conditions. In the context of Structural Health Monitoring (SHM), this method is utilized as damage detection technique because the presence of defects can be considered as abnormal to the structure. Nevertheless, the performance of such a method could be jeopardized if the structure is operating in harsh environmental and operational conditions (EOCs). In this paper, novelty detection statistical technique is used to investigate the detection of damages under various EOCs. Experiments were conducted with different scenarios: damage sizes and shapes. EOCs effects were simulated by adding stochastic noise to the collected experimental data. Different levels of noise were studied to determine the accuracy and the performance of the proposed method.

  12. Detection of structural damage using novelty detection algorithm under variational environmental and operational conditions

    International Nuclear Information System (INIS)

    Mountassir, M El; Yaacoubi, S; Dahmene, F

    2015-01-01

    Novelty detection is a widely used algorithm in different fields of study due to its capabilities to recognize any kind of abnormalities in a specific process in order to ensure better working in normal conditions. In the context of Structural Health Monitoring (SHM), this method is utilized as damage detection technique because the presence of defects can be considered as abnormal to the structure. Nevertheless, the performance of such a method could be jeopardized if the structure is operating in harsh environmental and operational conditions (EOCs). In this paper, novelty detection statistical technique is used to investigate the detection of damages under various EOCs. Experiments were conducted with different scenarios: damage sizes and shapes. EOCs effects were simulated by adding stochastic noise to the collected experimental data. Different levels of noise were studied to determine the accuracy and the performance of the proposed method. (paper)

  13. An optical flow-based approach to robust face recognition under expression variations.

    Science.gov (United States)

    Hsieh, Chao-Kuei; Lai, Shang-Hong; Chen, Yung-Chang

    2010-01-01

    Face recognition is one of the most intensively studied topics in computer vision and pattern recognition, but few are focused on how to robustly recognize faces with expressions under the restriction of one single training sample per class. A constrained optical flow algorithm, which combines the advantages of the unambiguous correspondence of feature point labeling and the flexible representation of optical flow computation, has been developed for face recognition from expressional face images. In this paper, we propose an integrated face recognition system that is robust against facial expressions by combining information from the computed intraperson optical flow and the synthesized face image in a probabilistic framework. Our experimental results show that the proposed system improves the accuracy of face recognition from expressional face images.

  14. Variation of biometric parameters in corn cobs under the influence of nitrogen fertilization

    Science.gov (United States)

    Gigel, Prisecaru; Florin, Sala

    2017-07-01

    Biometric parameters as elements of productivity on corn cobs, along with plant density per unit area (ha) are essential in achieving production. The influence of differentiated fertilization with nitrogen was evaluated at the level of productivity elements on corn cobs, Andreea hybrid. Biometric parameters of the corn cobs (total length - L; usable length - l; uncoated length with corn kernels - lu; diameter at the base - Db, middle - Dm, and top of the corn cobs - Dt; corn cob weight - Cw, grain weight - Gw) were directly influenced by the doses of nitrogen. Regression analysis has facilitated the prediction of grain weight as the main element of productivity under different statistical certainty based on nitrogen doses (R2 = 0.962, pcorn cobs (R2 = 0.985, pcorn cobs (R2 = 0.996, pcorn cobs (R2 = 0.824, pcorn cobs (R2 = 0.807, pcorn kernels (R2 = 0.624, pcorn cobs (R2 = 0.384, p=0.015).

  15. Interannual variations in needle and sapwood traits of Pinus edulis branches under an experimental drought

    Energy Technology Data Exchange (ETDEWEB)

    Guerin, Marceau; Martin-Benito, Dario; Von Arx, Georg; Andreu-Hayles, Laia; Griffin, Kevin L.; Hamdan, Rayann; McDowell, Nate G.; Muscarella, Robert; Pockman, William T.; Gentine, Pierre

    2018-01-31

    In recent years, widespread forest mortality in response to drought has been documented worldwide (Allen, Breshears & McDowell 2015). An example of widespread and rapid increase in drought-induced mortality, or die-off, was observed for Pinus edulis Engelm. across the Southwestern USA in response to several years of reduced rainfall and high vapor pressure deficits (VPD) (Breshears et al. 2009; Allen et al. 2010; Williams et al. 2013). Although stomatal closure under drought has been hypothesized to increase mortality through carbon starvation (McDowell et al. 2008; Breshears et al. 2009), more evidences exist for mortality being caused by hydraulic failure (Plaut et al. 2012; McDowell et al. 2013; Sevanto et al. 2014; Garcia-Forner et al. 2016). Regardless of the mechanism of drought-induced decline, maintaining a positive supply of water to the foliage is critical for tree functioning and survival.

  16. Variations in the U-Value Measurement of a Whole Dwelling Using Infrared Thermography under Controlled Conditions

    Directory of Open Access Journals (Sweden)

    Alex Marshall

    2018-03-01

    Full Text Available U-values of building elements are often determined using point measurements, where infrared imagery may be used to identify a suitable location for these measurements. Current methods identify that surface areas exhibiting a homogeneous temperature—away from regions of thermal bridging—can be used to obtain U-values. In doing so, however, the resulting U-value is assumed to represent that entire building element, contrary to the information given by the initial infrared inspection. This can be problematic when applying these measured U-values to models for predicting energy performance. Three techniques have been used to measure the U-values of external building elements of a full-scale replica of a pre-1920s U.K. home under controlled conditions: point measurements, using heat flux meters, and two variations of infrared thermography at high and low resolutions. U-values determined from each technique were used to calibrate a model of that building and predictions of the heat transfer coefficient, annual energy consumption, and fuel cost were made. Point measurements and low-resolution infrared thermography were found to represent a relatively small proportion of the overall U-value distribution. By propagating the variation of U-values found using high-resolution thermography, the predicted heat transfer coefficient (HTC was found to vary between 183 W/K to 235 W/K (±12%. This also led to subsequent variations in the predictions for annual energy consumption for heating (between 4923 kWh and 5481 kWh, ±11%; and in the predicted cost of that energy consumption (between £227 and £281, ±24%. This variation is indicative of the sensitivity of energy simulations to sensor placement when carrying out point measurements for U-values.

  17. Real-time electrical impedimetric monitoring of blood coagulation process under temperature and hematocrit variations conducted in a microfluidic chip.

    Directory of Open Access Journals (Sweden)

    Kin Fong Lei

    Full Text Available Blood coagulation is an extremely complicated and dynamic physiological process. Monitoring of blood coagulation is essential to predict the risk of hemorrhage and thrombosis during cardiac surgical procedures. In this study, a high throughput microfluidic chip has been developed for the investigation of the blood coagulation process under temperature and hematocrit variations. Electrical impedance of the whole blood was continuously recorded by on-chip electrodes in contact with the blood sample during coagulation. Analysis of the impedance change of the blood was conducted to investigate the characteristics of blood coagulation process and the starting time of blood coagulation was defined. The study of blood coagulation time under temperature and hematocrit variations was shown a good agreement with results in the previous clinical reports. The electrical impedance measurement for the definition of blood coagulation process provides a fast and easy measurement technique. The microfluidic chip was shown to be a sensitive and promising device for monitoring blood coagulation process even in a variety of conditions. It is found valuable for the development of point-of-care coagulation testing devices that utilizes whole blood sample in microliter quantity.

  18. Intraspecific competition drives increased resource use diversity within a natural population.

    Science.gov (United States)

    Svanbäck, Richard; Bolnick, Daniel I

    2007-03-22

    Resource competition is thought to play a major role in driving evolutionary diversification. For instance, in ecological character displacement, coexisting species evolve to use different resources, reducing the effects of interspecific competition. It is thought that a similar diversifying effect might occur in response to competition among members of a single species. Individuals may mitigate the effects of intraspecific competition by switching to use alternative resources not used by conspecific competitors. This diversification is the driving force in some models of sympatric speciation, but has not been demonstrated in natural populations. Here, we present experimental evidence confirming that competition drives ecological diversification within natural populations. We manipulated population density of three-spine sticklebacks (Gasterosteus aculeatus) in enclosures in a natural lake. Increased population density led to reduced prey availability, causing individuals to add alternative prey types to their diet. Since phenotypically different individuals added different alternative prey, diet variation among individuals increased relative to low-density control enclosures. Competition also increased the diet-morphology correlations, so that the frequency-dependent interactions were stronger in high competition. These results not only confirm that resource competition promotes niche variation within populations, but also show that this increased diversity can arise via behavioural plasticity alone, without the evolutionary changes commonly assumed by theory.

  19. Modelling soil water content variations under drought stress on soil column cropped with winter wheat

    Directory of Open Access Journals (Sweden)

    Csorba Szilveszter

    2014-12-01

    Full Text Available Mathematical models are effective tools for evaluating the impact of predicted climate change on agricultural production, but it is difficult to test their applicability to future weather conditions. We applied the SWAP model to assess its applicability to climate conditions, differing from those, for which the model was developed. We used a database obtained from a winter wheat drought stress experiment. Winter wheat was grown in six soil columns, three having optimal water supply (NS, while three were kept under drought-stressed conditions (S. The SWAP model was successfully calibrated against measured values of potential evapotranspiration (PET, potential evaporation (PE and total amount of water (TSW in the soil columns. The Nash-Sutcliffe model efficiency coefficient (N-S for TWS for the stressed columns was 0.92. For the NS treatment, we applied temporally variable soil hydraulic properties because of soil consolidation caused by regular irrigation. This approach improved the N-S values for the wetting-drying cycle from -1.77 to 0.54. We concluded that the model could be used for assessing the effects of climate change on soil water regime. Our results indicate that soil water balance studies should put more focus on the time variability of structuredependent soil properties.

  20. The geostatistic-based spatial distribution variations of soil salts under long-term wastewater irrigation.

    Science.gov (United States)

    Wu, Wenyong; Yin, Shiyang; Liu, Honglu; Niu, Yong; Bao, Zhe

    2014-10-01

    The purpose of this study was to determine and evaluate the spatial changes in soil salinity by using geostatistical methods. The study focused on the suburb area of Beijing, where urban development led to water shortage and accelerated wastewater reuse to farm irrigation for more than 30 years. The data were then processed by GIS using three different interpolation techniques of ordinary kriging (OK), disjunctive kriging (DK), and universal kriging (UK). The normality test and overall trend analysis were applied for each interpolation technique to select the best fitted model for soil parameters. Results showed that OK was suitable for soil sodium adsorption ratio (SAR) and Na(+) interpolation; UK was suitable for soil Cl(-) and pH; DK was suitable for soil Ca(2+). The nugget-to-sill ratio was applied to evaluate the effects of structural and stochastic factors. The maps showed that the areas of non-saline soil and slight salinity soil accounted for 6.39 and 93.61%, respectively. The spatial distribution and accumulation of soil salt were significantly affected by the irrigation probabilities and drainage situation under long-term wastewater irrigation.

  1. Variations of Growth and Toxin Yield in Cylindrospermopsis raciborskii under Different Phosphorus Concentrations

    Directory of Open Access Journals (Sweden)

    Yiming Yang

    2016-12-01

    Full Text Available The bloom-forming cyanobacteria, Cylindrospermopsis raciborskii, is a producer of the cytotoxic cylindrospermopsin (CYN. In this study, the growth, toxin yield, and expression of CYN biosynthesis genes of C. raciborskii were examined under varying phosphorus (P concentrations. The results show the cell number at 0.00 and 0.01 mg·L−1 P was significantly lower than that at higher P concentrations (≥0.5 mg·L−1. The chlorophyll a content, filament length, heterocyst, and akinete numbers at P ≤ 0.05 mg·L−1 were also significantly reduced. The intracellular and extracellular CYN concentrations and the extracellular proportions increased during the culture period, and larger values were observed at higher P concentrations. Total CYN content reached 45.34–63.83 fg·cell−1 and extracellular CYN proportion reached 11.49%–20.44% at the stationary growth phase. A significantly positive correlation was observed between CYN production and cell growth rate. Three cyr genes were expressed constantly even at P-deficient conditions. The transcription of cyr genes at P-replete conditions or after P supplementation increased from 1.18-fold to 8.33-fold. In conclusion, C. raciborskii may rapidly reorganize metabolic processes as an adaptive response to environmental P fluctuations. CYN production and cyr gene expression were constitutive metabolic processes in toxic C. raciborskii.

  2. Variation of saponin contents and physiological status in Quillaja saponaria under different environmental conditions.

    Science.gov (United States)

    Grandón, Angélica S; Espinosa, B Miguel; Ríos, Darcy L; Sánchez, O Manuel; Sáez, C Katia; Hernández, S Víctor; Becerra, A José

    2013-12-01

    Quillaja saponaria (Quillay), an evergreen tree found in Chile, is one of the main sources of saponins. Quillaja saponins have hypocholesterolaemic, anticarcinogenic, antioxidant and pesticidal properties, and are used as adjuvants for vaccines. Samples of Quillay growing at three zones in O'Higgins Region, Chile (Coastal, Central and Mountain zones) were analyzed for content of saponins and physiological status. The results revealed differences in the content of saponins depending on the zone of sample collection. The highest contents were found in samples from the Mountain zone, where the highest saponin contents were accompanied by the lowest foliar nitrogen contents, the highest antioxidant activity and the highest carotenoid contents. The results suggest a physiological and adaptive mechanism of saponins in plants to survive under unfavourable environmental conditions. The results have important implications for a theoretical basis for the design of a reasonable harvest, to avoid the cost of poor quality material, and also to provide a sustainable use and conservation of this important species. Further research on the effects of stress will improve our understanding of the saponins production and their physiological functions in plants, whereas they have generally been studied for their biological and chemical applications.

  3. Detection of Variations of Local Irregularity of Traffic under DDOS Flood Attack

    Directory of Open Access Journals (Sweden)

    Ming Li

    2008-01-01

    Full Text Available The aim of distributed denial-of-service (DDOS flood attacks is to overwhelm the attacked site or to make its service performance deterioration considerably by sending flood packets to the target from the machines distributed all over the world. This is a kind of local behavior of traffic at the protected site because the attacked site can be recovered to its normal service state sooner or later even though it is in reality overwhelmed during attack. From a view of mathematics, it can be taken as a kind of short-range phenomenon in computer networks. In this paper, we use the Hurst parameter (H to measure the local irregularity or self-similarity of traffic under DDOS flood attack provided that fractional Gaussian noise (fGn is used as the traffic model. As flood attack packets of DDOS make the H value of arrival traffic vary significantly away from that of traffic normally arriving at the protected site, we discuss a method to statistically detect signs of DDOS flood attacks with predetermined detection probability and false alarm probability.

  4. Sexually antagonistic selection on genetic variation underlying both male and female same-sex sexual behavior.

    Science.gov (United States)

    Berger, David; You, Tao; Minano, Maravillas R; Grieshop, Karl; Lind, Martin I; Arnqvist, Göran; Maklakov, Alexei A

    2016-05-13

    Intralocus sexual conflict, arising from selection for different alleles at the same locus in males and females, imposes a constraint on sex-specific adaptation. Intralocus sexual conflict can be alleviated by the evolution of sex-limited genetic architectures and phenotypic expression, but pleiotropic constraints may hinder this process. Here, we explored putative intralocus sexual conflict and genetic (co)variance in a poorly understood behavior with near male-limited expression. Same-sex sexual behaviors (SSBs) generally do not conform to classic evolutionary models of adaptation but are common in male animals and have been hypothesized to result from perception errors and selection for high male mating rates. However, perspectives incorporating sex-specific selection on genes shared by males and females to explain the expression and evolution of SSBs have largely been neglected. We performed two parallel sex-limited artificial selection experiments on SSB in male and female seed beetles, followed by sex-specific assays of locomotor activity and male sex recognition (two traits hypothesized to be functionally related to SSB) and adult reproductive success (allowing us to assess fitness consequences of genetic variance in SSB and its correlated components). Our experiments reveal both shared and sex-limited genetic variance for SSB. Strikingly, genetically correlated responses in locomotor activity and male sex-recognition were associated with sexually antagonistic fitness effects, but these effects differed qualitatively between male and female selection lines, implicating intralocus sexual conflict at both male- and female-specific genetic components underlying SSB. Our study provides experimental support for the hypothesis that widespread pleiotropy generates pervasive intralocus sexual conflict governing the expression of SSBs, suggesting that SSB in one sex can occur due to the expression of genes that carry benefits in the other sex.

  5. Variation in Metabolic Rate among Individuals Is Related to Tissue-Specific Differences in Mitochondrial Leak Respiration.

    Science.gov (United States)

    Salin, Karine; Auer, Sonya K; Rudolf, Agata M; Anderson, Graeme J; Selman, Colin; Metcalfe, Neil B

    Standard metabolic rate (SMR) and maximum metabolic rate (MMR) typically vary two- or threefold among conspecifics, with both traits assumed to significantly impact fitness. However, the underlying mechanisms that determine such intraspecific variation are not well understood. We examined the influence of mitochondrial properties on intraspecific variation in SMR and MMR and hypothesized that if SMR supports the cost of maintaining the metabolic machinery required for MMR, then the mitochondrial properties underlying these traits should be shared. Mitochondrial respiratory capacity (leak and phosphorylating respiration) and mitochondrial content (cytochrome c oxidase activity) were determined in the liver and white muscle of brown trout Salmo trutta of similar age and maintenance conditions. SMR and MMR were uncorrelated across individuals and were not associated with the same mitochondrial properties, suggesting that they are under the control of separate physiological processes. Moreover, tissue-specific relationships between mitochondrial properties and whole-organism metabolic traits were observed. Specifically, SMR was positively associated with leak respiration in liver mitochondria, while MMR was positively associated with muscle mitochondrial leak respiration and mitochondrial content. These results suggest that a high SMR or MMR, rather than signaling a higher ability for respiration-driven ATP synthesis, may actually reflect greater dissipation of energy, driven by proton leak across the mitochondrial inner membrane. Knowledge of these links should aid interpretation of the potential fitness consequences of such variation in metabolism, given the importance of mitochondria in the utilization of resources and their allocation to performance.

  6. Linking Changes to Intraspecific Trait Diversity to Community Functional Diversity and Biomass in Response to Snow and Nitrogen Addition Within an Inner Mongolian Grassland.

    Science.gov (United States)

    Mao, Wei; Felton, Andrew J; Zhang, Tonghui

    2017-01-01

    In recent years, both the intraspecific and interspecific functional diversity (FD) of plant communities have been studied with new approaches to improve an understanding about the mechanisms underlying plant species coexistence. Yet, little is known about how global change drivers will impact intraspecific FD and trait overlap among species, and in particular how this may scale to impacts on community level FD and ecosystem functioning. To address this uncertainty, we assessed the direct and indirect responses of specific leaf area (SLA) among both dominant annual and subordinate perennial species to the independent and interactive effects of nitrogen and snow addition within the Inner Mongnolian steppe. More specifically, we investigated the consequences for these responses on plant community FD, trait overlap and biomass. Nitrogen addition increased the biomass of the dominant annual species and as a result increased total community biomass. This occurred despite concurrent decreases in the biomass of subordinate perennial species. Nitrogen addition also increased intraspecific FD and trait overlap of both annual species and perennial species, and consequently increased the degree of trait overlap in SLA at the community level. However, snow addition did not significantly impact intraspecific FD and trait overlap of SLA for perennial species, but increased intraspecific FD and trait overlap of annual species, of which scaled to changes in community level FD. We found that the responses of the dominant annual species to nitrogen and snow additions were generally more sensitive than the subordinate perennial species within the inner Mongolian grassland communities of our study. As a consequence of this sensitivity, the responses of the dominant species largely drove impacts to community FD, trait overlap and community biomass. In total, our study demonstrates that the responses of dominant species in a community to environmental change may drive the initial

  7. Abiotic versus biotic drivers of ocean pH variation under fast sea ice in McMurdo Sound, Antarctica.

    Science.gov (United States)

    Matson, Paul G; Washburn, Libe; Martz, Todd R; Hofmann, Gretchen E

    2014-01-01

    Ocean acidification is expected to have a major effect on the marine carbonate system over the next century, particularly in high latitude seas. Less appreciated is natural environmental variation within these systems, particularly in terms of pH, and how this natural variation may inform laboratory experiments. In this study, we deployed sensor-equipped moorings at 20 m depths at three locations in McMurdo Sound, comprising deep (bottom depth>200 m: Hut Point Peninsula) and shallow environments (bottom depth ∼25 m: Cape Evans and New Harbor). Our sensors recorded high-frequency variation in pH (Hut Point and Cape Evans only), tide (Cape Evans and New Harbor), and water mass properties (temperature and salinity) during spring and early summer 2011. These collective observations showed that (1) pH differed spatially both in terms of mean pH (Cape Evans: 8.009±0.015; Hut Point: 8.020±0.007) and range of pH (Cape Evans: 0.090; Hut Point: 0.036), and (2) pH was not related to the mixing of two water masses, suggesting that the observed pH variation is likely not driven by this abiotic process. Given the large daily fluctuation in pH at Cape Evans, we developed a simple mechanistic model to explore the potential for biotic processes--in this case algal photosynthesis--to increase pH by fixing carbon from the water column. For this model, we incorporated published photosynthetic parameters for the three dominant algal functional groups found at Cape Evans (benthic fleshy red macroalgae, crustose coralline algae, and sea ice algal communities) to estimate oxygen produced/carbon fixed from the water column underneath fast sea ice and the resulting pH change. These results suggest that biotic processes may be a primary driver of pH variation observed under fast sea ice at Cape Evans and potentially at other shallow sites in McMurdo Sound.

  8. Abiotic versus biotic drivers of ocean pH variation under fast sea ice in McMurdo Sound, Antarctica.

    Directory of Open Access Journals (Sweden)

    Paul G Matson

    Full Text Available Ocean acidification is expected to have a major effect on the marine carbonate system over the next century, particularly in high latitude seas. Less appreciated is natural environmental variation within these systems, particularly in terms of pH, and how this natural variation may inform laboratory experiments. In this study, we deployed sensor-equipped moorings at 20 m depths at three locations in McMurdo Sound, comprising deep (bottom depth>200 m: Hut Point Peninsula and shallow environments (bottom depth ∼25 m: Cape Evans and New Harbor. Our sensors recorded high-frequency variation in pH (Hut Point and Cape Evans only, tide (Cape Evans and New Harbor, and water mass properties (temperature and salinity during spring and early summer 2011. These collective observations showed that (1 pH differed spatially both in terms of mean pH (Cape Evans: 8.009±0.015; Hut Point: 8.020±0.007 and range of pH (Cape Evans: 0.090; Hut Point: 0.036, and (2 pH was not related to the mixing of two water masses, suggesting that the observed pH variation is likely not driven by this abiotic process. Given the large daily fluctuation in pH at Cape Evans, we developed a simple mechanistic model to explore the potential for biotic processes--in this case algal photosynthesis--to increase pH by fixing carbon from the water column. For this model, we incorporated published photosynthetic parameters for the three dominant algal functional groups found at Cape Evans (benthic fleshy red macroalgae, crustose coralline algae, and sea ice algal communities to estimate oxygen produced/carbon fixed from the water column underneath fast sea ice and the resulting pH change. These results suggest that biotic processes may be a primary driver of pH variation observed under fast sea ice at Cape Evans and potentially at other shallow sites in McMurdo Sound.

  9. Intraspecific functional and genetic diversity ofPetriella setifera.

    Science.gov (United States)

    Pertile, Giorgia; Panek, Jacek; Oszust, Karolina; Siczek, Anna; Frąc, Magdalena

    2018-01-01

    The aim of the study was an analysis of the intraspecific genetic and functional diversity of the new isolated fungal strains of P. setifera . This is the first report concerning the genetic and metabolic diversity of Petriella setifera strains isolated from industrial compost and the first description of a protocol for AFLP fingerprinting analysis optimised for these fungal species. The results showed a significant degree of variability among the isolates, which was demonstrated by the clearly subdivision of all the isolates into two clusters with 51% and 62% similarity, respectively. For the metabolic diversity, the BIOLOG system was used and this analysis revealed clearly different patterns of carbon substrates utilization between the isolates resulting in a clear separation of the five isolates into three clusters with 0%, 42% and 54% of similarity, respectively. These results suggest that genetic diversity does not always match the level of functional diversity, which may be useful in discovering the importance of this fungus to ecosystem functioning. The results indicated that P. setifera strains were able to degrade substrates produced in the degradation of hemicellulose (D-Arabinose, L-Arabinose, D-Glucuronic Acid, Xylitol, γ-Amino-Butyric Acid, D-Mannose, D-Xylose and L-Rhamnose), cellulose (α-D-Glucose and D-Cellobiose) and the synthesis of lignin (Quinic Acid) at a high level, showing their importance in ecosystem services as a decomposer of carbon compounds and as organisms, which make a significant contribution to carbon cycling in the ecosystem.The results showed for the first time that the use of molecular biology techniques (such as AFLP and BIOLOG analyses) may allow for the identification of intraspecific diversity of as yet poorly investigated fungal species with favourable consequences for our understanding their ecosystem function.

  10. Variation in Broccoli Cultivar Phytochemical Content under Organic and Conventional Management Systems: Implications in Breeding for Nutrition

    Science.gov (United States)

    Renaud, Erica N. C.; Lammerts van Bueren, Edith T.; Myers, James R.; Paulo, Maria João; van Eeuwijk, Fred A.; Zhu, Ning; Juvik, John A.

    2014-01-01

    Organic agriculture requires cultivars that can adapt to organic crop management systems without the use of synthetic pesticides as well as genotypes with improved nutritional value. The aim of this study encompassing 16 experiments was to compare 23 broccoli cultivars for the content of phytochemicals associated with health promotion grown under organic and conventional management in spring and fall plantings in two broccoli growing regions in the US (Oregon and Maine). The phytochemicals quantified included: glucosinolates (glucoraphanin, glucobrassicin, neoglucobrassin), tocopherols (δ-, γ-, α-tocopherol) and carotenoids (lutein, zeaxanthin, β-carotene). For glucoraphanin (17.5%) and lutein (13%), genotype was the major source of total variation; for glucobrassicin, region (36%) and the interaction of location and season (27.5%); and for neoglucobrassicin, both genotype (36.8%) and its interactions (34.4%) with season were important. For δ- and γ- tocopherols, season played the largest role in the total variation followed by location and genotype; for total carotenoids, genotype (8.41–13.03%) was the largest source of variation and its interactions with location and season. Overall, phytochemicals were not significantly influenced by management system. We observed that the cultivars with the highest concentrations of glucoraphanin had the lowest for glucobrassicin and neoglucobrassicin. The genotypes with high concentrations of glucobrassicin and neoglucobrassicin were the same cultivars and were early maturing F1 hybrids. Cultivars highest in tocopherols and carotenoids were open pollinated or early maturing F1 hybrids. We identified distinct locations and seasons where phytochemical performance was higher for each compound. Correlations among horticulture traits and phytochemicals demonstrated that glucoraphanin was negatively correlated with the carotenoids and the carotenoids were correlated with one another. Little or no association between

  11. Nitrate-nitrogen contamination in groundwater: Spatiotemporal variation and driving factors under cropland in Shandong Province, China

    Science.gov (United States)

    Liu, J.; Jiang, L. H.; Zhang, C. J.; Li, P.; Zhao, T. K.

    2017-08-01

    High groundwater nitrate-N is a serious problem especially in highly active agricultural areas. In study, the concentration and spatialtemporal distribution of groundwater nitrate-N under cropland in Shandong province were assessed by statistical and geostatistical techniques. Nitrate-N concentration reached a maximum of 184.60 mg L-1 and 29.5% of samples had levels in excess of safety threshold concentration (20 mg L-1). The median nitrate-N contents after rainy season were significantly higher than those before rainy season, and decreased with increasing groundwater depth. Nitrate-N under vegetable and orchard area are significantly higher than ones under grain. The kriging map shows that groundwater nitrate-N has a strong spatial variability. Many districts, such as Weifang, Linyi in Shandong province are heavily contaminated with nitrate-N. However, there are no significant trends of NO3 --N for most cities. Stepwise regression analysis showed influencing factors are different for the groundwater in different depth. But overall, vegetable yield per unit area, percentages of orchard area, per capita agricultural production, unit-area nitrogen fertilizer, livestock per unit area, percentages of irrigation areas, population per unit area and annual mean temperature are significant variables for groundwater nitrate-N variation.

  12. Dilatometer for measurements of linear dimension variations under the effects of temperature, magnetic field and mechanical stress

    Science.gov (United States)

    Cherepin, V. T.; Glavatska, N. I.; Glavatsky, I. N.; Gavriljuk, V. G.

    2002-02-01

    A multi-purpose automated dilatometer has been developed for simultaneous measurements of the expansion/contraction under the effects of magnetic field and/or mechanical stress and/or temperature. The differential capacitive position sensor, operating together with the microprocessor controlled digital transformer bridge, is used as a displacement transducer with the resolution of several tens of nanometres. Measurements are accomplished in the temperature range from -150 to 200 °C. The automatically controlled variation of the applied magnetic field is provided by the electromagnet with the field homogeneity of 0.5×10-5 of the magnetic field strength (maximum 1.1 T). A special controlling system is developed for the automated mechanical loading of the sample under investigation. Some examples of the measurements completed on the magnetic shape memory alloy Ni2MnGa are presented for three cases: (i) strain as a function of the applied magnetic field; (ii) creep under constant magnetic field or mechanical stress; and (iii) phase transformations during heating/cooling with and without the applied magnetic field.

  13. Chromosome number and genome size variation in Colocasia (Araceae) from China.

    Science.gov (United States)

    Wang, Guang-Yan; Zhang, Xiao-Ming; Qian, Min; Hu, Xiang-Yang; Yang, Yong-Ping

    2017-11-01

    Chromosome number and genome size are important cytological characters that significantly influence various organismal traits. We investigated chromosome number and genome size variation in 73 accessions belonging to four Colocasia species from China. Five different chromosome counts (2n = 26, 28, 38, 42, and 56) were found, the largest one representing a new record in Colocasia. The basic chromosome numbers are x = 13, 14, and 19, corresponding to 2x, 3x, and 4x cytotypes. Yunnan Province, China is considered the center of Colocasia polyploid origin. The 2C values in our accessions ranged from 3.29 pg in C. gigantea to 12.51 pg in C. esculenta. All species exhibit inter- and intraspecific chromosomal variation. Differences in DNA content among the Colocasia species seem to have occurred by chromosomal gain under similar habitats. Polyploidization also obviously contributes to 2C value variation.

  14. An improved model for predicting performance of finned tube heat exchanger under frosting condition, with frost thickness variation along fin

    Energy Technology Data Exchange (ETDEWEB)

    Tso, C.P. [Multimedia University, Jalan Ayer Keroh Lama, Melaka (Malaysia). Faculty of Engineering and Technology; Cheng, Y.C.; Lai, A.C.K. [Nanyang Technological University, Singapore (Singapore). School of Mechanical and Aerospace Engineering

    2006-01-15

    Frost accumulation on a heat exchanger, a direct result of combined heat and mass transfer between the moist air flowing across a cold surface, causes heat transfer performance degradation due to the insulating effect of frost layer and the coil blockage as the frost grows. The complex geometry of finned tube heat exchangers leads to uneven wall and air temperature distribution inside the coil, and causes variations of frost growth rate and densification along the coil. In this study, a general distributed model with frost formation was developed. The equations for finned tube heat exchanger were derived in non-steady-state manner and quasi-steady state in the frost model. In order to make the model more realistic, the variation of frost along fin due to uneven temperature distribution was included. The presented model is able to predict the dynamic behavior of an air cooler both under non-frost and frost condition. Comparisons were made based on the frost mass accumulation, pressure drop across coil and energy transfer coefficient, and results were found to agree well with reported experimental results. (author)

  15. A novel method for determining and improving the quality of a quadrupolar fiber gyro coil under temperature variations.

    Science.gov (United States)

    Li, Zhihong; Meng, Zhuo; Liu, Tiegen; Yao, X Steve

    2013-01-28

    We introduce a parameter called pointing error thermal sensitivity (PETS) for quantitatively determining the quality of a quadrupolar (QAD) fiber coil under radial temperature variations. We show both analytically and experimentally that the pointing error of a fiber gyro incorporating the fiber coil is linearly proportional to the final radial thermal gradient on the coil, with PETS as the proportional constant. We further show that PETS is linearly proportional to another parameter called effective asymmetric length of the coil. By thermally inducing different radial thermal gradients on the fiber coil and measuring the corresponding pointing errors in a gyroscopic measurement setup, we can confidently determine the PETS of the fiber coil and its associated effective asymmetric length caused by imperfections in coil winding. Consequently, we are able to precisely trim the coil to achieve best thermal performance.

  16. Identification of Nonstandard Multifractional Brownian Motions under White Noise by Multiscale Local Variations of Its Sample Paths

    Directory of Open Access Journals (Sweden)

    Kwang-Il Ahn

    2013-01-01

    Full Text Available The Hurst exponent and variance are two quantities that often characterize real-life, high-frequency observations. Such real-life signals are generally measured under noise environments. We develop a multiscale statistical method for simultaneous estimation of a time-changing Hurst exponent H(t and a variance parameter C in a multifractional Brownian motion model in the presence of white noise. The method is based on the asymptotic behavior of the local variation of its sample paths which applies to coarse scales of the sample paths. This work provides stable and simultaneous estimators of both parameters when independent white noise is present. We also discuss the accuracy of the simultaneous estimators compared with a few selected methods and the stability of computations with regard to adapted wavelet filters.

  17. An ecophysiological and developmental perspective on variation in vessel diameter.

    Science.gov (United States)

    Hacke, Uwe G; Spicer, Rachel; Schreiber, Stefan G; Plavcová, Lenka

    2017-06-01

    Variation in xylem vessel diameter is one of the most important parameters when evaluating plant water relations. This review provides a synthesis of the ecophysiological implications of variation in lumen diameter together with a summary of our current understanding of vessel development and its endogenous regulation. We analyzed inter-specific variation of the mean hydraulic vessel diameter (D v ) across biomes, intra-specific variation of D v under natural and controlled conditions, and intra-plant variation. We found that the D v measured in young branches tends to stay below 30 µm in regions experiencing winter frost, whereas it is highly variable in the tropical rainforest. Within a plant, the widest vessels are often found in the trunk and in large roots; smaller diameters have been reported for leaves and small lateral roots. D v varies in response to environmental factors and is not only a function of plant size. Despite the wealth of data on vessel diameter variation, the regulation of diameter is poorly understood. Polar auxin transport through the vascular cambium is a key regulator linking foliar and xylem development. Limited evidence suggests that auxin transport is also a determinant of vessel diameter. The role of auxin in cell expansion and in establishing longitudinal continuity during secondary growth deserve further study. © 2016 John Wiley & Sons Ltd.

  18. Wheat genotypic variation in dynamic fluxes of WSC components in different stem segments under drought during grain filling

    Directory of Open Access Journals (Sweden)

    Jingjuan eZhang

    2015-08-01

    Full Text Available In wheat, stem water soluble carbohydrates (WSC, composed mainly of fructans, are the major carbon sources for grain filling during periods of decreasing photosynthesis or under drought stress after anthesis. Here, in a field drought experiment, WSC levels and associated enzyme activities were followed in different stem segments (peduncle, penultimate internode, lower parts of stem, and sheath during grain filling. The focus was on two double haploid (DH lines, DH 307 and DH 338, derived from a Westonia/Kauz cross, two drought-tolerant wheat varieties that follow different drought adaptation strategies during grain filling. The results showed that in irrigated plants, in the period between 20 to 30 days after anthesis (DAA, 70-80% of WSC were fructans. Before and after this period, the fructan proportion varied from 10 to 60%, depending on the location along the stem. Under drought, the fructan proportion changed, depending on genotype and developmental stages. After anthesis, stem fructans accumulation occurred mainly in the peduncle and penultimate internode until 14 DAA in both DH lines, with clear genotypic variation in subsequent fructan degradation under drought. In DH 307 a significant reduction of fructans with a concomitant increase in fructose levels occurred earlier in the lower parts of the stem and the sheath, as compared to DH 338 or other stem segments in both lines. This was associated with an earlier increase of grain weight and thousand grain weight in DH 307. Spatiotemporal analysis of fructan dynamics and enzymatic activities in fructan metabolism revealed that several types of FEHs are involved in fructan remobilization to the grain under drought.

  19. Effects of Spatial Patch Arrangement and Scale of Covarying Resources on Growth and Intraspecific Competition of a Clonal Plant.

    Science.gov (United States)

    Wang, Yong-Jian; Shi, Xue-Ping; Meng, Xue-Feng; Wu, Xiao-Jing; Luo, Fang-Li; Yu, Fei-Hai

    2016-01-01

    Spatial heterogeneity in two co-variable resources such as light and water availability is common and can affect the growth of clonal plants. Several studies have tested effects of spatial heterogeneity in the supply of a single resource on competitive interactions of plants, but none has examined those of heterogeneous distribution of two co-variable resources. In a greenhouse experiment, we grew one (without intraspecific competition) or nine isolated ramets (with competition) of a rhizomatous herb Iris japonica under a homogeneous environment and four heterogeneous environments differing in patch arrangement (reciprocal and parallel patchiness of light and soil water) and patch scale (large and small patches of light and water). Intraspecific competition significantly decreased the growth of I. japonica, but at the whole container level there were no significant interaction effects of competition by spatial heterogeneity or significant effect of heterogeneity on competitive intensity. Irrespective of competition, the growth of I. japonica in the high and the low water patches did not differ significantly in the homogeneous treatments, but it was significantly larger in the high than in the low water patches in the heterogeneous treatments with large patches. For the heterogeneous treatments with small patches, the growth of I. japonica was significantly larger in the high than in the low water patches in the presence of competition, but such an effect was not significant in the absence of competition. Furthermore, patch arrangement and patch scale significantly affected competitive intensity at the patch level. Therefore, spatial heterogeneity in light and water supply can alter intraspecific competition at the patch level and such effects depend on patch arrangement and patch scale.

  20. Variation in size frequency distribution of coral populations under different fishing pressures in two contrasting locations in the Indian Ocean.

    Science.gov (United States)

    Grimsditch, G; Pisapia, C; Huck, M; Karisa, J; Obura, D; Sweet, M

    2017-10-01

    This study aimed to assess how the size-frequency distributions of coral genera varied between reefs under different fishing pressures in two contrasting Indian Ocean locations (the Maldives and East Africa). Using generalized linear mixed models, we were able to demonstrate that complex interactions occurred between coral genera, coral size class and fishing pressure. In both locations, we found Acropora coral species to be more abundant in non-fished compared to fished sites (a pattern which was consistent for nearly all the assessed size classes). Coral genera classified as 'stress tolerant' showed a contrasting pattern i.e. were higher in abundance in fished compared to non-fished sites. Site specific variations were also observed. For example, Maldivian reefs exhibited a significantly higher abundance in all size classes of 'competitive' corals compared to East Africa. This possibly indicates that East African reefs have already been subjected to higher levels of stress and are therefore less suitable environments for 'competitive' corals. This study also highlights the potential structure and composition of reefs under future degradation scenarios, for example with a loss of Acropora corals and an increase in dominance of 'stress tolerant' and 'generalist' coral genera. Copyright © 2017. Published by Elsevier Ltd.

  1. Axially perpendicular offset Raman scheme for reproducible measurement of housed samples in a noncircular container under variation of container orientation.

    Science.gov (United States)

    Duy, Pham K; Chang, Kyeol; Sriphong, Lawan; Chung, Hoeil

    2015-03-17

    An axially perpendicular offset (APO) scheme that is able to directly acquire reproducible Raman spectra of samples contained in an oval container under variation of container orientation has been demonstrated. This scheme utilized an axially perpendicular geometry between the laser illumination and the Raman photon detection, namely, irradiation through a sidewall of the container and gathering of the Raman photon just beneath the container. In the case of either backscattering or transmission measurements, Raman sampling volumes for an internal sample vary when the orientation of an oval container changes; therefore, the Raman intensities of acquired spectra are inconsistent. The generated Raman photons traverse the same bottom of the container in the APO scheme; the Raman sampling volumes can be relatively more consistent under the same situation. For evaluation, the backscattering, transmission, and APO schemes were simultaneously employed to measure alcohol gel samples contained in an oval polypropylene container at five different orientations and then the accuracies of the determination of the alcohol concentrations were compared. The APO scheme provided the most reproducible spectra, yielding the best accuracy when the axial offset distance was 10 mm. Monte Carlo simulations were performed to study the characteristics of photon propagation in the APO scheme and to explain the origin of the optimal offset distance that was observed. In addition, the utility of the APO scheme was further demonstrated by analyzing samples in a circular glass container.

  2. Foliar Substrate Affects Cuticular Hydrocarbon Profiles and Intraspecific Aggression in the Leafcutter Ant Atta sexdens

    Directory of Open Access Journals (Sweden)

    Lohan Valadares

    2015-02-01

    Full Text Available Cuticular hydrocarbons (CHCs are traditionally considered to be one of the most important chemical cues used in the nestmate recognition process of social hymenopterans. However, it has been suggested that in the leafcutter ant genus Atta, it is not the CHCs, but the alarm pheromone that is involved in the nestmate recognition process. In this study we used a laboratory population of Atta sexdens to explore the association between their CHC profile variation and intraspecific aggression. In the first part of the experiment, four colonies were divided into two groups with distinct diets to stimulate differentiation of their CHC profiles. In the second part of the experiment, all colonies received the same diet to examine resemblance of chemical profiles. At the end of each part of the experiment we extracted the CHCs from workers. The results demonstrated that colonies that shared the same food resource had similar cuticular hydrocarbon profiles. Furthermore, colonies were significantly more aggressive towards conspecifics that used a different foliar substrate and consequently had greater differences in their cuticular chemical composition. This study suggests that the CHC profiles of A. sexdens can be affected by the foliar substrates used, and that the CHCs are used in the nestmate recognition process of this species.

  3. Effects of intraspecific larval competition on adult longevity in the mosquitoes Aedes aegypti and Aedes albopictus.

    Science.gov (United States)

    Reiskind, M H; Lounibos, L P

    2009-03-01

    Larval competition is common in container-breeding mosquitoes. The impact of competition on larval growth has been thoroughly examined and findings that larval competition can lead to density-dependent effects on adult body size have been documented. The effects of larval competition on adult longevity have been less well explored. The effects of intraspecific larval densities on the longevity of adults maintained under relatively harsh environmental conditions were tested in the laboratory by measuring the longevity of adult Aedes aegypti (L.) and Aedes albopictus (Skuse) (Diptera: Culicidae) that had been reared under a range of larval densities and subsequently maintained in high- or low-humidity regimes (85% or 35% relative humidity [RH], respectively) as adults. We found significant negative effects of competition on adult longevity in Ae. aegypti, but not in Ae. albopictus. Multivariate analysis of variance suggested that the negative effect of the larval environment on the longevity of Ae. aegypti adults was most strongly associated with increased development time and decreased wing length as adults. Understanding how larval competition affects adult longevity under a range of environmental conditions is important in establishing the relationship between models of mosquito population regulation and epidemiological models of vector-borne disease transmission.

  4. Aerosol composition and properties variation at the ground and over the column under different air masses advection in South Italy.

    Science.gov (United States)

    Pavese, G; Lettino, A; Calvello, M; Esposito, F; Fiore, S

    2016-04-01

    Aerosol composition and properties variation under the advection of different air masses were investigated, as case studies, by contemporary measurements over the atmospheric column and at the ground in a semi-rural site in South Italy. The absence of local strong sources in this area allowed to characterize background aerosol and to compare particle mixing effects under various atmospheric circulation conditions. Aerosol optical depth (AOD) and Ǻngström parameters from radiometric measurements allowed the detection and identification of polluted, dust, and volcanic atmospheric conditions. AODs were the input for a suitable model to evaluate the columnar aerosol composition, according to six main atmospheric components (water-soluble, soot, sea salt accumulation, sea salt coarse, mineral dus,t and biological). Scanning electron microscope (SEM) analysis of particulate sampled with a 13-stage impactor at the ground showed not only fingerprints typical of the different air masses but also the effects of transport and aging on atmospheric particles, suggesting processes that changed their chemical and optical properties. Background columnar aerosol was characterized by 72% of water-soluble and soot, in agreement with ground-based findings that highlighted 60% of contribution from anthropogenic carbonate particles and soot. In general, a good agreement between ground-based and columnar results was observed. Under the advection of trans-boundary air masses, water-soluble and soot were always present in columnar aerosol, whereas, in variable percentages, sea salt and mineral particles characterized both dust and volcanic conditions. At the ground, sulfates characterized the amorphous matrix produced in finer stages by the evaporation of solutions of organic and inorganic aerosols. Sulfates were also one of the key players involved in heterogeneous chemical reactions, producing complex secondary aerosol, as such clay-sulfate internally mixed particle externally mixed

  5. Parasite fitness traits under environmental variation: disentangling the roles of a chytrid's immediate host and external environment.

    Science.gov (United States)

    Van den Wyngaert, Silke; Vanholsbeeck, Olivier; Spaak, Piet; Ibelings, Bas W

    2014-10-01

    Parasite environments are heterogeneous at different levels. The first level of variability is the host itself. The second level represents the external environment for the hosts, to which parasites may be exposed during part of their life cycle. Both levels are expected to affect parasite fitness traits. We disentangle the main and interaction effects of variation in the immediate host environment, here the diatom Asterionella formosa (variables host cell volume and host condition through herbicide pre-exposure) and variation in the external environment (variables host density and acute herbicide exposure) on three fitness traits (infection success, development time and reproductive output) of a chytrid parasite. Herbicide exposure only decreased infection success in a low host density environment. This result reinforces the hypothesis that chytrid zoospores use photosynthesis-dependent chemical cues to locate its host. At high host densities, chemotaxis becomes less relevant due to increasing chance contact rates between host and parasite, thereby following the mass-action principle in epidemiology. Theoretical support for this finding is provided by an agent-based simulation model. The immediate host environment (cell volume) substantially affected parasite reproductive output and also interacted with the external herbicide exposed environment. On the contrary, changes in the immediate host environment through herbicide pre-exposure did not increase infection success, though it had subtle effects on zoospore development time and reproductive output. This study shows that both immediate host and external environment as well as their interaction have significant effects on parasite fitness. Disentangling these effects improves our understanding of the processes underlying parasite spread and disease dynamics.

  6. Singing from North to South: Latitudinal variation in timing of dawn singing under natural and artificial light conditions.

    Science.gov (United States)

    Da Silva, Arnaud; Kempenaers, Bart

    2017-10-01

    Animals breeding at northern latitudes experience drastic changes in daily light conditions during the breeding season with decreasing periods of darkness, whereas those living at lower latitudes are exposed to naturally dark nights throughout the year. Nowadays, many animals are also exposed to artificial night lighting (often referred to as light pollution). Animals strongly rely on variation in light levels to time their daily and seasonal behaviour. Previous work on passerine birds showed that artificial night lighting leads to earlier onset of dawn song. However, these studies were carried out at intermediate latitudes with more limited seasonal changes in daylength, and we still lack an understanding of the impact of artificial night lighting in relation to variation in natural light conditions. We investigated the influence of natural and artificial light conditions on the timing of dawn singing in five common songbird species in each of three regions in Europe that differed in natural variation in daylength (northern Finland, 65°N; southern Germany, 48°N; southern Spain, 37°N). In each region, we selected five peri-urban forest sites with and five without street lighting, and we recorded dawn singing at the beginning of the local breeding season. Our results show that the earliest natural singers, that is, European robins (Erithacus rubecula) and common blackbirds (Turdus merula), started dawn singing earlier along with the natural increase in night brightness in Finland, with no additional effects of artificial night lighting. In contrast, the later singers, such as, great tits (Parus major), blue tits (Cyanistes caeruleus) and chaffinches (Fringilla coelebs), showed similar onsets of dawn song relative to sunrise across the season and similar effects of artificial night lighting at all latitudes. Artificial night lighting affected great tits, blue tits and chaffinches even in northern Finland where nights became very bright. Proximate factors such as

  7. Phenotypic and genotypic background underlying variations in fatty acid composition and sensory parameters in European bovine breeds.

    Science.gov (United States)

    Sevane, Natalia; Levéziel, Hubert; Nute, Geoffrey R; Sañudo, Carlos; Valentini, Alessio; Williams, John; Dunner, Susana

    2014-01-01

    Consuming moderate amounts of lean red meat as part of a balanced diet valuably contributes to intakes of essential nutrients. In this study, we merged phenotypic and genotypic information to characterize the variation in lipid profile and sensory parameters and to represent the diversity among 15 cattle populations. Correlations between fat content, organoleptic characteristics and lipid profiles were also investigated. A sample of 436 largely unrelated purebred bulls belonging to 15 breeds and reared under comparable management conditions was analyzed. Phenotypic data -including fatness score, fat percentage, individual fatty acids (FA) profiles and sensory panel tests- and genotypic information from 11 polymorphisms was used. The correlation coefficients between muscle total lipid measurements and absolute vs. relative amounts of polyunsaturated FA (PUFA) were in opposite directions. Increasing carcass fat leads to an increasing amount of FAs in triglycerides, but at the same time the relative amount of PUFAs is decreasing, which is in concordance with the negative correlation obtained here between the percentage of PUFA and fat measurements, as well as the weaker correlation between total phospholipids and total lipid muscle content compared with neutral lipids. Concerning organoleptic characteristics, a negative correlation between flavour scores and the percentage of total PUFA, particularly to n-6 fraction, was found. The correlation between juiciness and texture is higher than with flavour scores. The distribution of SNPs plotted by principal components analysis (PCA) mainly reflects their known trait associations, although influenced by their specific breed allele frequencies. The results presented here help to understand the phenotypic and genotypic background underlying variations in FA composition and sensory parameters between breeds. The wide range of traits and breeds studied, along with the genotypic information on polymorphisms previously

  8. Using stable isotopes to determine seasonal variations in water uptake of summer maize under different fertilization treatments

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Ying, E-mail: maying@igsnrr.ac.cn [Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, 100101 Beijing (China); State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, 210008 Nanjing (China); Song, Xianfang [Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, 100101 Beijing (China)

    2016-04-15

    Fertilization and water both affect root water uptake in the nutrient and water cycle of the Soil-Plant-Atmosphere-Continuum (SPAC). In this study, dual stable isotopes (D and {sup 18}O) were used to determine seasonal variations in water uptake patterns of summer maize under different fertilization treatments in Beijing, China during 2013–2014. The contributions of soil water at different depths to water uptake were quantified by the MixSIAR Bayesian mixing model. Water uptake was mainly sourced from soil water in the 0–20 cm depth at the seeding (67.7%), jointing (60.5%), tasseling (47.5%), dough (41.4%), and harvest (43.9%) stages, and the 20–50 cm depth at the milk stage (32.8%). Different levels of fertilization application led to considerable differences in the proportional contribution of soil water at 0–20 cm (6.0–58.5%) and 20–50 cm (6.1–26.3%). There was little difference of contributions in the deep layers (50–200 cm) among treatments in 2013, whereas differences were observed in 50–90 cm at the milk stage and 50–200 cm at the dough stage during 2014. The main water uptake depth was concentrated in the upper soil layers (0–50 cm) during the wet season (2013), whereas a seasonal drought in 2014 promoted the contribution of soil water in deep layers. The contribution of soil water was significantly and positively correlated with the proportions of root length (r = 0.753, p < 0.01). The changes of soil water distribution were consistent with the seasonal variation in water uptake patterns. The present study identified water sources for summer maize under varying fertilization treatments and provided scientific implications for fertilization and irrigation management. - Highlights: • Dual stable isotopes and MixSIAR were coupled to quantify water uptake of maize. • Maize mainly used soil water in 20–50 cm at milk stage and 0–20 cm at other stages. • Fertilization treatments led to distinct water uptake pattern at 0–50 cm

  9. [Effects of silicon supply on diurnal variations of physiological properties at rice heading stage under elevated UV-B radiation].

    Science.gov (United States)

    Wu, Lei; Lou, Yun-sheng; Meng, Yan; Wang, Wei-qing; Cui, He-yang

    2015-01-01

    A pot experiment was conducted to investigate the effects of silicon (Si) supply on diurnal variations of photosynthesis and transpiration-related physiological parameters at rice heading stage under elevated UV-B radiation. The experiment was designed with two UV-B radiation levels, i.e. ambient UV-B. (ambient, A) and elevated UV-B (elevated by 20%, E), and four Si supply levels, i.e. Sio (control, 0 kg SiO2 . hm-2), Si, (sodium silicate, 100 kg SiO2 . hm-2), Si2 (sodium silicate, 200 kg SiO2 . hm2), Si3 (slag fertilizer, 200 kg SiO2 . hm-2). The results showed that, compared with ambient UV-B radiation, elevated UV-B radiation decreased the net photosynthesis rate (Pn) , intercellular CO2 concentration (Ci), transpiration rate (Tr), stomatal conductivity (gs) and water use efficiency (WUE) by 11.3%, 5.5%, 10.4%, 20.3% and 6.3%, respectively, in the treatment without Si supply (Si, level), and decreased the above parameters by 3.8%-5.5%, 0.7%-4.8%, 4.0%-8.7%, 7.4%-20.2% and 0.7%-5.9% in the treatments with Si supply (Si1, Si2 and Si3 levels) , respectively. Namely, elevated UV-B radiation decreased the photosynthesis and transpiration-related physiological parameters, but silicon supply could obviously mitigate the depressive effects of elevated UV-B radiation. Under elevated UV-B radiation, compared with control (Si0 level), silicon supply increased Pn, Ci, gs and WUE by 16.9%-28.0%, 3.5%-14.3%, 16.8% - 38.7% and 29.0% - 51.2%, respectively, but decreased Tr by 1.9% - 10.8% in the treatments with Si supply (Si1 , Si2 and Si3 levels). That is, silicon supply could mitigate the depressive effects of elevated UV-B radiation through significantly increasingnP., CigsgK and WUE, but decreasing T,. However, the difference existed in ameliorating the depressive effects of elevated UV-B radiation on diurnal variations of physiological parameters among the treatments of silicon supply, with the sequence of Si3>Si2>1i >Si0. This study suggested that fertilizing slag was

  10. Projecting pest population dynamics under global warming: the combined effect of inter- and intra-annual variations.

    Science.gov (United States)

    Zidon, Royi; Tsueda, Hirotsugu; Morin, Efrat; Morin, Shai

    2016-06-01

    The typical short generation length of insects makes their population dynamics highly sensitive not only to mean annual temperatures but also to their intra-annual variations. To consider the combined effect of both thermal factors under global warming, we propose a modeling framework that links general circulation models (GCMs) with a stochastic weather generator and population dynamics models to predict species population responses to inter- and intra-annual temperature changes. This framework was utilized to explore future changes in populations of Bemisia tabaci, an invasive insect pest-species that affects multiple agricultural systems in the Mediterranean region. We considered three locations representing different pest status and climatic conditions: Montpellier (France), Seville (Spain), and Beit-Jamal (Israel). We produced ensembles of local daily temperature realizations representing current and future (mid-21st century) climatic conditions under two emission scenarios for the three locations. Our simulations predicted a significant increase in the average number of annual generations and in population size, and a significant lengthening of the growing season in all three locations. A negative effect was found only in Seville for the summer season, where future temperatures lead to a reduction in population size. High variability in population size was observed between years with similar annual mean temperatures, suggesting a strong effect of intra-annual temperature variation. Critical periods were from late spring to late summer in Montpellier and from late winter to early summer in Seville and Beit-Jamal. Although our analysis suggested that earlier seasonal activity does not necessarily lead to increased populations load unless an additional generation is produced, it is highly likely that the insect will become a significant pest of open-fields at Mediterranean latitudes above 40° during the next 50 years. Our simulations also implied that current

  11. Using stable isotopes to determine seasonal variations in water uptake of summer maize under different fertilization treatments

    International Nuclear Information System (INIS)

    Ma, Ying; Song, Xianfang

    2016-01-01

    Fertilization and water both affect root water uptake in the nutrient and water cycle of the Soil-Plant-Atmosphere-Continuum (SPAC). In this study, dual stable isotopes (D and 18 O) were used to determine seasonal variations in water uptake patterns of summer maize under different fertilization treatments in Beijing, China during 2013–2014. The contributions of soil water at different depths to water uptake were quantified by the MixSIAR Bayesian mixing model. Water uptake was mainly sourced from soil water in the 0–20 cm depth at the seeding (67.7%), jointing (60.5%), tasseling (47.5%), dough (41.4%), and harvest (43.9%) stages, and the 20–50 cm depth at the milk stage (32.8%). Different levels of fertilization application led to considerable differences in the proportional contribution of soil water at 0–20 cm (6.0–58.5%) and 20–50 cm (6.1–26.3%). There was little difference of contributions in the deep layers (50–200 cm) among treatments in 2013, whereas differences were observed in 50–90 cm at the milk stage and 50–200 cm at the dough stage during 2014. The main water uptake depth was concentrated in the upper soil layers (0–50 cm) during the wet season (2013), whereas a seasonal drought in 2014 promoted the contribution of soil water in deep layers. The contribution of soil water was significantly and positively correlated with the proportions of root length (r = 0.753, p < 0.01). The changes of soil water distribution were consistent with the seasonal variation in water uptake patterns. The present study identified water sources for summer maize under varying fertilization treatments and provided scientific implications for fertilization and irrigation management. - Highlights: • Dual stable isotopes and MixSIAR were coupled to quantify water uptake of maize. • Maize mainly used soil water in 20–50 cm at milk stage and 0–20 cm at other stages. • Fertilization treatments led to distinct water uptake pattern at 0–50 cm depth.

  12. Chimpanzee population structure in Cameroon and Nigeria is associated with habitat variation that may be lost under climate change.

    Science.gov (United States)

    Sesink Clee, Paul R; Abwe, Ekwoge E; Ambahe, Ruffin D; Anthony, Nicola M; Fotso, Roger; Locatelli, Sabrina; Maisels, Fiona; Mitchell, Matthew W; Morgan, Bethan J; Pokempner, Amy A; Gonder, Mary Katherine

    2015-01-21

    The Nigeria-Cameroon chimpanzee (Pan troglodytes ellioti) is found in the Gulf of Guinea biodiversity hotspot located in western equatorial Africa. This subspecies is threatened by habitat fragmentation due to logging and agricultural development, hunting for the bushmeat trade, and possibly climate change. Although P. t. ellioti appears to be geographically separated from the neighboring central chimpanzee (P. t. troglodytes) by the Sanaga River, recent population genetics studies of chimpanzees from across this region suggest that additional factors may also be important in their separation. The main aims of this study were: 1) to model the distribution of suitable habitat for P. t. ellioti across Cameroon and Nigeria, and P. t. troglodytes in southern Cameroon, 2) to determine which environmental factors best predict their optimal habitats, and 3) to compare modeled niches and test for their levels of divergence from one another. A final aim of this study was to examine the ways that climate change might impact suitable chimpanzee habitat across the region under various scenarios. Ecological niche models (ENMs) were created using the software package Maxent for the three populations of chimpanzees that have been inferred to exist in Cameroon and eastern Nigeria: (i) P. t. troglodytes in southern Cameroon, (ii) P. t. ellioti in northwestern Cameroon, and (iii) P. t. ellioti in central Cameroon. ENMs for each population were compared using the niche comparison test in ENMtools, which revealed complete niche divergence with very little geographic overlap of suitable habitat between populations. These findings suggest that a positive relationship may exist between environmental variation and the partitioning of genetic variation found in chimpanzees across this region. ENMs for each population were also projected under three different climate change scenarios for years 2020, 2050, and 2080. Suitable habitat of P. t. ellioti in northwest Cameroon / eastern Nigeria is

  13. Testing whether macroevolution follows microevolution: Are colour differences among swans (Cygnus attributable to variation at the MC1R locus?

    Directory of Open Access Journals (Sweden)

    Pointer Marie A

    2008-09-01

    Full Text Available Abstract Background The MC1R (melanocortin-1 receptor locus underlies intraspecific variation in melanin-based dark plumage coloration in several unrelated birds with plumage polymorphisms. There is far less evidence for functional variants of MC1R being involved in interspecific variation, in which spurious genotype-phenotype associations arising through population history are a far greater problem than in intraspecific studies. We investigated the relationship between MC1R variation and plumage coloration in swans (Cygnus, which show extreme variation in melanic plumage phenotypes among species (white to black. Results The two species with melanic plumage, C. atratus and C. melanocoryphus (black and black-necked swans respectively, both have amino acid changes at important functional sites in MC1R that are consistent with increased MC1R activity and melanism. Reconstruction of MC1R evolution over a newly generated independent molecular phylogeny of Cygnus and related genera shows that these putative melanizing mutations were independently derived in the two melanic lineages. However, interpretation is complicated by the fact that one of the outgroup genera, Coscoroba, also has a putative melanizing mutation at MC1R that has arisen independently but has nearly pure white plumage. Epistasis at other loci seems the most likely explanation for this discrepancy. Unexpectedly, the phylogeny shows that the genus Cygnus may not be monophyletic, with C. melanocoryphus placed as a sister group to true geese (Anser, but further data will be needed to confirm this. Conclusion Our study highlights the difficulty of extrapolating from intraspecific studies to understand the genetic basis of interspecific adaptive phenotypic evolution, even with a gene whose structure-function relationships are as well understood as MC1R as confounding variation make clear genotype/phenotype associations difficult at the macroevolutionary scale. However, the identification

  14. Transcriptome analysis of intraspecific competition in Arabidopsis thaliana reveals organ-specific signatures related to nutrient acquisition and general stress response pathways.

    Science.gov (United States)

    Masclaux, Frédéric G; Bruessow, Friederike; Schweizer, Fabian; Gouhier-Darimont, Caroline; Keller, Laurent; Reymond, Philippe

    2012-11-29

    Plants are sessile and therefore have to perceive and adjust to changes in their environment. The presence of neighbours leads to a competitive situation where resources and space will be limited. Complex adaptive responses to such situation are poorly understood at the molecular level. Using microarrays, we analysed whole-genome expression changes in Arabidopsis thaliana plants subjected to intraspecific competition. The leaf and root transcriptome was strongly altered by competition. Differentially expressed genes were enriched in genes involved in nutrient deficiency (mainly N, P, K), perception of light quality, and responses to abiotic and biotic stresses. Interestingly, performance of the generalist insect Spodoptera littoralis on densely grown plants was significantly reduced, suggesting that plants under competition display enhanced resistance to herbivory. This study provides a comprehensive list of genes whose expression is affected by intraspecific competition in Arabidopsis. The outcome is a unique response that involves genes related to light, nutrient deficiency, abiotic stress, and defence responses.

  15. Spatial Heterogeneity in Light Supply Affects Intraspecific Competition of a Stoloniferous Clonal Plant

    OpenAIRE

    Wang, Pu; Lei, Jing-Pin; Li, Mai-He; Yu, Fei-Hai

    2012-01-01

    Spatial heterogeneity in light supply is common in nature. Many studies have examined the effects of heterogeneous light supply on growth, morphology, physiology and biomass allocation of clonal plants, but few have tested those effects on intraspecific competition. In a greenhouse experiment, we grew one (no competition) or nine ramets (with intraspecific competition) of a stoloniferous clonal plant, Duchesnea indica, in three homogeneous light conditions (high, medium and low light intensit...

  16. Intraspecific competition reduces niche width in experimental populations.

    Science.gov (United States)

    Parent, Christine E; Agashe, Deepa; Bolnick, Daniel I

    2014-10-01

    Intraspecific competition is believed to drive niche expansion, because otherwise suboptimal resources can provide a refuge from competition for preferred resources. Competitive niche expansion is well supported by empirical observations, experiments, and theory, and is often invoked to explain phenotypic diversification within populations, some forms of speciation, and adaptive radiation. However, some foraging models predict the opposite outcome, and it therefore remains unclear whether competition will promote or inhibit niche expansion. We conducted experiments to test whether competition changes the fitness landscape to favor niche expansion, and if competition indeed drives niche expansion as expected. Using Tribolium castaneum flour beetles fed either wheat (their ancestral resource), corn (a novel resource) or mixtures of both resources, we show that fitness is maximized on a mixed diet. Next, we show that at higher population density, the optimal diet shifts toward greater use of corn, favoring niche expansion. In stark contrast, when beetles were given a choice of resources, we found that competition caused niche contraction onto the ancestral resource. This presents a puzzling mismatch between how competition alters the fitness landscape, versus competition's effects on resource use. We discuss several explanations for this mismatch, highlighting potential reasons why optimality models might be misleading.

  17. Does intraspecific competition facilitate age separation in timing of southward migration in waders?

    Science.gov (United States)

    Minias, Piotr; Kaczmarek, Krzysztof; Włodarczyk, Radosław; Janiszewski, Tomasz

    2014-07-01

    In many Palaearctic wader species there is a clear separation in the timing of adult and juvenile southward migration. This phenomenon is traditionally explained by the selection on adults to depart early from breeding grounds and necessity of juveniles to prepare longer for migration. In this study we hypothesize that late departure from natal grounds may also be adaptive for juveniles, as it allows them to avoid intensified interference competition at stopover sites with adult, usually more dominant conspecifics. To test this hypothesis we analysed long-term data on stopover behaviour of juvenile wood sandpipers (Tringa glareola) staying at a central Polish stopover site under varying levels of competition from adult birds. The results clearly indicated that juveniles were highly disadvantaged by the simultaneous presence of adults at the same staging site, as under intense competition from older conspecifics they refuelled more slowly and attained lower fat reserves. It was also found that juveniles which were forced to compete with adults left the site quickly and possibly searched for more favourable staging places. All these imply that delayed departure from natal grounds may be adaptive for juvenile waders, allowing them to mismatch the timing of their first migration with the peak of adult passage and, thus, reduce the negative consequences of intraspecific competition during migration.

  18. Population-Level Differentiation in Growth Rates and Leaf Traits in Seedlings of the Neotropical Live Oak Quercus oleoides Grown under Natural and Manipulated Precipitation Regimes

    Directory of Open Access Journals (Sweden)

    Jose A. Ramírez-Valiente

    2017-05-01

    Full Text Available Widely distributed species are normally subjected to spatial heterogeneity in environmental conditions. In sessile organisms like plants, adaptive evolution and phenotypic plasticity of key functional traits are the main mechanisms through which species can respond to environmental heterogeneity and climate change. While extended research has been carried out in temperate species in this regard, there is still limited knowledge as to how species from seasonally-dry tropical climates respond to spatial and temporal variation in environmental conditions. In fact, studies of intraspecific genetically-based differences in functional traits are still largely unknown and studies in these ecosystems have largely focused on in situ comparisons where environmental and genetic effects cannot be differentiated. In this study, we tested for ecotypic differentiation and phenotypic plasticity in leaf economics spectrum (LES traits, water use efficiency and growth rates under natural and manipulated precipitation regimes in a common garden experiment where seedlings of eight populations of the neotropical live oak Quercus oleoides were established. We also examined the extent to which intraspecific trait variation was associated with plant performance under different water availability. Similar to interspecific patterns among seasonally-dry tropical tree species, live oak populations with long and severe dry seasons had higher leaf nitrogen content and growth rates than mesic populations, which is consistent with a “fast” resource-acquisition strategy aimed to maximize carbon uptake during the wet season. Specific leaf area (SLA was the best predictor of plant performance, but contrary to expectations, it was negatively associated with relative and absolute growth rates. This observation was partially explained by the negative association between SLA and area-based photosynthetic rates, which is contrary to LES expectations but similar to other recent

  19. Spatial heterogeneity in light supply affects intraspecific competition of a stoloniferous clonal plant.

    Science.gov (United States)

    Wang, Pu; Lei, Jing-Pin; Li, Mai-He; Yu, Fei-Hai

    2012-01-01

    Spatial heterogeneity in light supply is common in nature. Many studies have examined the effects of heterogeneous light supply on growth, morphology, physiology and biomass allocation of clonal plants, but few have tested those effects on intraspecific competition. In a greenhouse experiment, we grew one (no competition) or nine ramets (with intraspecific competition) of a stoloniferous clonal plant, Duchesnea indica, in three homogeneous light conditions (high, medium and low light intensity) and two heterogeneous ones differing in patch size (large and small patch treatments). The total light in the two heterogeneous treatments was the same as that in the homogeneous medium light treatment. Both decreasing light intensity and intraspecific competition significantly decreased the growth (biomass, number of ramets and total stolon length) of D. indica. As compared with the homogeneous medium light treatment, the large patch treatment significantly increased the growth of D. indica without intraspecific competition. However, the growth of D. indica with competition did not differ among the homogeneous medium light, the large and the small patch treatments. Consequently, light heterogeneity significantly increased intraspecific competition intensity, as measured by the decreased log response ratio. These results suggest that spatial heterogeneity in light supply can alter intraspecific interactions of clonal plants.

  20. Spatial heterogeneity in light supply affects intraspecific competition of a stoloniferous clonal plant.

    Directory of Open Access Journals (Sweden)

    Pu Wang

    Full Text Available Spatial heterogeneity in light supply is common in nature. Many studies have examined the effects of heterogeneous light supply on growth, morphology, physiology and biomass allocation of clonal plants, but few have tested those effects on intraspecific competition. In a greenhouse experiment, we grew one (no competition or nine ramets (with intraspecific competition of a stoloniferous clonal plant, Duchesnea indica, in three homogeneous light conditions (high, medium and low light intensity and two heterogeneous ones differing in patch size (large and small patch treatments. The total light in the two heterogeneous treatments was the same as that in the homogeneous medium light treatment. Both decreasing light intensity and intraspecific competition significantly decreased the growth (biomass, number of ramets and total stolon length of D. indica. As compared with the homogeneous medium light treatment, the large patch treatment significantly increased the growth of D. indica without intraspecific competition. However, the growth of D. indica with competition did not differ among the homogeneous medium light, the large and the small patch treatments. Consequently, light heterogeneity significantly increased intraspecific competition intensity, as measured by the decreased log response ratio. These results suggest that spatial heterogeneity in light supply can alter intraspecific interactions of clonal plants.

  1. Wood density variations of Norway spruce (Picea abies (L. Karst. under contrasting climate conditions in southwestern Germany

    Directory of Open Access Journals (Sweden)

    Marieke van der Maaten-Theunissen

    2013-05-01

    Full Text Available We analyzed inter-annual variations in ring width and maximumwood density of Norway spruce (Picea abies (L. Karst. at different altitudes in Baden-Württemberg, southwestern Germany, to determine the climate response of these parameters under contrasting climate conditions. In addition, we compared maximum, average and minimum wood density between sites. Bootstrapped correlation coefficients of ring width and maximum wood density with monthly temperature and precipitation, revealed a different climate sensitivity of both parameters. Ring width showed strong correlations with climate variables in the previous year and in the first half of the growingseason. Further, a negative relationship with summer temperature was observed at the low-altitude sites. Maximum wood density correlated best with temperature during the growing season, whereby strongest correlations were found between September temperature and maximum wood density at the high-altitude sites. Observed differences in maximum, average and minimum wood density are suggested to relate to the local climate; with lower temperature and higher water availability having a negative effect on wood density.

  2. Wood density variations of Norway spruce (Picea abies (L. Karst. under contrasting climate conditions in southwestern Germany

    Directory of Open Access Journals (Sweden)

    Marieke van der Maaten-Theunissen

    2013-07-01

    Full Text Available We analyzed inter-annual variations in ring width and maximum wood density of Norway spruce (Picea abies (L. Karst. at different altitudes in Baden-Württemberg, southwestern Germany, to determine the climate response of these parameters under contrasting climate conditions. In addition, we compared maximum, average and minimum wood density between sites. Bootstrapped correlation coefficients of ring width and maximum wood density with monthly temperature and precipitation, revealed a different climate sensitivity of both parameters. Ring width showed strong correlations with climate variables in the previous year and in the first half of the growing season. Further, a negative relationship with summer temperature was observed at the low-altitude sites. Maximum wood density correlated best with temperature during the growing season, whereby strongest correlations were found between September temperature and maximum wood density at the high-altitude sites. Observed differences in maximum, average and minimum wood density are suggested to relate to the local climate; with lower temperatures and higher water availability having a negative effect on wood density. 

  3. Refractive variation under accommodative demand: curvital and scaled torsional variances and covariance across the meridians of the eye.

    Science.gov (United States)

    van Gool, R D; Harris, W F

    1997-06-01

    Autorefractor measurements were taken on the right eye of 10 students with an external target at vergences -1.00 and -3.00 D. The refractive errors in the form of sphere, cylinder, and axis were converted to vectors h and variance-covariance matrices calculated for different reference meridians. Scatter plots are drawn in symmetric dioptric power space. The profiles of curvital and scaled torsional variances, the scaled torsional fraction, and the scaled torsional-curvital correlation are shown using a polar representation. This form of representation provides a meridional pattern of variation under accommodative demand. The profile for scaled torsional variance is characteristically in the form of a pair of rabbit ears. At both target vergences curvital variance is larger than scaled torsional variance in all the meridians of the eye: the relative magnitudes are quantified by the scaled torsional fraction. An increase in accommodative demand generally results in an increase in variance. The rabbit ears usually become larger but less well divided. The correlation between curvital and torsional powers is usually positive in the first quadrant and negative in the second quadrant. Typical, atypical, and mean typical responses are discussed.

  4. A Heuristic Algorithm for Constrained Multi-Source Location Problem with Closest Distance under Gauge: The Variational Inequality Approach

    Directory of Open Access Journals (Sweden)

    Jian-Lin Jiang

    2013-01-01

    Full Text Available This paper considers the locations of multiple facilities in the space , with the aim of minimizing the sum of weighted distances between facilities and regional customers, where the proximity between a facility and a regional customer is evaluated by the closest distance. Due to the fact that facilities are usually allowed to be sited in certain restricted areas, some locational constraints are imposed to the facilities of our problem. In addition, since the symmetry of distances is sometimes violated in practical situations, the gauge is employed in this paper instead of the frequently used norms for measuring both the symmetric and asymmetric distances. In the spirit of the Cooper algorithm (Cooper, 1964, a new location-allocation heuristic algorithm is proposed to solve this problem. In the location phase, the single-source subproblem with regional demands is reformulated into an equivalent linear variational inequality (LVI, and then, a projection-contraction (PC method is adopted to find the optimal locations of facilities, whereas in the allocation phase, the regional customers are allocated to facilities according to the nearest center reclassification (NCR. The convergence of the proposed algorithm is proved under mild assumptions. Some preliminary numerical results are reported to show the effectiveness of the new algorithm.

  5. Tooth counts through growth in diapsid reptiles: implications for interpreting individual and size-related variation in the fossil record.

    Science.gov (United States)

    Brown, Caleb Marshall; VanBuren, Collin S; Larson, Derek W; Brink, Kirstin S; Campione, Nicolás E; Vavrek, Matthew J; Evans, David C

    2015-04-01

    Tooth counts are commonly recorded in fossil diapsid reptiles and have been used for taxonomic and phylogenetic purposes under the assumption that differences in the number of teeth are largely explained by interspecific variation. Although phylogeny is almost certainly one of the greatest factors influencing tooth count, the relative role of intraspecific variation is difficult, and often impossible, to test in the fossil record given the sample sizes available to palaeontologists and, as such, is best investigated using extant models. Intraspecific variation (largely manifested as size-related or ontogenetic variation) in tooth counts has been examined in extant squamates (lizards and snakes) but is poorly understood in archosaurs (crocodylians and dinosaurs). Here, we document tooth count variation in two species of extant crocodylians (Alligator mississippiensis and Crocodylus porosus) as well as a large varanid lizard (Varanus komodoensis). We test the hypothesis that variation in tooth count is driven primarily by growth and thus predict significant correlations between tooth count and size, as well as differences in the frequency of deviation from the modal tooth count in the premaxilla, maxilla, and dentary. In addition to tooth counts, we also document tooth allometry in each species and compare these results with tooth count change through growth. Results reveal no correlation of tooth count with size in any element of any species examined here, with the exception of the premaxilla of C. porosus, which shows the loss of one tooth position. Based on the taxa examined here, we reject the hypothesis, as it is evident that variation in tooth count is not always significantly correlated with growth. However, growth trajectories of smaller reptilian taxa show increases in tooth counts and, although current samples are small, suggest potential correlates between tooth count trajectories and adult size. Nevertheless, interspecific variation in growth patterns

  6. Effect of commercial enzymes on berry cell wall deconstruction in the context of intravineyard ripeness variation under winemaking conditions

    DEFF Research Database (Denmark)

    Gao, Yu; Fangel, Jonatan Ulrik; Willats, William George Tycho

    2016-01-01

    Significant intravineyard variation in grape berry ripening occurs within vines and between vines. However, no cell wall data are available on such variation. Here we used a checkerboard panel design to investigate ripening variation in pooled grape bunches for enzyme-assisted winemaking...... positively influence the consistency of winemaking and provides a foundation for further research into the relationship between grape berry cell wall architecture and enzyme formulations....

  7. Quantitative trait loci in hop (Humulus lupulus L.) reveal complex genetic architecture underlying variation in sex, yield and cone chemistry.

    Science.gov (United States)

    McAdam, Erin L; Freeman, Jules S; Whittock, Simon P; Buck, Emily J; Jakse, Jernej; Cerenak, Andreja; Javornik, Branka; Kilian, Andrzej; Wang, Cai-Hong; Andersen, Dave; Vaillancourt, René E; Carling, Jason; Beatson, Ron; Graham, Lawrence; Graham, Donna; Darby, Peter; Koutoulis, Anthony

    2013-05-30

    genetic control of traits of current economic and breeding significance in hop and demonstrate the complex genetic architecture underlying variation in these traits. The linkage information obtained in this study, based on transferable markers, can be used to facilitate the validation of QTL, crucial to the success of MAS.

  8. Environmental and geographic variables are effective surrogates for genetic variation in conservation planning.

    Science.gov (United States)

    Hanson, Jeffrey O; Rhodes, Jonathan R; Riginos, Cynthia; Fuller, Richard A

    2017-11-28

    Protected areas buffer species from anthropogenic threats and provide places for the processes that generate and maintain biodiversity to continue. However, genetic variation, the raw material for evolution, is difficult to capture in conservation planning, not least because genetic data require considerable resources to obtain and analyze. Here we show that freely available environmental and geographic distance variables can be highly effective surrogates in conservation planning for representing adaptive and neutral intraspecific genetic variation. We obtained occurrence and genetic data from the IntraBioDiv project for 27 plant species collected over the European Alps using a gridded sampling scheme. For each species, we identified loci that were potentially under selection using outlier loci methods, and mapped their main gradients of adaptive and neutral genetic variation across the grid cells. We then used the cells as planning units to prioritize protected area acquisitions. First, we verified that the spatial patterns of environmental and geographic variation were correlated, respectively, with adaptive and neutral genetic variation. Second, we showed that these surrogates can predict the proportion of genetic variation secured in randomly generated solutions. Finally, we discovered that solutions based only on surrogate information secured substantial amounts of adaptive and neutral genetic variation. Our work paves the way for widespread integration of surrogates for genetic variation into conservation planning.

  9. Intraspecific Variation in Maximum Ingested Food Size and Body Mass in Varecia rubra and Propithecus coquereli

    OpenAIRE

    Hartstone-Rose, Adam; Perry, Jonathan M. G.

    2011-01-01

    In a recent study, we quantified the scaling of ingested food size (Vb )—the maximum size at which an animal consistently ingests food whole—and found that Vb scaled isometrically between species of captive strepsirrhines. The current study examines the relationship between Vb and body size within species with a focus on the frugivorous Varecia rubra and the folivorous Propithecus coquereli. We found no overlap in Vb between the species (all V. rubra ingested larger pieces of food relative to...

  10. Intraspecific ploidy variation: a hidden, minor player in plant-soil-mycorrhizal fungi interactions

    Czech Academy of Sciences Publication Activity Database

    Sudová, Radka; Pánková, Hana; Rydlová, Jana; Münzbergová, Zuzana; Suda, Jan

    2014-01-01

    Roč. 101, č. 1 (2014), s. 26-33 ISSN 0002-9122 R&D Projects: GA ČR GA206/06/0598; GA ČR GAP504/10/1486 Institutional support: RVO:67985939 Keywords : polyploidy * arbuscular mycorhizal symbiosis * Aster amellus Subject RIV: EF - Botanics Impact factor: 2.603, year: 2014

  11. Intraspecific variation of cuticular hydrocarbon profiles in the Anastrepha fraterculus (Diptera: Tephritidae) species complex

    Czech Academy of Sciences Publication Activity Database

    Vaníčková, Lucie; Břízová, Radka; Mendonca, A. L.; Pompeiano, A.; do Nascimento, R. R.

    2015-01-01

    Roč. 139, č. 9 (2015), s. 679-689 ISSN 0931-2048 Institutional support: RVO:61388963 Keywords : chemotaxonomy * GCxGC/TOFMS * multiple factorial analyses * putative species * South American fruit fly Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 1.517, year: 2015

  12. Intraspecific sequence variation in 16S rRNA gene of Ureaplasma diversum isolates.

    Science.gov (United States)

    Marques, L M; Buzinhani, M; Guimaraes, A M S; Marques, R C P; Farias, S T; Neto, R L; Yamaguti, M; Oliveira, R C; Timenetsky, J

    2011-08-26

    Ureaplasma diversum infection in bulls may result in seminal vesiculitis, balanoposthitis and alterations in spermatozoids. In cows, it can cause placentitis, fetal alveolitis, abortion and the birth of weak calves. U. diversum ATCC 49782 (serogroups A), ATCC 49783 (serogroup C) and 34 field isolates were used for this study. These microorganisms were submitted to Polymerase Chain Reaction for 16S gene sequence determination using Taq High Fidelity and the products were purified and bi-directionally sequenced. Using the sequence obtained, a fragment containing four hypervariable regions was selected and nucleotide polymorphisms were identified based on their position within the 16S rRNA gene. Forty-four single nucleotide polymorphisms (SNP) were detected. The genotypic variability of the 16S rRNA gene of U. diversum isolates shows that the taxonomy classification of these organisms is likely much more complex than previously described and that 16S rRNA gene sequencing may be used to suggest an epidemiologic pattern of different origin strains. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. Intraspecific variation in plant size, secondary plant compounds, herbivory and parasitoid assemblages during secondary succession

    NARCIS (Netherlands)

    Kostenko, O.; Bezemer, T.M.

    2013-01-01

    During secondary succession on abandoned agricultural fields the diversity and abundance of insect communities often increases, whereas the performance and nutritional quality of early successional plants often declines. As the diversity and abundance of insects on a single plant are determined by

  14. Intraspecific ploidy variation: A hidden, minor player in plant-soil-mycorrhizal fungi interactions.

    Science.gov (United States)

    Sudová, Radka; Pánková, Hana; Rydlová, Jana; Münzbergová, Zuzana; Suda, Jan

    2014-01-01

    Genome duplication and arbuscular mycorrhizal (AM) symbiosis are ubiquitous in angiosperms. While the significance of each of these phenomena separately has been intensively studied, their interaction remains to be understood. Three diploid and three hexaploid populations of Aster amellus (Asteraceae) were characterized in terms of the soil conditions in situ and mycorrhizal root colonization. In a greenhouse experiment, the effects of ploidy level, substrate conditions, and AM fungi on plant performance were then separated by growing noninoculated plants or plants inoculated with AM fungi in substrates native to either the diploids or hexaploids. The diploids inhabited nutritionally richer sites but did not differ from hexaploid plants in the level of mycorrhizal root colonization in situ. In the experiment, hexaploids generally performed better than the diploids. This intercytotype growth difference was enhanced by soil fertility, with hexaploids benefiting more from nutritionally richer substrate than the diploids. AM inoculation was crucial for plant growth and phosphorus uptake. The interaction between ploidy level and AM inoculation significantly influenced only dry mass of roots, phosphorus concentrations in shoot biomass, and the length of the extraradical mycelium in the nonsterile substrates. Our results support the idea that polyploidy can affect the mycorrhizal growth response of host plants. Nevertheless, the effects of the interaction between ploidy and inoculation were weaker than the main effects of these factors.

  15. Intraspecific variation of the cephalic labial gland secretions in Bombus terrestris (L.) (Hymenoptera: Apidae)

    Czech Academy of Sciences Publication Activity Database

    Coppée, A.; Terzo, M.; Valterová, Irena; Rasmont, P.

    2008-01-01

    Roč. 5, č. 12 (2008), s. 2654-2661 ISSN 1612-1872 Institutional research plan: CEZ:AV0Z40550506 Keywords : bumblebees * labial gland secretions * pheromones * male-marking pheromones * Bombus terrestris Subject RIV: CC - Organic Chemistry Impact factor: 1.659, year: 2008

  16. Intraspecific variation in female sex pheromone of the codling moth Cydia pomonella

    NARCIS (Netherlands)

    Duménil, C.; Judd, G.J.R.; Bosch, D.; Baldessari, M.; Gemeno, C.; Groot, A.T.

    2014-01-01

    The codling moth, Cydia pomonella L. (Lepidoptera, Tortricidae), is a major pest of apple, pear and walnut orchards worldwide. This pest is often controlled using the biologically friendly control method known as pheromone-based mating disruption. Mating disruption likely exerts selection on the

  17. Inter- and intraspecific variation of carbon and nitrogen stable isotope ratios in freshwater bivalves

    OpenAIRE

    Novais, Adriana; Dias, Ester; Sousa, Ronaldo Gomes

    2016-01-01

    Freshwater bivalves provide important ecosystem functions and services, yet many of their ecological traits such as feeding mechanisms and resource use are largely ignored. In this study, we aimed to evaluate the potential overlap in resource use by bivalve species living in sympatry in European freshwater ecosystems. This was accomplished by analyzing the stable isotope ratios of carbon (C) and nitrogen (N) values of six bivalve species (five native species plus th...

  18. Kangaroo rats: intraspecific variation in Dipodomys spectabilis Merriam and Dipodomys deserti Stephens

    National Research Council Canada - National Science Library

    Nader, Iyad A

    1978-01-01

    Twenty morpholoigcl characters in addition to color were studied throughout the geographic range of two species of kangaroo rats, the banner-tailed kangaroo rat Dipodomys spectabilis and the desert...

  19. Intraspecific shape variation in horseshoe crabs: the importance of sexual and natural selection for local adaptation

    DEFF Research Database (Denmark)

    Faurby, Søren; Nielsen, Kasper Sauer Kollerup; Bussarawit, Somchai

    2011-01-01

    A morphometric analysis of the body shape of three species of horseshoe crabs was undertaken in order to infer the importance of natural and sexual selection. It was expected that natural selection would be most intense, leading to highest regional differentiation, in the American species Limulus...... polyphemus, which has the largest climatic differences between different populations. Local adaptation driven by sexual selection was expected in males but not females because horseshoe crab mating behaviour leads to competition between males, but not between females. Three hundred fifty-nine horseshoe crabs...

  20. Intraspecific variation in the wing shape and genetic differentiation of Reed Warblers Acrocephalus scirpaceus in Croatia

    Czech Academy of Sciences Publication Activity Database

    Kralj, J.; Procházka, Petr; Fainová, Drahomíra; Patzenhauerová, Hana; Tutiš, V.

    2010-01-01

    Roč. 45, č. 1 (2010), s. 51-58 ISSN 0001-6454 R&D Projects: GA AV ČR KJB600930508 Institutional research plan: CEZ:AV0Z60930519 Keywords : wing morphology * migration * microsatellites * genetic diversity Subject RIV: EG - Zoology Impact factor: 0.889, year: 2010

  1. Inter- and intraspecific variation in mercury bioaccumulation by snakes inhabiting a contaminated river floodplain.

    Science.gov (United States)

    Drewett, David V V; Willson, John D; Cristol, Daniel A; Chin, Stephanie Y; Hopkins, William A

    2013-04-01

    Although mercury (Hg) is a well-studied contaminant, knowledge about Hg accumulation in snakes is limited. The authors evaluated Hg bioaccumulation within and among four snake species (northern watersnakes, Nerodia sipedon; queen snakes, Regina septemvittata; common garter snakes, Thamnophis sirtalis; and rat snakes, Elaphe obsoleta [Pantherophis alleghaniensis]) from a contaminated site on the South River (Waynesboro, VA, USA) and two nearby reference sites. Total Hg (THg) concentrations in northern watersnake tail tissue at the contaminated site ranged from 2.25 to 13.84 mg/kg dry weight (mean: 4.85 ± 0.29), or 11 to 19 times higher than reference sites. Blood THg concentrations (0.03-7.04 mg/kg wet wt; mean: 2.24 ± 0.42) were strongly correlated with tail concentrations and were the highest yet reported in a snake species. Within watersnakes, nitrogen stable isotope values indicated ontogenetic trophic shifts that correlated with THg bioaccumulation, suggesting that diet plays a substantial role in Hg exposure. Female watersnakes had higher mean THg concentrations (5.67 ± 0.46 mg/kg) than males (4.93 ± 0.49 mg/kg), but no significant differences between sexes were observed after correcting for body size. Interspecific comparisons identified differences in THg concentrations among snake species, with more aquatic species (watersnakes and queen snakes) accumulating higher mean concentrations (5.60 ± 0.40 and 4.59 ± 0.38 mg/kg in tail tissue, respectively) than the more terrestrial species, garter snakes and rat snakes (1.28 ± 0.32 and 0.26 ± 0.09 mg/kg, respectively). The results of the present study warrant further investigation of potential adverse effects and will aid in prioritizing conservation efforts. Copyright © 2013 SETAC.

  2. Environmental and organismal predictors of intraspecific variation in the stoichiometry of a neotropical freshwater fish.

    Science.gov (United States)

    El-Sabaawi, Rana W; Kohler, Tyler J; Zandoná, Eugenia; Travis, Joseph; Marshall, Michael C; Thomas, Steven A; Reznick, David N; Walsh, Matthew; Gilliam, James F; Pringle, Catherine; Flecker, Alexander S

    2012-01-01

    The elemental composition of animals, or their organismal stoichiometry, is thought to constrain their contribution to nutrient recycling, their interactions with other animals, and their demographic rates. Factors that affect organismal stoichiometry are generally poorly understood, but likely reflect elemental investments in morphological features and life history traits, acting in concert with the environmental availability of elements. We assessed the relative contribution of organismal traits and environmental variability to the stoichiometry of an insectivorous Neotropical stream fish, Rivulus hartii. We characterized the influence of body size, life history phenotype, stage of maturity, and environmental variability on organismal stoichiometry in 6 streams that differ in a broad suite of environmental variables. The elemental composition of R. hartii was variable, and overlapped with the wide range of elemental composition documented across freshwater fish taxa. Average %P composition was ∼3.2%(±0.6), average %N∼10.7%(±0.9), and average %C∼41.7%(±3.1). Streams were the strongest predictor of organismal stoichiometry, and explained up to 18% of the overall variance. This effect appeared to be largely explained by variability in quality of basal resources such as epilithon N:P and benthic organic matter C:N, along with variability in invertebrate standing stocks, an important food source for R. hartii. Organismal traits were weak predictors of organismal stoichiometry in this species, explaining when combined up to 7% of the overall variance in stoichiometry. Body size was significantly and positively correlated with %P, and negatively with N:P, and C:P, and life history phenotype was significantly correlated with %C, %P, C:P and C:N. Our study suggests that spatial variability in elemental availability is more strongly correlated with organismal stoichiometry than organismal traits, and suggests that the stoichiometry of carnivores may not be completely buffered from environmental variability. We discuss the relevance of these findings to ecological stoichiometry theory.

  3. Environmental and organismal predictors of intraspecific variation in the stoichiometry of a neotropical freshwater fish.

    Directory of Open Access Journals (Sweden)

    Rana W El-Sabaawi

    Full Text Available The elemental composition of animals, or their organismal stoichiometry, is thought to constrain their contribution to nutrient recycling, their interactions with other animals, and their demographic rates. Factors that affect organismal stoichiometry are generally poorly understood, but likely reflect elemental investments in morphological features and life history traits, acting in concert with the environmental availability of elements. We assessed the relative contribution of organismal traits and environmental variability to the stoichiometry of an insectivorous Neotropical stream fish, Rivulus hartii. We characterized the influence of body size, life history phenotype, stage of maturity, and environmental variability on organismal stoichiometry in 6 streams that differ in a broad suite of environmental variables. The elemental composition of R. hartii was variable, and overlapped with the wide range of elemental composition documented across freshwater fish taxa. Average %P composition was ∼3.2%(±0.6, average %N∼10.7%(±0.9, and average %C∼41.7%(±3.1. Streams were the strongest predictor of organismal stoichiometry, and explained up to 18% of the overall variance. This effect appeared to be largely explained by variability in quality of basal resources such as epilithon N:P and benthic organic matter C:N, along with variability in invertebrate standing stocks, an important food source for R. hartii. Organismal traits were weak predictors of organismal stoichiometry in this species, explaining when combined up to 7% of the overall variance in stoichiometry. Body size was significantly and positively correlated with %P, and negatively with N:P, and C:P, and life history phenotype was significantly correlated with %C, %P, C:P and C:N. Our study suggests that spatial variability in elemental availability is more strongly correlated with organismal stoichiometry than organismal traits, and suggests that the stoichiometry of carnivores may not be completely buffered from environmental variability. We discuss the relevance of these findings to ecological stoichiometry theory.

  4. Cuticular hydrocarbons of Triatoma dimidiata (Hemiptera: Reduviidae): intraspecific variation and chemotaxonomy.

    Science.gov (United States)

    Calderón-Fernández, Gustavo M; Girotti, Juan R; Juárez, M Patricia

    2011-03-01

    Triatoma dimidiata Latreille is a major vector of Chagas disease with an extensive geographic distribution from Central Mexico, through Central America, to northern South America. As a result of its variability in phenetic and genetic characters, disagreement concerning its taxonomic status has been raised. In this study, the cuticular hydrocarbon pattern of T. dimidiata populations from Mexico, Belize, Guatemala, Honduras, Costa Rica, and Colombia was analyzed by capillary gas chromatography coupled to mass spectrometry; linear discriminant analysis was used to help elucidate population structure. Vector populations segregated into five distinct groups; specimens from Yucatan Peninsula, together with those from Central Mexico, Central America, and Colombia corresponded to different T. dimidiata subspecies, a putative different species comprising insects from Belize, together with an isolated population collected at bat caves in Guatemala. The analysis revalidates the earlier division of T dimidiata into three subspecies, T. d. maculipennis, T. d. dimidiata, and T. d. capitata; and an additional subspecies and a distinct species are proposed.

  5. Functional genetics of intraspecific ecological interactions in Arabidopsis thaliana.

    Science.gov (United States)

    Wolf, Jason B; Mutic, Joshua J; Kover, Paula X

    2011-05-12

    Studying the genetic basis of traits involved in ecological interactions is a fundamental part of elucidating the connections between evolutionary and ecological processes. Such knowledge allows one to link genetic models of trait evolution with ecological models describing interactions within and between species. Previous work has shown that connections between genetic and ecological processes in Arabidopsis thaliana may be mediated by the fact that quantitative trait loci (QTL) with 'direct' effects on traits of individuals also have pleiotropic 'indirect' effects on traits expressed in neighbouring plants. Here, we further explore these connections by examining functional relationships between traits affected directly and indirectly by the same QTL. We develop a novel approach using structural equation models (SEMs) to determine whether observed pleiotropic effects result from traits directly affected by the QTL in focal individuals causing the changes in the neighbours' phenotypes. This hypothesis was assessed using SEMs to test whether focal plant phenotypes appear to mediate the connection between the focal plants' genotypes and the phenotypes of their neighbours, or alternatively, whether the connection between the focal plants' genotypes and the neighbours' phenotypes is mediated by unmeasured traits. We implement this analysis using a QTL of major effect that maps to the well-characterized flowering locus, FRIGIDA. The SEMs support the hypothesis that the pleiotropic indirect effects of this locus arise from size and developmental timing-related traits in focal plants affecting the expression of developmental traits in their neighbours. Our findings provide empirical insights into the genetics and nature of intraspecific ecological interactions. Our technique holds promise in directing future work into the genetic basis and functional relationship of traits mediating and responding to ecological interactions.

  6. Ligand partitioning into lipid bilayer membranes under high pressure: Implication of variation in phase-transition temperatures.

    Science.gov (United States)

    Matsuki, Hitoshi; Kato, Kentaro; Okamoto, Hirotsugu; Yoshida, Shuntaro; Goto, Masaki; Tamai, Nobutake; Kaneshina, Shoji

    2017-12-01

    The variation in phase-transition temperatures of dipalmitoylphosphatidylcholine (DPPC) bilayer membrane by adding two membrane-active ligands, a long-chain fatty acid (palmitic acid (PA)) and an inhalation anesthetic (halothane (HAL)), was investigated by light-transmittance measurements and fluorometry. By assuming the thermodynamic colligative property for the bilayer membrane at low ligand concentrations, the partitioning behavior of these ligands into the DPPC bilayer membrane was considered. It was proved from the differential partition coefficients between two phases that PA has strong affinity with the gel (lamellar gel) phase in a micro-molal concentration range and makes the bilayer membrane more ordered, while HAL has strong affinity with the liquid crystalline phase in a milli-molal concentration range and does the bilayer membrane more disordered. The transfer volumes of both ligands from the aqueous solution to each phase of the DPPC bilayer membrane showed that the preferential partitioning of the PA molecule into the gel (lamellar gel) produces about 20% decrease in transfer volume as compared with the liquid crystalline phase, whereas that of the HAL molecule into the liquid crystalline phase does about twice increase in transfer volume as compared with the gel (ripple gel) phase. Furthermore, changes in thermotropic and barotropic phase behavior of the DPPC bilayer membrane by adding the ligand was discussed from the viewpoint of the ligand partitioning. Reflecting the contrastive partitioning of PA and HAL into the pressure-induced interdigitated gel phase among the gel phases, it was revealed that PA suppresses the formation of the interdigitated gel phase under high pressure while HAL promotes it. These results clearly indicate that each phase of the DPPC bilayer membrane has a potential to recognize various ligand molecules. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Variation in spread of Heterobasidion annosum in clones of Picea abies grown at different vegetation phases under greenhouse conditions

    Energy Technology Data Exchange (ETDEWEB)

    Svedjemark, G.; Stenlid, J. [Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Dept. of Forest Mycology and Pathology

    1996-06-01

    Forty-nine Picea abies (L.) Karst clones were inoculated under greenhouse conditions with a Heterobasidion annosum (Fr.) Bref. isolate of the S intersterility group. The cuttings were inoculated at the following vegetation stages; bud-flushing stage, vegetative stage and after bud-set. Fungal growth in sapwood and leison length in the inner bark were measured after 34 days. The susceptibility of the various clones to H. annosum was strongly correlated among the three vegetation stages, both in terms of mean growth and mean growth ranking. Partitioning of variance components showed that variation in growth was explained by physiological stages and clone to 4% and 24%, respectively, and for interaction between clone and physiological stage to 9%. Corresponding values for leison length in the inner bark were 3%, 14% and 5%, respectively. Fungal growth in wood and leison length in the inner bark were strongly correlated (r{sup 2} ranging between 0.23 and 0.36). When cuttings were inoculated during bud-flushing, leison length and fungal growth in wood were both strongly correlated with bud-flushing index of the cuttings (r{sup 2} = 0.03 and 0.04 respectively) but that was not the case for the other stages. The number of active fine-roots and the degree of wilting of the cuttings were negatively correlated with leison length and fungal growth (r{sup 2} ranging between 0.01 and 0.13). Height and diameter varied greatly between the clones and both were negatively correlated with fungal extension (r{sup 2} ranging between 0.01 and 0.09). 33 refs, 2 figs, 3 tabs

  8. Larval size in acanthocephalan parasites: Influence of intraspecific competition and effects on intermediate host behavioural changes

    Directory of Open Access Journals (Sweden)

    Dianne Lucile

    2012-08-01

    Full Text Available Abstract Background Parasites often face a trade-off between exploitation of host resources and transmission probabilities to the next host. In helminths, larval growth, a major component of adult parasite fitness, is linked to exploitation of intermediate host resources and is influenced by the presence of co-infecting conspecifics. In manipulative parasites, larval growth strategy could also interact with their ability to alter intermediate host phenotype and influence parasite transmission. Methods We used experimental infections of Gammarus pulex by Pomphorhynchus laevis (Acanthocephala, to investigate larval size effects on host behavioural manipulation among different parasite sibships and various degrees of intra-host competition. Results Intra-host competition reduced mean P. laevis cystacanth size, but the largest cystacanth within a host always reached the same size. Therefore, all co-infecting parasites did not equally suffer from intraspecific competition. Under no intra-host competition (1 parasite per host, larval size was positively correlated with host phototaxis. At higher infection intensities, this relationship disappeared, possibly because of strong competition for host resources, and thus larval growth, and limited manipulative abilities of co-infecting larval acanthocephalans. Conclusions Our study indicates that behavioural manipulation is a condition-dependant phenomenon that needs the integration of parasite-related variables to be fully understood.

  9. Larval size in acanthocephalan parasites: influence of intraspecific competition and effects on intermediate host behavioural changes.

    Science.gov (United States)

    Dianne, Lucile; Bollache, Loïc; Lagrue, Clément; Franceschi, Nathalie; Rigaud, Thierry

    2012-08-09

    Parasites often face a trade-off between exploitation of host resources and transmission probabilities to the next host. In helminths, larval growth, a major component of adult parasite fitness, is linked to exploitation of intermediate host resources and is influenced by the presence of co-infecting conspecifics. In manipulative parasites, larval growth strategy could also interact with their ability to alter intermediate host phenotype and influence parasite transmission. We used experimental infections of Gammarus pulex by Pomphorhynchus laevis (Acanthocephala), to investigate larval size effects on host behavioural manipulation among different parasite sibships and various degrees of intra-host competition. Intra-host competition reduced mean P. laevis cystacanth size, but the largest cystacanth within a host always reached the same size. Therefore, all co-infecting parasites did not equally suffer from intraspecific competition. Under no intra-host competition (1 parasite per host), larval size was positively correlated with host phototaxis. At higher infection intensities, this relationship disappeared, possibly because of strong competition for host resources, and thus larval growth, and limited manipulative abilities of co-infecting larval acanthocephalans. Our study indicates that behavioural manipulation is a condition-dependant phenomenon that needs the integration of parasite-related variables to be fully understood.

  10. Genotypic Variation in Nitrogen Utilization Efficiency of Oilseed Rape (Brassica napus Under Contrasting N Supply in Pot and Field Experiments

    Directory of Open Access Journals (Sweden)

    Huiying He

    2017-10-01

    Full Text Available Oilseed rape (Brassica napus characteristically has high N uptake efficiency and low N utilization efficiency (NUtE, seed yield/shoot N accumulation. Determining the NUtE phenotype of various genotypes in different growth conditions is a way of finding target traits to improve oilseed rape NUtE. The aim of this study was to compare oilseed rape genotypes grown on contrasting N supply rates in pot and field experiments to investigate the genotypic variations of NUtE and to identify indicators of N efficient genotypes. For 50 oilseed rape genotypes, NUtE, dry matter and N partitioning, morphological characteristics, and the yield components were investigated under high and low N supplies in a greenhouse pot experiment and a field trial. Although the genotype rankings of NUtE were different between the pot experiment and the field trial, some genotypes performed consistently in both two environments. N-responder, N-nonresponder, N-efficient and N-inefficient genotypes were identified from these genotypes with consistent NUtE. The correlations between the pot experiment and the field trial in NUtE were only 0.34 at high N supplies and no significant correlations were found at low N supplies. However, Pearson coefficient correlation (r and principal component analysis showed NUtE had similar genetic correlations with other traits across the pot and field experiment. Among the yield components, only seeds per silique showed strong and positive correlations with NUtE under varying N supply in both experiments (r = 0.47**; 0.49**; 0.47**; 0.54**. At high and low N supply, NUtE was positively correlated with seed yield (r = 0.45**; 0.53**; 0.39**; 0.87**, nitrogen harvest index (NHI, r = 0.68**; 0.82**; 0.99**; 0.89**, and harvest index (HI, r = 0.79**; 0.83**; 0.90**; 0.78** and negatively correlated with biomass distribution to stem and leaf (r = −0.34**; −0.45**; −0.37**; 0.62**, all aboveground plant section N concentration (r from −0.30* to

  11. Empirical analysis of skin friction under variations of temperature; Variacion de la resistencia al corte con temperatura

    Energy Technology Data Exchange (ETDEWEB)

    Parra Alvarez, A. R. de la; Groot Viana, M. de

    2014-07-01

    In soil geotechnical characterization, strength parameters, cohesion (c) and internal friction angle (Φ) has been traditional measured without taking into account temperature, been a very important issue in energy geostructures. The present document analyzes the variation of these parameters in soil-concrete interface at different temperatures. A traditional shear strength case with a forced plane of failure was used. Several tests were carried out to determine the variation of skin friction in granular and cohesive oils with temperature. (Author)

  12. Physiological basis of genetic variation in leaf photosynthesis among rice (Oryza sativa L.) introgression lines under drought and well-watered conditions

    Science.gov (United States)

    Yin, Xinyou

    2012-01-01

    To understand the physiological basis of genetic variation and resulting quantitative trait loci (QTLs) for photosynthesis in a rice (Oryza sativa L.) introgression line population, 13 lines were studied under drought and well-watered conditions, at flowering and grain filling. Simultaneous gas exchange and chlorophyll fluorescence measurements were conducted at various levels of incident irradiance and ambient CO2 to estimate parameters of a model that dissects photosynthesis into stomatal conductance (g s), mesophyll conductance (g m), electron transport capacity (J max), and Rubisco carboxylation capacity (V cmax). Significant genetic variation in these parameters was found, although drought and leaf age accounted for larger proportions of the total variation. Genetic variation in light-saturated photosynthesis and transpiration efficiency (TE) were mainly associated with variation in g s and g m. One previously mapped major QTL of photosynthesis was associated with variation in g s and g m, but also in J max and V cmax at flowering. Thus, g s and g m, which were demonstrated in the literature to be responsible for environmental variation in photosynthesis, were found also to be associated with genetic variation in photosynthesis. Furthermore, relationships between these parameters and leaf nitrogen or dry matter per unit area, which were previously found across environmental treatments, were shown to be valid for variation across genotypes. Finally, the extent to which photosynthesis rate and TE can be improved was evaluated. Virtual ideotypes were estimated to have 17.0% higher photosynthesis and 25.1% higher TE compared with the best genotype investigated. This analysis using introgression lines highlights possibilities of improving both photosynthesis and TE within the same genetic background. PMID:22888131

  13. Molecular assessment of trematode co-infection and intraspecific competition in molluscan intermediate hosts.

    Science.gov (United States)

    Thiele, Elizabeth A; Minchella, Dennis J

    2013-01-01

    In natural populations of the human parasite Schistosoma mansoni, parasite distribution among snail intermediate hosts is generally overdispersed, such that a small proportion of hosts harbor the majority of parasite genotypes. Within these few infected snails, researchers have found that it can be common for hosts to harbor multiple parasite genotypes, creating circumstances in which co-infecting parasites are faced with potential competition over limited host resources. Much theoretical modeling has focused on parasite competition, especially regarding the influence of co-infection on parasite exploitation strategy evolution. However, particularly in the case of intra-molluscan intermediate stages, empirical investigations of parasite-parasite competition have often hinged on the untested assumption that co-exposure produces co-infection. That is, infected hosts exposed to multiple strains have been assumed to harbor multiple strains, regardless of the true nature of the infection outcome. Here we describe a real-time quantitative PCR method to distinguish the conditions of multiple- versus single-strain infection, as well as quantify the relative larval output of co-infecting strains. We applied the method to an empirical investigation of intraspecific parasite competition between S. mansoni strains within the intermediate snail host Biomphalaria glabrata, assessing co-exposure's effects on parasite infectivity and productivity and the concomitant effects on host fitness. Overall, there was no effect of parasite co-infection on snail life history traits relative to single-strain infection. Parasite infectivity significantly increased as a result of increasing overall miracidial dose, rather than co-exposure, though strain-specific productivity was significantly reduced in co-infections in manner consistent with resource competition. Moreover, we show that less than half of infected, co-exposed hosts had patent co-infections and demonstrate the utility of this

  14. Influence of swirl ratio on fuel distribution and cyclic variation under flash boiling conditions in a spark ignition direct injection gasoline engine

    International Nuclear Information System (INIS)

    Yang, Jie; Xu, Min; Hung, David L.S.; Wu, Qiang; Dong, Xue

    2017-01-01

    Highlights: • Influence of swirl on fuel distribution studied using laser induced fluorescence. • Gradient is sufficient for fuel spatial distribution variation analysis. • Close relation between fuel distribution and flame initiation/development. • Quantitative analysis shows high swirl suppresses variation of fuel distribution. • High order modes capable of identifying the distribution fluctuation patterns. - Abstract: One effective way of suppressing the cycle-to-cycle variation in engine is to design a combustion system that is robust to the root causes of engine variation over the entire engine working process. Flash boiling has been demonstrated as an ideal technique to produce stable fuel spray. But the generation of stable intake flow and fuel mixture remains challenging. In this study, to evaluate the capability of enhanced swirl flow to produce repeatable fuel mixture formation, the fuel distribution inside a single cylinder optical engine under two swirl ratios were measured using laser induced fluorescence technique. The swirl ratio was regulated by a swirl control valve installed in one of the intake ports. A 266 nm wavelength laser sheet from a frequency-quadrupled laser was directed into the optical engine through the quartz liner 15 mm below the tip of the spark plug. The fluorescence signal from the polycyclic aromatic hydrocarbon in gasoline was collected by applying a 320–420 nm band pass filter mounted in front of an intensified charge coupled device camera. Test results show that the in-cylinder fuel distribution is strongly influenced by the swirl ratio. Specifically, under high swirl condition, the fuel is mainly concentrated on the left side of the combustion chamber. While under the low swirl flow, fuel is distributed more randomly over the observing plane. This agrees well with the measurements of the stable flame location. Additionally, the cycle-to-cycle variation of the fuel distribution were analyzed. Results show that well

  15. In situ visualization and detection of surface potential variation of mono and multilayer MoS2 under different humidities using Kelvin probe force microscopy.

    Science.gov (United States)

    Feng, Yulin; Zhang, Kailiang; Li, Hui; Wang, Fang; Zhou, Baozeng; Fang, Mingxu; Wang, Weichao; Wei, Jun; Wong, H S Philip

    2017-06-30

    The surface potential (SP) variations in mono and multilayer molybdenum disulfide (MoS 2 ) are visualized in situ and detected using Kelvin probe force microscopy (KPFM) in different humidity conditions for the first time. N-type doping, which originates from the SiO 2 substrate, is discovered in the exfoliated MoS 2 and is accompanied by a screening length of five layers. The influence of water, which serves as an environmental gating for MoS 2 , is investigated by controlling the relative humidities (RHs) in the environmental chamber. A monotonic decrease in the SP is observed when the threshold concentration is achieved. This corresponds to the Fermi level variation, which is dominated by different processes. The results also indicate that water adsorption could result in MoS 2 p-type doping and provide compensation that partially counteracts the substrate effect. Under this condition, the interlayer screening effect is influenced because of the water dipole-induced electric field. Density functional theory calculations are performed to determine the band structure variations and the interactions between water molecules and between water molecules and the MoS 2 surface in mono and trilayer MoS 2 under different RHs. The calculations are in excellent agreement with the experimental results. We propose that in situ measurements of the SP using KPFM under different environmental regimes is a noninvasive and effective method to provide real-time visualization and detection of electronic property variations in two-dimensional materials.

  16. Inter- and intraspecific sexual discrimination in the flour beetles Tribolium castaneum and Tribolium confusum.

    Science.gov (United States)

    Serrano, J M; Castro, L; Toro, M A; López-Fanjul, C

    2000-08-01

    In Tribolium castaneum (CS) and T. confusum (CF), intra- and interspecific rates of homosexual mounting have been measured. The intraspecific results are compatible with the hypothesis of both species being sexually indiscriminate. However, the CF intraspecific rates were very high (35%-53% of mountings were homosexual), suggesting a lower sexual attractiveness, or a stronger rejection to being mounted, of CF females relative to conspecific males. CS males discriminate between species but, in interspecific contacts, preferentially mounted CF males rather than CF females. CF males do not discriminate between species, but the loss of sexual attractiveness of CF females, or their rejection to being mounted, may act as a precopulatory isolation mechanism.

  17. Photosynthetic variation and responsiveness to CO2 in a widespread riparian tree

    Science.gov (United States)

    Quentin, Audrey; Ivković, Milos; Furbank, Robert T.; Pinkard, Elizabeth

    2018-01-01

    Phenotypic responses to rising CO2 will have consequences for the productivity and management of the world’s forests. This has been demonstrated through extensive free air and controlled environment CO2 enrichment studies. However intraspecific variation in plasticity remains poorly characterised in trees, with the capacity to produce unexpected trends in response to CO2 across a species distribution. Here we examined variation in photosynthesis traits across 43 provenances of a widespread, genetically diverse eucalypt, E. camaldulensis, under ambient and elevated CO2 conditions. Genetic variation suggestive of local adaptation was identified for some traits under ambient conditions. Evidence of genotype by CO2 interaction in responsiveness was limited, however support was identified for quantum yield (φ). In this case local adaptation was invoked to explain trends in provenance variation in response. The results suggest potential for genetic variation to influence a limited set of photosynthetic responses to rising CO2 in seedlings of E. camaldulensis, however further assessment in mature stage plants in linkage with growth and fitness traits is needed to understand whether trends in φ could have broader implications for productivity of red gum forests. PMID:29293528

  18. Genome-wide association implicates numerous genes and pleiotropy underlying ecological trait variation in natural populations of Populus trichocarpa

    Energy Technology Data Exchange (ETDEWEB)

    McKown, Athena [University of British Columbia, Vancouver; Klapste, Jaroslav [University of British Columbia, Vancouver; Guy, Robert [University of British Columbia, Vancouver; Geraldes, Armando [University of British Columbia, Vancouver; Porth, Ilga [University of British Columbia, Vancouver; Hannemann, Jan [University of Victoria, Canada; Friedmann, Michael [University of British Columbia, Vancouver; Muchero, Wellington [ORNL; Tuskan, Gerald A [ORNL; Ehlting, Juergen [University of Victoria, Canada; Cronk, Quentin [University of British Columbia, Vancouver; El-Kassaby, Yousry [University of British Columbia, Vancouver; Mansfield, Shawn [University of British Columbia, Vancouver; Douglas, Carl [University of British Columbia, Vancouver

    2014-01-01

    To uncover the genetic basis of phenotypic trait variation, we used 448 unrelated wild accessions of black cottonwood (Populus trichocarpa Torr. & Gray) from natural populations throughout western North America. Extensive information from large-scale trait phenotyping (with spatial and temporal replications within a common garden) and genotyping (with a 34K Populus SNP array) of all accessions were used for gene discovery in a genome-wide association study (GWAS).

  19. The variation of cloud amount and light rainy days under heavy pollution over South China during 1960-2009.

    Science.gov (United States)

    Fu, Chuanbo; Dan, Li

    2018-01-01

    The ground observation data was used to analyze the variation of cloud amount and light precipitation over South China during 1960-2009. The total cloud cover (TCC) decreases in this period, whereas the low cloud cover (LCC) shows the obvious opposite change with increasing trends. LCP defined as low cloud cover/total cloud cover has increased, and small rainy days (cloud amount and light precipitation over South China.

  20. A control approach for the operation of DG units under variations of interfacing impedance in grid-connected mode

    DEFF Research Database (Denmark)

    Hoseini, S. Kazem; Pouresmaeil, E.; Hosseinnia, S. H.

    2016-01-01

    converter is highly sensitive to the impacts of this impedance changes; then, DG unit cannot inject appropriate currents. To deal with the instability problem, a control method based on fractional order active sliding mode is proposed in this paper, which is less sensitive to variations of interfacing...... to confirm the performance and feasibility of the proposed control method in DG technology. © 2015 Published by Elsevier Ltd....

  1. Response of tree growth to climatic variation and stand dynamics: Implications for modeling stand dynamics under varying climatic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Graumlich, L.J.; Holmes, R.L. (Univ. of Arizona, Tucson, AZ (United States))

    1994-06-01

    We used tree-ring data to assess the relative importance of regional climate vs. stand-level processes in controlling tree growth for seven forest dominants of the mixed conifer forest of the Sierra Nevada. For each species, increment cores were collected from at least 20 canopy dominants at several sites arrayed along elevational gradients extending from lower to upper elevational limits. Species sampled include ponderosa pine (Pinus ponderosa), Jeffrey pine (P. jeffreyi), sugar pine (P. lambertina), white fir (Abies concolor), red fir (A. magnifica), incense cedar (Calocedrus decurrens), and black oak (Quercus keloggii). Stand-level processes generate low to medium frequency variation in growth that is not held in common among trees within a site or between sites. Stand-level processes are most important for white and red fir and least important for ponderosa pine. Regional climatic variation generates medium to high frequency variation that is coherent among trees of the same species (and often same genera). Results such as these have utility for parameterizing and validating stand simulation models, especially for use in climatic change scenarios.

  2. Genome-Wide Identification of the Mutation Underlying Fleece Variation and Discriminating Ancestral Hairy Species from Modern Woolly Sheep.

    Science.gov (United States)

    Demars, Julie; Cano, Margarita; Drouilhet, Laurence; Plisson-Petit, Florence; Bardou, Philippe; Fabre, Stéphane; Servin, Bertrand; Sarry, Julien; Woloszyn, Florent; Mulsant, Philippe; Foulquier, Didier; Carrière, Fabien; Aletru, Mathias; Rodde, Nathalie; Cauet, Stéphane; Bouchez, Olivier; Pirson, Maarten; Tosser-Klopp, Gwenola; Allain, Daniel

    2017-07-01

    The composition and structure of fleece variation observed in mammals is a consequence of a strong selective pressure for fiber production after domestication. In sheep, fleece variation discriminates ancestral species carrying a long and hairy fleece from modern domestic sheep (Ovis aries) owning a short and woolly fleece. Here, we report that the "woolly" allele results from the insertion of an antisense EIF2S2 retrogene (called asEIF2S2) into the 3' UTR of the IRF2BP2 gene leading to an abnormal IRF2BP2 transcript. We provide evidence that this chimeric IRF2BP2/asEIF2S2 messenger 1) targets the genuine sense EIF2S2 RNA and 2) creates a long endogenous double-stranded RNA which alters the expression of both EIF2S2 and IRF2BP2 mRNA. This represents a unique example of a phenotype arising via a RNA-RNA hybrid, itself generated through a retroposition mechanism. Our results bring new insights on the sheep population history thanks to the identification of the molecular origin of an evolutionary phenotypic variation. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  3. Intraspecific gestural laterality in chimpanzees and gorillas and the impact of social propensities.

    Science.gov (United States)

    Prieur, Jacques; Pika, Simone; Barbu, Stéphanie; Blois-Heulin, Catherine

    2017-09-01

    A relevant approach to address the mechanisms underlying the emergence of the right-handedness/left-hemisphere language specialization of humans is to investigate both proximal and distal causes of language lateralization through the study of non-human primates' gestural laterality. We carried out the first systematic, quantitative comparison of within-subjects' and between-species' laterality by focusing on the laterality of intraspecific gestures of chimpanzees (Pan troglodytes) and gorillas (Gorilla gorilla) living in six different captive groups. We addressed the following two questions: (1) Do chimpanzees and gorillas exhibit stable direction of laterality when producing different types of gestures at the individual level? If yes, is it related to the strength of laterality? (2) Is there a species difference in gestural laterality at the population level? If yes, which factors could explain this difference? During 1356 observation hours, we recorded 42335 cases of dyadic gesture use in the six groups totalling 39 chimpanzees and 35 gorillas. Results showed that both species could exhibit either stability or flexibility in their direction of gestural laterality. These results suggest that both stability and flexibility may have differently modulated the strength of laterality depending on the species social structure and dynamics. Furthermore, a multifactorial analysis indicates that these particular social components may have specifically impacted gestural laterality through the influence of gesture sensory modality and the position of the recipient in the signaller's visual field during interaction. Our findings provide further support to the social theory of laterality origins proposing that social pressures may have shaped laterality through natural selection. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Metabolites and hormones are involved in the intraspecific variability of drought hardening in radiata pine.

    Science.gov (United States)

    De Diego, N; Saiz-Fernández, I; Rodríguez, J L; Pérez-Alfocea, P; Sampedro, M C; Barrio, R J; Lacuesta, M; Moncaleán, P

    2015-09-01

    Studies of metabolic and physiological bases of plant tolerance and hardening against drought are essential to improve genetic breeding programs, especially in productive species such as Pinus radiata. The exposure to different drought cycles is a highly effective tool that improves plant conditioning, but limited information is available about the mechanisms that modulate this process. To clarify this issue, six P. radiata breeds with well-known differences in drought tolerance were analyzed after two consecutive drought cycles. Survival rate, concentration of several metabolites such as free soluble amino acids and polyamines, and main plant hormones varied between them after drought hardening, while relative growth ratio and water potential at both predawn and dawn did not. Hardening induced a strong increase in total soluble amino acids in all breeds, accumulating mainly those implicated in the glutamate metabolism (GM), especially L-proline, in the most tolerant breeds. Other amino acids from GM such as γ-aminobutyric acid (GABA) and L-arginine (Arg) were also strongly increased. GABA pathway could improve the response against drought, whereas Arg acts as precursor for the synthesis of spermidine. This polyamine showed a positive relationship with the survival capacity, probably due to its role as antioxidant under stress conditions. Finally, drought hardening also induced changes in phytohormone content, showing each breed a different profile. Although all of them accumulated indole-3-acetic acid and jasmonic acid and reduced zeatin content in needles, significant differences were observed regarding abscisic acid, salicylic acid and mainly zeatin riboside. These results confirm that hardening is not only species-dependent but also an intraspecific processes controlled through metabolite changes. Copyright © 2015 Elsevier GmbH. All rights reserved.

  5. Intraspecific correlations of basal and maximal metabolic rates in birds and the aerobic capacity model for the evolution of endothermy.

    Science.gov (United States)

    Swanson, David L; Thomas, Nathan E; Liknes, Eric T; Cooper, Sheldon J

    2012-01-01

    The underlying assumption of the aerobic capacity model for the evolution of endothermy is that basal (BMR) and maximal aerobic metabolic rates are phenotypically linked. However, because BMR is largely a function of central organs whereas maximal metabolic output is largely a function of skeletal muscles, the mechanistic underpinnings for their linkage are not obvious. Interspecific studies in birds generally support a phenotypic correlation between BMR and maximal metabolic output. If the aerobic capacity model is valid, these phenotypic correlations should also extend to intraspecific comparisons. We measured BMR, M(sum) (maximum thermoregulatory metabolic rate) and MMR (maximum exercise metabolic rate in a hop-flutter chamber) in winter for dark-eyed juncos (Junco hyemalis), American goldfinches (Carduelis tristis; M(sum) and MMR only), and black-capped chickadees (Poecile atricapillus; BMR and M(sum) only) and examined correlations among these variables. We also measured BMR and M(sum) in individual house sparrows (Passer domesticus) in both summer, winter and spring. For both raw metabolic rates and residuals from allometric regressions, BMR was not significantly correlated with either M(sum) or MMR in juncos. Moreover, no significant correlation between M(sum) and MMR or their mass-independent residuals occurred for juncos or goldfinches. Raw BMR and M(sum) were significantly positively correlated for black-capped chickadees and house sparrows, but mass-independent residuals of BMR and M(sum) were not. These data suggest that central organ and exercise organ metabolic levels are not inextricably linked and that muscular capacities for exercise and shivering do not necessarily vary in tandem in individual birds. Why intraspecific and interspecific avian studies show differing results and the significance of these differences to the aerobic capacity model are unknown, and resolution of these questions will require additional studies of potential mechanistic

  6. Intraspecific correlations of basal and maximal metabolic rates in birds and the aerobic capacity model for the evolution of endothermy.

    Directory of Open Access Journals (Sweden)

    David L Swanson

    Full Text Available The underlying assumption of the aerobic capacity model for the evolution of endothermy is that basal (BMR and maximal aerobic metabolic rates are phenotypically linked. However, because BMR is largely a function of central organs whereas maximal metabolic output is largely a function of skeletal muscles, the mechanistic underpinnings for their linkage are not obvious. Interspecific studies in birds generally support a phenotypic correlation between BMR and maximal metabolic output. If the aerobic capacity model is valid, these phenotypic correlations should also extend to intraspecific comparisons. We measured BMR, M(sum (maximum thermoregulatory metabolic rate and MMR (maximum exercise metabolic rate in a hop-flutter chamber in winter for dark-eyed juncos (Junco hyemalis, American goldfinches (Carduelis tristis; M(sum and MMR only, and black-capped chickadees (Poecile atricapillus; BMR and M(sum only and examined correlations among these variables. We also measured BMR and M(sum in individual house sparrows (Passer domesticus in both summer, winter and spring. For both raw metabolic rates and residuals from allometric regressions, BMR was not significantly correlated with either M(sum or MMR in juncos. Moreover, no significant correlation between M(sum and MMR or their mass-independent residuals occurred for juncos or goldfinches. Raw BMR and M(sum were significantly positively correlated for black-capped chickadees and house sparrows, but mass-independent residuals of BMR and M(sum were not. These data suggest that central organ and exercise organ metabolic levels are not inextricably linked and that muscular capacities for exercise and shivering do not necessarily vary in tandem in individual birds. Why intraspecific and interspecific avian studies show differing results and the significance of these differences to the aerobic capacity model are unknown, and resolution of these questions will require additional studies of potential

  7. Intraspecific and interspecific pre-adult competition on the neotropical region colonizer Zaprionus indianus (Diptera: Drosophilidae under laboratory conditions Competição pré-adulta intra e interespecífica, em Zaprionus indianus (Diptera: Drosophilidae, espécie colonizadora da região neotropical, sob condições laboratoriais

    Directory of Open Access Journals (Sweden)

    Luís Gustavo da Conceição Galego

    2005-01-01

    Full Text Available This study analyzes the pre-adult interactions of Zaprionus indianus, a recently-introduced species in Brazil, with two others Drosophilidae under laboratory conditions. The effects of larval residues on the viability and on the developmental time of Z. indianus, Drosophila simulans and D. sturtevanti were used to evaluate pre-adult competitive interactions, conditioning the culture medium with larval residues. Pre-adult interactions between Z. indianus, D. sturtevanti and D. simulans may affect their relative abundance over time, since the viability of Z. indianus was negatively affected by residues of D. sturtevanti, and its residues reduced the viability of D. simulans and the developmental time of both D. simulans and D. sturtevanti.Este estudo é uma análise das interações pré-adultas, sob condições laboratoriais, da mosca-do-figo Zaprionus indianus, espécie recentemente introduzida no Brasil, com dois outros drosofilídeos. A interferência de meio de cultura, acrescido de resíduos larvais, sobre a viabilidade e o tempo de desenvolvimento de Z. indianus, Drosophila simulans e D. sturtevanti foi utilizada para avaliar as interações competitivas pré-adultas. As interações pré-adultas entre Z. indianus, D. sturtevanti e D. simulans podem afetar sua abundância relativa ao longo do tempo, pois a viabilidade de Z. indianus foi negativamente afetada por resíduos de D. sturtevanti; os resíduos da mosca-do-figo reduziram a viabilidade de D. simulans e o tempo de desenvolvimento tanto de D. simulans como de D. sturtevanti.

  8. Growth and intraspecific competitive abilities of the dioecious Lindera melissifolia (Lauraceae) in varied flooding regimes

    Science.gov (United States)

    Tracy S. Hawkins; Nathan M. Schiff; Theodor D. Leininger; Emile S Gardiner; Margaret S. Devall; Paul B. Hamel; A. Dan Wilson; Kristina F. Connor

    2009-01-01

    Forest Service, Southern Research Station, Stoneville, MS 38776). Growth and intraspecific competitive abilities of the dioecious Lindera melissifolia (Lauraceae) in varied flooding regimes. J. Torrey Bot. Soc. 136: 91–101. 2009.—The contribution of sexual dimorphism to malebiased colony ratios observed in field populations of the federally...

  9. Time-lagged intraspecific competition in temporally separated cohorts of a generalist insect.

    Science.gov (United States)

    Barnes, Elizabeth E; Murphy, Shannon M

    2018-03-01

    Competition can have far-reaching consequences for insect fitness and dispersion. Time-lagged interspecific competition is known to negatively affect fitness, yet time-lagged intraspecific competition is rarely studied outside of outbreak conditions. We tested the impact of competition between larval cohorts of the western tent caterpillar (Malacosoma californicum) feeding on chokecherry (Prunus virginiana). We reared larvae on host plants that either had or did not have feeding damage from tent caterpillars the previous season to test the bottom-up fitness effects of intraspecific competition. We measured host-plant quality to test potential mechanisms for bottom-up effects and conducted field oviposition surveys to determine if female adult tent caterpillars avoided host plants with evidence of prior tent caterpillar presence. We found that time-lagged intraspecific competition impacted tent caterpillar fitness by reducing female pupal mass, which is a predictor of lifetime fitness. We found that plants that had been fed upon by tent caterpillars the previous season had leaves that were significantly tougher than plants that had not been fed upon by tent caterpillars, which may explain why female tent caterpillars suffered reduced fitness on these plants. Finally, we found that there were fewer tent caterpillar egg masses on plants that had tent caterpillars earlier in the season than plants without tent caterpillars, which suggests that adult females avoid these plants for oviposition. Our results confirm that intraspecific competition occurs among tent caterpillars and suggests that time-lagged intraspecific competition has been overlooked as an important component of insect fitness.

  10. Plant diversity maintains long-term ecosystem productivity under frequent drought by increasing short-term variation.

    Science.gov (United States)

    Wagg, Cameron; O'Brien, Michael J; Vogel, Anja; Scherer-Lorenzen, Michael; Eisenhauer, Nico; Schmid, Bernhard; Weigelt, Alexandra

    2017-11-01

    Increasing frequency of extreme climatic events can disrupt ecosystem processes and destabilize ecosystem functioning. Biodiversity may dampen these negative effects of environmental perturbations to provide greater ecosystem stability. We assessed the effects of plant diversity on the resistance, recovery and stability of experimental grassland ecosystems in response to recurring summer drought over 7 yr. Plant biomass production was reduced during the summer drought treatment compared with control plots. However, the negative effect of drought was relatively less pronounced at high than at low plant diversity, demonstrating that biodiversity increased ecosystem resistance to environmental perturbation. Furthermore, more diverse plant communities compensated for the reduced productivity during drought by increasing spring productivity compared to control plots. The drought-induced compensatory recovery led to increased short-term variations in productivity across growing seasons in more diverse communities that stabilized the longer-term productivity across years. Our findings show that short-term variation between seasons in the face of environmental perturbation can lead to longer-term stability of annual productivity in diverse ecosystems compared to less diverse ecosystems. © 2017 by the Ecological Society of America.

  11. Long-term diffuse phosphorus pollution dynamics under the combined influence of land use and soil property variations.

    Science.gov (United States)

    Huang, Haobo; Ouyang, Wei; Wu, Haotian; Liu, Hongbin; Andrea, Critto

    2017-02-01

    Analyses of the spatial-temporal distribution of diffuse pollution in agricultural regions are essential to the sustained management of water resources. Although nutrients, such as phosphorus fertilizers, can promote crop growth while improving soil fertility, excessive nutrient inputs can produce diffuse pollution, which may results in water quality degradation. The objective of this paper is to employ the SWAT (Soil and Water Assessment Tool) to estimate diffuse P effects on temporal and spatial distributions for a typical agricultural watershed and to identify the conjunct and independent influences of long-term land use and soil properties variation on diffuse P. With the validated model, the four-period simulation results (from 1979 to 2009) indicate that land use changes from agricultural development increased diffuse P yields. However, regarding updated soil properties, no significant differences of P yield were found between 1979 and 2009, demonstrating that impact of the cropland expansion were naturalized with soil property variations. An F-test was employed to assess the essentiality of all of the variables examined during the simulation period, and the test results indicated that diffuse P loading was more sensitive to soil properties than to land use. Before the P pollution control project about the land use optimization planning, it is more effective to distinguish the impacts of land use and soil properties. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Osteology and postmetamorphic development of Telmatobius oxycephalus (Anura: Telmatobiidae) with an analysis of skeletal variation in the genus.

    Science.gov (United States)

    Barrionuevo, J Sebastián

    2013-01-01

    The osteological diversity among species of Telmatobius has been considered conservative. Nonetheless, the degree of ossification of several features varies both intraspecifically and interspecifically. Herein, intraspecific osteological variation and postmetamorphic ontogenetic changes in osteological features are described in Telmatobius oxycephalus. These data are compared with published descriptions of congeners. There is a considerable intraspecific osteological variation in T. oxycephalus, with cranial characters varying polymorphically, and the hyoid and postcranial characters being sexually dimorphic. This intraspecific variation is expressed by subtle differences in the degree of ossification or mineralization. Interspecific variation also can be described in terms of differential development of osteological features; these differences are more obvious than intraspecifically variable characters. The adult skeletons of several species of Telmatobius resemble the morphology observed in early stages of postmetamorphic development of T. oxycephalus. This is especially evident in the neopalatines, parasphenoid, sphenethmoid, exoccipitals, prootics, vomers, nasals, and plectra. These results suggest that within the conservative osteological architecture of Telmatobius, the variation observed is the result of heterochronic changes during the ossification process. Copyright © 2012 Wiley Periodicals, Inc.

  13. Chlorophyll fluorescence ratio F685/F735 in brown algae and its variation under excitation by two types of light and dehydration

    Science.gov (United States)

    Wu, Baogan; Zang, Rubo

    1993-03-01

    Calculation and comparative study of the chlorophyll fluorescence ratio F685/F735 in brown alage ( Laminaria japonica, Underia pinnatifida and Padina crassa) excited by blue and green light showed that the fluorescence ratios were higher when the algae were excited by blue light (440 nm), but reduced obviously under green light (540 nm) excitation. The values also reduced under dehydration but could recover during rehydration if the stress was not serious. The variation of the fluorescence ratio under dehydration was mainly because changes in fluorescence emission at 735 nm were always sharper than those at 685 nm. The ratio was sensitive to stress and has potential as a stress indicator in phycological research. Measurement of the fluorescence excitation spectra showed that the only peak at 540 nm changed apparently during dehydration. It meant that the function of the Ch1 a/Fucoxanthin protein complex for energy transfer was easily inhibited by water stress. However, no variation of the ratio was found in green alga Ulva pertusa under dehydration. So it seemed to be something special for brown algae. The mechanism of this phenomenon is still unclear but may be related to the photosynthetic pigments and structural characteristics of brown algae.

  14. Variations in water status, gas exchange, and growth in Rosmarinus officinalis plants infected with Glomus deserticola under drought conditions.

    Science.gov (United States)

    Sánchez-Blanco, Ma Jesús; Ferrández, Trinitario; Morales, Ma Angeles; Morte, Asunción; Alarcón, Juan José

    2004-06-01

    The influence of the arbuscular mycorrhizal fungus Glomus deserticola on the water relations, gas exchange parameters, and vegetative growth of Rosmarinus officinalis plants under water stress was studied. Plants were grown with and without the mycorrhizal fungus under glasshouse conditions and subjected to water stress by withholding irrigation water for 14 days. Along the experimental period, a significant effect of the fungus on the plant growth was observed, and under water stress, mycorrhizal plants showed an increase in aerial and root biomass compared to non-mycorrhizal plants. The decrease in the soil water potential generated a decrease in leaf water potential (psi(l)) and stem water potential (psi(x)) of mycorrhizal and non-mycorrhizal plants, with this decrease being lower in mycorrhizal water-stressed plants. Mycorrhization also had positive effects on the root hydraulic conductivity (Lp) of water stressed plants. Furthermore, mycorrhizal-stressed plants showed a more important decrease in osmotic potential at full turgor (psi(os)) than did non-mycorrhizal-stressed plants, indicating the capacity of osmotic adjustment. Mycorrhizal infection also improved photosynthetic activity (Pn) and stomatal conductance (g(s)) in plants under water stress compared to the non-mycorrhizal-stressed plants. A similar behaviour was observed in the photochemical efficiency of PSII (Fv/Fm) with this parameter being lower in non-mycorrhizal plants than in mycorrhizal plants under water stress conditions. In the same way, under water restriction, mycorrhizal plants showed higher values of chlorophyll content than did non-mycorrhizal plants. Thus, the results obtained indicated that the mycorrhizal symbiosis had a beneficial effect on the water status and growth of Rosmarinus officinalis plants under water-stress conditions.

  15. Spatial and temporal variations of winter discharge under climate change: Case study of rivers in European Russia

    Directory of Open Access Journals (Sweden)

    E. A. Telegina

    2015-05-01

    Full Text Available An important problem in hydrology is the re-evaluation of the current resources of surface and underground waters in the context of ongoing climate changes. The main feature of the present-day changes in water regime in the major portion of European Russia (ER is the substantial increase in low-water runoff, especially in winter. In this context, some features of the spatial–temporal variations of runoff values during the winter low-water period are considered. Calculations showed that the winter runoff increased at more than 95% of hydrological gauges. Changes in the minimum and average values of runoff during winter low-water period and other characteristics are evaluated against the background of climate changes in the recent decades. The spatial and temporal variability of winter runoff in European Russia is evaluated for the first time.

  16. Intraspecific competition of .i.Glyptotendipes paripes./i. (Diptera: Chironomidae) larvae under laboratory conditions

    Czech Academy of Sciences Publication Activity Database

    Frouz, Jan; Lobinske, R.J.; Ali, A.

    2009-01-01

    Roč. 43, č. 2 (2009), s. 487-500 ISSN 1386-2588 Institutional research plan: CEZ:AV0Z60660521; CEZ:AV0Z6066911 Keywords : food availability * Glyptotendipes paripes * larval density Subject RIV: EH - Ecology, Behaviour Impact factor: 1.549, year: 2009

  17. Intraspecific eye color variability in birds and mammals: a recent evolutionary event exclusive to humans and domestic animals.

    Science.gov (United States)

    Negro, Juan J; Carmen Blázquez, M; Galván, Ismael

    2017-01-01

    Human populations and breeds of domestic animals are composed of individuals with a multiplicity of eye (= iris) colorations. Some wild birds and mammals may have intraspecific eye color variability, but this variation seems to be due to the developmental stage of the individual, its breeding status, and/or sexual dimorphism. In other words, eye colour tends to be a species-specific trait in wild animals, and the exceptions are species in which individuals of the same age group or gender all develop the same eye colour. Domestic animals, by definition, include bird and mammal species artificially selected by humans in the last few thousand years. Humans themselves may have acquired a diverse palette of eye colors, likewise in recent evolutionary time, in the Mesolithic or in the Upper Paleolithic. We posit two previously unrecognized hypotheses regarding eye color variation: 1) eye coloration in wild animals of every species tends to be a fixed trait. 2) Humans and domestic animal populations, on the contrary, have eyes of multiple colors. Sexual selection has been invoked for eye color variation in humans, but this selection mode does not easily apply in domestic animals, where matings are controlled by the human breeder. Eye coloration is polygenic in humans. We wish to investigate the genetics of eye color in other animals, as well as the ecological correlates. Investigating the origin and function of eye colors will shed light on the reason why some species may have either light-colored irises (e.g., white, yellow or light blue) or dark ones (dark red, brown or black). The causes behind the vast array of eye colors across taxa have never been thoroughly investigated, but it may well be that all Darwinian selection processes are at work: sexual selection in humans, artificial selection for domestic animals, and natural selection (mainly) for wild animals.

  18. Evidence for multiple sources of invasion and intraspecific hybridization in Brachypodium sylvaticum (Hudson) Beauv. in North America.

    Science.gov (United States)

    Rosenthal, David M; Ramakrishnan, Alisa P; Cruzan, Mitchell B

    2008-11-01

    We compared the levels and distribution of genetic diversity in Eurasian and North American populations of Brachypodium sylvaticum (Huds.) Beauv. (false brome), a newly invasive perennial bunchgrass in western North America. Our goals were to identify source regions for invasive populations, determine the number of independent invasion events, and assess the possibility that postinvasion bottlenecks and hybridization have affected patterns of genetic diversity in the invaded range. We tested the hypothesis that this Eurasian grass was accidentally introduced into two areas in Oregon and one site in California by examining nuclear microsatellites and chloroplast haplotype variation in 23 introduced and 25 native populations. In the invaded range, there was significantly lower allelic richness (R(S)), observed heterozygosity (H(O)) and within-population gene diversity (H(S)), although a formal test failed to detect a significant genetic bottleneck. Most of the genetic variation existed among populations in the native range but within populations in the invaded range. All of the allelic variation in the invaded range could be explained based on alleles found in western European populations. The distribution of identified genetic clusters in the North American populations and the unique alleles associated with them is consistent with two historical introductions in Oregon and a separate introduction to California. Further analyses of population structure indicate that intraspecific hybridization among genotypes from geographically distinct regions of western Europe occurred following colonization in Oregon. The California populations, however, are more likely to be derived from one or perhaps several genetically similar regions in the native range. The emergence and spread of novel recombinant genotypes may be facilitating the rapid spread of this invasive species in Oregon.

  19. Open-water and under-ice seasonal variations in trace element content and physicochemical associations in fluvial bed sediment.

    Science.gov (United States)

    Doig, Lorne E; Carr, Meghan K; Meissner, Anna G N; Jardine, Tim D; Jones, Paul D; Bharadwaj, Lalita; Lindenschmidt, Karl-Erich

    2017-11-01

    Across the circumpolar world, intensive anthropogenic activities in the southern reaches of many large, northward-flowing rivers can cause sediment contamination in the downstream depositional environment. The influence of ice cover on concentrations of inorganic contaminants in bed sediment (i.e., sediment quality) is unknown in these rivers, where winter is the dominant season. A geomorphic response unit approach was used to select hydraulically diverse sampling sites across a northern test-case system, the Slave River and delta (Northwest Territories, Canada). Surface sediment samples (top 1 cm) were collected from 6 predefined geomorphic response units (12 sites) to assess the relationships between bed sediment physicochemistry (particle size distribution and total organic carbon content) and trace element content (mercury and 18 other trace elements) during open-water conditions. A subset of sites was resampled under-ice to assess the influence of season on these relationships and on total trace element content. Concentrations of the majority of trace elements were strongly correlated with percent fines and proxies for grain size (aluminum and iron), with similar trace element grain size/grain size proxy relationships between seasons. However, finer materials were deposited under ice with associated increases in sediment total organic carbon content and the concentrations of most trace elements investigated. The geomorphic response unit approach was effective at identifying diverse hydrological environments for sampling prior to field operations. Our data demonstrate the need for under-ice sampling to confirm year-round consistency in trace element-geochemical relationships in fluvial systems and to define the upper extremes of these relationships. Whether contaminated or not, under-ice bed sediment can represent a "worst-case" scenario in terms of trace element concentrations and exposure for sediment-associated organisms in northern fluvial systems

  20. A Comparison of Dielectric Properties of Palm Oil with Mineral and Synthetic Types Insulating Liquid under Temperature Variation

    Directory of Open Access Journals (Sweden)

    Abdul Rajab

    2011-11-01

    Full Text Available Mineral oil is known to have a low biodegradability level and high susceptibility to the fire. These conditions motivate many researchers to look for alternative sources for insulating oil. One of the alternative liquid is palm oil. To verify the suitability of using palm oil as an insulating liquid, it is important to make dielectric properties comparison with the commonly used insulating liquid. This paper presents comparison of temperature effect on dielectric properties of palm oil with mineral type insulating liquid and silicone oil. The measured parameters were breakdown voltage, dissipation factor (tan δ, and dielectric constant. Breakdown voltage measurement was performed in accordance with IEC 156 standard, whereas, the dissipation factor and dielectric constant measurement were conducted based on IEC 60247 standard test methods. The results showed that variations of dielectric properties of palm oil to the temperature change, in general, have the same tendency with those of commonly used insulating liquids i.e. mineral oil and silicone oil. Breakdown voltages and dissipation factors of all tested oils were increased, while their dielectric constants were slightly decreased with the increase of temperature.

  1. Seasonal variation of reproductive success under female philopatry and male-biased dispersal in a common vole population.

    Science.gov (United States)

    Borkowska, Anetta

    2011-01-01

    Variation of reproductive success, an important determinant of the opportunity for sexual selection, is an outcome of competition within one sex for mating with members of the other sex. In promiscuous species, males typically compete for access to females, and their reproductive strategies are strongly related to the spatial distribution of females. I used 10 microsatellite loci and the mtDNA control region to determine seasonal differences in the reproductive success of males and females of the common vole (Microtus arvalis), one of the most numerous mammals in Europe. The sex-related spatial structure and bias in dispersal between genders were also assessed. Standardized variance of the reproductive success of females did not vary seasonally due to the continuity of female philopatry throughout the breeding season and to the constancy of the number of females reproducing successfully in each season. The males are the dispersing sex, undergoing both natal and breeding dispersal. Their standardized variance of reproductive success was significantly higher than that for females in July, when only two males monopolized 80% of the females in the population and when variance of male reproductive success was highest (I(m)=7.70). The seasonally varying and high standardized variance of male reproductive success may be explained by male-male competition for matings, coupled with seasonal changes in the age structure of the population. Copyright © 2010 Elsevier B.V. All rights reserved.

  2. Variation in bioactive content in broccoli (Brassica oleracea var. italica) grown under conventional and organic production systems.

    Science.gov (United States)

    Valverde, Juan; Reilly, Kim; Villacreces, Salvador; Gaffney, Michael; Grant, James; Brunton, Nigel

    2015-04-01

    Broccoli and other cruciferous vegetables contain a number of bioactive compounds, in particular glucosinolates and polyphenols, which are proposed to confer health benefits to the consumer. Demand for organic crops is at least partly based on a perception that organic crops may contain higher levels of bioactive compounds; however, insufficient research has been carried out to either support or refute such claims. In this study we examined the effect of conventional, organic, and mixed cultivation practices on the content of total phenolics, total flavonoids, and total and individual glucosinolates in two varieties of broccoli grown over 2 years in a split-plot factorial systems comparison trial. Levels of total phenolics and total flavonoids showed a significant year-on-year variation but were not significantly different between organic and conventional production systems. In contrast, levels of the indolyl glucosinolates glucobrassicin and neoglucobrassicin were significantly higher (P broccoli florets; however, other investigated compounds were unaffected by production practices. © 2014 Society of Chemical Industry.

  3. The genetic basis underlying variation in production of the flavour compound diacetyl by Lactobacillus rhamnosus strains in milk.

    Science.gov (United States)

    Lo, Raquel; Ho, Van Thi Thuy; Bansal, Nidhi; Turner, Mark S

    2018-01-16

    Diacetyl and the closely related compound acetoin impart desirable buttery flavour and odour to many foods including cheese and are generated through the metabolism of citrate by lactic acid bacteria (LAB). To increase the levels of these compounds, adjunct cultures capable of producing them can be added to cheese fermentations. In this study, we compared the diacetyl and acetoin producing abilities of 13 Lactobacillus rhamnosus strains from cheese sources. Diacetyl and acetoin production was found to be a common feature of Lb. rhamnosus grown in milk, with 12 strains producing these compounds. Whole genome sequencing of four strains revealed that genes encoding the citrate metabolising pathway present in other LAB are conserved in Lb. rhamnosus. One strain was, however, totally defective in diacetyl and acetoin production. This was likely due to an inability to produce the diacetyl/acetoin precursor compound acetolactate resulting from a frameshift mutation in the acetolactate synthase (als) gene. Complementation of this defective strain with a complete als gene from a diacetyl producing strain restored production of diacetyl and acetoin to levels equivalent to naturally high producing strains. Introduction of the same als-containing plasmid into the probiotic Lb. rhamnosus strain GG also increased diacetyl and acetoin levels. In model cheesemaking experiments, the als-complemented strain produced very high levels of diacetyl and acetoin over 35days of ripening. These findings identify the genetic basis for natural variation in production of a key cheese flavour compound in Lb. rhamnosus strains. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Flight Morphology, Compound Eye Structure and Dispersal in the Bog and the Cranberry Fritillary Butterflies: An Inter- and Intraspecific Comparison.

    Directory of Open Access Journals (Sweden)

    Camille Turlure

    Full Text Available Understanding dispersal is of prime importance in conservation and population biology. Individual traits related to motion and navigation during dispersal may differ: (1 among species differing in habitat distribution, which in turn, may lead to interspecific differences in the potential for and costs of dispersal, (2 among populations of a species that experiences different levels of habitat fragmentation; (3 among individuals differing in their dispersal strategy and (4 between the sexes due to sexual differences in behaviour and dispersal tendencies. In butterflies, the visual system plays a central role in dispersal, but exactly how the visual system is related to dispersal has received far less attention than flight morphology. We studied two butterfly species to explore the relationships between flight and eye morphology, and dispersal. We predicted interspecific, intraspecific and intersexual differences for both flight and eye morphology relative to i species-specific habitat distribution, ii variation in dispersal strategy within each species and iii behavioural differences between sexes. However, we did not investigate for potential population differences. We found: (1 sexual differences that presumably reflect different demands on both male and female visual and flight systems, (2 a higher wing loading (i.e. a proxy for flight performance, larger eyes and larger facet sizes in the frontal and lateral region of the eye (i.e. better navigation capacities in the species inhabiting naturally fragmented habitat compared to the species inhabiting rather continuous habitat, and (3 larger facets in the frontal region in dispersers compared to residents within a species. Hence, dispersers may have similar locomotory capacity but potentially better navigation capacity. Dispersal ecology and evolution have attracted much attention, but there are still significant gaps in our understanding of the mechanisms of dispersal. Unfortunately, for many

  5. Flight Morphology, Compound Eye Structure and Dispersal in the Bog and the Cranberry Fritillary Butterflies: An Inter- and Intraspecific Comparison.

    Science.gov (United States)

    Turlure, Camille; Schtickzelle, Nicolas; Van Dyck, Hans; Seymoure, Brett; Rutowski, Ronald

    2016-01-01

    Understanding dispersal is of prime importance in conservation and population biology. Individual traits related to motion and navigation during dispersal may differ: (1) among species differing in habitat distribution, which in turn, may lead to interspecific differences in the potential for and costs of dispersal, (2) among populations of a species that experiences different levels of habitat fragmentation; (3) among individuals differing in their dispersal strategy and (4) between the sexes due to sexual differences in behaviour and dispersal tendencies. In butterflies, the visual system plays a central role in dispersal, but exactly how the visual system is related to dispersal has received far less attention than flight morphology. We studied two butterfly species to explore the relationships between flight and eye morphology, and dispersal. We predicted interspecific, intraspecific and intersexual differences for both flight and eye morphology relative to i) species-specific habitat distribution, ii) variation in dispersal strategy within each species and iii) behavioural differences between sexes. However, we did not investigate for potential population differences. We found: (1) sexual differences that presumably reflect different demands on both male and female visual and flight systems, (2) a higher wing loading (i.e. a proxy for flight performance), larger eyes and larger facet sizes in the frontal and lateral region of the eye (i.e. better navigation capacities) in the species inhabiting naturally fragmented habitat compared to the species inhabiting rather continuous habitat, and (3) larger facets in the frontal region in dispersers compared to residents within a species. Hence, dispersers may have similar locomotory capacity but potentially better navigation capacity. Dispersal ecology and evolution have attracted much attention, but there are still significant gaps in our understanding of the mechanisms of dispersal. Unfortunately, for many species

  6. Clock gene variation is associated with breeding phenology and maybe under directional selection in the migratory barn swallow.

    Directory of Open Access Journals (Sweden)

    Manuela Caprioli

    Full Text Available In diverse taxa, photoperiodic responses that cause seasonal physiological and behavioural shifts are controlled by genes, including the vertebrate Clock orthologues, that encode for circadian oscillator mechanisms. While the genetic network behind circadian rhythms is well described, relatively few reports exist of the phenological consequences of and selection on Clock genes in the wild. Here, we investigated variation in breeding phenology in relation to Clock genetic diversity in a long-distance migratory bird, the barn swallow (Hirundo rustica.In a sample of 922 adult barn swallows from a single population breeding in Italy we found one very common (Q(7 and three rare (Q(5, Q(6, Q(8 length variants of a functionally significant polyglutamine repeat. Rare (2.9% Q(7/Q(8 heterozygous females, but not males, bred significantly later than common (91.5% Q(7/Q(7 females, consistent with the expectation that 'long' alleles cause late breeding, as observed in a resident population of another bird species. Because breeding date depends on arrival date from migration, present results suggest that the association between breeding date and Clock might be mediated by migration phenology. In addition, fecundity selection appears to be operating against Q(7/Q(8 because late migrating/breeding swallows have fewer clutches per season, and late breeding has additional negative selection effects via reduced offspring longevity. Genotype frequencies varied marginally non-significantly with age, as Q(7/Q(8 frequency showed a 4-fold reduction in old individuals. This result suggests negative viability selection against Q(7/Q(8, possibly mediated by costs of late breeding.This is the first study of migratory birds showing an association between breeding phenology and Clock genotype and suggesting that negative selection occurs on a phenologically deviant genotype. Low polymorphism at Clock may constrain microevolutionary phenological response to changing climate

  7. Spatial variation in the frequency-magnitude distribution of earthquakes under the tectonic framework in the Middle East

    Science.gov (United States)

    Mousavi, S. Mostafa

    2017-10-01

    Spatial variations of seismic energy released and b-value over the Middle East region are investigated based on a seismicity catalog from 1995 to 2007. The goal is to use these seismic parameters and based on other geodetic and geophysical observations, such as GPS measurements, strain rate model, fault distribution, focal mechanism, crustal model, Q model, and gravity measurements, etc., to uncover spatial patterns that seem anomalous. Areas of high energy released (cumulative) seem to correspond to the areas of relatively high b-values. Areas of high energy released and high b-values seem to correspond very well with the location of continental collision where earthquake activities are high. The divergent boundary between Arabia and African plates and subduction zone at Makran seem to correspond to low to moderate energy release. Northern Pamir, Azerbaijan-Caucasus, the lower part of Zagros Mountains, eastern Turkey, Owen Fracture Zone, Strait of Bob-el-Mandeb, and south of the Sulaiman Shear Zone seem to correspond to high cumulative energy-released, high strain rate, high b-values, and high fault density. While, the central and eastern Iran, southern Zagros, northern Pakistan, Gulf of Aden, Alborz, southwest of the Caspian Sea, western Caucasus and Kopeh-Dagh seem to correspond with lower b-values. The cross-section map for Hindu-Kush shows general decreasing of the b-values with depth, however, a region of high b-value is observed underneath Pamir at depths from 170 to 230 km. This anomaly region can be due to dehydration of Pamir crustal slab at depth.

  8. Rainfall variation and child health: effect of rainfall on diarrhea among under 5 children in Rwanda, 2010.

    Science.gov (United States)

    Mukabutera, Assumpta; Thomson, Dana; Murray, Megan; Basinga, Paulin; Nyirazinyoye, Laetitia; Atwood, Sidney; Savage, Kevin P; Ngirimana, Aimable; Hedt-Gauthier, Bethany L

    2016-08-05

    Diarrhea among children under 5 years of age has long been a major public health concern. Previous studies have suggested an association between rainfall and diarrhea. Here, we examined the association between Rwandan rainfall patterns and childhood diarrhea and the impact of household sanitation variables on this relationship. We derived a series of rain-related variables in Rwanda based on daily rainfall measurements and hydrological models built from daily precipitation measurements collected between 2009 and 2011. Using these data and the 2010 Rwanda Demographic and Health Survey database, we measured the association between total monthly rainfall, monthly rainfall intensity, runoff water and anomalous rainfall and the occurrence of diarrhea in children under 5 years of age. Among the 8601 children under 5 years of age included in the survey, 13.2 % reported having diarrhea within the 2 weeks prior to the survey. We found that higher levels of runoff were protective against diarrhea compared to low levels among children who lived in households with unimproved toilet facilities (OR = 0.54, 95 % CI: [0.34, 0.87] for moderate runoff and OR = 0.50, 95 % CI: [0.29, 0.86] for high runoff) but had no impact among children in household with improved toilets. Our finding that children in households with unimproved toilets were less likely to report diarrhea during periods of high runoff highlights the vulnerabilities of those living without adequate sanitation to the negative health impacts of environmental events.

  9. Experimental Investigation of the Variation of Concrete Pores under the Action of Freeze-Thaw Cycles by Using X-Ray CT

    Directory of Open Access Journals (Sweden)

    Jie Yuan

    2014-01-01

    Full Text Available The variation of concrete pores under the action of freeze-thaw cycles was investigated experimentally by using the X-ray CT. Firstly, the statistical characteristics of pores of concrete specimens were obtained by using the X-ray image analysis. Secondly, the variation of porosity and pore volume of concrete pores were analyzed and discussed by comparing with above characteristics. Thirdly, the failure process of the concrete specimens acted by the freeze-thaw cycles was investigated by scanning the interior of concrete specimens. The results showed that the pore volumes of concrete pores whose volumes were located at the interval [0.5 mm3, 20 mm3] have no big variation in both the amounts and volume of concrete pores, while others were found to have huge change during the process of experiment. The extent of damage acted by the repeated freezing and thawing gradually ranged from surface to complete disintegration of the interior of concrete specimens after 30 cycles of freeze-thaw acting.

  10. Species interactions and chemical stress combined effects of intraspecific and interspecific interactions and pyrene n Daphnia magna populations dynamics

    NARCIS (Netherlands)

    Viaene, K.P.J.; Laender, de F.; Rico, A.; Brink, van den P.J.; Guardo, Di A.; Morselli, M.; Janssen, C.R.

    2015-01-01

    Species interactions are often suggested as an important factor when assessing the effects of chemicals on higher levels of biological organization. Nevertheless, the contribution of intraspecific and interspecific interactions to chemical effects on populations is often overlooked. In the present

  11. A Variationally Formulated Problem of the Stationary Heat Conduction in a Plate with Radiation Reduction Factor Increased under Temperature

    Directory of Open Access Journals (Sweden)

    V. S. Zarubin

    2016-01-01

    dependence of the absorption factor on the local intensity of this radiation. Furthermore, it can be a significant dependence of this factor on the local value of the material temperature, reflecting the above-mentioned relationship between the absorption of electromagnetic wave energy and the excitation of material microparticles. This process can be described by Boltzmann distribution function that comprises the energy to activate microparticles and the local value of temperature.This paper presents a variational formulation of the nonlinear problem of stationary heat conduction in a plate for the case when the radiation reduction factor in relation to the Bouguer law depends on the local temperature. This formulation includes a functional that can have several fixed points corresponding to different steady states of the plate temperature. Analysis of the properties of this functional enabled us to identify the stationary points, which correspond to the realized temperature distribution in the plate.

  12. Intraspecific competition and high food availability are associated with insular gigantism in a lizard

    Science.gov (United States)

    Pafilis, Panayiotis; Meiri, Shai; Foufopoulos, Johannes; Valakos, Efstratios

    2009-09-01

    Resource availability, competition, and predation commonly drive body size evolution. We assess the impact of high food availability and the consequent increased intraspecific competition, as expressed by tail injuries and cannibalism, on body size in Skyros wall lizards ( Podarcis gaigeae). Lizard populations on islets surrounding Skyros (Aegean Sea) all have fewer predators and competitors than on Skyros but differ in the numbers of nesting seabirds. We predicted the following: (1) the presence of breeding seabirds (providing nutrients) will increase lizard population densities; (2) dense lizard populations will experience stronger intraspecific competition; and (3) such aggression, will be associated with larger average body size. We found a positive correlation between seabird and lizard densities. Cannibalism and tail injuries were considerably higher in dense populations. Increases in cannibalism and tail loss were associated with large body sizes. Adult cannibalism on juveniles may select for rapid growth, fuelled by high food abundance, setting thus the stage for the evolution of gigantism.

  13. The role of demography, intra-species variation, and species distribution models in species’ projections under climate change

    DEFF Research Database (Denmark)

    Swab, Rebecca Marie; Regan, Helen M.; Matthies, Diethart

    2015-01-01

    and linked it to a SDM that predicted changes in habitat suitability through time with changes in climatic variables. We then varied the demographic parameters based upon observed vital rates of local populations from a translocation experiment. Despite the fact that the SDM alone predicted C. vulgaris......Organisms are projected to shift their distribution ranges under climate change. The typical way to assess range shifts is by species distribution models (SDMs), which predict species’ responses to climate based solely on projected climatic suitability. However, life history traits can impact...... species’ responses to shifting habitat suitability. Additionally, it remains unclear if differences in vital rates across populations within a species can offset or exacerbate the effects of predicted changes in climatic suitability on population viability. In order to obtain a fuller understanding...

  14. Seasonal variations and effects of nutrient applications on N and P and microbial biomass under two temperate heathland plants

    DEFF Research Database (Denmark)

    Nielsen, Pia Lund; Andresen, Louise Christoffersen; Michelsen, Anders

    2009-01-01

    . The microbial biomass on the other hand was positively related to soil water content in fertilized plots indicating that this was due to an indirect effect of enhanced nutrient availability. Microbial N and P pools were respectively 1000 and 100 times higher than the pool of inorganic N and P, and microbes......Eutrofication is a threat against nutrient-poor habitats as increased amounts of nutrients in ecosystems may cause changes in the vegetation. Nitrogen (N) deposition leads to conversion of Calluna heathlands into graminoid dominated heath, but low availability of P may hinder or slow down...... this process. In this study the soil properties under two dominant heathland plants, the dwarf shrub Calluna vulgaris and the grass Deschampsia flexuosa, were investigated, with focus on nutrient content in the organic top soil and soil microbes during the main growing season and effects of nutrient amendments...

  15. Genetic variation of loci potentially under selection confounds species-genetic diversity correlations in a fragmented habitat.

    Science.gov (United States)

    Bertin, Angeline; Gouin, Nicolas; Baumel, Alex; Gianoli, Ernesto; Serratosa, Juan; Osorio, Rodomiro; Manel, Stephanie

    2017-01-01

    Positive species-genetic diversity correlations (SGDCs) are often thought to result from the parallel influence of neutral processes on genetic and species diversity. Yet, confounding effects of non-neutral mechanisms have not been explored. Here, we investigate the impact of non-neutral genetic diversity on SGDCs in high Andean wetlands. We compare correlations between plant species diversity and genetic diversity (GD) calculated with and without loci potentially under selection (outlier loci). The study system includes 2188 specimens from five species (three common aquatic macroinvertebrate and two dominant plant species) that were genotyped for 396 amplified fragment length polymorphism loci. We also appraise the importance of neutral processes on SGDCs by investigating the influence of habitat fragmentation features. Significant positive SGDCs were detected for all five species (mean SGDC = 0.52 ± 0.05). While only a few outlier loci were detected in each species, they resulted in significant decreases in GD and in SGDCs. This supports the hypothesis that neutral processes drive species-genetic diversity relationships in high Andean wetlands. Unexpectedly, the effects on genetic diversity GD of the habitat fragmentation characteristics in this study increased with the presence of outlier loci in two species. Overall, our results reveal pitfalls in using habitat features to infer processes driving SGDCs and show that a few loci potentially under selection are enough to cause a significant downward bias in SGDC. Investigating confounding effects of outlier loci thus represents a useful approach to evidence the contribution of neutral processes on species-genetic diversity relationships. © 2016 John Wiley & Sons Ltd.

  16. Rare insights into intraspecific brood parasitism and apparent quasi–parasitism in black–capped chickadees

    OpenAIRE

    Otter, K. A.; Murray, B. W.; Holschuh, C. I.; Fort, K. T.

    2011-01-01

    Genetic analysis of passerine birds often finds evidence of extra–pair copulations within species, but genetic evidence of intraspecific brood parasitism (IBP) and quasi–parasitism (Q–P) are relatively rare. Further, it is even rarer for genetic patterns that might indicate quasi–parasitism (resident male sires offspring through extra–pair copulations, and allows the female to lay these within the male’s nest) to be coupled with observational evidence of this behavior. In this paper, we repor...

  17. Behavioral signature of intraspecific competition and density dependence in colony-breeding marine predators.

    Science.gov (United States)

    Breed, Greg A; Don Bowen, W; Leonard, Marty L

    2013-10-01

    In populations of colony-breeding marine animals, foraging around colonies can lead to intraspecific competition. This competition affects individual foraging behavior and can cause density-dependent population growth. Where behavioral data are available, it may be possible to infer the mechanism of intraspecific competition. If these mechanics are understood, they can be used to predict the population-level functional response resulting from the competition. Using satellite relocation and dive data, we studied the use of space and foraging behavior of juvenile and adult gray seals (Halichoerus grypus) from a large (over 200,000) and growing population breeding at Sable Island, Nova Scotia (44.0 (o)N 60.0 (o)W). These data were first analyzed using a behaviorally switching state-space model to infer foraging areas followed by randomization analysis of foraging region overlap of competing age classes. Patterns of habitat use and behavioral time budgets indicate that young-of-year juveniles (YOY) were likely displaced from foraging areas near (intraspecific competition between adults and juveniles, resulting in the currently observed decelerating logistic population growth. Competition theory predicts that intraspecific competition resulting in a clear losing competitor should cause compensatory population regulation. This functional response produces a smooth logistic growth curve as carrying capacity is approached, and is consistent with census data collected from this population over the past 50 years. The competitive mechanism causing compensatory regulation likely stems from the capital-breeding life-history strategy employed by gray seals. This strategy decouples reproductive success from resources available around breeding colonies and prevents females from competing with each other while young are dependent.

  18. Effects of Intraspecific Competition and Host-Parasitoid Developmental Timing on Foraging Behaviour of a Parasitoid Wasp

    OpenAIRE

    Couchoux, Christelle; van Nouhuys, Saskya

    2014-01-01

    In a context where hosts are distributed in patches and susceptible to parasitism for a limited time, female parasitoids foraging for hosts might experience intraspecific competition. We investigated the effects of host and parasitoid developmental stage and intraspecific competition among foraging females on host-searching behaviour in the parasitoid wasp Hyposoter horticola. We found that H. horticola females have a pre-reproductive adult stage during which their eggs are not mature yet and...

  19. Predicting the variation in Echinogammarus marinus at its southernmost limits under global warming scenarios: can the sex-ratio make a difference?

    Science.gov (United States)

    Guerra, Alexandra; Leite, Nuno; Marques, João Carlos; Ford, Alex T; Martins, Irene

    2014-01-01

    Understanding the environmental parameters that constrain the distribution of a species at its latitudinal extremes is critical for predicting how ecosystems react to climate change. Our first aim was to predict the variation in the amphipod populations of Echinogammarus marinus from the southernmost limit of its distribution under global warming scenarios. Our second aim was to test whether sex-ratio fluctuations - a mechanism frequently displayed by amphipods - respond to the variations in populations under altered climate conditions. To achieve these aims, scenarios were run with a validated model of E. marinus populations. Simulations were divided into: phase I - simulation of the effect of climate change on amphipod populations, and phase II - simulation of the effect of climate change on populations with male and female proportions. In both phases, temperature (T), salinity (S) and temperature and salinity (T-S) were tested. Results showed that E. marinus populations are highly sensitive to increases in temperature (>2 °C), which has adverse effects on amphipod recruitment and growth. Results from the climate change scenarios coupled with the sex-ratio fluctuations depended largely on the degree of female bias within population. Temperature increase of 2 °C had less impact on female-biased populations, particularly when conjugated with increases in salinity. Male-biased populations were highly sensitive to any variation in temperature and/or salinity; these populations exhibited a long-term decline in density. Simulations in which temperature increased more than 4 °C led to a continuous decline in the E. marinus population. According to this work, E. marinus populations at their southernmost limit are vulnerable to global warming. We anticipate that in Europe, temperature increases of 2 °C will incite a withdrawal of the population of 5°N from the amphipod species located at southernmost geographical borders. This effect is discussed in relation to the

  20. Intraspecific differentiation of Colletotrichum gloeosporioides sensu lato based on in silico multilocus PCR-RFLP fingerprinting.

    Science.gov (United States)

    Ramdeen, Stephen; Rampersad, Sephra N

    2013-02-01

    Colletotrichum gloeosporioides sensu lato is one of the most common and widely distributed plant pathogens in the world. Understanding fungal biodiversity is hinged on accurate identification and delimitation at the inter- and intraspecific levels. Sequences of the ITS1-5.8S-ITS2 region (ITS), β-tubulin (TUB), actin (ACT), and glyceraldehyde-3-phosphate dehydrogenase (GPDH) genes of 30 C. gloeosporioides sensu lato isolates, collected from anthracnose infected papaya fruits grown in the main production areas in Trinidad, were analyzed by in silico PCR-RFLP analysis with the aim of identifying which gene region(s) had the highest level of intraspecific polymorphism. Restriction site polymorphisms generated from 13 restriction enzymes enabled the identification of specific enzymes that were successful at intraspecific discrimination of the C. gloeosporioides isolates. Genetic distance values were reflective of the level of polymorphisms obtained for the four different gene regions. In both cases (calculated genetic distance and percentage of polymorphic loci from RFLP profiles), ACT and ITS gene regions had the highest level of restriction site polymorphisms and genetic diversity, GPDH and TUB had the lowest. Cluster analysis based on PCR-RFLP genetic distance data revealed sub-specific placement of the isolates which appeared to be gene-dependent. The implications of these findings are discussed relative to biodiversity monitoring and the need for multilocus, polyphasic investigations which must take into account the possibility of exaggerated estimates of genetic diversity.

  1. Experimental test of intraspecific competition mechanisms among tadpoles of Leptodactylus ocellatus (Anura: Leptodactylidae).

    Science.gov (United States)

    Laufer, Gabriel; Maneyro, Raúl

    2008-03-01

    Intraspecific competition is predicted to strongly influence species abundance and dynamics through two main mechanisms: consumption and interference of resources. Tadpoles were used in experiments in which we tried to elucidate the relative importance of each mechanism. Our goal was to apply this experimental procedure to Leptodactylus ocellatus, a common South American anuran, a species whose larvae exhibit aggregative behavior and receive parental care. Previous work suggests that tadpole schools should present lower levels of intraspecific competition. Tadpoles from a single nest were reared in the laboratory in three densities (1, 2, and 4 individuals/container) and three food levels (1, 2, and 4 ration multiples) in a randomized three-block design for a factorial analysis of variance, up to day eight. Contrary to previous work with other species, our results show both the absence of interference competition effects, and that larval growth depends only on per capita food availability. The differences between species in intraspecific competition mechanisms are probably related to strong differences in ecology and life history. Leptodactylus ocellatus tadpoles could be directing interference competition away from their kin, reducing schooling costs. Further studies (including kinship as a factor) would give more information about these larvae, allowing a better understanding of the evolutionary and ecological mechanisms behind the biological patterns observed in Leptodactylus species.

  2. Intraspecific Competition and Inbreeding Depression: Increased Competitive Effort by Inbred Males Is Costly to Outbred Opponents.

    Science.gov (United States)

    Richardson, Jon; Smiseth, Per T

    2017-05-01

    A recent theoretical model suggests that intraspecific competition is an important determinant of the severity of inbreeding depression. The reason for this is that intraspecific competition is density dependent, leading to a stronger negative effect on inbred individuals if they are weaker competitors than outbred ones. In support of this prediction, previous empirical work shows that inbred individuals are weaker competitors than outbred ones and that intraspecific competition often exacerbates inbreeding depression. Here, we report an experiment on the burying beetle Nicrophorus vespilloides, in which we recorded the outcome of competition over a small vertebrate carcass between an inbred or outbred male resident caring for a brood and a size-matched inbred or outbred male intruder. We found that inbred males were more successful as intruders in taking over a carcass from a male resident and were injured more frequently as either residents or intruders. Furthermore, inbred males gained less mass during the breeding attempt and had a shorter adult life span than outbred males. Finally, successful resident males reared a substantially smaller brood comprised of lighter larvae when the intruder was inbred than when it was outbred. Our results shows that inbred males increased their competitive effort, thus contradicting previous work suggesting that inbred males are weaker competitors. Furthermore, our results shows that inbred intruders impose a greater cost to resident males, suggesting that outbred individuals can suffer fitness costs as a result of competition with inbred ones.

  3. Effects of clonal fragmentation on intraspecific competition of a stoloniferous floating plant.

    Science.gov (United States)

    Wang, P; Xu, Y-S; Dong, B-C; Xue, W; Yu, F-H

    2014-11-01

    Disturbance is common and can fragment clones of plants. Clonal fragmentation may affect the density and growth of ramets so that it could alter intraspecific competition. To test this hypothesis, we grew one (low density), five (medium density) or nine (high density) parent ramets of the floating invasive plant Pistia stratiotes in buckets, and newly produced offspring ramets were either severed (with fragmentation) or remained connected to parent ramets (no fragmentation). Increasing density reduced biomass of the whole clone (i.e. parent ramet plus its offspring ramets), showing intense intraspecific competition. Fragmentation decreased biomass of offspring ramets, but increased biomass of parent ramets and the whole clone, suggesting significant resource translocation from parent to offspring ramets when clones were not fragmented. There was no interaction effect of density x fragmentation on biomass of the whole clone, and fragmentation did not affect competition intensity index. We conclude that clonal fragmentation does not alter intraspecific competition between clones of P. stratiotes, but increases biomass production of the whole clone. Thus, fragmentation may contribute to its interspecific competitive ability and invasiveness, and intentional fragmentation should not be recommended as a measure to stop the rapid growth of this invasive species. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.

  4. Hourly variations of water-soluble ions under different sand and dust weather processes in Lanzhou, China

    Science.gov (United States)

    Zhai, Guangyu; Chai, Guorong; Zhang, Haifeng

    2017-08-01

    In this paper we aimed to collect water-soluble anion and cationic through rapid capturing system of atmospheric fine particles in order to analyze the source of water-soluble ions of atmospheric PM2.5 in Lanzhou city, and the characteristics of hourly concentration changes in different sand and dust weather processes. The author also applied Hysplit4.8 to conduct backward trajectory analysis. The results showed that the correlation between water-soluble ions is instrumental to infer the forms of water-soluble ions in Lanzhou, such as (NH4) 2 SO4, NH4NO3, CaSO4, and NH4Cl. Lanzhou has been severely polluted by sand and dust apart from the increasing amount of Ca2+ under different dust sources and transmission paths. Na+ was also elevated in March, resulted from the dust going through the Hexi Corridor from the Taklimakan. Furthermore, in April Cl- also increased due to the dust being derived from Outer Mongolia then passing Qaidam Basin. In addition, Na+ dramatically went up in the process of precipitation.

  5. Variation Analysis of Physiological Traits in Betula platyphylla Overexpressing TaLEA-ThbZIP Gene under Salt Stress.

    Directory of Open Access Journals (Sweden)

    Xiyang Zhao

    Full Text Available The aim of this study was to determine whether transgenic birch (Betula platyphylla ectopic overexpressing a late embryogenesis abundant (LEA gene and a basic leucine zipper (bZIP gene from the salt-tolerant genus Tamarix (salt cedar show increased tolerance to salt (NaCl stress. Co-transfer of TaLEA and ThbZIP in birch under the control of two independent CaMV 35S promoters significantly enhanced salt stress. PCR and northern blot analyses indicated that the two genes were ectopically overexpressed in several dual-gene transgenic birch lines. We compared the effects of salt stress among three transgenic birch lines (L-4, L-5, and L-8 and wild type (WT. In all lines, the net photosynthesis values were higher before salt stress treatment than afterwards. After the salt stress treatment, the transgenic lines L-4 and L-8 showed higher values for photosynthetic traits, chlorophyll fluorescence, peroxidase and superoxide dismutase activities, and lower malondialdehyde and Na+ contents, compared with those in WT and L-5. These different responses to salt stress suggested that the transcriptional level of the TaLEA and ThbZIP genes differed among the transgenic lines, resulting in a variety of genetic and phenotypic effects. The results of this research can provide a theoretical basis for the genetic engineering of salt-tolerant trees.

  6. A carryover effect of migration underlies individual variation in reproductive readiness and extreme egg size dimorphism in macaroni penguins.

    Science.gov (United States)

    Crossin, Glenn T; Trathan, Phil N; Phillips, Richard A; Dawson, Alistair; Le Bouard, Fabrice; Williams, Tony D

    2010-09-01

    Where life-history stages overlap, there is the potential for physiological conflicts that might be important in mediating carryover effects. However, our knowledge of the specific physiological mechanisms underlying carryover effects remains rudimentary, and specific examples remain rare. Here we show that female macaroni penguins (Eudyptes chrysolophus) initiate vitellogenesis and yolk formation while at sea during return migrations to breeding colonies; yolk formation takes approximately 16 days, but females lay only 7-14 days after their return. Once on land, Eudyptes penguins show a unique reproductive pattern of extreme egg size dimorphism in which the smaller, first-laid A-egg is 55%-75% of the size of the larger B-egg. We show that the degree of egg size dimorphism is inversely correlated with time between arrival and laying; that is, females that begin reproductive development well in advance of their return produce more dimorphic eggs. Furthermore, late-arriving females that produce the most dimorphic eggs have lower plasma levels of the yolk precursor vitellogenin on arrival; that is, they show lower reproductive "readiness." These data support the hypothesis that extreme egg size dimorphism in Eudyptes penguins is due to a physiological constraint imposed by a migratory carryover effect and argue against small A-eggs having a specific, adaptive function.

  7. Dissecting the Variations of Ripening Progression and Flavonoid Metabolism in Grape Berries Grown under Double Cropping System

    Directory of Open Access Journals (Sweden)

    Wei-Kai Chen

    2017-11-01

    Full Text Available A double cropping system has been commercially adopted in southern China, where there is abundant sunshine and heat resources. In this viticulture system, the first growing season normally starts as a summer cropping cycle; then, the vine is pruned and forced, resulting in a second crop in winter. Due to climate differences between the summer and winter growing seasons, grape ripening progression and flavonoid metabolism vary greatly. Here, the metabolites and transcriptome of flavonoid pathways were analyzed in grapes grown under two growing seasons at different stages. Notably, the winter cropping cycle strongly increased flavonoid levels by several times in comparison to summer grapes, while the summer season took a major toll on anthocyanin and flavonol accumulation, since the winter cropping greatly triggered the expression of upstream genes in the flavonoid pathway in a coordinated expression pattern. Moreover, the ratio of VviF3′5′Hs (flavonoid 3′5′-hydroxylase to VviF3′Hs (flavonoid 3′-hydroxylase transcript levels correlated remarkably well with the ratio of 3′5′-substituted to 3′-substituted flavonoids, which was presumed to control the flux of intermediates into different flavonoid branches. On the other hand, the phenological phase also varied greatly in the two crops. Compared to summer cropping, winter growing season accelerated the duration from budburst to veraison, therefore advancing the onset of ripening, but also prolonging the duration of ripening progression due to the purposes to harvest high-quality grapes. The differential expression pattern of hormone-related genes between the two cropping cycles might explain this phenomenon.

  8. In-depth variations of the quality of organic matter in a gypsiferous forest soil under controlled burning

    Directory of Open Access Journals (Sweden)

    J.A. González-Pérez

    2013-05-01

    Full Text Available Forest fires exert changes in soil organic matter quality and quantity mainly in the organic top soil and first centimetres in the mineral horizon. These effects are highly variable