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Sample records for subantarctic plant populations

  1. Plant dispersal in the sub-Antarctic inferred from anisotropic genetic structure.

    Science.gov (United States)

    Born, Céline; Le Roux, Peter C; Spohr, Colin; McGeoch, Melodie A; Van Vuuren, Bettine Jansen

    2012-01-01

    Climatic conditions and landscape features often strongly affect species' local distribution patterns, dispersal, reproduction and survival and may therefore have considerable impacts on species' fine-scale spatial genetic structure (SGS). In this study, we demonstrate the efficacy of combining fine-scale SGS analyses with isotropic and anisotropic spatial autocorrelation techniques to infer the impact of wind patterns on plant dispersal processes. We genotyped 1304 Azorella selago (Apiaceae) specimens, a wind-pollinated and wind-dispersed plant, from four populations distributed across sub-Antarctic Marion Island. SGS was variable with Sp values ranging from 0.001 to 0.014, suggesting notable variability in dispersal distance and wind velocities between sites. Nonetheless, the data supported previous hypotheses of a strong NW-SE gradient in wind strength across the island. Anisotropic autocorrelation analyses further suggested that dispersal is strongly directional, but varying between sites depending on the local prevailing winds. Despite the high frequency of gale-force winds on Marion Island, gene dispersal distance estimates (σ) were surprisingly low (<10 m), most probably because of a low pollen dispersal efficiency. An SGS approach in association with isotropic and anisotropic analyses provides a powerful means to assess the relative influence of abiotic factors on dispersal and allow inferences that would not be possible without this combined approach. © 2011 Blackwell Publishing Ltd.

  2. Contrasting nurse plants and nurse rocks: The spatial distribution of seedlings of two sub-Antarctic species

    Science.gov (United States)

    Haussmann, N. S.; McGeoch, M. A.; Boelhouwers, J. C.

    2010-05-01

    Positive plant interactions, such as those associated with nurse plants, have been suggested to dominate over negative interactions in environments with high abiotic stress. Here we demonstrate that the sub-Antarctic cushion plant species, Azorella selago (Apiaceae), positively affects the distribution of both its own seedlings and those of the perennial grass, Agrostis magellanica (Poaceae). As a result of the light weight and small size of seeds of both species, coupled with strong winds experienced in the study area, we consider it unlikely that these patterns are the result of very localized seed dispersal from the study cushions themselves. Instead, we suggest that both cushions and rocks act as seed traps, trapping seeds dispersed by wind, runoff and/or downslope sediment transport through frost creep. In addition, increased A. selago seedling numbers around cushions, but not around rocks, suggest that cushions provide a biological nurse effect, such as improving soil nutrient status or providing mychorrizae, to seedlings of their own kind.

  3. Gene flow and hybridization between numerically imbalanced populations of two duck species on the subantarctic island of South Georgia.

    Directory of Open Access Journals (Sweden)

    Kevin G McCracken

    Full Text Available Hybridization is common between species of animals, particularly in waterfowl (Anatidae. One factor shown to promote hybridization is restricted mate choice, which can occur when 2 species occur in sympatry but one is rare. According to the Hubbs principle, or "desperation hypothesis," the rarer species is more likely to mate with heterospecifics. We report the second of 2 independent examples of hybridization between 2 species of ducks inhabiting island ecosystems in the Subantarctic and South Atlantic Ocean. Yellow-billed pintails (Anas georgica and speckled teal (Anas flavirostris are abundant in continental South America, where they are sympatric and coexist in mixed flocks. But on South Georgia, an isolated island in the Subantarctic, the pintail population of approximately 6000 pairs outnumbers a small breeding population of speckled teal 300∶1. Using 6 genetic loci (mtDNA and 5 nuclear introns and Bayesian assignment tests coupled with coalescent analyses, we identified hybrid-origin speckled teal alleles in 2 pintails on South Georgia. While it is unclear whether introgression has also occurred into the speckled teal population, our data suggest that this hybridization was not a recent event, but occurred some time ago. We also failed to identify unequivocal evidence of introgression in a much larger sample of pintails and speckled teal from Argentina using a 3-population "Isolation-with-Migration" coalescent analysis. Combined with parallel findings of hybridization between these same 2 duck species in the Falkland Islands, where population ratios are reversed and pintails are outnumbered by speckled teal 1:10, our results provide further support for the desperation hypothesis, which predicts that scarcity in one population and abundance of another will often lead to hybridization. While the South Georgia pintail population appears to be thriving, it's possible that low density of conspecific mates and inverse density dependence

  4. Dispersal in the sub-Antarctic: king penguins show remarkably little population genetic differentiation across their range.

    Science.gov (United States)

    Clucas, Gemma V; Younger, Jane L; Kao, Damian; Rogers, Alex D; Handley, Jonathan; Miller, Gary D; Jouventin, Pierre; Nolan, Paul; Gharbi, Karim; Miller, Karen J; Hart, Tom

    2016-10-13

    Seabirds are important components of marine ecosystems, both as predators and as indicators of ecological change, being conspicuous and sensitive to changes in prey abundance. To determine whether fluctuations in population sizes are localised or indicative of large-scale ecosystem change, we must first understand population structure and dispersal. King penguins are long-lived seabirds that occupy a niche across the sub-Antarctic zone close to the Polar Front. Colonies have very different histories of exploitation, population recovery, and expansion. We investigated the genetic population structure and patterns of colonisation of king penguins across their current range using a dataset of 5154 unlinked, high-coverage single nucleotide polymorphisms generated via restriction site associated DNA sequencing (RADSeq). Despite breeding at a small number of discrete, geographically separate sites, we find only very slight genetic differentiation among colonies separated by thousands of kilometers of open-ocean, suggesting migration among islands and archipelagos may be common. Our results show that the South Georgia population is slightly differentiated from all other colonies and suggest that the recently founded Falkland Island colony is likely to have been established by migrants from the distant Crozet Islands rather than nearby colonies on South Georgia, possibly as a result of density-dependent processes. The observed subtle differentiation among king penguin colonies must be considered in future conservation planning and monitoring of the species, and demographic models that attempt to forecast extinction risk in response to large-scale climate change must take into account migration. It is possible that migration could buffer king penguins against some of the impacts of climate change where colonies appear panmictic, although it is unlikely to protect them completely given the widespread physical changes projected for their Southern Ocean foraging grounds

  5. New records of alien vascular plants from Marion and Prince Edward Islands, sub-Antarctic

    NARCIS (Netherlands)

    Gremmen, N.J.M.; Smith, V.

    1999-01-01

    A survey was made of the distribution of introduced vascular plants on Marion and Prince Edward Islands. The results of this survey were compared to results of previous surveys (1965/66, 1975, 1981, 1989). Four new introductions to Marion Island have taken place, three of which involved species that

  6. A tale of two islands: contrasting fortunes for Subantarctic skuas at ...

    African Journals Online (AJOL)

    Subantarctic skuas Catharacta antarctica are key predators of burrowing petrels at sub-Antarctic islands, and can be used to monitor the health of burrowing petrel populations. A survey of skuas at the Prince Edward Islands was conducted during December 2008, repeating a previous survey in December 2001.

  7. Skull morphometrics of male Subantarctic fur seals ( Arctocephalus ...

    African Journals Online (AJOL)

    Skull morphometrics of two populations of Subantarctic fur seal (Arctocephalus tropicalis) were compared in order to identify possible geographic variation as an indicator of gene flow between the populations, as well as a potential tool to identify the source of vagrant seals. Nineteen metric variables were recorded from ...

  8. Kelp gulls Larus dominicanus nest in Antarctica, at subantarctic ...

    African Journals Online (AJOL)

    spamer

    Kelp gulls Larus dominicanus nest in Antarctica, at subantarctic islands, in South America, New Zealand,. Australia and in southern Africa (Burger and Gochfield. 1996). All populations, except that in southern. Africa, are of the nominate race L. d. dominicanus. That in southern Africa comprises an endemic sub- species, L. d.

  9. Endoparasites of the subantarctic fur seal Arctocephalus tropicalis ...

    African Journals Online (AJOL)

    1989-03-03

    Mar 3, 1989 ... A. tropicalis is a new host record for the tetraphyllidean cestode ... of the subantarctic fur seal population of Gough Island. Necropsies were .... Seals of the world. British Mus. (Nat. Hist.) London. PAULIAN, P. 1964. Contribution a I'etude de I'otarie de l'ile Amsterdam. Mammalia 28: 1-146. SHAUGHNESSY ...

  10. Evolution and biogeography of Pleurophyllum (Astereae, Asteraceae), a small genus of megaherbs endemic to the subantarctic islands

    National Research Council Canada - National Science Library

    Steven J. Wagstaff; Ilse Breitwieser; Motomi Ito

    2011-01-01

    ... played a pivotal role in shaping plant distributions in the southern hemisphere. Although the Antarctic flora was largely erased by glaciation during the Pleistocene, at least some Antarctic plant species found refuge on the subantarctic islands. Methods...

  11. Kelp genes reveal effects of subantarctic sea ice during the Last Glacial Maximum.

    Science.gov (United States)

    Fraser, Ceridwen I; Nikula, Raisa; Spencer, Hamish G; Waters, Jonathan M

    2009-03-03

    The end of the Last Glacial Maximum (LGM) dramatically reshaped temperate ecosystems, with many species moving poleward as temperatures rose and ice receded. Whereas reinvading terrestrial taxa tracked melting glaciers, marine biota recolonized ocean habitats freed by retreating sea ice. The extent of sea ice in the Southern Hemisphere during the LGM has, however, yet to be fully resolved, with most palaeogeographic studies suggesting only minimal or patchy ice cover in subantarctic waters. Here, through population genetic analyses of the widespread Southern Bull Kelp (Durvillaea antarctica), we present evidence for persistent ice scour affecting subantarctic islands during the LGM. Using mitochondrial and chloroplast genetic markers (COI; rbcL) to genetically characterize some 300 kelp samples from 45 Southern Ocean localities, we reveal a remarkable pattern of recent recolonization in the subantarctic. Specifically, in contrast to the marked phylogeographic structure observed across coastal New Zealand and Chile (10- to 100-km scales), subantarctic samples show striking genetic homogeneity over vast distances (10,000-km scales), with a single widespread haplotype observed for each marker. From these results, we suggest that sea ice expanded further and ice scour during the LGM impacted shallow-water subantarctic marine ecosystems more extensively than previously suggested.

  12. Impacts of Insect Herbivores on Plant Populations.

    Science.gov (United States)

    Myers, Judith H; Sarfraz, Rana M

    2017-01-31

    Apparent feeding damage by insects on plants is often slight. Thus, the influences of insect herbivores on plant populations are likely minor. The role of insects on host-plant populations can be elucidated via several methods: stage-structured life tables of plant populations manipulated by herbivore exclusion and seed-addition experiments, tests of the enemy release hypothesis, studies of the effects of accidentally and intentionally introduced insect herbivores, and observations of the impacts of insect species that show outbreak population dynamics. These approaches demonstrate that some, but not all, insect herbivores influence plant population densities. At times, insect-feeding damage kills plants, but more often, it reduces plant size, growth, and seed production. Plant populations for which seed germination is site limited will not respond at the population level to reduced seed production. Insect herbivores can influence rare plant species and need to be considered in conservation programs. Alterations due to climate change in the distributions of insect herbivores indicate the possibility of new influences on host plants. Long-term studies are required to show if density-related insect behavior stabilizes plant populations or if environmental variation drives most temporal fluctuations in plant densities. Finally, insects can influence plant populations and communities through changing the diversity of nonhost species, modifying nutrient fluxes, and rejuvenating over mature forests.

  13. First records of aphid-pathogenic Entomophthorales in the sub-Antarctic archipelagos of Crozet and Kerguelen

    Directory of Open Access Journals (Sweden)

    Bernard Papierok

    2016-07-01

    Full Text Available Since the 20th century, the sub-Antarctic islands have suffered an increasing number of biological invasions. Despite the large number of publications on this topic, there is a lack of knowledge on parasitism rates of invasive species and on the role of parasites and pathogens to regulate their populations. Six aphid species have been introduced in the archipelagos of Crozet (Île de la Possession, 46° 25’ S–51° 51’ E and Kerguelen (49° 21’ S–70° 13’ E. Five of these species were found infected by entomopathogenic fungi of the order Entomophthorales. All these fungal species are cosmopolitan. Conidiobolus obscurus and Entomophthora planchoniana were the most frequently observed on Île de la Possession and in Archipel des Kerguelen, respectively. This is the first report of pathogenic fungi of aphids on the sub-Antarctic islands. We discuss these results in the light of our current knowledge of these insect pathogens. Their introduction by aphids surviving on plants during transportation is the most likely hypothesis to explain their presence on these remote islands.

  14. Between-population outbreeding affects plant defence.

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    Roosa Leimu

    Full Text Available Between-population crosses may replenish genetic variation of populations, but may also result in outbreeding depression. Apart from direct effects on plant fitness, these outbreeding effects can also alter plant-herbivore interactions by influencing plant tolerance and resistance to herbivory. We investigated effects of experimental within- and between-population outbreeding on herbivore resistance, tolerance and plant fitness using plants from 13 to 19 Lychnis flos-cuculi populations. We found no evidence for outbreeding depression in resistance reflected by the amount of leaf area consumed. However, herbivore performance was greater when fed on plants from between-population compared to within-population crosses. This can reflect outbreeding depression in resistance and/or outbreeding effects on plant quality for the herbivores. The effects of type of cross on the relationship between herbivore damage and plant fitness varied among populations. This demonstrates how between-population outbreeding effects on tolerance range from outbreeding depression to outbreeding benefits among plant populations. Finally, herbivore damage strengthened the observed outbreeding effects on plant fitness in several populations. These results raise novel considerations on the impact of outbreeding on the joint evolution of resistance and tolerance, and on the evolution of multiple defence strategies.

  15. Leaf and floral heating in cold climates: do sub-Antarctic megaherbs resemble tropical alpine giants?

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    Lorna Little

    2016-08-01

    Full Text Available High latitude and altitude floras are characterized by low-statured, small, wind-pollinated plants, which mainly reproduce by self-pollination or asexual reproduction. However, at odds with this are some sub-Antarctic islands that have plant species with giant growth forms and large, brightly coloured flowers which require insect visitation for pollination. The size, colour and shape of the inflorescences and leaves of these megaherbs suggest thermal benefits similar to giant tropical alpine plants of equatorial Africa, South America and Hawaii. We evaluated whether heating occurs in sub-Antarctic megaherbs, and to what extent it is related to environmental variables. We measured leaf and inflorescence temperature in six sub-Antarctic megaherb species on Campbell Island, latitude 52.3°S, New Zealand Biological Region. Using thermal imaging techniques, in combination with measurement of solar radiation, ambient air temperature, wind speed, wind chill and humidity, we assessed environmental influences on leaf and floral heating. We found that leaf and inflorescence temperatures of all megaherbs were higher than simultaneously measured ambient temperatures. Greatest heating was seen in Pleurophyllum speciosum, with observed leaves 9°C higher, and inflorescences nearly 11°C higher, than ambient temperature. Heating was highly correlated with brief, unpredictable periods of solar radiation, and occurred most rapidly in species with hairy, corrugated leaves and darkly pigmented, densely packed inflorescences. This is the first evidence that floral and leaf heating occurs in sub-Antarctic megaherbs, and suggests that leaf hairiness, flower colour and shape could provide thermal benefits like those seen in tropical alpine megaherbs.

  16. Aeolian processes and landforms in the sub-Antarctic: preliminary observations from Marion Island

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    David W. Hedding

    2015-11-01

    Full Text Available Sub-Antarctic Marion Island has a hyperoceanic climate, with cold and wet conditions and consistently strong wind velocities throughout the year. Recent observations recognized the increasing role of aeolian processes as a geomorphic agent, and this paper presents the first data for transport by aeolian processes on a sub-Antarctic island. Data were collected through an intensive and high-resolution measurement campaign at three study sites using Big Spring Number Eight sediment traps and surface sediment samplers in conjunction with an array of climatic and soil logger sensors. Observed aeolian landforms are megaripples, and the data suggest that aeolian processes are also modifying solifluction landforms. The sediment traps and sediment samplers collected wind-blown scoria at all three study sites, and the annual (horizontal aeolian sediment flux extrapolated from this preliminary data is estimated at 0.36–3.85 kg cm−2 y−1. Importantly, plant material of various species was trapped during the study that suggests the efficiency of wind for the dispersal of plants in this sub-Antarctic environment may be underestimated. This paper advocates long-term monitoring of aeolian processes and that the link between aeolian processes and synoptic climate must be established. Furthermore, wind as a means to disperse genetic material on Marion Island should be investigated.

  17. [Recent progress in plant molecular population genetics].

    Science.gov (United States)

    Wang, Yun-Sheng; Huang, Hong-Wen; Wang, Ying

    2007-10-01

    Molecular population genetics is not only one of the most important subjects of evolutionary biology, but also the basics subject of breeding, association mapping, and linkage analysis. Molecular population genetics has been developed from the classical population genetics aiming at studying population genetic structure and the factors that affect the population genetic structure by investigating the variation of DNA sequences. Therefore, population evolving history can be deduced accurately and quantitatively for evaluating the former conclusions about long-term evolution and the stability of genetic systems. Thus, molecular population genetics can avoid the shortcomings of classical population genetics, i.e. limiting to deduce the short evolving history of a population. Moreover, understanding of molecular variation patterns leads to further evaluation of the evolution theory, which is based on "Natural Selection" and introduced by Darwin. Molecular population genetics has made great progress and revealed many important scientific issues, such as the pattern of DNA polymorphism, the level of linkage disequilibrium, demographical history, and the genetic forces affecting gene evolvement. Furthermore, new research areas have been developed from molecular population genetics and become the hot fields, such as molecular phylogeography. In this review, we summarized studies and progresses of plant molecular population genetics.

  18. Photosynthesis in a sub-Antarctic shore-zone lichen

    NARCIS (Netherlands)

    Smith, V.; Gremmen, N.J.M.

    2001-01-01

    Photosynthetic responses to moisture, light, temperature, salinity and inorganic nitrogen fertilization are reported for a shore-zone lichen Turgidiusculum complicatulum (formerly Mastodia tesselata), a possible recent introduction to sub-Antarctic Marion Island. Optimum moisture contents for net

  19. Host plant adaptation in Drosophila mettleri populations.

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    Sergio Castrezana

    Full Text Available The process of local adaptation creates diversity among allopatric populations, and may eventually lead to speciation. Plant-feeding insect populations that specialize on different host species provide an excellent opportunity to evaluate the causes of ecological specialization and the subsequent consequences for diversity. In this study, we used geographically separated Drosophila mettleri populations that specialize on different host cacti to examine oviposition preference for and larval performance on an array of natural and non-natural hosts (eight total. We found evidence of local adaptation in performance on saguaro cactus (Carnegiea gigantea for populations that are typically associated with this host, and to chemically divergent prickly pear species (Opuntia spp. in a genetically isolated population on Santa Catalina Island. Moreover, each population exhibited reduced performance on the alternative host. This finding is consistent with trade-offs associated with adaptation to these chemically divergent hosts, although we also discuss alternative explanations for this pattern. For oviposition preference, Santa Catalina Island flies were more likely to oviposit on some prickly pear species, but all populations readily laid eggs on saguaro. Experiments with non-natural hosts suggest that factors such as ecological opportunity may play a more important role than host plant chemistry in explaining the lack of natural associations with some hosts.

  20. Population genetics of fungal diseases of plants

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    Giraud T.

    2008-09-01

    Full Text Available Although parasitism is one of the most common lifestyles among eukaryotes, population genetics on parasites lag far behind those on free-living organisms. Yet, the advent of molecular markers offers great tools for studying important processes, such as dispersal, mating systems, adaptation to host and speciation. Here we highlight some studies that used molecular markers to address questions about the population genetics of fungal (including oomycetes plant pathogens. We conclude that population genetics approaches have provided tremendous insights into the biology of a few fungal parasites and warrant more wide use in phytopathology. However, theoretical advances are badly needed to best apply the existing methods. Fungi are of prime interest not only because they are major parasites of plants and animals, but they also constitute tractable and highly useful models for understanding evolutionary processes. We hope that the emerging field of fungal evolution will attract more evolutionary biologists in the near future.

  1. Ecological and population genetics of locally rare plants: A review

    Science.gov (United States)

    Simon A. Lei

    2001-01-01

    Plant species with limited dispersal ability, narrow geographical and physiological tolerance ranges, as well as with specific habitat and ecological requirements are likely to be rare. Small and isolated populations and species contain low levels of within-population genetic variation in many plant species. The gene pool of plants is a product of phenotype-environment...

  2. The Bryozoa of subantarctic Marion and Prince Edward Islands ...

    African Journals Online (AJOL)

    The Bryozoa of subantarctic Marion and Prince Edward Islands were sampled over the period 1982–1989 by dredging, SCUBA-diving and intertidal surveys. This paper comprises illustrated keys to all 82 species of Bryozoa collected during these and previous surveys, including 15 new species, 17 new records and 8 ...

  3. The macaroni penguin Eudyptes chrysolophus has a subantarctic ...

    African Journals Online (AJOL)

    spamer

    The macaroni penguin Eudyptes chrysolophus has a subantarctic distribution in the south-eastern Pacific, south Atlantic and south-western Indian oceans, breeding at several localities between southern Chile and Heard and McDonald Islands, including South. Africa's Prince Edward Islands (Marchant and Higgins. 1990).

  4. Submesoscale processes promote seasonal restratification in the Subantarctic Ocean

    CSIR Research Space (South Africa)

    Du Plessis, M

    2017-04-01

    Full Text Available compare 5 months of glider data in the Subantarctic Zone to simulations of a 1-D mixing model to show that the magnitude of restratification of the ML cannot be explained by heat, freshwater, and momentum fluxes alone. During early spring, we estimate...

  5. Adjustment of pigment composition in Desmarestia (Desmarestiaceae species along a sub-Antarctic to Antarctic latitudinal gradient

    Directory of Open Access Journals (Sweden)

    Andrés Mansilla

    2016-08-01

    Full Text Available Photosynthesis at high latitudes demands efficient strategies of light utilization to maintain algal fitness and performance. The fitness, and physiological adaptation, of a plant or algae species depends in part on the abundance and efficiency of the pigments it can produce to utilize the light resource from its environment. We quantified pigment composition and concentration in six species of the brown macroalgal genus Desmarestia, collected from sub-Antarctic sites (Strait of Magellan, Beagle Channel–Cape Horn Province and sites on the Antarctic Peninsula and adjacent islands. Sub-Antarctic Desmarestia species exhibited lower concentrations of chlorophyll a, chlorophyll c and fucoxanthin than endemic Antarctic species. Antarctic samples of D. menziesii and D. antarctica collected along a decreasing latitudinal gradient showed spatial and interspecific differences in light-harvesting pigment composition. Our results suggest distinct physiological adjustments in Desmarestia species in response to heterogeneous abiotic environmental conditions. The marine sub-Antarctic and Antarctic ecosystems are characterized by harsh environments (e.g., extreme irradiance, photoperiod, temperature, salinity to which the physiology of macroalgal species must adapt.

  6. Muscle growth in Antarctic and Subantarctic notothenioid fishes

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    Daniel Alfredo Fernández

    2005-12-01

    Full Text Available The suborder Notothenioidei comprises 122 species divided into 8 families, with members of 6 of the families living outside Antarctic waters. The Antarctic species underwent an extensive radiation from a small demersal ancestor to occupy different ecological niches and levels in the water column. The axial muscle of Antarctic and some Subantarctic notothenioids is unusual in containing very large diameter muscle fibres and a low muscle fibre number. Maximum fibre diameters are greater than 500 mm in many species. There is no indication of systematic differences in fibre number, fibre type composition, ATPase activity, time of cessation of fibre recruitment (hyperplasia and swimming performance between Antarctic and Subantarctic species. Instead, fibre number is significantly decreased in species belonging to the most derived families relative to the more basal families (a trend that also correlates with an increase in the diameter of the fibres. The length of the cell cycle of the muscle fibres shows cold compensation in the Antarctic species H. antarcticus relative to the closely related Subantarctic one (H. bispinis. Feeding after a starvation period results in a strong stimulation of the proliferation of muscle fiber progenitors in H. bispinis. Similar studies have not yet been performed on any Antarctic species.

  7. Submesoscale processes promote seasonal restratification in the Subantarctic Ocean

    Science.gov (United States)

    du Plessis, M.; Swart, S.; Ansorge, I. J.; Mahadevan, A.

    2017-04-01

    Traditionally, the mechanism driving the seasonal restratification of the Southern Ocean mixed layer (ML) is thought to be the onset of springtime warming. Recent developments in numerical modeling and North Atlantic observations have shown that submesoscale ML eddies (MLE) can drive a restratifying flux to shoal the deep winter ML prior to solar heating at high latitudes. The impact of submesoscale processes on the intraseasonal variability of the Subantarctic ML is still relatively unknown. We compare 5 months of glider data in the Subantarctic Zone to simulations of a 1-D mixing model to show that the magnitude of restratification of the ML cannot be explained by heat, freshwater, and momentum fluxes alone. During early spring, we estimate that periodic increases in the vertical buoyancy flux by MLEs caused small increases in stratification, despite predominantly down-front winds that promote the destruction of stratification. The timing of seasonal restratification was consistent between 1-D model estimates and the observations. However, during up-front winds, the strength of springtime stratification increased over twofold compared to the 1-D model, with a rapid shoaling of the MLD from >200 m to Ekman buoyancy flux during down-front winds, resulting in the destruction of ML stratification and deepening of the MLD. These results propose the importance of submesoscale buoyancy fluxes enhancing seasonal restratification and mixing of the Subantarctic ML.

  8. A record of the sub-Antarctic fur seal Arctocephalus tropicalis in ...

    African Journals Online (AJOL)

    A record of the sub-Antarctic fur seal Arctocephalus tropicalis in Angola. T Carr, Nicole Carr, J.H.M. David. Abstract. Two individuals of the sub-Antarctic fur seal, Arctocephalus tropicalis, one of which was photographed, were seen on the beach 1 km south of the mouth of the Kwanza River, Angola, on 2 October 1983.

  9. Population Exposure Estimates in Proximity to Nuclear Power Plants, Locations

    Data.gov (United States)

    National Aeronautics and Space Administration — The Population Exposure Estimates in Proximity to Nuclear Power Plants, Locations data set combines information from a global data set developed by Declan Butler of...

  10. Yield response of Bambara groundnut to plant population and ...

    African Journals Online (AJOL)

    2001-04-22

    Apr 22, 2001 ... The experiment was designed with three seedbed types split-plot; flat, ridge and furrow in the main plots and bambara groundnut population densities (9, 13, 22 and 66 plants m-2) in the sub plots. At 63 days after sowing (DAS), leaf area index (LAI) was highest for 66 plants m-2 and/or when planted on the ...

  11. The effect of plant population and nitrogen fertilizer on

    Directory of Open Access Journals (Sweden)

    mohamad reza asgaripor

    2009-06-01

    Full Text Available Interest has increased towards hemp (Cannabis sativa L. fibre production due to renewed demand for natural fibre in the world. A Study was conducted in 2005 at Shirvan in Northern Khorasan province, Iran, to determine the effects of three plant populations (30, 90 and 150 plant per m2 and three rates of nitrogen application (50, 150 and 250 kg N per ha on final stand, stalk height, basal stalk diameter, total stalk yield as well as fibre content from stalk and fibre yield in male and female plants. A split plot experimental with three replications was used. The result indicated that due to enhanced competition for light at higher population on density and N2 level plant mortality was higher than other treatment Morphological characteristics were highly correlated with plant sexual, plant population and nitrogen fertilizer. Highest stem, leaf and inflorescence yield were obtained at 250 plant m-2 when 150 kg N ha-1 was used. Lowest plant density did not show self-thinning but reduced above ground dry matter. Shoot dry matter increased with increasing plant density and nitrogen supply. Apparently, fibre content was greater at medium density and lowest nitrogen fertilizer, however, fibre yield was greatest at highest plant population and nitrogen fertilizer. In terms of fibre yield, approximate 31.7% of the fibre was located in the bottom parts, 22.4% in the middle and only 9.9% in the top part of the stem. The results suggest that hemp can yield large quantities of useful fibre at Shirvan when planted in proper plant densities and suitable nitrogen fertilizer.

  12. ECOLOGO-GENETIC MONITORING OF CULTIVATED AND WILD PLANT POPULATION

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    A. E. SHPAKOV

    2010-01-01

    Full Text Available Quantitative estimation of genotypic structure dynamic of three plant species: Nicotiana tabacum L., Anacamptus pyramidalis (L. Rich., Teucrium chamaedrys L. in different ecological conditions has been conducted. The effectiveness of systemic analyses of the trait complex with the aim of ecologo-genetic monitoring of the plant population has been established.

  13. Advancing environmentally explicit structured population models of plants

    DEFF Research Database (Denmark)

    Ehrlén, Johan; Morris, William; von Euler, Tove

    2016-01-01

    as species distributions and abundances. We searched the literature for studies that have linked abiotic and biotic environmental factors to vital rates and, using structured demographic models, population growth rates of plants. We found 136 studies that had examined the environmental drivers of plant...

  14. Surface destabilisation by the invasive burrowing engineer Mus musculus on a sub-Antarctic island

    Science.gov (United States)

    Eriksson, Bert; Eldridge, David J.

    2014-10-01

    Invasive species are known to have substantial trophic effects on ecosystems and ecosystem processes. The invasion of the house mouse (Mus musculus) onto sub-Antarctic islands has had a devastating effect on plants, invertebrates, and birds with substantial changes in ecosystem functions. Less well understood, however, are the nontrophic, geomorphic effects of mice resulting from their burrowing activities. We examined the extent of burrow construction by M. musculus across an area of about 20 ha on Marion Island and the effects of burrows on water flow and sediment movement. We recorded a density of 0.59 ± 0.48 (mean ± SD) burrows m- 2, with more burrows at lower altitudes and shallower slopes, and twice the density in the solifluction risers (0.86 ± 0.54 m- 2) than the intervening terraces or treads (0.40 ± 0.51 m- 2). Most burrows were dug horizontally into the slope and tended to extend about 20 cm deep before turning. A very conservative estimate of sediment removed from burrows from this depth is 2.4 t ha- 1. However, taking into account more detailed data on burrow morphology based on excavations, actual amounts may be closer to 8.4 t ha- 1. Average soil displacement rate for a single burrow, measured over 5 days, was 0.18 kg burrow- 1 day- 1. Burrows acted as conduits for water and warmer air. Stones at burrow entrances were moved eight times farther by water (10.4 cm) than those not associated with burrows. Similarly, temperatures adjacent to burrow entrances were 4.1 °C higher than sites 10 cm away. Together our data indicate that mice are having substantial deleterious and geomorphic effects on sub-Antarctic ecosystems through their burrowing. With lower rates of mouse mortality resulting from warmer climates predicted under global climate models, we can expect an increase in damage resulting from mouse activity.

  15. Human population, grasshopper and plant species richness in European countries

    Science.gov (United States)

    Steck, Claude E.; Pautasso, Marco

    2008-11-01

    Surprisingly, several studies over large scales have reported a positive spatial correlation of people and biodiversity. This pattern has important implications for conservation and has been documented for well studied taxa such as plants, amphibians, reptiles, birds and mammals. However, it is unknown whether the pattern applies also to invertebrates other than butterflies and more work is needed to establish whether the species-people relationship is explained by both variables correlating with other environmental factors. We studied whether grasshopper species richness (Orthoptera, suborder Caelifera) is related to human population size in European countries. As expected, the number of Caelifera species increases significantly with increasing human population size. But this is not the case when controlling for country area, latitude and number of plant species. Variations in Caelifera species richness are primarily associated with variations in plant species richness. Caelifera species richness also increases with decreasing mean annual precipitation, Gross Domestic Product per capita (used as an indicator for economic development) and net fertility rate of the human population. Our analysis confirms the hypothesis that the broad-scale human population-biodiversity correlations can be explained by concurrent variations in factors other than human population size such as plant species richness, environmental productivity, or habitat heterogeneity. Nonetheless, more populated countries in Europe still have more Caelifera species than less populated countries and this poses a particular challenge for conservation.

  16. Effects of an invasive plant on population dynamics in toads.

    Science.gov (United States)

    Greenberg, Daniel A; Green, David M

    2013-10-01

    When populations decline in response to unfavorable environmental change, the dynamics of their population growth shift. In populations that normally exhibit high levels of variation in recruitment and abundance, as do many amphibians, declines may be difficult to identify from natural fluctuations in abundance. However, the onset of declines may be evident from changes in population growth rate in sufficiently long time series of population data. With data from 23 years of study of a population of Fowler's toad (Anaxyrus [ = Bufo] fowleri) at Long Point, Ontario (1989-2011), we sought to identify such a shift in dynamics. We tested for trends in abundance to detect a change point in population dynamics and then tested among competing population models to identify associated intrinsic and extrinsic factors. The most informative models of population growth included terms for toad abundance and the extent of an invasive marsh plant, the common reed (Phragmites australis), throughout the toads' marshland breeding areas. Our results showed density-dependent growth in the toad population from 1989 through 2002. After 2002, however, we found progressive population decline in the toads associated with the spread of common reeds and consequent loss of toad breeding habitat. This resulted in reduced recruitment and population growth despite the lack of significant loss of adult habitat. Our results underscore the value of using long-term time series to identify shifts in population dynamics coincident with the advent of population decline. © 2013 Society for Conservation Biology.

  17. Ambit determination method in estimating rice plant population density

    Directory of Open Access Journals (Sweden)

    Abu Bakar, B.,

    2017-11-01

    Full Text Available Rice plant population density is a key indicator in determining the crop setting and fertilizer application rate. It is therefore essential that the population density is monitored to ensure that a correct crop management decision is taken. The conventional method of determining plant population is by manually counting the total number of rice plant tillers in a 25 cm x 25 cm square frame. Sampling is done by randomly choosing several different locations within a plot to perform tiller counting. This sampling method is time consuming, labour intensive and costly. An alternative fast estimating method was developed to overcome this issue. The method relies on measuring the outer circumference or ambit of the contained rice plants in a 25 cm x 25 cm square frame to determine the number of tillers within that square frame. Data samples of rice variety MR219 were collected from rice plots in the Muda granary area, Sungai Limau Dalam, Kedah. The data were taken at 50 days and 70 days after seeding (DAS. A total of 100 data samples were collected for each sampling day. A good correlation was obtained for the variety of 50 DAS and 70 DAS. The model was then verified by taking 100 samples with the latching strap for 50 DAS and 70 DAS. As a result, this technique can be used as a fast, economical and practical alternative to manual tiller counting. The technique can potentially be used in the development of an electronic sensing system to estimate paddy plant population density.

  18. Effect of plant populations on the productivity of plantain and ...

    African Journals Online (AJOL)

    The results in Experiment I showed that growth, harvestable yields and productivity of plantain and cassava intercrops were enhanced by the plant populations of each intercrop Thus, suggesting that complementary rather than competitive yielding prevailed in the mixtures. The spatial and temporal factors in complementary ...

  19. Nitrogen rate and plant population effects on yield and yield ...

    African Journals Online (AJOL)

    This research was carried out to determine the effect of plant population and nitrogen rates on yield and yield components in soybean under Bursa, Mustafakemalpaa ecological conditions. Trials were conducted during 2000 and 2001 at the experimental fields of the Mustafakemalpaa Vocational High School, University of ...

  20. Nitrogen rate and plant population effects on yield and yield ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-12-17

    Dec 17, 2008 ... This research was carried out to determine the effect of plant population and nitrogen rates on yield and yield components in soybean under Bursa, Mustafakemalpaşa ecological conditions. Trials were conducted during 2000 and 2001 at the experimental fields of the Mustafakemalpaşa Vocational High.

  1. Plant population and row spacing on biomass sorghum yield performance

    Directory of Open Access Journals (Sweden)

    Andre May

    2015-01-01

    Full Text Available ABSTRACT: Biomass sorghum is one of the most promising crops for the production of electricity through the burning in high-pressure boilers, due to its high calorific value, high yield, seed propagation, short cycle, and to the possibility of full mechanization of its agricultural processes. However, there is still a lack of information about its cultural practices. To this end, this research aimed to evaluate the influence of row spacing and plant population on the yield performance of biomass sorghum. The experimental design was a randomized block, in factorial scheme of 4 x 4, with four row spacings (0.5, 0.7, 0.9 and 1.1m, and four plant populations (80,000; 100,000; 120,000 and 140,000 plants ha-1, with three replications. The characteristics evaluated were: plant height, stem diameter, number of leaves, number of tillers per plant, fresh weight per plant and biomass. Total biomass yield was greatly influenced by the row spacing, showing a sharp reduction when row spacing increased, in the two years of study, changing from 180.27 to 114.42t ha-1 in the 2012/13 crop year, and from 146.50 to 102.56t ha-1 in the 2013/14 crop year, for 0.5 and 1.1m between rows, respectively. The lowest yields observed in the second year of the study were due to unfavorable weather conditions in the period.

  2. Effects of host-plant population size and plant sex on a specialist leaf-miner

    Science.gov (United States)

    Bañuelos, María-José; Kollmann, Johannes

    2011-03-01

    Animal population density has been related to resource patch size through various hypotheses such as those derived from island biogeography and resource concentration theory. This theoretical framework can be also applied to plant-herbivore interactions, and it can be modified by the sex of the host-plant, and density-dependent relationships. Leaf-miners are specialised herbivores that leave distinct traces on infested leaves in the form of egg scars, mines, signs of predation and emergence holes. This allows the life cycle of the insect to be reconstructed and the success at the different stages to be estimated. The main stages of the leaf-miner Phytomyza ilicis were recorded in eleven populations of the evergreen host Ilex aquifolium in Denmark. Survival rates were calculated and related to population size, sex of the host plant, and egg and mine densities. Host population size was negatively related to leaf-miner prevalence, with larger egg and mine densities in small populations. Percentage of eggs hatching and developing into mines, and percentage of adult flies emerging from mines also differed among host populations, but were not related to population size or host cover. Feeding punctures left by adults were marginally more frequent on male plants, whereas egg scars and mines were more common on females. Overall survival rate from egg stage to adult emergence was higher on female plants. Egg density was negatively correlated with hatching, while mine density was positively correlated with emergence of the larvae. The inverse effects of host population size were not in line with predictions based on island biogeography and resource concentration theory. We discuss how a thorough knowledge of the immigration behaviour of this fly might help to understand the patterns found.

  3. Individualism in plant populations: using stochastic differential equations to model individual neighbourhood-dependent plant growth.

    Science.gov (United States)

    Lv, Qiming; Schneider, Manuel K; Pitchford, Jonathan W

    2008-08-01

    We study individual plant growth and size hierarchy formation in an experimental population of Arabidopsis thaliana, within an integrated analysis that explicitly accounts for size-dependent growth, size- and space-dependent competition, and environmental stochasticity. It is shown that a Gompertz-type stochastic differential equation (SDE) model, involving asymmetric competition kernels and a stochastic term which decreases with the logarithm of plant weight, efficiently describes individual plant growth, competition, and variability in the studied population. The model is evaluated within a Bayesian framework and compared to its deterministic counterpart, and to several simplified stochastic models, using distributional validation. We show that stochasticity is an important determinant of size hierarchy and that SDE models outperform the deterministic model if and only if structural components of competition (asymmetry; size- and space-dependence) are accounted for. Implications of these results are discussed in the context of plant ecology and in more general modelling situations.

  4. Planting geometry and plant population affect dryland maize grain yield and harvest index

    Science.gov (United States)

    Water for dryland grain production in the Texas panhandle is limited. Agronomic practices such as reduction in plant population or change in sowing time may help increase maize (Zea mays L.) yield potential. Tiller formation under dryland conditions leads to more vegetative growth and reduced yield....

  5. Source population characteristics affect heterosis following genetic rescue of fragmented plant populations

    Science.gov (United States)

    Pickup, M.; Field, D. L.; Rowell, D. M.; Young, A. G.

    2013-01-01

    Understanding the relative importance of heterosis and outbreeding depression over multiple generations is a key question in evolutionary biology and is essential for identifying appropriate genetic sources for population and ecosystem restoration. Here we use 2455 experimental crosses between 12 population pairs of the rare perennial plant Rutidosis leptorrhynchoides (Asteraceae) to investigate the multi-generational (F1, F2, F3) fitness outcomes of inter-population hybridization. We detected no evidence of outbreeding depression, with inter-population hybrids and backcrosses showing either similar fitness or significant heterosis for fitness components across the three generations. Variation in heterosis among population pairs was best explained by characteristics of the foreign source or home population, and was greatest when the source population was large, with high genetic diversity and low inbreeding, and the home population was small and inbred. Our results indicate that the primary consideration for maximizing progeny fitness following population augmentation or restoration is the use of seed from large, genetically diverse populations. PMID:23173202

  6. Effects in Plant Populations Resulting from Chronic Radiation Exposure

    Energy Technology Data Exchange (ETDEWEB)

    Geras' kin, Stanislav A.; Volkova, Polina Yu.; Vasiliyev, Denis V.; Dikareva, Nina S.; Oudalova, Alla A. [Russian Institute of Agricultural Radiology and Agroecology, 249032, Obninsk (Russian Federation)

    2014-07-01

    Human industrial activities have left behind a legacy of ecosystems strongly impacted by a wide range of contaminants, including radionuclides. Phyto-toxic effects of acute impact are well known, but the consequences of long-term chronic exposure to low pollutant concentrations is neither well understood nor adequately included in risk assessments. To understand effects of real-world contaminant exposure properly we must pay attention to what is actually going on in the field. However, for many wildlife groups and endpoints, there are no, or very few, studies that link accumulation, chronic exposure and biological effects in natural settings. To fill the gaps, results of field studies carried out on different plant species (winter rye and wheat, spring barley, oats, Scots pine, wild vetch, crested hair-grass) in various radioecological situations (nuclear weapon testing, the Chernobyl accident, uranium and radium processing) to investigate effects of long-term chronic exposure to radionuclides are discussed. Because each impacted site developed in its own way due to a unique history of events, the experience from one case study is rarely directly applicable to another situation. In spite of high heterogeneity in response, we have detected several general patterns. Plant populations growing in areas with relatively low levels of pollution are characterized by the increased level of both cytogenetic alterations and genetic diversity. Accumulation of cellular alterations may afterward influence biological parameters important for populations such as health and reproduction. Presented data provide evidence that in plant populations inhabiting heavily contaminated territories cytogenetic damage were accompanied by decrease in reproductive ability. In less contaminated sites, because of the scarcity of data available, it is impossible to establish exactly the relationship between cytogenetic effects and reproductive ability. Radioactive contamination of the plants

  7. Characterisation of the swimming muscles of two Subantarctic notothenoids

    Directory of Open Access Journals (Sweden)

    Daniel Alfredo Fernández

    1999-12-01

    Full Text Available The histochemical characteristics and distribution of muscle fibre types have been investigated in the swimming muscles of the róbalo, Eleginops maclovinus and the lorcho, Patagonotothen tessellata, Subantarctic notothenioids that inhabit the Beagle Channel. The fibre types were differentiated on the basis of glycogen and lipid contents and succinate dehydrogenase and myofibrillar ATPase (mATPase activities. White, red, intermediate and tonic fibres were present in the axial muscle of both species. The same fibre types were identified in the pectoral fin adductor muscles, although the intermediate type was absent. The mATPase technique performed at room temperature (21ºC allowed a good differentiation of fibre types, overcoming the problems found by previous researchers when applying this technique to Antarctic notothenioids. Four different zones (peripheral, mosaic, main and adjacent to the bone were found in the adductor profundis muscle. The proportion of the zones varied along the length of the adductor muscle. For both species, the percentage of red fibres found in the axial muscles was less than 5%, indicating that sustained swimming ability is not dependent on these muscles. The pectoral muscle mass/carcase mass ratio was significantly greater in E. maclovinus than in P. tessellata, reflecting a greater capacity for sustained swimming using pectoral fins.

  8. Mesoscale eddies in the Subantarctic Front-Southwest Atlantic

    Directory of Open Access Journals (Sweden)

    Pablo D. Glorioso

    2005-12-01

    Full Text Available Satellite and ship observations in the southern southwest Atlantic (SSWA reveal an intense eddy field and highlight the potential for using continuous real-time satellite altimetry to detect and monitor mesoscale phenomena with a view to understanding the regional circulation. The examples presented suggest that mesoscale eddies are a dominant feature of the circulation and play a fundamental role in the transport of properties along and across the Antarctic Circumpolar Current (ACC. The main ocean current in the SSWA, the Falkland-Malvinas Current (FMC, exhibits numerous embedded eddies south of 50°S which may contribute to the patchiness, transport and mixing of passive scalars by this strong, turbulent current. Large eddies associated with meanders are observed in the ACC fronts, some of them remaining stationary for long periods. Two particular cases are examined using a satellite altimeter in combination with in situ observations, suggesting that cross-frontal eddy transport and strong meandering occur where the ACC flow intensifies along the sub-Antarctic Front (SAF and the Southern ACC Front (SACCF.

  9. Plant-associated bacterial populations on native and invasive plant species: comparisons between 2 freshwater environments.

    Science.gov (United States)

    Olapade, Ola A; Pung, Kayleigh

    2012-06-01

    Plant-microbial interactions have been well studied because of the ecological importance of such relationships in aquatic systems. However, general knowledge regarding the composition of these biofilm communities is still evolving, partly as a result of several confounding factors that are attributable to plant host properties and to hydrodynamic conditions in aquatic environments. In this study, the occurrences of various bacterial phylogenetic taxa on 2 native plants, i.e., mayapple (Podophyllum peltatum L.) and cow parsnip (Heracleum maximum Bartram), and on an invasive species, i.e., garlic mustard (Alliaria petiolata (M. Bieb.) Cavara & Grande), were quantitatively examined using nucleic acid staining and fluorescence in situ hybridization. The plants were incubated in triplicates for about a week within the Kalamazoo River and Pierce Cedar Creek as well as in microcosms. The bacterial groups targeted for enumeration are known to globally occur in relatively high abundance and are also ubiquitously distributed in freshwater environments. Fluorescence in situ hybridization analyses of the bacterioplankton assemblages revealed that the majority of bacterial cells that hybridized with the different probes were similar between the 2 sites. In contrast, the plant-associated populations while similar on the 3 plants incubated in Kalamazoo River, their representations were highest on the 2 native plants relative to the invasive species in Pierce Cedar Creek. Overall, our results further suggested that epiphytic bacterial assemblages are probably under the influences of and probably subsequently respond to multiple variables and conditions in aquatic milieus.

  10. Do we need demographic data to forecast plant population dynamics?

    Science.gov (United States)

    Tredennick, Andrew T.; Hooten, Mevin B.; Adler, Peter B.

    2017-01-01

    Rapid environmental change has generated growing interest in forecasts of future population trajectories. Traditional population models built with detailed demographic observations from one study site can address the impacts of environmental change at particular locations, but are difficult to scale up to the landscape and regional scales relevant to management decisions. An alternative is to build models using population-level data that are much easier to collect over broad spatial scales than individual-level data. However, it is unknown whether models built using population-level data adequately capture the effects of density-dependence and environmental forcing that are necessary to generate skillful forecasts.Here, we test the consequences of aggregating individual responses when forecasting the population states (percent cover) and trajectories of four perennial grass species in a semi-arid grassland in Montana, USA. We parameterized two population models for each species, one based on individual-level data (survival, growth and recruitment) and one on population-level data (percent cover), and compared their forecasting accuracy and forecast horizons with and without the inclusion of climate covariates. For both models, we used Bayesian ridge regression to weight the influence of climate covariates for optimal prediction.In the absence of climate effects, we found no significant difference between the forecast accuracy of models based on individual-level data and models based on population-level data. Climate effects were weak, but increased forecast accuracy for two species. Increases in accuracy with climate covariates were similar between model types.In our case study, percent cover models generated forecasts as accurate as those from a demographic model. For the goal of forecasting, models based on aggregated individual-level data may offer a practical alternative to data-intensive demographic models. Long time series of percent cover data already exist

  11. Terrestrial invasions on sub-Antarctic Marion and Prince Edward Islands

    Directory of Open Access Journals (Sweden)

    Michelle Greve

    2017-03-01

    Full Text Available Background: The sub-Antarctic Prince Edward Islands (PEIs, South Africa’s southernmost territories have high conservation value. Despite their isolation, several alien species have established and become invasive on the PEIs. Objectives: Here we review the invasion ecology of the PEIs. Methods: We summarise what is known about the introduction of alien species, what influences their ability to establish and spread, and review their impacts. Results: Approximately 48 alien species are currently established on the PEIs, of which 26 are known to be invasive. Introduction pathways for the PEIs are fairly well understood – species have mainly been introduced with ship cargo and building material. Less is known about establishment, spread and impact of aliens. It has been estimated that less than 5% of the PEIs is covered by invasive plants, but invasive plants have attained circuminsular distributions on both PEIs. Studies on impact have primarily focussed on the effects of vertebrate invaders, of which the house mouse, which is restricted to Marion Island, probably has the greatest impact on the biodiversity of the islands. Because of the risk of alien introductions, strict biosecurity regulations govern activities at the PEIs. These are particularly aimed at stemming the introduction of alien species, and are likely to have reduced the rates of new introductions. In addition, some effort is currently being made to eradicate selected range-restricted species. However, only one species that had established and spread on the PEIs, the cat, has been successfully eradicated from the islands. Conclusion: Given the ongoing threat of introductions, and the impacts of invaders, it is essential that future invasions to the PEIs are minimised, that the islands’ management policies deal with all stages of the invasion process and that a better understanding of the risks and impacts of invasions is obtained.

  12. Population and community ecology of the rare plant amsinckia grandiflora

    Energy Technology Data Exchange (ETDEWEB)

    Carlsen, T.M.

    1996-11-01

    Research was conducted between the fall of 1992 and the spring on the population and community ecology of the rare annual plant, Amsinckia glandiflora (Gray) Kleeb. ex Greene (Boraginaceae). The research goal was to investigate the causes of the species rarity, data useful to restorative efforts. The work focused on the examination of competitive suppression by exotic annual grasses; comparisons with common, weedy congener; and the role of litter cover and seed germination and seedling establishment. Annual exotic grasses reduced A. grandiflora reproductive output to a greater extent than did the native perennial bunch grass.

  13. Ecological genomics of natural plant populations: the Israeli perspective.

    Science.gov (United States)

    Nevo, Eviatar

    2009-01-01

    The genomic era revolutionized evolutionary population biology. The ecological genomics of the wild progenitors of wheat and barley reviewed here was central in the research program of the Institute of Evolution, University of Haifa, since 1975 ( http://evolution.haifa.ac.il ). We explored the following questions: (1) How much of the genomic and phenomic diversity of wild progenitors of cultivars (wild emmer wheat, Triticum dicoccoides, the progenitor of most wheat, plus wild relatives of the Aegilops species; wild barley, Hordeum spontaneum, the progenitor of cultivated barley; wild oat, Avena sterilis, the progenitor of cultivated oats; and wild lettuce species, Lactuca, the progenitor and relatives of cultivated lettuce) are adaptive and processed by natural selection at both coding and noncoding genomic regions? (2) What is the origin and evolution of genomic adaptation and speciation processes and their regulation by mutation, recombination, and transposons under spatiotemporal variables and stressful macrogeographic and microgeographic environments? (3) How much genetic resources are harbored in the wild progenitors for crop improvement? We advanced ecological genetics into ecological genomics and analyzed (regionally across Israel and the entire Near East Fertile Crescent and locally at microsites, focusing on the "Evolution Canyon" model) hundreds of populations and thousands of genotypes for protein (allozyme) and deoxyribonucleic acid (DNA) (coding and noncoding) diversity, partly combined with phenotypic diversity. The environmental stresses analyzed included abiotic (climatic and microclimatic, edaphic) and biotic (pathogens, demographic) stresses. Recently, we introduced genetic maps, cloning, and transformation of candidate genes. Our results indicate abundant genotypic and phenotypic diversity in natural plant populations. The organization and evolution of molecular and organismal diversity in plant populations, at all genomic regions and

  14. Effects of host-plant population size and plant sex on a specialist leaf-miner

    DEFF Research Database (Denmark)

    Bañuelos, María-José; Kollmann, Johannes Christian

    2011-01-01

    was negatively related to leaf-miner prevalence, with larger egg and mine densities in small populations. Percentage of eggs hatching and developing into mines, and percentage of adult flies emerging from mines also differed among host populations, but were not related to population size or host cover. Feeding......Animal population density has been related to resource patch size through various hypotheses such as those derived from island biogeography and resource concentration theory. This theoretical framework can be also applied to planteherbivore interactions, and it can be modified by the sex...... of the host-plant, and density-dependent relationships. Leaf-miners are specialised herbivores that leave distinct traces on infested leaves in the form of egg scars, mines, signs of predation and emergence holes. This allows the life cycle of the insect to be reconstructed and the success at the different...

  15. Deglacial palaeoclimate at Puerto del Hambre, subantarctic Patagonia, Chile

    Science.gov (United States)

    Heusser, Calvin J.; Heusser, Linda E.; Lowell, Thomas V.; Moreira M., Andrés; Moreira M., Simón

    2000-02-01

    The primary objective of this study is to further substantiate multistep climatic forcing of late-glacial vegetation in southern South America. A secondary objective is to establish the age of deglaciation in Estrecho de Magallanes-Bahía Inútil. Pollen assemblages at 2-cm intervals in a core of the mire at Puerto del Hambre (53°3621S, 70°5553W) provide the basis for reconstructing the vegetation and a detailed account of palaeoclimate in subantarctic Patagonia. Chronology over the 262-cm length of core is regulated by 20 AMS radiocarbon dates between 14 455 and 10 089 14C yr BP. Of 13 pollen assemblage zones, the earliest representing the Oldest Dryas chronozone (14 455-13 000 14C yr BP) records impoverished steppe with decreasing frequencies and loss of southern beech (Nothofagus). Successive 100-yr-long episodes of grass/herbs and of heath (Empetrum/Ericaceae) before 14 000 14C yr BP infer deglacial successional communities under a climate of increased continentality prior to the establishment of grass-dominated steppe. The Bølling-Allerød (13 000-11 000 14C yr BP) is characterised by mesic grassland under moderating climate that with abrupt change to heath dominance after 12 000 14C yr BP was warmer and not as humid. At the time of the Younger Dryas (11 000-10 000 14C yr BP), grass steppe expanded with a return of colder, more humid climate. Later, with gradual warming, communities were invaded by southern beech. The Puerto del Hambre record parallels multistep, deglacial palaeoclimatic sequences reported elsewhere in the Southern Andes and at Taylor Dome in Antarctica. Deglaciation of Estrecho de Magallanes-Bahía Inútil is dated close to 14 455 14C yr BP, invalidating earlier dates of between 15 800 and 16 590 14C yr BP.

  16. Symbiont abundance can affect host plant population dynamics.

    Science.gov (United States)

    Rock-Blake, Rachel; McCormick, Melissa K; Brooks, Hope E A; Jones, Cynthia S; Whigham, Dennis F

    2017-01-01

    Symbioses are almost universal, but little is known about how symbiont abundance can affect host performance. Many orchids undergo vegetative dormancy and frequent and protracted dormancy have been associated with population declines. If mycorrhizal fungi affect host plant performance, those effects are likely to alter patterns of vegetative dormancy. The goal of this study was to determine whether the abundance of mycorrhizal fungi is related to the likelihood of entering dormancy and whether fungal abundance varied with dormancy duration in the federally listed threatened orchid Isotria medeoloides. We studied three populations of the threatened North American terrestrial orchid Isotria medeoloides using long-term emergence data and evaluated the relationship between the abundance of associated mycorrhizal fungi (Russulaceae) and orchid dormancy and emergence. Mycorrhizal fungi in soil adjacent to orchids were quantified in two ways. First, ectomycorrhizal (ECM) fungi on adjacent root tips were identified using DNA sequencing to determine their phylogenetic relationship to fungi that are known to form mycorrhizae with I. medeoloides. Second, we extracted DNA from soil samples and used quantitative real-time PCR to estimate the abundance of Russulaceae hyphae adjacent to each orchid. We found that the abundance of Russulaceae, both in the soil and on nearby ECM root tips, was significantly related to orchid prior emergence. Both abundance and prior emergence history were predictive of future emergence. These results suggest that the abundance of mycorrhizal fungi can influence orchid population dynamics and is an essential component of orchid conservation. © 2017 Botanical Society of America.

  17. Molecular insights into seed dispersal mutualisms driving plant population recruitment

    Science.gov (United States)

    García, Cristina; Grivet, Delphine

    2011-11-01

    Most plant species require mutualistic interactions with animals to fulfil their demographic cycle. In this regard frugivory (i.e., the intake of fruits by animals) enhances natural regeneration by mobilizing a large amount of seeds from source trees to deposition sites across the landscape. By doing so, frugivores move propagules, and the genotypes they harbour creating the spatial, ecological, and genetic environment under which subsequent recruitment proceeds. Recruitment patterns can be envisioned as the result of two density- and distance-dependent processes: seed dispersal and seed/seedling survival (the Janzen-Connell model). Population genetic studies add another layer of complexity for understanding the fate of dispersed propagules: the genetic relatedness among neighbouring seeds within a seed clump, a major outcome of frugivore activity, modifies their chances of germinating and surviving. Yet, we virtually ignore how the spatial distribution of maternal progenies and recruitment patterns relate with each other in frugivore-generated seed rains. Here we focus on the critical role of frugivore-mediated seed dispersal in shaping the spatial distribution of maternal progenies in the seed rain. We first examine which genetic mechanisms underlying recruitment are influenced by the spatial distribution of maternal progenies. Next, we examine those studies depicting the spatial distribution of maternal progenies in a frugivore-generated seed rain. In doing so, we briefly review the most suitable analytical approaches applied to track the contribution of fruiting trees to the seed rain based on molecular data. Then we look more specifically at the role of distinct frugivore guilds in determining maternal genetic correlations and their expected consequences for recruitment patterns. Finally we posit some general conclusions and suggest future research directions that would provide a more comprehensive understanding of the ecological and evolutionary consequences

  18. Population structure of a vector-borne plant parasite.

    Science.gov (United States)

    Yule, Kelsey M; Koop, Jennifer A H; Alexandre, Nicolas M; Johnston, Lauren R; Whiteman, Noah K

    2016-07-01

    Parasites are among the most diverse groups of life on Earth, yet complex natural histories often preclude studies of their speciation processes. The biology of parasitic plants facilitates in situ collection of data on both genetic structure and the mechanisms responsible for that structure. Here, we studied the role of mating, dispersal and establishment in host race formation of a parasitic plant. We investigated the population genetics of a vector-borne desert mistletoe (Phoradendron californicum) across two legume host tree species (Senegalia greggii and Prosopis velutina) in the Sonoran desert using microsatellites. Consistent with host race formation, we found strong host-associated genetic structure in sympatry, little genetic variation due to geographic site and weak isolation by distance. We hypothesize that genetic differentiation results from differences in the timing of mistletoe flowering by host species, as we found initial flowering date of individual mistletoes correlated with genetic ancestry. Hybrids with intermediate ancestry were detected genetically. Individuals likely resulting from recent, successful establishment events following dispersal between the host species were detected at frequencies similar to hybrids between host races. Therefore, barriers to gene flow between the host races may have been stronger at mating than at dispersal. We also found higher inbreeding and within-host individual relatedness values for mistletoes on the more rare and isolated host species (S. greggii). Our study spanned spatial scales to address how interactions with both vectors and hosts influence parasitic plant structure with implications for parasite virulence evolution and speciation. © 2016 John Wiley & Sons Ltd.

  19. Effect of crop development on biogenic emissions from plant populations grown in closed plant growth chambers

    Science.gov (United States)

    Batten, J. H.; Stutte, G. W.; Wheeler, R. M.

    1995-01-01

    The Biomass Production Chamber at John F. Kennedy Space Center is a closed plant growth chamber facility that can be used to monitor the level of biogenic emissions from large populations of plants throughout their entire growth cycle. The head space atmosphere of a 26-day-old lettuce (Lactuca sativa cv. Waldmann's Green) stand was repeatedly sampled and emissions identified and quantified using GC-mass spectrometry. Concentrations of dimethyl sulphide, carbon disulphide, alpha-pinene, furan and 2-methylfuran were not significantly different throughout the day; whereas, isoprene showed significant differences in concentration between samples collected in light and dark periods. Volatile organic compounds from the atmosphere of wheat (Triticum aestivum cv. Yecora Rojo) were analysed and quantified from planting to maturity. Volatile plant-derived compounds included 1-butanol, 2-ethyl-1-hexanol, nonanal, benzaldehyde, tetramethylurea, tetramethylthiourea, 2-methylfuran and 3-methylfuran. Concentrations of volatiles were determined during seedling establishment, vegetative growth, anthesis, grain fill and senescence and found to vary depending on the developmental stage. Atmospheric concentrations of benzaldehyde and nonanal were highest during anthesis, 2-methylfuran and 3-methylfuran concentrations were greatest during grain fill, and the concentration of the tetramethylurea peaked during senescence.

  20. Genetic consequences of habitat fragmentation in plant populations: susceptible signals in plant traits and methodological approaches.

    Science.gov (United States)

    Aguilar, Ramiro; Quesada, Mauricio; Ashworth, Lorena; Herrerias-Diego, Yvonne; Lobo, Jorge

    2008-12-01

    Conservation of genetic diversity, one of the three main forms of biodiversity, is a fundamental concern in conservation biology as it provides the raw material for evolutionary change and thus the potential to adapt to changing environments. By means of meta-analyses, we tested the generality of the hypotheses that habitat fragmentation affects genetic diversity of plant populations and that certain life history and ecological traits of plants can determine differential susceptibility to genetic erosion in fragmented habitats. Additionally, we assessed whether certain methodological approaches used by authors influence the ability to detect fragmentation effects on plant genetic diversity. We found overall large and negative effects of fragmentation on genetic diversity and outcrossing rates but no effects on inbreeding coefficients. Significant increases in inbreeding coefficient in fragmented habitats were only observed in studies analyzing progenies. The mating system and the rarity status of plants explained the highest proportion of variation in the effect sizes among species. The age of the fragment was also decisive in explaining variability among effect sizes: the larger the number of generations elapsed in fragmentation conditions, the larger the negative magnitude of effect sizes on heterozygosity. Our results also suggest that fragmentation is shifting mating patterns towards increased selfing. We conclude that current conservation efforts in fragmented habitats should be focused on common or recently rare species and mainly outcrossing species and outline important issues that need to be addressed in future research on this area.

  1. Genecological approaches to predicting the effects of climate change on plant populations

    Science.gov (United States)

    Francis F. Kilkenny

    2015-01-01

    Climate change threatens native plant populations and plant communities globally. It is critical that land managers have a clear understanding of climate change impacts on plant species and populations so that restoration efforts can be adjusted accordingly. This paper reviews the develop.ment and use of seed transfer guidelines for restoration in the face of global...

  2. Geology and geochronology of the Sub-Antarctic Snares Islands/Tini Heke, New Zealand

    DEFF Research Database (Denmark)

    Scott, JM; Turnbull, IM; Sagar, MW

    2015-01-01

    The first comprehensive geological map, a summary of lithologies and new radiogenic isotope data (U–Pb, Rb–Sr) are presented for crystalline rocks of the Sub-Antarctic Snares Islands/Tini Heke, 150 km south of Stewart Island. The main lithology is Snares Granite (c. 109 Ma from U–Pb dating...

  3. Summer diet of the Salvin's prion at sub-Antarctic Marion Island

    African Journals Online (AJOL)

    1988-02-14

    Feb 14, 1988 ... Zoo!. 1988,23(4). 309. Summer diet of the Salvin's prion at sub-Antarctic Marion Island. N.A. Gartshore and W.K. Steele*. Percy FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch, 7700 Republic of South Africa. N.T. Klages. Port Elizabeth Museum, P.O. Box 13147, Humewood, ...

  4. Prey and seasonal abundance of killer whales at sub-Antarctic ...

    African Journals Online (AJOL)

    The diet of killer whales Orcinus orca was investigated from 48 predation events observed during sightings at sub-Antarctic Marion Island between 2006 and 2009. From these events, there were 10 cases where prey could be identified. Killer whales fed on fur seals Arctocephalus tropicalis, elephant seals Mirounga leonina ...

  5. Summer diet of the Salvin's prion at sub-Antarctic Marion Island ...

    African Journals Online (AJOL)

    Thirty-nine food samples were collected from Salvin's prions Pachyptila salvini at sub-Antarctic Marion Island, Prince Edward Islands. The diet was dominated by crustaceans which formed 44,2% of the mass, 99,7% of prey items and occurred in 97,4% of the samples. Amphipods were of particular importance, the most ...

  6. New records of Acari from the sub-Antarctic Prince Edward Islands

    NARCIS (Netherlands)

    Marshall, D.J.; Gremmen, N.J.M.; Coetzee, L.; Oconnor, B.M.; Pugh, P.J.A.; Theron, P.D.; Ueckermann, E.A.

    1999-01-01

    Sixty species of Acari are recorded from the sub-Antarctic Marion and Prince Edward Islands (the Prince Edward archipelago). Twenty of the 45 species collected on recent expeditions are new and currently undescribed. Other new taxa include a family of Mesostigmata, four new genera, and the first

  7. Additions and corrections to the lichen mycobiota of the subantarctic Prince Edward Islands

    NARCIS (Netherlands)

    Øvstedal, D.O.; Gremmen, N.J.M.

    2007-01-01

    Fifteen species are reported as new to the subantarctic Prince Edward Islands (47 degrees S, 38 degrees E). Of these 12 are added to the known lichens of Prince Edward Island, and four are added to the Marion Island species list. Two species are new to science, viz. Gyalecta azorellae Ovstedal, with

  8. Thuidium delicatulum (Hedw.) Schimp. (Thuidiaceae) another bipolar moss disjunct from Subantarctic Marion Island

    NARCIS (Netherlands)

    Ochyra, R.; Smith, V.; Gremmen, N.J.M.

    2003-01-01

    Thuidium delicatulum (Hedw.) Schimp. is recorded from Marion Island in the Prince Edward Islands Archipelago in the Subantarctic. This is the first report of the genus Thuidium Schimp. from the subpolar region of the Southern Hemisphere and establishes Th. delicatulum as a bipolar species with

  9. Diet of the blue petrel at sub-Antarctic Marion Island | Steele | African ...

    African Journals Online (AJOL)

    Food samples were collected from 49 blue petrels Halobaena caerulea at Marion Island in the sub-Antarctic region. These were analysed and the results compared with previously published data collected at other islands. Crustaceans formed the major prey by mass (59,5%) and frequency (100%), with Euphausia vallentini ...

  10. Population differences in host plant preference and the importance of yeast and plant substrate to volatile composition

    OpenAIRE

    Date, Priya; Crowley?Gall, Amber; Diefendorf, Aaron F.; Rollmann, Stephanie M.

    2017-01-01

    Abstract Divergent selection between environments can result in changes to the behavior of an organism. In many insects, volatile compounds are a primary means by which host plants are recognized and shifts in plant availability can result in changes to host preference. Both the plant substrate and microorganisms can influence this behavior, and host plant choice can have an impact on the performance of the organism. In Drosophila mojavensis, four geographically isolated populations each use ...

  11. Underwater Optics in Sub-Antarctic and Antarctic Coastal Ecosystems.

    Directory of Open Access Journals (Sweden)

    Pirjo Huovinen

    Full Text Available Understanding underwater optics in natural waters is essential in evaluating aquatic primary production and risk of UV exposure in aquatic habitats. Changing environmental conditions related with global climate change, which imply potential contrasting changes in underwater light climate further emphasize the need to gain insights into patterns related with underwater optics for more accurate future predictions. The present study evaluated penetration of solar radiation in six sub-Antarctic estuaries and fjords in Chilean North Patagonian region (39-44°S and in an Antarctic bay (62°S. Based on vertical diffuse attenuation coefficients (Kd, derived from measurements with a submersible multichannel radiometer, average summer UV penetration depth (z1% in these water bodies ranged 2-11 m for UV-B (313 nm, 4-27 m for UV-A (395 nm, and 7-30 m for PAR (euphotic zone. UV attenuation was strongest in the shallow Quempillén estuary, while Fildes Bay (Antarctica exhibited the highest transparency. Optically non-homogeneous water layers and seasonal variation in transparency (lower in winter characterized Comau Fjord and Puyuhuapi Channel. In general, multivariate analysis based on Kd values of UV and PAR wavelengths discriminated strongly Quempillén estuary and Puyuhuapi Channel from other study sites. Spatial (horizontal variation within the estuary of Valdivia river reflected stronger attenuation in zones receiving river impact, while within Fildes Bay a lower spatial variation in water transparency could in general be related to closeness of glaciers, likely due to increased turbidity through ice-driven processes. Higher transparency and deeper UV-B penetration in proportion to UV-A/visible wavelengths observed in Fildes Bay suggests a higher risk for Antarctic ecosystems reflected by e.g. altered UV-B damage vs. photorepair under UV-A/PAR. Considering that damage repair processes often slow down under cool temperatures, adverse UV impact could be

  12. The presence of Bt-transgenic oilseed rape in wild mustard populations affects plant growth.

    Science.gov (United States)

    Liu, Yongbo; Stewart, C Neal; Li, Junsheng; Huang, Hai; Zhang, Xitao

    2015-12-01

    The adventitious presence of transgenic plants in wild plant populations is of ecological and regulatory concern, but the consequences of adventitious presence are not well understood. Here, we introduced Bacillus thuringiensis Cry1Ac (Bt)-transgenic oilseed rape (Bt OSR, Brassica napus) with various frequencies into wild mustard (Brassica juncea) populations. We sought to better understand the adventitious presence of this transgenic insecticidal crop in a wild-relative plant population. We assessed the factors of competition, resource availability and diamondback moth (Plutella xylostella) infestation on plant population dynamics. As expected, Bt OSR performed better than wild mustard in mixed populations under herbivore attack in habitats with enough resources, whereas wild mustard had higher fitness when Bt OSR was rarer in habitats with limited resources. Results suggest that the presence of insect-resistant transgenic plants could decrease the growth of wild mustard and Bt OSR plants and their populations, especially under high herbivore pressure.

  13. Model of yield response of corn to plant population and absorption of solar energy.

    Directory of Open Access Journals (Sweden)

    Allen R Overman

    Full Text Available Biomass yield of agronomic crops is influenced by a number of factors, including crop species, soil type, applied nutrients, water availability, and plant population. This article is focused on dependence of biomass yield (Mg ha(-1 and g plant(-1 on plant population (plants m(-2. Analysis includes data from the literature for three independent studies with the warm-season annual corn (Zea mays L. grown in the United States. Data are analyzed with a simple exponential mathematical model which contains two parameters, viz. Y(m (Mg ha(-1 for maximum yield at high plant population and c (m(2 plant(-1 for the population response coefficient. This analysis leads to a new parameter called characteristic plant population, x(c = 1/c (plants m(-2. The model is shown to describe the data rather well for the three field studies. In one study measurements were made of solar radiation at different positions in the plant canopy. The coefficient of absorption of solar energy was assumed to be the same as c and provided a physical basis for the exponential model. The three studies showed no definitive peak in yield with plant population, but generally exhibited asymptotic approach to maximum yield with increased plant population. Values of x(c were very similar for the three field studies with the same crop species.

  14. Plant defences limit herbivore population growth by changing predator-prey interactions.

    Science.gov (United States)

    Kersch-Becker, Mônica F; Kessler, André; Thaler, Jennifer S

    2017-09-13

    Plant quality and predators are important factors affecting herbivore population growth, but how they interact to regulate herbivore populations is not well understood. We manipulated jasmonate-induced plant resistance, exposure to the natural predator community and herbivore density to test how these factors jointly and independently affect herbivore population growth. On low-resistance plants, the predator community was diverse and abundant, promoting high predator consumption rates. On high-resistance plants, the predator community was less diverse and abundant, resulting in low predator consumption rate. Plant resistance only directly regulated aphid population growth on predator-excluded plants. When predators were present, plant resistance indirectly regulated herbivore population growth by changing the impact of predators on the herbivorous prey. A possible mechanism for the interaction between plant resistance and predation is that methyl salicylate, a herbivore-induced plant volatile attractive to predators, was more strongly induced in low-resistance plants. Increased plant resistance reduced predator attractant lures, preventing predators from locating their prey. Low-resistance plants may regulate herbivore populations via predators by providing reliable information on prey availability and increasing the effectiveness of predators. © 2017 The Author(s).

  15. Controls and variability of solute and sedimentary fluxes in Antarctic and sub-Antarctic Environments

    Science.gov (United States)

    Zwolinski, Zbigniew

    2015-04-01

    The currently prepared SEDIBUD Book on "Source-to-Sink Fluxes in Undisturbed Cold Environments" (edited by Achim A. Beylich, John C. Dixon and Zbigniew Zwolinski and published by Cambridge University Press) is summarizing and synthesizing the achievements of the International Association of Geomorphologists` (I.A.G./A.I.G.) Working Group SEDIBUD (Sediment Budgets in Cold Environments), which has been active since 2005 (http://www.geomorph.org/wg/wgsb.html). The book comprises five parts. One of them is part about sub-Antarctic and Antarctic Environments. This part "Sub-Antarctic and Antarctic Environments" describes two different environments, namely oceanic and continental ones. Each part contains results of research on environmental drivers and rates of contemporary solute and sedimentary fluxes in selected sites. Apart from describing the environmental conditions of the whole continent of Antarctica and sub-Antarctic islands (Zb.Zwolinski, M.Kejna, A.N.Lastochkin, A.Zhirov, S.Boltramovich) this part of the book characterizes terrestrial polar oases free from multi-year ice and snow covers (Zb.Zwolinski). The detailed results of geoecological and sedimentological research come from different parts of Antarctica. Antarctic continental shelf (E.Isla) is an example of sub-Antarctic oceanic environment. South Shetlands, especially King George Island (Zb.Zwolinski, M.Kejna, G.Rachlewicz, I.Sobota, J.Szpikowski), is an example of sub-Antarctic terrestrial environment. Antarctic Peninsula (G.Vieira, M.Francelino, J.C.Fernandes) and surroundings of McMurdo Dry Valleys (W.B.Lyons, K.A.Welch, J.Levy, A.Fountain, D.McKnight) are examples of Antarctic continental environments. The key goals of the Antarctic and sub-Antarctic book chapters are following: (i) identify the main environmental drivers and rates of contemporary solute and sedimentary fluxes, and (ii) model possible effects of projected climate change on solute and sedimentary fluxes in cold climate environments

  16. A New Stable Isotope Record From the Subantarctic Southeastern Pacific

    Science.gov (United States)

    Waddell, L. M.; Hendy, I. L.; Moore, T. C.; Lyle, M. W.

    2007-12-01

    Few stable isotope records exist from the southeast Pacific Ocean due to its remote location, low sedimentation rates, and shallow carbonate compensation depth (CCD). The CCD in the southeast Pacific, however, has been found to be unusually deep (~4750 m), thereby allowing for the preservation of Neogene carbonates at abyssal depths. Herein we present stable isotope results from MV0502-4JC, which was recently recovered from the subantarctic region of the Southwest Pacific (50°20S, 148°08W, 4286 m). Dating the record with radiolarian biostratigraphy, we have generated a benthic stable isotope record back to the Middle Miocene from Cibicidoides spp. and a planktic record from Globigerina bulloides into the Late Pliocene. These stable isotope records, in conjunction with carbonate contents and counts of ice-rafted debris (IRD) and manganese micronodules show the effect of global ice sheet build up on this poorly understood region. A prominent negative δ13C shift of ~1‰ (from ~1 to ~0.2‰) in the benthic record occurs at ~15.3 MBSF (Middle Miocene) as carbonate contents in the core decrease from ~80% to ~20%, and significant changes in the bottom water are indicated by changes in the dominant Cibicidoides spp. at the site from C. robertsonianus to C. wuellerstorfi. Trace amounts of IRD and abundant manganese micronodules also appear at the site at this time. A significant hiatus (from the Late Miocene to the Middle Pliocene) occurs somewhere between 11.4 and 9.8 MBSF. From 9.8 to 8 MBSF (Late Pliocene) benthic δ18O increases and δ13C decreases by ~1‰. Also, IRD increases, manganese micronodules decrease, and there is a dramatic increase in the preservation of planktic foraminifera at the site. A planktic δ13C shift of >1‰ (from 0 to 1‰) occurs at ~5 MBSF (Pleistocene) coincident with a 20% increase in carbonate concentration. After this interval, the variability in both benthic δ18O and δ13C and planktic δ18O increases significantly. We interpret the

  17. Community structure of actively growing bacterial populations in plant pathogen suppressive soil

    NARCIS (Netherlands)

    Hjort, K.; Lembke, A.; Speksnijder, A.G.C.L.; Smalla, K.; Jansson, J.K.

    2007-01-01

    The bacterial community in soil was screened by using various molecular approaches for bacterial populations that were activated upon addition of different supplements. Plasmodiophora brassicae spores, chitin, sodium acetate, and cabbage plants were added to activate specific bacterial populations

  18. Effects of Plant Population and Tiller Number on the Growth and ...

    African Journals Online (AJOL)

    The plant populations were 166,000 250,000 and 500,000 plants/ha and tiller numbers of one, three and five were maintained and compared to a control where tiller production was not regulated. Grain yield was significantly (p<0.05) reduced at low and increased at high population densities. Dry matter was however, ...

  19. The balance of planting and mortality in a street tree population

    Science.gov (United States)

    Lara A. Roman; John J. Battles; Joe R. McBride

    2013-01-01

    Street trees have aesthetic, environmental, human health, and economic benefits in urban ecosystems. Street tree populations are constructed by cycles of planting, growth, death, removal and replacement. The goals of this study were to understand how tree mortality and planting rates affect net population growth, evaluate the shape of the mortality curve, and assess...

  20. Ability of Matrix Models to Explain the Past and Predict the Future of Plant Populations

    NARCIS (Netherlands)

    Crone, E.E.; Ellis, M.M.; Morris, W.F.; Stanley, A.; Bell, T.; Bierzychudek, P.; Ehrlén, J.; Kaye, T.N.; Knight, T.M.; Lesica, P.; Oostermeijer, G.; Quintana-Ascencio, P.F.; Ticktin, T.; Valverde, T.; Williams, J.L.; Doak, D.F.; Ganesan, R.; McEachern, K.A.; Thorpe, A.; Menges, E.S.

    2013-01-01

    Uncertainty associated with ecological forecasts has long been recognized, but forecast accuracy is rarely quantified. We evaluated how well data on 82 populations of 20 species of plants spanning 3 continents explained and predicted plant population dynamics. We parameterized stage-based matrix

  1. Highly diverse endophytic and soil Fusarium oxysporum populations associated with field-grown tomato plants.

    Science.gov (United States)

    Demers, Jill E; Gugino, Beth K; Jiménez-Gasco, María Del Mar

    2015-01-01

    The diversity and genetic differentiation of populations of Fusarium oxysporum associated with tomato fields, both endophytes obtained from tomato plants and isolates obtained from soil surrounding the sampled plants, were investigated. A total of 609 isolates of F. oxysporum were obtained, 295 isolates from a total of 32 asymptomatic tomato plants in two fields and 314 isolates from eight soil cores sampled from the area surrounding the plants. Included in this total were 112 isolates from the stems of all 32 plants, a niche that has not been previously included in F. oxysporum population genetics studies. Isolates were characterized using the DNA sequence of the translation elongation factor 1α gene. A diverse population of 26 sequence types was found, although two sequence types represented nearly two-thirds of the isolates studied. The sequence types were placed in different phylogenetic clades within F. oxysporum, and endophytic isolates were not monophyletic. Multiple sequence types were found in all plants, with an average of 4.2 per plant. The population compositions differed between the two fields but not between soil samples within each field. A certain degree of differentiation was observed between populations associated with different tomato cultivars, suggesting that the host genotype may affect the composition of plant-associated F. oxysporum populations. No clear patterns of genetic differentiation were observed between endophyte populations and soil populations, suggesting a lack of specialization of endophytic isolates. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  2. Wild Plant Species with Extremely Small Populations Require Conservation and Reintroduction in China

    Science.gov (United States)

    Hai Ren; Qianmei Zhang; Hongfang Lu; Hongxiao Liu; Qinfeng Guo; Jun Wang; Shuguang Jian; Hai’ou Bao

    2012-01-01

    China is exceptionally rich in biodiversity, with more than 30000 vascular plant species that include many endemic genera, species of ancient origin, and cultivated plants (Yang et al. 2005). Because of rapid economic development, population growth, pollution, and continuing resource exploitation, China’s plant diversity faces severe threats. According to the Chinese...

  3. Iron fertilization of the Subantarctic ocean during the last ice age.

    Science.gov (United States)

    Martínez-García, Alfredo; Sigman, Daniel M; Ren, Haojia; Anderson, Robert F; Straub, Marietta; Hodell, David A; Jaccard, Samuel L; Eglinton, Timothy I; Haug, Gerald H

    2014-03-21

    John H. Martin, who discovered widespread iron limitation of ocean productivity, proposed that dust-borne iron fertilization of Southern Ocean phytoplankton caused the ice age reduction in atmospheric carbon dioxide (CO2). In a sediment core from the Subantarctic Atlantic, we measured foraminifera-bound nitrogen isotopes to reconstruct ice age nitrate consumption, burial fluxes of iron, and proxies for productivity. Peak glacial times and millennial cold events are characterized by increases in dust flux, productivity, and the degree of nitrate consumption; this combination is uniquely consistent with Subantarctic iron fertilization. The associated strengthening of the Southern Ocean's biological pump can explain the lowering of CO2 at the transition from mid-climate states to full ice age conditions as well as the millennial-scale CO2 oscillations.

  4. Extended hatching periods in the subantarctic lithodid crabs Lithodes santolla and Paralomis granulosa (Crustacea: Decapoda: Lithodidae)

    Science.gov (United States)

    Thatje, S.; Calcagno, J. A.; Lovrich, G. A.; Sartoris, F. J.; Anger, K.

    2003-06-01

    Temporal pattern of hatching was studied in the subantarctic lithodid crabs Lithodes santolla (Molina) and Paralomis granulosa (Jaquinot) from the Argentine Beagle Channel. In both species, larval hatching occurred in low daily numbers over an extended period of up to several weeks, depending on hatch size. Low daily hatching activity and low oxygen-consumption rates in freshly hatched P. granulosa larvae are discussed as life history adaptations to, and/or physiological constraints by, the environmental conditions of high latitudes.

  5. Magellan Bryozoa: a review of the diversity and of the Subantarctic and Antarctic zoogeographical links

    Directory of Open Access Journals (Sweden)

    H. I. Moyano G.

    1999-12-01

    Full Text Available Based principally on previous work by the author, the Magellan Bryozoa are reviewed in terms of endemism, specific diversity, zoarial diversity and polymorphism. The Magellan, Atlantic, Pacific, Subantarctic and Antarctic zoogeographical relationships are reevaluated. New data related to the distribution of Magellanic and Antarctic species along the archipelagos of the Scotia Arc and new data on Bryozoa from the Magellan continental slope are added.

  6. Kelp genes reveal effects of subantarctic sea ice during the Last Glacial Maximum

    OpenAIRE

    Fraser, Ceridwen I.; Nikula, Raisa; Spencer, Hamish G.; Waters, Jonathan M.

    2009-01-01

    The end of the Last Glacial Maximum (LGM) dramatically reshaped temperate ecosystems, with many species moving poleward as temperatures rose and ice receded. Whereas reinvading terrestrial taxa tracked melting glaciers, marine biota recolonized ocean habitats freed by retreating sea ice. The extent of sea ice in the Southern Hemisphere during the LGM has, however, yet to be fully resolved, with most palaeogeographic studies suggesting only minimal or patchy ice cover in subantarctic waters. H...

  7. Transients drive the demographic dynamics of plant populations in variable environments

    DEFF Research Database (Denmark)

    McDonald, Jenni L; Stott, Iain; Townley, Stuart

    2016-01-01

    The dynamics of structured plant populations in variable environments can be decomposed into the ‘asymptotic’ growth contributed by vital rates, and ‘transient’ growth caused by deviation from stable stage structure. We apply this framework to a large, global data base of longitudinal studies...... of projection matrix models for plant populations. We ask, what is the relative contribution of transient boom and bust to the dynamic trajectories of plant populations in stochastic environments? Is this contribution patterned by phylogeny, growth form or the number of life stages per population and per...... dynamics in the real world....

  8. Plant mortality varies with arbuscular mycorrhizal fungal species identities in a self-thinning population

    Science.gov (United States)

    Zhang, Qian; Tang, Jianjun; Chen, Xin

    2011-01-01

    Because arbuscular mycorrhizal fungal (AMF) species differ in stimulating the growth of particular host plant species, AMF species may vary in their effects on plant intra-specific competition and the self-thinning process. We tested this hypothesis using a microcosm experiment with Medicago sativa L. as a model plant population and four AMF species. Our results showed that the AMF species Glomus diaphanum stimulated host plant growth more than the other three AMF species did when the plants were grown individually. Glomus diaphanum also induced the highest rate of mortality in the self-thinning plant populations. We also found a positive correlation between mortality and growth response to colonization. Our results demonstrate that AMF species can affect plant mortality and the self-thinning process by affecting plant growth differently. PMID:21147829

  9. Biological response to millennial variability of dust and nutrient supply in the Subantarctic South Atlantic Ocean.

    Science.gov (United States)

    Anderson, Robert F; Barker, Stephen; Fleisher, Martin; Gersonde, Rainer; Goldstein, Steven L; Kuhn, Gerhard; Mortyn, P Graham; Pahnke, Katharina; Sachs, Julian P

    2014-07-13

    Fluxes of lithogenic material and fluxes of three palaeo-productivity proxies (organic carbon, biogenic opal and alkenones) over the past 100,000 years were determined using the (230)Th-normalization method in three sediment cores from the Subantarctic South Atlantic Ocean. Features in the lithogenic flux record of each core correspond to similar features in the record of dust deposition in the EPICA Dome C ice core. Biogenic fluxes correlate with lithogenic fluxes in each sediment core. Our preferred interpretation is that South American dust, most probably from Patagonia, constitutes a major source of lithogenic material in Subantarctic South Atlantic sediments, and that past biological productivity in this region responded to variability in the supply of dust, probably due to biologically available iron carried by the dust. Greater nutrient supply as well as greater nutrient utilization (stimulated by dust) contributed to Subantarctic productivity during cold periods, in contrast to the region south of the Antarctic Polar Front (APF), where reduced nutrient supply during cold periods was the principal factor limiting productivity. The anti-phased patterns of productivity on opposite sides of the APF point to shifts in the physical supply of nutrients and to dust as cofactors regulating productivity in the Southern Ocean. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  10. Reduced fecundity in small populations of the rare plant Gentianopsis ciliate (Gentianaceae)

    Science.gov (United States)

    Kery, M.; Matthies, D.

    2004-01-01

    Habitat destruction is the main cause for the biodiversity crisis. Surviving populations are often fragmented, i.e., small and isolated from each other. Reproduction of plants in small populations is often reduced, and this has been attributed to inbreeding depression, reduced attractiveness for pollinators, and reduced habitat quality in small populations. Here we present data on the effects of fragmentation on the rare, self-compatible perennial herb Gentianopsis ciliata (Gentianaceae), a species with very small and presumably well-dispersed seeds. We studied the relationship between population size, plant size, and the number of flowers produced in 63 populations from 1996-1998. In one of the years, leaf and flower size and the number of seeds produced per fruit was studied in a subset of 25 populations. Plant size, flower size, and the number of seeds per fruit and per plant increased with population size, whereas leaf length and the number of flowers per plant did not. The effects of population size on reproduction and on flower size remained significant if the effects were adjusted for differences in plant size, indicating that they could not be explained by differences in habitat quality. The strongly reduced reproduction in small populations may be due to pollination limitation, while the reduced flower size could indicate genetic effects.

  11. Iron fertilization of the Subantarctic Ocean during the last ice age

    Science.gov (United States)

    Martinez-Garcia, A.

    2015-12-01

    Dust has the potential to modify global climate by influencing the radiative balance of the atmosphere and by supplying iron and other essential limiting micronutrients to the ocean. The scarcity of iron limits marine productivity and carbon uptake in one-quarter of the world ocean where the concentration of major nutrients (phosphorus and nitrogen) is perennially high. The Southern Ocean is the region where variations in iron availability can have the largest effect on Earth's carbon cycle through its fertilizing effect on marine ecosystems. Paleoceanographic records from the Subantarctic Atlantic have revealed a remarkable correlation between phytoplankton productivity and aeolian iron flux during glacial periods supporting the iron fertilization hypothesis. In addition, a recent study has shown that peak glacial times and millennial cold events were nearly universally associated not only with increases in dust flux and export production, but also with an increase in nutrient consumption (the last indicated by higher foraminifera-bound δ15N) (Martinez-Garcia et al. 2014). This combination of changes is uniquely consistent with ice age iron fertilization of the Subantarctic Atlantic. The strengthening of the biological pump associated with the observed increase in Subantarctic nutrient consumption during the high-dust intervals of the last two ice ages can explain up to ~40 ppm of the CO2 decrease that characterizes the transitions from mid-climate states to full ice age conditions. However, the impact of iron fertilization in other sectors of the Southern Ocean characterized by lower ice age dust fluxes than the Atlantic remains unclear. A series of recently published records from the Subantarctic Pacific indicate that dust deposition and marine export production were three times higher during glacial periods than during interglacials (Lamy et al. 2014). Here we present new measurements of foraminifera-bound nitrogen isotopes in a sediment core located in the

  12. Popping expansion and yield responses of popcorn cultivars under different row spacings and plant populations

    Directory of Open Access Journals (Sweden)

    José Antonio de Souza Rossato Junior

    2013-12-01

    Full Text Available The objective of this work was to evaluate the agronomic traits and the popping expansion index of three Brazilian popcorn cultivars under different row spacings and plant populations. The trials were performed during two crop seasons, under field conditions. The experimental design used was a randomized complete block, in a split-split plot, with 27 treatments and four replicates. Treatments were represented in a triple factorial arrangement: three row spacings (0.40, 0.60, and 0.80 m, three plant populations (40,000, 60,000, and 80,000 plants per hectare, and three popcorn cultivars (IAC-TC 01, IAC 12, and Zelia. The increase in plant population causes a reduction in the number of grains per ear, lower prolificacy, and grain weight loss. Cultivar grain yield is affected by row spacing and popcorn plant population. Cultivar IAC 12 shows highest grain yield under row spacings of 0.40 and 0.60 m and plant population between 60,000 and 80,000 plants per hectare. The popping expansion index is not affected by row spacing or plant population.

  13. 75 FR 13012 - Endangered and Threatened Wildlife and Plants: Threatened Status for Southern Distinct Population...

    Science.gov (United States)

    2010-03-18

    ... Wildlife and Plants: Threatened Status for Southern Distinct Population Segment of Eulachon AGENCY... Population Segment (DPS) of Pacific eulachon (Thaleichthys pacificus; hereafter ``eulachon'') as a threatened..., to list and designate critical habitat for Columbia River populations of eulachon. On November 29...

  14. The demographic consequences of mutualism: ants increase host-plant fruit production but not population growth.

    Science.gov (United States)

    Ford, Kevin R; Ness, Joshua H; Bronstein, Judith L; Morris, William F

    2015-10-01

    The impact of mutualists on a partner's demography depends on how they affect the partner's multiple vital rates and how those vital rates, in turn, affect population growth. However, mutualism studies rarely measure effects on multiple vital rates or integrate them to assess the ultimate impact on population growth. We used vital rate data, population models and simulations of long-term population dynamics to quantify the demographic impact of a guild of ant species on the plant Ferocactus wislizeni. The ants feed at the plant's extrafloral nectaries and attack herbivores attempting to consume reproductive organs. Ant-guarded plants produced significantly more fruit, but ants had no significant effect on individual growth or survival. After integrating ant effects across these vital rates, we found that projected population growth was not significantly different between unguarded and ant-guarded plants because population growth was only weakly influenced by differences in fruit production (though strongly influenced by differences in individual growth and survival). However, simulations showed that ants could positively affect long-term plant population dynamics through services provided during rare but important events (herbivore outbreaks that reduce survival or years of high seedling recruitment associated with abundant precipitation). Thus, in this seemingly clear example of mutualism, the interaction may actually yield no clear benefit to plant population growth, or if it does, may only do so through the actions of the ants during rare events. These insights demonstrate the value of taking a demographic approach to studying the consequences of mutualism.

  15. Ability of matrix models to explain the past and predict the future of plant populations.

    Science.gov (United States)

    Crone, Elizabeth E; Ellis, Martha M; Morris, William F; Stanley, Amanda; Bell, Timothy; Bierzychudek, Paulette; Ehrlén, Johan; Kaye, Thomas N; Knight, Tiffany M; Lesica, Peter; Oostermeijer, Gerard; Quintana-Ascencio, Pedro F; Ticktin, Tamara; Valverde, Teresa; Williams, Jennifer L; Doak, Daniel F; Ganesan, Rengaian; McEachern, Kathyrn; Thorpe, Andrea S; Menges, Eric S

    2013-10-01

    Uncertainty associated with ecological forecasts has long been recognized, but forecast accuracy is rarely quantified. We evaluated how well data on 82 populations of 20 species of plants spanning 3 continents explained and predicted plant population dynamics. We parameterized stage-based matrix models with demographic data from individually marked plants and determined how well these models forecast population sizes observed at least 5 years into the future. Simple demographic models forecasted population dynamics poorly; only 40% of observed population sizes fell within our forecasts' 95% confidence limits. However, these models explained population dynamics during the years in which data were collected; observed changes in population size during the data-collection period were strongly positively correlated with population growth rate. Thus, these models are at least a sound way to quantify population status. Poor forecasts were not associated with the number of individual plants or years of data. We tested whether vital rates were density dependent and found both positive and negative density dependence. However, density dependence was not associated with forecast error. Forecast error was significantly associated with environmental differences between the data collection and forecast periods. To forecast population fates, more detailed models, such as those that project how environments are likely to change and how these changes will affect population dynamics, may be needed. Such detailed models are not always feasible. Thus, it may be wiser to make risk-averse decisions than to expect precise forecasts from models. © 2013 Society for Conservation Biology.

  16. Changes in plant-parasitic nematode populations in pineapple fields following inter-cycle cover crops.

    Science.gov (United States)

    Ko, M P; Schmitt, D P

    1996-12-01

    The use of plant-covers oat (Arena sativa L.), rhodesgrass (Chloris gayana Kunth), soybean (Glycine max [L.] Merr.), and marigold (Tagetes patula L.) during pineapple inter-cycle planting periods was investigated at two sites (Kunia and Whitmore, Oahu, HI) as a potential means to reduce population densities of Rotylenchulus reniformis, Helicotylenchus dihystera, and Paratylenchus spp. Clean fallow and fallow covered with pineapple-plant residues (mulch) were the controls without plant-cover. Regardless of treatments, population densities of R. reniformis declined with time at both sites to low residue levels by the end of the 6-month period. Treatment means of R. reniformis population densities in the plant-cover treatments were lower than the controls' (P = 0.05). The plant-cover treatments also effected higher rates of R. reniformis population decline at both sites during the period, being 2.0 to 2.2 times that of the mulch control and 1.2 to 1.4 times that of the fallow control. Plant-covers' effect on H. dihystera during the same period at both sites was variable, resulting in decreased, unchanged, or increased population densities. The change was especially obvious in the oat-cover treatment, where H. dihystera population densities increased 9 to 15-fold at both sites. Population of Paratylenchus spp. was absent or present at low levels at the sites throughout the period. Biological activities antagonistic to R. reniformis at Kunia were estimated at the end of 6 months by comparing the extent of nematode's reproduction (on cowpea seedlings) in the treatment soils that had been subjected to autoclaving or freezing temperature. Although higher indices of antagonistic activities were observed in soils with prior plant-cover treatments than in soils from the controls, none of the treatments resulted in conferring soils the increased ability to suppress re-introduced R. reniformis populations or enhance subsequent pineapple-plant growth.

  17. Forest succession and population viability of grassland plants

    DEFF Research Database (Denmark)

    Lehtilä, Kari; Dahlgren, Johan; Garcia, Maria Begona

    2016-01-01

    Time lags in responses of organisms to deteriorating environmental conditions delay population declines and extinctions. We examined how local processes at the population level contribute to extinction debt, and how cycles of habitat deterioration and recovery may delay extinction. We carried out...... the environmental conditions that enable long-term persistence and to design management for species experiencing extinction debts.......Time lags in responses of organisms to deteriorating environmental conditions delay population declines and extinctions. We examined how local processes at the population level contribute to extinction debt, and how cycles of habitat deterioration and recovery may delay extinction. We carried out...... a demographic analysis of the fate of the grassland perennial Primula veris after the cessation of grassland management, where we used either a unidirectional succession model for forest habitat or a rotation model with a period of forest growth followed by a clear-cut and a new successional cycle...

  18. Influence of Nonhost Plants on Population Decline of Rotylenchulus reniformis.

    Science.gov (United States)

    Caswell, E P; Defrank, J; Apt, W J; Tang, C S

    1991-01-01

    The influence of Chloris gayana, Crotalaria juncea, Digitaria decumbens, Tagetes patula, and a chitin-based soil amendment on Hawaiian populations of Rotylenchulus reniformis was examined. Chloris gayana was a nonhost for R. reniformis. The nematode did not penetrate the roots, and in greenhouse and field experiments, C. gayana reduced reniform nematode numbers at least as well as fallow. Tagetes patula was a poor host for reniform nematode and reduced reniform nematode numbers in soil better than did fallow. Crotalaria juncea was a poor host for R. reniformis, and only a small fraction of the nematode population penetrated the roots. Crotalaria juncea and D. decumbens reduced reniform nematode populations at least as well as fallow. A chitin-based soil amendment, applied at 2.24 t/ha to fallow soil, did not affect the population decline of reniform nematode.

  19. Population Exposure Estimates in Proximity to Nuclear Power Plants, Country-Level Aggregates

    Data.gov (United States)

    National Aeronautics and Space Administration — The Population Exposure Estimates in Proximity to Nuclear Power Plants, Country-Level Aggregates data set consists of country-level estimates of total, urban, and...

  20. Assessing populations of a disease suppressive microorganism and a plant pathogen using DNA arrays

    NARCIS (Netherlands)

    Lievens, B.; Claes, L.; Krause, M.S.; Vanachter, A.C.R.C.; Cammue, B.P.A.; Thomma, B.P.H.J.

    2007-01-01

    Understanding the relationships between disease suppressive microbial populations and plant pathogens is essential to develop procedures for effective and consistent disease control. Currently, DNA array technology is the most suitable technique to simultaneously detect multiple microorganisms.

  1. The Genetic Basis of Plant Architecture in 10 Maize Recombinant Inbred Line Populations.

    Science.gov (United States)

    Pan, Qingchun; Xu, Yuancheng; Li, Kun; Peng, Yong; Zhan, Wei; Li, Wenqiang; Li, Lin; Yan, Jianbing

    2017-10-01

    Plant architecture is a key factor affecting planting density and grain yield in maize ( Zea mays ). However, the genetic mechanisms underlying plant architecture in diverse genetic backgrounds have not been fully addressed. Here, we performed a large-scale phenotyping of 10 plant architecture-related traits and dissected the genetic loci controlling these traits in 10 recombinant inbred line populations derived from 14 diverse genetic backgrounds. Nearly 800 quantitative trait loci (QTLs) with major and minor effects were identified as contributing to the phenotypic variation of plant architecture-related traits. Ninety-two percent of these QTLs were detected in only one population, confirming the diverse genetic backgrounds of the mapping populations and the prevalence of rare alleles in maize. The numbers and effects of QTLs are positively associated with the phenotypic variation in the population, which, in turn, correlates positively with parental phenotypic and genetic variations. A large proportion (38.5%) of QTLs was associated with at least two traits, suggestive of the frequent occurrence of pleiotropic loci or closely linked loci. Key developmental genes, which previously were shown to affect plant architecture in mutant studies, were found to colocalize with many QTLs. Five QTLs were further validated using the segregating populations developed from residual heterozygous lines present in the recombinant inbred line populations. Additionally, one new plant height QTL, qPH3 , has been fine-mapped to a 600-kb genomic region where three candidate genes are located. These results provide insights into the genetic mechanisms controlling plant architecture and will benefit the selection of ideal plant architecture in maize breeding. © 2017 American Society of Plant Biologists. All Rights Reserved.

  2. Population dynamics of a long-lived alpine plant with sexual and clonal reproduction

    OpenAIRE

    Weppler, Tina

    2006-01-01

    This thesis focuses on the demography, reproduction, and pre-dispersal seed predation of the alpine clonal plant Geum reptans. In chapter 2, I studied the population dynamics of G. reptans, thereby I particularly addressed the relative importance of sexual vs. clonal reproduction for population growth in this longlived species. In chapter 3, the balance between sexual and clonal reproduction in plants of different sizes and the frequency of life-cycle stages i...

  3. Occupational hazard evaluation of working population in a select automotive industrial plant.

    Science.gov (United States)

    Wójcik, Alicja; Borzecki, Zdzisław; Kowalska, Edyta; Borzecki, Andrzej

    2004-01-01

    The research was conducted in the selected vehicle industry plant. Work conditions were assessed on the assembly line by measuring chemical and physical factors. Exposure to noise in the investigated plant exceeded the values of permissible standards. The pollution on the posts did not exceed the standards except singular concentrations. While assessing the values of chemical factors concentration, no toxicological danger was revealed in the investigated population. The work conditions of the investigated plant did not create the danger of professional diseases.

  4. Influence of plant species on population dynamics, genotypic diversity and antibiotic production by indigenous Pseudomonas spp

    NARCIS (Netherlands)

    Bergsma-Vlami, M.; Prins, M.E.; Raaijmakers, J.M.

    2005-01-01

    The population dynamics, genotypic diversity and activity of naturally-occurring 2,4-diacetylphloroglucinol (DAPG)-producing Pseudomonas spp. was investigated for four plant species (wheat, sugar beet, potato, lily) grown in two different soils. All four plant species tested, except lily and in some

  5. Effect of plant population and N fertilizer on the growth and yield of ...

    African Journals Online (AJOL)

    Responses of bambara groundnut (Vigna subterranea (L.) Verdc) to 3 levels of fertilizer N (0, 50, and 100 kg N/ha) and seven plant populations (55555, 63492, 74074, 88888, 111111, 148148 and 222222 plants/ha) were studied under field conditions in Nsukka, Nigeria. The experimental design was a randomized ...

  6. Effects of summer frost exposures on the cold tolerance strategy of a sub-Antarctic beetle.

    Science.gov (United States)

    Bale, J S.; Worland, M R.; Block, W

    2001-09-01

    The sub-Antarctic beetle Hydromedion sparsutum (Coleoptera, Perimylopidae) is common locally on the island of South Georgia where sub-zero temperatures can be experienced in any month of the year. Larvae were known to be weakly freeze tolerant in summer with a mean supercooling point (SCP) around -4 degrees C and a lower lethal temperature of -10 degrees C (15min exposure). This study investigated the effects of successive freezing exposures on the SCP and subsequent survival of summer acclimatised larvae. The mean SCP of field fresh larvae was -4.2+/-0.2 degrees C with a range from -1.0 to -6.1 degrees C. When larvae were cooled to -6.5 degrees C on 10 occasions at intervals of 30min and one and four days, survival was 44, 70 and 68%, respectively. The 'end of experiment' SCP of larvae surviving 10 exposures at -6.5 degrees C showed distinct changes and patterns from the original field population depending on the interval between exposure. In the 30min interval group, most larvae froze between -6 and -8 degrees C, a depression of up to 6 degrees C from the original sample; all larvae were dead when cooling was continued below the SCP to -12 degrees C. In the one and four day interval groups, most larvae froze above -6 degrees C, showing no change as a result of the 10 exposures at -6.5 degrees C. As with the 30min interval group, some larvae froze below -6 degrees C, but with a wider range, and again, all were dead when cooled to -12 degrees C. However, in the one and four day interval groups, some larvae remained unfrozen when cooled to -12 degrees C, a depression of their individual SCP of at least 6 degrees C, and were alive 24h after cooling. In a further experiment, larvae were cooled to their individual SCP temperature at daily intervals on 10 occasions to ensure that every larva froze every day. Most larvae which showed a depression of their SCP of 2-4 degrees C from their day one value became moribund or died after six or seven freezing events. Survival

  7. The Genetic Basis of Plant Architecture in 10 Maize Recombinant Inbred Line Populations1[OPEN

    Science.gov (United States)

    Pan, Qingchun; Xu, Yuancheng; Peng, Yong; Zhan, Wei; Li, Wenqiang; Li, Lin

    2017-01-01

    Plant architecture is a key factor affecting planting density and grain yield in maize (Zea mays). However, the genetic mechanisms underlying plant architecture in diverse genetic backgrounds have not been fully addressed. Here, we performed a large-scale phenotyping of 10 plant architecture-related traits and dissected the genetic loci controlling these traits in 10 recombinant inbred line populations derived from 14 diverse genetic backgrounds. Nearly 800 quantitative trait loci (QTLs) with major and minor effects were identified as contributing to the phenotypic variation of plant architecture-related traits. Ninety-two percent of these QTLs were detected in only one population, confirming the diverse genetic backgrounds of the mapping populations and the prevalence of rare alleles in maize. The numbers and effects of QTLs are positively associated with the phenotypic variation in the population, which, in turn, correlates positively with parental phenotypic and genetic variations. A large proportion (38.5%) of QTLs was associated with at least two traits, suggestive of the frequent occurrence of pleiotropic loci or closely linked loci. Key developmental genes, which previously were shown to affect plant architecture in mutant studies, were found to colocalize with many QTLs. Five QTLs were further validated using the segregating populations developed from residual heterozygous lines present in the recombinant inbred line populations. Additionally, one new plant height QTL, qPH3, has been fine-mapped to a 600-kb genomic region where three candidate genes are located. These results provide insights into the genetic mechanisms controlling plant architecture and will benefit the selection of ideal plant architecture in maize breeding. PMID:28838954

  8. Reconstructing Export Production in the Subantarctic South Pacific during the Last Ice Age

    Science.gov (United States)

    Park, J. W.; Winckler, G.; Anderson, R. F.; Schwartz, R.; Lamy, F.; Gersonde, R.; Pahnke, K.

    2016-02-01

    Despite high concentration of major nutrients in the Southern Ocean, nutrient utilization is inefficient because the scarcity of iron limits phytoplankton growth and primary productivity. Input of eolian dust into the ocean may supply iron, leading to increased export production and nutrient utilization, and potentially affect the Earth's carbon cycle through its fertilizing effect on marine ecosystem. Recent studies (Martínez-Garcia et al., 2009, 2011, 2014) suggest that iron fertilization in the Subantarctic South Atlantic may have contributed to reducing atmospheric CO2 by 40ppm over the last glacial cycle. While most of current observations on the Southern Ocean come from the South Atlantic, the Pacific sector covers the largest surface area of the Southern Ocean, indicating its potential to store the largest fraction of carbon. Dust fluxes to the South Atlantic are generally stronger than those to the South Pacific, but the glacial-interglacial pattern of dust deposition is similar. A recent study (Lamy et al., 2014) suggests a threefold increase of dust deposition over glacial periods than over interglacial periods in the South Pacific, and show a correlation between dust records and preliminary export production. In this study, we examine a set of cores from the Subantarctic South Pacific at higher temporal resolution to observe variability of export production in response to changing dust flux. We present proxy records for paleoproductivity from excess Ba, biogenic opal and authigenic Uranium. The results will allow us to evaluate the importance of iron fertilization in the Subantarctic Pacific Ocean over glacial/interglacial timescale and its potential effect on the global carbon cycle.

  9. A 450 000 kyr Surface Hydrography History From the Subantarctic Atlantic Ocean (ODP Site 1089)

    Science.gov (United States)

    Cortese, G.; Abelmann, A.; Gersonde, R.

    2002-12-01

    We established a palaeo sea surface temperature (SST) record, by using a radiolarian-based transfer function, for the northern subantarctic Atlantic Ocean (ODP Site 1089, 400 56' S; 90 54 E), in order to reconstruct its surface hydrography and interocean heat exchange history during the last five climate cycles (ca. 450 ka). The produced record has a centennial scale time resolution, which makes it unique (in length and resolution) for the subantarctic zone. At this location, close to the subtropical front, ocean/atmosphere interactions, interoceanic exchange processes, and mesoscale eddy mixing play an important role in shaping the characteristics of sea water eventually advected to the North Atlantic. The centennial resolution allows to recognize millennial scale climatic events, similar to the Dansgaard-Oeschger cycles (originally described from Greenland ice cores), both during Marine Isotopic Stage (MIS) 3 and 6. Similar to observations from Termination I (Antarctic Cold Reversal), rapid cooling rebounds were encountered at Terminations II to V, and are not therefore limited either to the circum-Atlantic area or to last Termination. A comparison of SST and ice volume proxies suggests a lead of a few kyrs between SST and the minimum extent of global ice volume, indicating that temperatures rose substantially at subantarctic latitudes before any considerable northern hemisphere continental ice volume change was recorded. The climatic history of ODP Site 1089 displays good correlation to other records (e.g. Vostok) with the exception of MIS 10, where a warm SST anomaly was recognized. This anomaly is also present in oceanic records along the thermohaline circulation belt path, but absent in both Polar Zone and Vostok climatic records. The implications of our record for interhemispheric climate connecting mechanisms and the role played by the Southern Ocean in steering global climatic change will be discussed.

  10. Subantarctic Pacific hiatuses as clues to periods of enhanced oceanic circulation during the late Neogene

    Science.gov (United States)

    Waddell, L. M.; Hendy, I. L.; Moore, T. C.; Lyle, M. W.

    2009-12-01

    New stable isotope records from cores MV0502-4JC (50°20’S, 148°08’W, 4286m), ELT 25-11 (50°02’S, 127°31’W, 3969m), and ELT 20-11 (49°00’S, 144°50’W, 4517 m) obtained in close proximity to the Subantarctic Front in the southeast Pacific show a consistent pattern of hiatuses that could be related to late Neogene changes in the strength of the Antarctic Circumpolar Current (ACC). These subantarctic Pacific records show three hiatuses that we have dated to 1) the early Pliocene-early late Pliocene, 2) ~1.57-0.68 Ma, and 3) ~0.53-0.19 Ma. These hiatuses correspond well with the timing of the Pliocene Warm Period and the climatic transitions of the Mid-Pleistocene Revolution and the Mid-Brunhes, as well as with periods of reduced or non-deposition on the Maurice Ewing Bank, also located in the path of the ACC (Ciesielski, 1982). Interestingly, sediment cores recovered from regions outside of the ACC that experience significant bottom water flow (e.g. fracture zones and the western margins of continents), including the Vema Channel (Ledbetter et al., 1978), the South Australia Basin (Ledbetter, 1981), and the continental margin of Northwest Africa (Stein et al., 1986), also show intervals of reduced or non-deposition that correlate well with the timing of hiatuses in the subantarctic Pacific. This correlation could indicate that the Pliocene Warm Period and the climatic transitions of the Mid-Pleistocene Revolution and Mid-Brunhes were characterized not only by a more vigourous ACC but also by a stronger and more globally-distributed overturning circulation than the present day.

  11. Population studies of fungal plant pathogens: Perspectives for ...

    African Journals Online (AJOL)

    In this article the potential of how improved disease management strategies embodied in integrated disease management (IDM) can be developed based on a clear understanding of the pathosystem is discussed. We demonstrate that population and molecular genetics can be used to define pathosystems, estimate the ...

  12. Mangrove expansion and population structure at a planted site, East ...

    African Journals Online (AJOL)

    The expansion of mangroves was measured using past aerial photographs and Esri ArcGIS Desktop 10 software. In addition, field surveys were completed in 2011 to determine the population structure of the present mangrove forest and relate this to environmental conditions. The study showed that mangrove area cover ...

  13. Differences in endozoochorous dispersal between aquatic plant species, with reference to plant population persistence in rivers

    NARCIS (Netherlands)

    Pollux, B.J.A.; Santamaria, L.; Ouborg, N.J.

    2005-01-01

    1. In river ecosystems, populations are continuously subjected to unidirectional downstream currents resulting in a downstream movement of populations. To ensure long-term population persistence in rivers, organisms must have a mechanism for upstream dispersal, which allows them to re-colonise

  14. 77 FR 45869 - Endangered and Threatened Wildlife and Plants; Listing the British Columbia Distinct Population...

    Science.gov (United States)

    2012-08-01

    ... component of goshawk diets (Lewis et al. 2006, pp. 1153-1156). Red squirrel densities on the Queen Charlotte... stands by red squirrels. (7) Comment: Prey populations may be more stable within the range of the Queen... Wildlife and Plants; Listing the British Columbia Distinct Population Segment of the Queen Charlotte...

  15. Plant performance and population characteristics of Orchis simia (Orchidaceae) in two extremes of its distribution area

    NARCIS (Netherlands)

    Ellers, J.

    1996-01-01

    This is a comparative study on plant performance and population characteristics among populations of Orchis simia (Orchidaceae) in both the south-eastern and north-western limits of its distribution area, viz. on Cyprus and in northern France and the southern part of the Netherlands. Differences in

  16. Genetic variability in chronic irradiated plant populations - Polymorphism and activity of antioxidant enzymes in chronic irradiated plant populations

    Energy Technology Data Exchange (ETDEWEB)

    Volkova, Polina Y.; Geras' kin, Stanislav A. [Russian Institute of Agricultural Radiology and Agroecology, 249030, Obninsk, Kievskoe shosse 109 km (Russian Federation)

    2014-07-01

    Introduction: The gene pool of natural population is constantly changing in order to provide the greatest fitness at this time. Ability of population to adapt to changing environmental conditions depends on genetic polymorphism of traits which are operates by selection. Chronic stress exposure can change amount or structure intra-population variability. Therefore, it is necessary to analyze the relationships between genetic polymorphism and stress factors, such as radiation exposure. This studies my assist in the development of new bio-indication methods. Materials and methods: Studying sites: Bryansk region is the most contaminated region of Russia as a result of Chernobyl accident. The initial activity by {sup 137}Cs on this territory reached 1 MBq/m{sup 2} above surface. Our study conducted in several districts of Bryansk region, which are characterized the most dose rate. Experimental sites similar to climate characteristics, stand of trees is homogeneous, pine trees take up a significant part of phytocenosis. Heavy metals content in soils and cones be within background. Dose rates vary from 0.14 to 130 mGy/year. Object: Pinus sylvestris L.,the dominant tree species in North European and Asian boreal forests. Scots pine has a long maturation period (18-20 month), which means that significant DNA damage may accumulate in the undifferentiated stem cells, even at low doses (or dose rates) during exposure to low concentrations of contaminants Isozyme analysis: We evaluated isozyme polymorphism of three antioxidant enzymes: superoxide dismutase, glutatione reductase and glutatione peroxidase. Analysis of enzymes activities: We chose key enzymes of antioxidant system for this experiment: superoxide dismutase, catalase and peroxidase. Results and conclusions: We estimated frequency of each allele in reference and experimental populations. based It was showed that frequency of rare alleles increase in chronic irradiated populations, i.e. increase the sampling variance

  17. Plant-soil feedbacks and mycorrhizal type influence temperate forest population dynamics.

    Science.gov (United States)

    Bennett, Jonathan A; Maherali, Hafiz; Reinhart, Kurt O; Lekberg, Ylva; Hart, Miranda M; Klironomos, John

    2017-01-13

    Feedback with soil biota is an important determinant of terrestrial plant diversity. However, the factors regulating plant-soil feedback, which varies from positive to negative among plant species, remain uncertain. In a large-scale study involving 55 species and 550 populations of North American trees, the type of mycorrhizal association explained much of the variation in plant-soil feedbacks. In soil collected beneath conspecifics, arbuscular mycorrhizal trees experienced negative feedback, whereas ectomycorrhizal trees displayed positive feedback. Additionally, arbuscular mycorrhizal trees exhibited strong conspecific inhibition at multiple spatial scales, whereas ectomycorrhizal trees exhibited conspecific facilitation locally and less severe conspecific inhibition regionally. These results suggest that mycorrhizal type, through effects on plant-soil feedbacks, could be an important contributor to population regulation and community structure in temperate forests. Copyright © 2017, American Association for the Advancement of Science.

  18. Winter Climate Limits Subantarctic Low Forest Growth and Establishment

    Science.gov (United States)

    Harsch, Melanie A.; McGlone, Matt S.; Wilmshurst, Janet M.

    2014-01-01

    Campbell Island, an isolated island 600 km south of New Zealand mainland (52°S, 169°E) is oceanic (Conrad Index of Continentality  = −5) with small differences between mean summer and winter temperatures. Previous work established the unexpected result that a mean annual climate warming of c. 0.6°C since the 1940's has not led to upward movement of the forest limit. Here we explore the relative importance of summer and winter climatic conditions on growth and age-class structure of the treeline forming species, Dracophyllum longifolium and Dracophyllum scoparium over the second half of the 20th century. The relationship between climate and growth and establishment were evaluated using standard dendroecological methods and local climate data from a meteorological station on the island. Growth and establishment were correlated against climate variables and further evaluated within hierarchical regression models to take into account the effect of plot level variables. Winter climatic conditions exerted a greater effect on growth and establishment than summer climatic conditions. Establishment is maximized under warm (mean winter temperatures >7 °C), dry winters (total winter precipitation <400 mm). Growth, on the other hand, is adversely affected by wide winter temperature ranges and increased rainfall. The contrasting effect of winter warmth on growth and establishment suggests that winter temperature affects growth and establishment through differing mechanisms. We propose that milder winters enhance survival of seedlings and, therefore, recruitment, but increases metabolic stress on established plants, resulting in lower growth rates. Future winter warming may therefore have complex effects on plant growth and establishment globally. PMID:24691026

  19. POPULATION OF THE MACARONI PENGUIN EUDYPTES ...

    African Journals Online (AJOL)

    There is indication that numbers of macaroni penguins Eudyptes chrysolophus at subantarctic Marion Island have decreased since the early 1980s. Estimates of the population at the island fell from about 405 000 pairs in 1983/84 and 434 000 pairs in 1994/95 to about 356 000 pairs in 2002/03. Two large colonies, at ...

  20. POPULATION DYNAMICS OF THE WANDERING ALBATROSS ...

    African Journals Online (AJOL)

    The subantarctic Prince Edward Islands (Marion and Prince Edward) support the largest breeding population of the Vulnerable wandering albatross Diomedea exulans. The number of birds breeding at Marion Island has fluctuated over the past three decades apparently as a result of both real changes in the size of the ...

  1. POPULATION AND BREEDING OF THE GENTOO PENGUIN ...

    African Journals Online (AJOL)

    The numbers of gentoo penguins Pygoscelis papua breeding at subantarctic Marion Island fell by 40% from 1994/95 to 2002/03, from 1 352 pairs to 806 pairs. Apart from a slight increase in 1998/99, there was a steady decrease in numbers breeding between 1995/96 and 2000/01, when the population stabilized. There is ...

  2. Permeable bio-reactive barriers to address petroleum hydrocarbon contamination at subantarctic Macquarie Island.

    Science.gov (United States)

    Freidman, Benjamin L; Terry, Deborah; Wilkins, Dan; Spedding, Tim; Gras, Sally L; Snape, Ian; Stevens, Geoffrey W; Mumford, Kathryn A

    2017-05-01

    A reliance on diesel generated power and a history of imperfect fuel management have created a legacy of petroleum hydrocarbon contamination at subantarctic Macquarie Island. Increasing environmental awareness and advances in contaminant characterisation and remediation technology have fostered an impetus to reduce the environmental risk associated with legacy sites. A funnel and gate permeable bio-reactive barrier (PRB) was installed in 2014 to address the migration of Special Antarctic Blend diesel from a spill that occurred in 2002, as well as older spills and residual contaminants in the soil at the Main Power House. The PRB gate comprised of granular activated carbon and natural clinoptilolite zeolite. Petroleum hydrocarbons migrating in the soil water were successfully captured on the reactive materials, with concentrations at the outflow of the barrier recorded as being below reporting limits. The nutrient and iron concentrations delivered to the barrier demonstrated high temporal variability with significant iron precipitation observed across the bed. The surface of the granular activated carbon was largely free from cell attachment while natural zeolite demonstrated patchy biofilm formation after 15 months following PRB installation. This study illustrates the importance of informed material selection at field scale to ensure that adsorption and biodegradation processes are utilised to manage the environmental risk associated with petroleum hydrocarbon spills. This study reports the first installation of a permeable bio-reactive barrier in the subantarctic. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Cytotoxic activity of marine sponge extracts from the sub-Antarctic Islands and the Southern Ocean

    Directory of Open Access Journals (Sweden)

    Elisabeth K. Olsen

    2016-11-01

    Full Text Available Over the past 50 years, marine invertebrates, especially sponges, have proven to be a valuable source of new and/or bioactive natural products that have the potential to be further developed as lead compounds for pharmaceutical applications. Although marine benthic invertebrate communities occurring off the coast of South Africa have been explored for their biomedicinal potential, the natural product investigation of marine sponges from the sub-Antarctic Islands in the Southern Ocean for the presence of bioactive secondary metabolites has been relatively unexplored thus far. We report here the results for the biological screening of both aqueous and organic extracts prepared from nine specimens of eight species of marine sponges, collected from around Marion Island and the Prince Edward Islands in the Southern Ocean, for their cytotoxic activity against three cancer cell lines. The results obtained through this multidisciplinary collaborative research effort by exclusively South African institutions has provided an exciting opportunity to discover cytotoxic compounds from sub-Antarctic sponges, whilst contributing to our understanding of the biodiversity and geographic distributions of these cold-water invertebrates. Therefore, we acknowledge here the various contributions of the diverse scientific disciplines that played a pivotal role in providing the necessary platform for the future natural products chemistry investigation of these marine sponges from the sub- Antarctic Islands and the Southern Ocean.

  4. Population genetic structure in six sympatric and widespread aquatic plants inhabiting diverse lake environments in China.

    Science.gov (United States)

    Cao, Qian-Jin; Mei, Fang-Fang; Wang, Ling

    2017-08-01

    Many aquatic plant species are distributed over large areas and diverse environments with populations interconnected by abiotic and biotic mediators. Here, we examined differences and similarities in the population genetic structure of six sympatric and widespread aquatic plant species. We sampled the aquatic species from six Chinese lakes found on plateaus, plains, and different river systems and analyzed them using inter-simple sequence repeat (ISSR) markers. Samples originating from each lake tended to cluster together. Of the six species, only Nymphoides peltata and Myriophyllum spicatum could be divided into plateau and plain groups, once Taihu Lake individuals were excluded. Genetic similarities between populations connected by the Yangtze River were not consistently higher than unconnected populations. Populations from Taihu Lake and/or Weishanhu Lake were distant from other lake populations for all species except Potamogeton lucens . The Taihu and Weishanhu populations clustered for Ceratophyllum demersum and Typha latifolia . Hydrophilous C. demersum had the lowest gene flow ( Nm  = 0.913), whereas the entomophilous Hydrocharis dubia ( Nm  = 2.084) and N. peltata ( Nm  = 2.204) had the highest gene flow. The genetic relationships among distant populations of aquatic plants reflect the comprehensive effects of environmental selection pressure and biotic and abiotic connectivity. Differences in environmental factors between plateau and plain lakes and long distance hydrochory have limited importance on aquatic plant genetic structures. Among multiple evolutionary forces, gene flow mediated by birds may play the most important role in the formation of genetic patterns in the six species examined. For example, the close genetic relationship between Taihu Lake and Weishanhu Lake populations, each in different river systems and with different climates, may be related to the migration routes of birds. Differences in gene flow among the six aquatic plants

  5. Genotypic and phenotypic diversity in populations of plant-probiotic Pseudomonas spp. colonizing roots

    Science.gov (United States)

    Picard, Christine; Bosco, Marco

    2008-01-01

    Several soil microorganisms colonizing roots are known to naturally promote the health of plants by controlling a range of plant pathogens, including bacteria, fungi, and nematodes. The use of theses antagonistic microorganisms, recently named plant-probiotics, to control plant-pathogenic fungi is receiving increasing attention, as they may represent a sustainable alternative to chemical pesticides. Many years of research on plant-probiotic microorganisms (PPM) have indicated that fluorescent pseudomonads producing antimicrobial compounds are largely involved in the suppression of the most widespread soilborne pathogens. Phenotype and genotype analysis of plant-probiotic fluorescent pseudomonads (PFP) have shown considerable genetic variation among these types of strains. Such variability plays an important role in the rhizosphere competence and the biocontrol ability of PFP strains. Understanding the mechanisms by which genotypic and phenotypic diversity occurs in natural populations of PFP could be exploited to choose those agricultural practices which best exploit the indigenous PFP populations, or to isolate new plant-probiotic strains for using them as inoculants. A number of different methods have been used to study diversity within PFP populations. Because different resolutions of the existing microbial diversity can be revealed depending on the approach used, this review first describes the most important methods used for the assessment of fluorescent Pseudomonas diversity. Then, we focus on recent data relating how differences in genotypic and phenotypic diversity within PFP communities can be attributed to geographic location, climate, soil type, soil management regime, and interactions with other soil microorganisms and host plants. It becomes evident that plant-related parameters exert the strongest influence on the genotypic and phenotypic variations in PFP populations.

  6. The effects of plant cover on population of pear psylla (Cacopsylla pyricola and its predators

    Directory of Open Access Journals (Sweden)

    Mohammad Saeed Emami

    2017-01-01

    Full Text Available Cacopsylla pyricola (Förster, 1848 (Hemiptera: Psyllidae is a serious pest of pear in all pear growing areas. In the scope of an integrated pest management, a two consecutive years study was carried out to determine the effects of plant cover on pear psyllid population and its predators. Two treatments including plant cover and bare ground were applied in a randomized complete block design with three replicates. The sampling of the pest and its predators were done weekly by beating technique and leaf sampling. The data were subjected to analysis of variance (ANOVA. The results showed that plant cover had significant effect on the increase of predators on the trees (P < 0.001. The psyllid specialist predator, Anthocoris nemoralis (Fabricius, 1794, had the highest population among the pear psyllid predators (0.29 per sample. Plant cover had no significant effect on reducing the population of eggs, nymphs and adults of the pear psyllid. Despite the increase in the population of predators led by plant cover, lack of their effectiveness to reduce the pear psyllid population is discussed.

  7. Transcriptional variation associated with cactus host plant adaptation in Drosophila mettleri populations.

    Science.gov (United States)

    Hoang, Kim; Matzkin, Luciano M; Bono, Jeremy M

    2015-10-01

    Although the importance of host plant chemistry in plant-insect interactions is widely accepted, the genetic basis of adaptation to host plants is not well understood. Here, we investigate transcriptional changes associated with a host plant shift in Drosophila mettleri. While D. mettleri is distributed mainly throughout the Sonoran Desert where it specializes on columnar cacti (Carnegiea gigantea and Pachycereus pringleii), a population on Santa Catalina Island has shifted to chemically divergent coastal prickly pear cactus (Opuntia littoralis). We compared gene expression of larvae from the Sonoran Desert and Santa Catalina Island when reared on saguaro (C. gigantea), coastal prickly pear and laboratory food. Consistent with expectations based on the complexity and toxicity of cactus relative to laboratory food, within-population comparisons between larvae reared on these food sources revealed transcriptional differences in detoxification and other metabolic pathways. The majority of transcriptional differences between populations on the cactus hosts were independent of the rearing environment and included a disproportionate number of genes involved in processes relevant to host plant adaptation (e.g. detoxification, central metabolism and chemosensory pathways). Comparisons of transcriptional reaction norms between the two populations revealed extensive shared plasticity that likely allowed colonization of coastal prickly pear on Santa Catalina Island. We also found that while plasticity may have facilitated subsequent adaptive divergence in gene expression between populations, the majority of genes that differed in expression on the novel host were not transcriptionally plastic in the presumed ancestral state. © 2015 John Wiley & Sons Ltd.

  8. Isolation and characterization of Campylobacter jejuni subsp jejuni from macaroni penguins (Eudyptes chrysolophus) in the subantarctic region

    DEFF Research Database (Denmark)

    Broman, T.; Bergstrom, S.; On, Stephen L.W.

    2000-01-01

    On Bird Island, South Georgia, albatrosses (n = 140), penguins (n = 100), and fur seals (n = 206) were sampled for Campylobacter jejuni. C. jejuni subsp. jejuni was recovered from three macaroni penguins (Eudyptes chrysolophus). These isolates, the first reported for the subantarctic region, showed...

  9. Spatial dynamics of two introduced species of carabid beetles on the sub-Antarctic island of South Georgia.

    NARCIS (Netherlands)

    Brandjes, G.J.; Block, W.; Ernsting, G.

    1999-01-01

    On the sub-Antarctic island of South Georgia two species of predatory beetle, Trechisibus antarcticus and Oopterus soledadinus (Coleoptera, Carabidae), were accidentally introduced. The colonisation process offers unique opportunities for testing ecological hypotheses in the field. As a basis for

  10. Causes and consequences of complex population dynamics in an annual plant, Cardamine pensylvanica

    Energy Technology Data Exchange (ETDEWEB)

    Crone, E.E.

    1995-11-08

    The relative importance of density-dependent and density-independent factors in determining the population dynamics of plants has been widely debated with little resolution. In this thesis, the author explores the effects of density-dependent population regulation on population dynamics in Cardamine pensylvanica, an annual plant. In the first chapter, she shows that experimental populations of C. pensylvanica cycled from high to low density in controlled constant-environment conditions. These cycles could not be explained by external environmental changes or simple models of direct density dependence (N{sub t+1} = f[N{sub t}]), but they could be explained by delayed density dependence (N{sub t+1} = f[N{sub t}, N{sub t+1}]). In the second chapter, she shows that the difference in the stability properties of population growth models with and without delayed density dependence is due to the presence of Hopf as well as slip bifurcations from stable to chaotic population dynamics. She also measures delayed density dependence due to effects of parental density on offspring quality in C. pensylvanica and shows that this is large enough to be the cause of the population dynamics observed in C. pensylvanica. In the third chapter, the author extends her analyses of density-dependent population growth models to include interactions between competing species. In the final chapter, she compares the effects of fixed spatial environmental variation and variation in population size on the evolutionary response of C. pensylvanica populations.

  11. Population dynamics of bacteria involved in enhanced biological phosphorus removal in Danish wastewater treatment plants.

    Science.gov (United States)

    Mielczarek, Artur Tomasz; Nguyen, Hien Thi Thu; Nielsen, Jeppe Lund; Nielsen, Per Halkjær

    2013-03-15

    The enhanced biological phosphorus removal (EBPR) process is increasingly popular as a sustainable method for removal of phosphorus (P) from wastewater. This study consisted of a comprehensive three-year investigation of the identity and population dynamics of polyphosphate-accumulating organisms (PAOs) and glycogen-accumulating organisms (GAOs) in 28 Danish municipal wastewater treatment plants with nutrient removal. Fluorescence in situ hybridization was applied to quantify ten probe-defined populations of PAO and GAO that in total constituted a large fraction (30% on average) of the entire microbial community targeted by the EUBmix probes. Two PAO genera, Accumulibacter and Tetrasphaera, were very abundant in all EBPR plants (average of 3.7% and 27% of all bacteria, respectively), and their abundance was relatively stable in the Danish full-scale plants without clear temporal variations. GAOs were occasionally present in some plants (Competibacter in 11 plants, Defluviicoccus in 6 plants) and were consistent in only a few plants. This shows that these were not core species in the EBPR communities. The total GAO abundance was always lower than that of Accumulibacter. In plants without EBPR design, the abundance of PAO and GAO was significantly lower. Competibacter correlated in general with high fraction of industrial wastewater. In specific plants Accumulibacter correlated with high C/P ratio of the wastewater and Tetrasphaera with high organic loading. Interestingly, the relative microbial composition of the PAO/GAO species was unique to each plant over time, which gives a characteristic plant-specific "fingerprint". Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Herbivory and growth in terrestrial and aquatic populations of amphibious stream plants

    DEFF Research Database (Denmark)

    Sand-Jensen, Kaj; Jacobsen, Dean

    2002-01-01

    1. Many amphibious plant species grow in the transition between terrestrial and submerged vegetation in small lowland streams. We determined biomass development, leaf turnover rate and invertebrate herbivory during summer in terrestrial and aquatic populations of three amphibious species...... production (average 1.2-5.1%) than aquatic populations (2.9-17.3%), while the same plant dry mass was consumed per unit ground area. 3. Grazing loss increased linearly with leaf age apart from the youngest leaf stages. Grazing loss during the lifetime of leaves was therefore 2.4-3.1 times higher than mean...... apparent loss to standing leaves of all ages. The results imply that variation in density of grazers relative to plant production can account for differences in grazing impact between terrestrial and aquatic populations, and that fast leaf turnover keeps apparent grazing damage down. 4. We conclude...

  13. How to conserve threatened Chinese plant species with extremely small populations?

    Directory of Open Access Journals (Sweden)

    Sergei Volis

    2016-02-01

    Full Text Available The Chinese flora occupies a unique position in global plant diversity, but is severely threatened. Although biodiversity conservation in China has made significant progress over the past decades, many wild plant species have extremely small population sizes and therefore are in extreme danger of extinction. The concept of plant species with extremely small populations (PSESPs, recently adopted and widely accepted in China, lacks a detailed description of the methodology appropriate for conserving PSESPs. Strategies for seed sampling, reintroduction, protecting PSESP locations, managing interactions with the local human population, and other conservation aspects can substantially differ from those commonly applied to non-PSESPs. The present review is an attempt to provide a detailed conservation methodology with realistic and easy-to-follow guidelines for PSESPs in China.

  14. Host plant use drives genetic differentiation in syntopic populations of Maculinea alcon

    DEFF Research Database (Denmark)

    Tartally, András; Kelager, Andreas; Fürst, Matthias Alois

    2016-01-01

    The rare socially parasitic butterfly Maculinea alcon occurs in two forms, which are characteristic of hygric or xeric habitats and which exploit different host plants and host ants. The status of these two forms has been the subject of considerable controversy. Populations of the two forms...... on different host plants, each with a distinct flowering phenology, providing a temporal rather than spatial barrier to gene flow....

  15. Disjunct populations of European vascular plant species keep the same climatic niches

    OpenAIRE

    Wasof, Safaa; Lenoir, Jonathan; Aarrestad, Per Arild; Alsos, Inger Greve; Armbruster, W. Scott; Austrheim, Gunnar; Bakkestuen, Vegar; Birks, H. John B.; Bråthen, Kari Anne; Broennimann, Olivier; Brunet, Jörg; Bruun, Hans Henrik; Dahlberg, Carl Johan; Diekmann, Martin; Dullinger, Stefan

    2015-01-01

    Aim Previous research on how climatic niches vary across species ranges has focused on a limited number of species, mostly invasive, and has not, to date, been very conclusive. Here we assess the degree of niche conservatism between distant populations of native alpine plant species that have been separated for thousands of years.LocationEuropean Alps and Fennoscandia. Methods Of the studied pool of 888 terrestrial vascular plant species occurring in both the Alps and Fennoscandia, we used tw...

  16. POPULATION NUMBERS OF FUR SEALS AT PRINCE EDWARD ...

    African Journals Online (AJOL)

    At a mean intrinsic rate of natural increase of 16.2% per year, Antarctic fur seals appear to be in the rapid recolonization phase of population growth. Breeding colonies of Subantarctic fur seals, largely found on the entire east coast, produced an estimated 15 000 pups, and the population had maintained a mean intrinsic ...

  17. Conservation state of populations of rare plant species in highly transformed meadow steppes of Southern Opillya

    Directory of Open Access Journals (Sweden)

    I. I. Dmytrash-Vatseba

    2016-09-01

    Full Text Available Degradation of natural habitats causes rapid extinction of rare plant populations. The diversity of rare plant species in the meadow steppes of Southern Opillya (Western Ukraine depends strongly on patch area, pasture digression of vegetation and a variety of eco-coenotical conditions. The main threats for the rare components of the meadow steppe flora are reduction of habitat and overgrazing. Spatial connections between sites are unable to support a constant rare plant population. The analysis of the composition of rare plant meadow-steppe species indicated that habitats with similar rare species composition usually have similar parameters of area, stages of pasture digression and eco-coenotical conditions. Spatial connectivity of patches does not ensure species similarity of rare components of the flora. Rare plant species were grouped according to their preferences for habitat , area and condition. In small patches subject to any stage of pasture digression grow populations of Adonis vernalis L., Pulsatilla patens (L. Mill., P. grandis Wender., Stipa capillata L., S. рennata L., Chamaecytisus blockianus (Pawł. Klásková etc. On the contrary, populations of other species (Carlina onopordifolia Besser. ex Szafer., Kuecz. et Pawł., Adenophora liliifolia (L. Ledeb. ex A. DC., Crambe tataria Sebeók, Euphorbia volhynica Besser ex Racib., Stipa tirsa Stev. etc. prefer large habitats, not changed by pasture digression. Prevention of reduction of rare species diversity requires preservation (also extension of patch area and regulation of grazing intensity.

  18. Lead and zinc accumulation and tolerance in populations of six wetland plants

    Energy Technology Data Exchange (ETDEWEB)

    Deng, H. [Biology Department and Croucher Institute for Environmental Sciences, Hong Kong Baptist University, Kowloon, Hong Kong (China); Department of Environmental Science and Technology, East China Normal University, Shanghai (China); Ye, Z.H. [Biology Department and Croucher Institute for Environmental Sciences, Hong Kong Baptist University, Kowloon, Hong Kong (China); School of Life Sciences, Zhongshan (Sun Yat-sen) University, Guangzhou 510275 (China); Wong, M.H. [Biology Department and Croucher Institute for Environmental Sciences, Hong Kong Baptist University, Kowloon, Hong Kong (China)]. E-mail: mhwong@hkbu.edu.hk

    2006-05-15

    Wetland plants such as Typha latifolia and Phragmites australis have been indicated to show a lack of evolution of metal tolerance in metal-contaminated populations. The aim of the present study is to verify whether other common wetland plants such as Alternanthera philoxeroides and Beckmannia syzigachne, also possess the same characteristics. Lead and zinc tolerances in populations of six species collected from contaminated and clean sites were examined by hydroponics. In general, the contaminated populations did not show higher metal tolerance and accumulation than the controls. Similar growth responses and tolerance indices in the same metal treatment solution between contaminated and control populations suggest that metal tolerance in wetland plants are generally not further evolved by contaminated environment. The reasons may be related to the special root anatomy in wetland plants, the alleviated metal toxicity by the reduced rooting conditions and the relatively high innate metal tolerance in some species. - Populations from metal contaminated sites did not have significantly higher metal tolerance indices.

  19. Perceptions of Medicinal Plant Use Amongst the Hispanic Population in the St. Louis Metropolitan Area

    Directory of Open Access Journals (Sweden)

    Kim M. Grafford

    2016-10-01

    Full Text Available Introduction: Medicinal plant use in the United States has increased as reported by the National Center of Complementary and Integrative Health and U.S. Census Bureau.However, little is known about how many minority groups in the United States use medicinal plants.There is a rise in the Hispanic population; a community with a steep tradition of medicinal plant use, in the U.S., so understanding the perceptions of medicinal plant use is useful to healthcare providers. Methods: A survey was designed to gauge a better understanding of the perceptions of medicinal plant use amongst Latino patients with varying education levels who reside in the St. Louis Metropolitan Area. Survey questions highlighted the perceptions of medicinal plants use, patient communication regarding medicinal plant use with healthcare providers (pharmacists and doctors, and the impact the education level has on medicinal plant use. Results: Surveys were distributed to six different investigational sites around the St. Louis Metropolitan Area from August 2015 to December 2015. Survey respondents identified 45 different plants/herbs that they currently use or had used at some point in their life. Those with higher levels of education had varying opinions on medicinal plant use with their current practices. Conclusion: The participants’ high interest in the use of medicinal plants exemplifies the need for enhanced communication between patients and healthcare professionals about medicinal plant use. However, it was hard to determine whether the participants’ level of education had any direct relationship to this use. Conflict of Interest None   Type: Original Research

  20. Uncoupling the effects of seed predation and seed dispersal by granivorous ants on plant population dynamics.

    Directory of Open Access Journals (Sweden)

    Xavier Arnan

    Full Text Available Secondary seed dispersal is an important plant-animal interaction, which is central to understanding plant population and community dynamics. Very little information is still available on the effects of dispersal on plant demography and, particularly, for ant-seed dispersal interactions. As many other interactions, seed dispersal by animals involves costs (seed predation and benefits (seed dispersal, the balance of which determines the outcome of the interaction. Separate quantification of each of them is essential in order to understand the effects of this interaction. To address this issue, we have successfully separated and analyzed the costs and benefits of seed dispersal by seed-harvesting ants on the plant population dynamics of three shrub species with different traits. To that aim a stochastic, spatially-explicit individually-based simulation model has been implemented based on actual data sets. The results from our simulation model agree with theoretical models of plant response dependent on seed dispersal, for one plant species, and ant-mediated seed predation, for another one. In these cases, model predictions were close to the observed values at field. Nonetheless, these ecological processes did not affect in anyway a third species, for which the model predictions were far from the observed values. This indicates that the balance between costs and benefits associated to secondary seed dispersal is clearly related to specific traits. This study is one of the first works that analyze tradeoffs of secondary seed dispersal on plant population dynamics, by disentangling the effects of related costs and benefits. We suggest analyzing the effects of interactions on population dynamics as opposed to merely analyzing the partners and their interaction strength.

  1. Identification of Novel Growth Regulators in Plant Populations Expressing Random Peptides.

    Science.gov (United States)

    Bao, Zhilong; Clancy, Maureen A; Carvalho, Raquel F; Elliott, Kiona; Folta, Kevin M

    2017-10-01

    The use of chemical genomics approaches allows the identification of small molecules that integrate into biological systems, thereby changing discrete processes that influence growth, development, or metabolism. Libraries of chemicals are applied to living systems, and changes in phenotype are observed, potentially leading to the identification of new growth regulators. This work describes an approach that is the nexus of chemical genomics and synthetic biology. Here, each plant in an extensive population synthesizes a unique small peptide arising from a transgene composed of a randomized nucleic acid sequence core flanked by translational start, stop, and cysteine-encoding (for disulfide cyclization) sequences. Ten and 16 amino acid sequences, bearing a core of six and 12 random amino acids, have been synthesized in Arabidopsis (Arabidopsis thaliana) plants. Populations were screened for phenotypes from the seedling stage through senescence. Dozens of phenotypes were observed in over 2,000 plants analyzed. Ten conspicuous phenotypes were verified through separate transformation and analysis of multiple independent lines. The results indicate that these populations contain sequences that often influence discrete aspects of plant biology. Novel peptides that affect photosynthesis, flowering, and red light response are described. The challenge now is to identify the mechanistic integrations of these peptides into biochemical processes. These populations serve as a new tool to identify small molecules that modulate discrete plant functions that could be produced later in transgenic plants or potentially applied exogenously to impart their effects. These findings could usher in a new generation of agricultural growth regulators, herbicides, or defense compounds. © 2017 American Society of Plant Biologists. All Rights Reserved.

  2. THE DISTRIBUTION AND SPREAD OF ALIEN VASCULAR PLANTS ...

    African Journals Online (AJOL)

    Surveys of alien plants at subantarctic Prince Edward Island in 2001 show that the ranges of all three introduced species have increased since the last survey in 1998. Poa annua, the longest-established species, increased its range substantially after 1987, prior to which it was confined to a single site for more than 20 years ...

  3. Effects of precipitation change and neighboring plants on population dynamics of Bromus tectorum.

    Science.gov (United States)

    Prevéy, Janet S; Seastedt, Timothy R

    2015-11-01

    Shifting precipitation patterns resulting from global climate change will influence the success of invasive plant species. In the Front Range of Colorado, Bromus tectorum (cheatgrass) and other non-native winter annuals have invaded grassland communities and are becoming more abundant. As the global climate warms, more precipitation may fall as rain rather than snow in winter, and an increase in winter rain could benefit early-growing winter annuals, such as B. tectorum, to the detriment of native species. In this study we measured the effects of simulated changes in seasonal precipitation and presence of other plant species on population growth of B. tectorum in a grassland ecosystem near Boulder, Colorado, USA. We also performed elasticity analyses to identify life transitions that were most sensitive to precipitation differences. In both study years, population growth rates were highest for B. tectorum growing in treatments receiving supplemental winter precipitation and lowest for those receiving the summer drought treatment. Survival of seedlings to flowering and seed production contributed most to population growth in all treatments. Biomass of neighboring native plants was positively correlated with reduced population growth rates of B. tectorum. However, exotic plant biomass had no effect on population growth rates. This study demonstrates how interacting effects of climate change and presence of native plants can influence the population growth of an invasive species. Overall, our results suggest that B. tectorum will become more invasive in grasslands if the seasonality of precipitation shifts towards wetter winters and allows B. tectorum to grow when competition from native species is low.

  4. Large bottleneck size in Cauliflower Mosaic Virus populations during host plant colonization.

    Directory of Open Access Journals (Sweden)

    Baptiste Monsion

    2008-10-01

    Full Text Available The effective size of populations (Ne determines whether selection or genetic drift is the predominant force shaping their genetic structure and evolution. Despite their high mutation rate and rapid evolution, this parameter is poorly documented experimentally in viruses, particularly plant viruses. All available studies, however, have demonstrated the existence of huge within-host demographic fluctuations, drastically reducing Ne upon systemic invasion of different organs and tissues. Notably, extreme bottlenecks have been detected at the stage of systemic leaf colonization in all plant viral species investigated so far, sustaining the general idea that some unknown obstacle(s imposes a barrier on the development of all plant viruses. This idea has important implications, as it appoints genetic drift as a constant major force in plant virus evolution. By co-inoculating several genetic variants of Cauliflower mosaic virus into a large number of replicate host plants, and by monitoring their relative frequency within the viral population over the course of the host systemic infection, only minute stochastic variations were detected. This allowed the estimation of the CaMV Ne during colonization of successive leaves at several hundreds of viral genomes, a value about 100-fold higher than that reported for any other plant virus investigated so far, and indicated the very limited role played by genetic drift during plant systemic infection by this virus. These results suggest that the barriers that generate bottlenecks in some plant virus species might well not exist, or can be surmounted by other viruses, implying that severe bottlenecks during host colonization do not necessarily apply to all plant-infecting viruses.

  5. Large bottleneck size in Cauliflower Mosaic Virus populations during host plant colonization.

    Science.gov (United States)

    Monsion, Baptiste; Froissart, Rémy; Michalakis, Yannis; Blanc, Stéphane

    2008-10-01

    The effective size of populations (Ne) determines whether selection or genetic drift is the predominant force shaping their genetic structure and evolution. Despite their high mutation rate and rapid evolution, this parameter is poorly documented experimentally in viruses, particularly plant viruses. All available studies, however, have demonstrated the existence of huge within-host demographic fluctuations, drastically reducing Ne upon systemic invasion of different organs and tissues. Notably, extreme bottlenecks have been detected at the stage of systemic leaf colonization in all plant viral species investigated so far, sustaining the general idea that some unknown obstacle(s) imposes a barrier on the development of all plant viruses. This idea has important implications, as it appoints genetic drift as a constant major force in plant virus evolution. By co-inoculating several genetic variants of Cauliflower mosaic virus into a large number of replicate host plants, and by monitoring their relative frequency within the viral population over the course of the host systemic infection, only minute stochastic variations were detected. This allowed the estimation of the CaMV Ne during colonization of successive leaves at several hundreds of viral genomes, a value about 100-fold higher than that reported for any other plant virus investigated so far, and indicated the very limited role played by genetic drift during plant systemic infection by this virus. These results suggest that the barriers that generate bottlenecks in some plant virus species might well not exist, or can be surmounted by other viruses, implying that severe bottlenecks during host colonization do not necessarily apply to all plant-infecting viruses.

  6. Linking native and invader traits explains native spider population responses to plant invasion

    Science.gov (United States)

    Jennifer N. Smith; Douglas J. Emlen; Dean E. Pearson

    2016-01-01

    Theoretically, the functional traits of native species should determine how natives respond to invader-driven changes. To explore this idea, we simulated a large-scale plant invasion using dead spotted knapweed (Centaurea stoebe) stems to determine if native spiders' web-building behaviors could explain differences in spider population responses to...

  7. Agronomics and economics of plant population density on processing sweet corn

    Science.gov (United States)

    A detailed analysis of the effect of plant population density on processing sweet corn is lacking in the peer-reviewed literature. Therefore, field experiments were conducted utilizing six hybrids commonly grown in the North Central Region (NCR), a primary production region of processing sweet corn ...

  8. Disjunct populations of European vascular plant species keep the same climatic niches

    DEFF Research Database (Denmark)

    Wasof, Safaa; Lenoir, Jonathan; Aarrestad, Per Arild

    2015-01-01

    Aim: Previous research on how climatic niches vary across species ranges has focused on a limited number of species, mostly invasive, and has not, to date, been very conclusive. Here we assess the degree of niche conservatism between distant populations of native alpine plant species that have be...

  9. A Bioassay for Determining Resistance Levels in Tarnished Plant Bug Populations to Neonicotinoid Insecticides

    Science.gov (United States)

    A laboratory bioassay was developed and used to test field populations of the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), for resistance development to the neonicitinoid insecticides imidacloprid (Trimax®) and thiamethoxam (Centric®). The bioassay determined LC50 values by feeding...

  10. Regulation of the seasonal population patterns of Helicoverpa armigera moths by Bt cotton planting.

    Science.gov (United States)

    Gao, Yu-Lin; Feng, Hong-Qiang; Wu, Kong-Ming

    2010-08-01

    Transgenic cotton expressing the Bacillus thuringiensis (Bt) Cry1Ac toxin has been commercially cultivated in China since 1997, and by 2000 Bt cotton had almost completely replaced non-transgenic cotton cultivars. To evaluate the impact of Bt cotton planting on the seasonal population patterns of cotton bollworm, Helicoverpa armigera, the dynamics of H. armigera moths were monitored with light traps from four locations (Xiajin, Linqing and Dingtao of Shandong Province; Guantao of Hebei Province) in high Bt density region and five locations (Anci and Xinji of Hebei Province; Dancheng and Fengqiu of Henan Province; Gaomi of Shandong Province) in low Bt density region from 1996 to 2008. A negative correlation was found between moth densities of H. armigera and the planting years of Bt cotton in both high and low Bt density areas. These data indicate that the moth population density of H. armigera was reduced with the introduction of Bt cotton in northern China. Three generations of moths occurred between early June and late September in the cotton regions. Interestingly, second-generation moths decreased and seemed to vanish in recent years in high Bt density region, but this tendency was not found in low Bt density region. The data suggest that the planting of Bt cotton in high Bt density region was effective in controlling the population density of second-generation moths. Furthermore, the seasonal change of moth patterns associated with Bt cotton planting may regulate the regional occurrence and population development of this migratory insect.

  11. Past climate-driven range shifts and population genetic diversity in arctic plants

    DEFF Research Database (Denmark)

    Pellissier, Loïc; Eidesen, Pernille Bronken; Ehrich, Dorothee

    2016-01-01

    High intra-specific genetic diversity is necessary for species adaptation to novel environments under climate change, but species tracking suitable conditions are losing alleles through successive founder events during range shift. Here, we investigated the relationship between range shift since ...... the Last Glacial Maximum (LGM) and extant population genetic diversity across multiple plant species to understand variability in species responses...

  12. Multiple QTL mapping in related plant populations via a pedigree-analysis approach

    NARCIS (Netherlands)

    Bink, M.C.A.M.; Uimari, P.; Sillanpää, M.J.; Janss, L.L.G.; Jansen, R.C.

    2002-01-01

    QTL mapping experiments in plant breeding may involve multiple populations or pedigrees that are related through their ancestors. These known relationships have often been ignored for the sake of statistical analysis, despite their potential increase in power of mapping. We describe here a Bayesian

  13. Multiple QTL mapping in related plant populations via a pedigree-analysis approach

    NARCIS (Netherlands)

    Bink, M.C.A.M.; Uimari, P.; Sillanpää, M.J.; Janss, L.L.G.; Jansen, R.C.

    QTL mapping experiments in plant breeding may involve multiple populations or pedigrees that are related through their ancestors. These known relationships have often been ignored for the sake of statistical analysis, despite their potential increase in power of mapping. We describe here a Bayesian

  14. Head Kidney Transcriptome Analysis and Characterization for the Sub-Antarctic Notothenioid Fish Eleginops maclovinus

    Directory of Open Access Journals (Sweden)

    Danixa Martínez

    2018-01-01

    Full Text Available This study describes de novo transcriptome sequencing and annotation analyses for the head kidney of the sub-Antarctic notothenioid fish Eleginops maclovinus, a sister group of the Antarctic notothenioid fish clade. Moreover, E. maclovinus is one of the most eurythermal and euryhaline representatives of the Notothenioidei suborder. RNA-seq data were generated by the 454 GS Junior system, resulting in 11,207 contigs that were then assembled by the Genomic Workbench CLC software. The transcriptome was annotated by BLASTing each sequence against the universal, non-redundant NCBI database (National Center for Biotechnology Information using the AUSTRAL-omics computer cluster. A significant number of transcripts related to innate and adaptive immunity were found in the sequences, which could be used as references in future immunological studies in E. maclovinus.

  15. The Quarantine Protection of Sub-Antarctic Australia: Two Islands, Two Regimes

    Directory of Open Access Journals (Sweden)

    Sandra Potter

    2007-11-01

    Full Text Available Sub-Antarctic Heard Island and Macquarie Island are among Australia’s offshore properties susceptible to colonization by species introduced by humans. While both islands share World Heritage status and are IUCN Category Ia Protected Areas (Strict Nature Reserves, different quarantine protection regimes are in operation. Macquarie Island’s biosecurity appears to be less catered for while the means and likelihood of introductions are greater. The administrative, political, practical and geographical contexts within which quarantine management planning takes place variously impact on the level of quarantine protection provided to both islands. These and other remote sites of high conservation value are unlikely to receive heightened protection until the issues associated with such management contexts receive greater attention.

  16. Late Pliocene Changes in Abyssal Southern Ocean Ventilation: New Insights from the Subantarctic Pacific

    Science.gov (United States)

    Waddell, L. M.; Hendy, I. L.; Moore, T. C.; Lyle, M. W.

    2008-12-01

    New stable isotope records from subantarctic southeast Pacific cores MV0502-4JC (50°20'S, 148°08'W, 4286m) and ELT 25-11 (50°02'S, 127°31'W, 3969m) suggest that the late Pliocene climate transition (LPCT) at ~2.75 Ma marked a dramatic increase in cold, poorly ventilated water in the deepest portion of the Southern Ocean. This conclusion is based on a striking vertical stable isotopic gradient that developed between MV0502-4JC and shallower South Atlantic ODP Site 704 (46°52'S, 7°5'E, 2532 m) in the late Pliocene, a sharp contrast to the comparable benthic δ13C and δ18O values recorded at the two sites during the late Miocene. Similar to existing shallower records from the South Atlantic, benthic stable isotope records from MV0502-4JC and ELT 25-11 record a significant decrease in δ13C accompanied by an increase in δ18O in the Late Pliocene. While the δ13C decrease and δ18O increase recorded at the South Atlantic sites appears to represent the onset of a glacial pattern of oxygen isotope enrichment and reduced deep water ventilation in the Southern Ocean, the transition in MV0502-4JC and ELT 25-11 signals a far more dramatic shift in conditions at abyssal depths. First, the benthic δ13C shift appears to be more extensive and prolonged in the deep subantarctic Pacific than in the South Atlantic, and second, the δ13C decrease was accompanied by an equally dramatic increase in benthic δ18O that stands out amongst other deep sea records prior to the late Pleistocene. In MV0502-4JC these δ13C and δ18O shifts amount to -1.05‰ and +1.1‰, respectively, over the period ~2.7 to 1.9 Ma (9.6-7.3 MBSF) and are followed by a dramatic return of the benthic δ13C values to pre-LPCT values after ~1.7 Ma that is also recorded in the planktonic record. These benthic δ13C and δ18O shifts likely indicate the accumulation of an ever-larger percentage of cold, poorly-ventilated AABW in the abyssal Southern Ocean during the late Pliocene, probably due to sea ice

  17. Postglacial Records of Southern Hemisphere Westerly Wind Variability From the New Zealand Subantarctic Auckland Islands

    Science.gov (United States)

    Moy, C. M.; Vandergoes, M.; Gilmer, G. J.; Nichols, J. E.; Dagg, B. J.; Wilson, G. S.; Browne, I. M.; Curtin, L. G.; Aebig, C.; McGlone, M.

    2015-12-01

    The strength and latitudinal position of the Southern Hemisphere westerly winds (SHWW) play a fundamental role in influencing mid latitude climate and carbon dioxide exchange between the Southern Ocean and the atmosphere. Despite their importance, our understanding of past changes in the SHWW is limited by few paleoclimate records from the modern wind maximum that are often not in agreement. The New Zealand subantarctic Auckland Islands are located within the core of the modern wind belt (50°S) where the ocean-atmospheric linkages between the Antarctic and middle latitudes are strong. In contrast to other subantarctic islands on the Campbell Plateau, the Auckland Islands have protected fjord sub-basins, deep lakes, and peatlands that are advantageous for the development of high-resolution paleoclimate records. We will present ongoing work towards the establishment of multi-proxy and multi-site reconstructions of past SHWW variability from the Auckland Islands. Modern process and paleoclimate results from two research cruises in 2014 and 2015 suggest that in lacustrine and fjord settings, the degree of water column mixing, the stable isotopic composition of n-alkanes and benthic foraminifera, the influx of terrestrial organic matter are good indicators of wind-induced mixing of the water column or precipitation-driven erosion within catchments. In ombrotrophic peatlands, hydrogen isotope ratios of specific organic molecules allow reconstructions of the hydrogen isotope ratios of precipitation, which is related to precipitation source area and the latitudinal position of the SHWW. Using macrofossil counts paired with abundances of leaf wax biomarkers, we are able to estimate the moisture balance at peatland coring sites. Early results indicate an overall strengthening of the SHWW at the Auckland Islands through the Holocene. We will discuss these results within the context of complimentary records developed from New Zealand and southern South America to ultimately

  18. Different adaptations of Chinese winter-over expeditioners during prolonged Antarctic and sub-Antarctic residence

    Science.gov (United States)

    Chen, Nan; Wu, Quan; Li, Hao; Zhang, Tao; Xu, Chengli

    2016-05-01

    Prolonged residence in Antarctica is characterized by exposure to isolated, confined, and extreme (ICE) environment. Winter-over expeditioners at research stations often exhibit a complex of psychophysiological symptoms, which varied by stations and sociocultural backgrounds. To understand the different patterns of psychophysiological responses provoked by environmental stress, we conducted a longitudinal assessment of mood and endocrine function in two groups of Chinese expeditioners who were deployed to sub-Antarctic (Great Wall Station, 62°S, N = 12) and Antarctic (Zhongshan Station, 66°S, N = 16) from December 2003 to 2005. Measures of mood, thyroid function, the levels of plasma catecholamine, and circulating interleukins were obtained at departure from China, mid-winter (Antarctica), end of winter (Antarctica), and return to China, respectively. The Zhongshan Station crew experienced significant increases in fatigue, anger, tension, confusion, and decrease in free thyroxine (FT4), norepinephrine (NE), and epinephrine (E) during the winter, increase in thyrotropin (TSH) and total triiodothyronine (TT3) when returning, whereas their counterparts at Great Wall Station only experienced increased TT3 after deployment. Moreover, compared with the Great Wall Station crew, the Zhongshan Station crew exhibited greater increase in anger, greater decrease in FT4, total thyroxine (TT4), NE and E over the winter, and greater increase in TSH when returning. Chinese expeditioners who lived and worked at the Antarctic station and the sub-Antarctic station for over a year showed different change patterns in mood and endocrine hormones. Negative mood and endocrine dysfunction were positively associated with the severity of environment. The study is a supplement to scientific knowledge on psychophysiological variation under ICE environment, which has certain applied value for the development of preventive countermeasures or interventions.

  19. Plant and animal protein intake and its association with overweight and obesity among the Belgian population.

    Science.gov (United States)

    Lin, Yi; Bolca, Selin; Vandevijvere, Stefanie; De Vriese, Stephanie; Mouratidou, Theodora; De Neve, Melissa; Polet, Anja; Van Oyen, Herman; Van Camp, John; De Backer, Guy; De Henauw, Stefaan; Huybrechts, Inge

    2011-04-01

    The objective of the present study was to assess animal and plant protein intakes in the Belgian population and to examine their relationship with overweight and obesity (OB). The subjects participated in the Belgian National Food Consumption Survey conducted in 2004. Food consumption was assessed by using two non-consecutive 24 h dietary recalls. About 3083 participants ( ≥ 15 years of age; 1546 males, 1537 females) provided completed dietary information. Animal protein intake (47 g/d) contributed more to total protein intakes of 72 g/d than plant protein intake, which accounted for 25 g/d. Meat and meat products were the main contributors to total animal protein intakes (53 %), whereas cereals and cereal products contributed most to plant protein intake (54 %). Males had higher animal and plant protein intakes than females (P protein intakes were low in the whole population (0·101 and 0·174 g/d, respectively). In males, animal protein intake was positively associated with BMI (β = 0·013; P = 0·001) and waist circumference (WC; β = 0·041; P = 0·002). Both in males and females, plant protein intake was inversely associated with BMI (males: β = - 0·036; P protein intakes were lower than animal protein intakes among a representative sample of the Belgian population and decreased with age. Associations with anthropometric data indicated that plant proteins could offer a protective effect in the prevention of overweight and OB in the Belgian population.

  20. Population genetic structure of the endangered and endemic medicinal plant Commiphora wightii.

    Science.gov (United States)

    Haque, Inamul; Bandopadhyay, Rajib; Mukhopadhyay, Kunal

    2010-02-01

    Commiphora wightii is a medicinally important endangered species endemic to the Thar Desert of Rajasthan, India and adjoining areas of Pakistan. The populations of this species are declining sharply because of its extensive use as a natural herb. Random amplified polymorphic DNA analysis was conducted to find the genetic variation among 7 populations of C. wightii. Of the 100 random primers screened, 44 primers yielded 220 loci. Statistical analysis indicated low genetic diversity (H (pop) = 0.0958; I = 0.1498; mean polymorphic loci = 14.28%), and high genetic differentiation among the populations (G (ST) = 0.3990; AMOVA Phi (ST) of 0.3390; Bayesian theta ((II)) = 0.3002). The low genetic diversity may be due to geographic isolation and restricted gene flow (N (m) = 0.7533) between the fragmented populations. Unsustainable utilization of the plant has fragmented the population continuum which served the purpose of genetic exchange between populations. Mantel's test was performed which revealed a highly significant positive correlation between genetic and geographic distance (r (2) = 0.614, P = 0.023) among the populations studied. Low variation can also be attributed to poor seed setting and the slow growth pattern of the species, which is also an apomict. In UPGMA dendrogram the Commiphora wightii samples were divided into two major and one minor cluster. These findings can serve as a guide to preserving the genetic resources of this medicinal plant species.

  1. Forecasting climate change impacts on plant populations over large spatial extents

    Science.gov (United States)

    Tredennick, Andrew T.; Hooten, Mevin B.; Aldridge, Cameron L.; Homer, Collin G.; Kleinhesselink, Andrew R.; Adler, Peter B.

    2016-01-01

    Plant population models are powerful tools for predicting climate change impacts in one location, but are difficult to apply at landscape scales. We overcome this limitation by taking advantage of two recent advances: remotely sensed, species-specific estimates of plant cover and statistical models developed for spatiotemporal dynamics of animal populations. Using computationally efficient model reparameterizations, we fit a spatiotemporal population model to a 28-year time series of sagebrush (Artemisia spp.) percent cover over a 2.5 × 5 km landscape in southwestern Wyoming while formally accounting for spatial autocorrelation. We include interannual variation in precipitation and temperature as covariates in the model to investigate how climate affects the cover of sagebrush. We then use the model to forecast the future abundance of sagebrush at the landscape scale under projected climate change, generating spatially explicit estimates of sagebrush population trajectories that have, until now, been impossible to produce at this scale. Our broadscale and long-term predictions are rooted in small-scale and short-term population dynamics and provide an alternative to predictions offered by species distribution models that do not include population dynamics. Our approach, which combines several existing techniques in a novel way, demonstrates the use of remote sensing data to model population responses to environmental change that play out at spatial scales far greater than the traditional field study plot.

  2. Boom or bust? A comparative analysis of transient population dynamics in plants

    DEFF Research Database (Denmark)

    Stott, Iain; Franco, Miguel; Carslake, David

    2010-01-01

    researchers as further possible effectors of complicated dynamics. Previously published methods of transient analysis have tended to require knowledge of initial population structure. However, this has been overcome by the recent development of the parametric Kreiss bound (which describes how large...... a population must become before reaching its maximum possible transient amplification following a disturbance) and the extension of this and other transient indices to simultaneously describe both amplified and attenuated transient dynamics. We apply the Kreiss bound and other transient indices to a data base...... worrying artefact of basic model parameterization. Synthesis. Transient indices describe how big or how small plant populations can get, en route to long-term stable rates of increase or decline. The patterns we found in the potential for transient dynamics, across many species of plants, suggest...

  3. Medicinal plants profile used by the 3rd District population of Maceió-AL

    Directory of Open Access Journals (Sweden)

    S. A. S. Griz

    2017-05-01

    Full Text Available Abstract Herein the use of medicinal plants by the population of the 3rd Sanitary District of Maceió-AL city is reported. Transversal description was conducted from February 2013 to January 2014, with a sample of 116 individuals of both Gender Genders aged over 18 years. The ethnobotanical information interviews ethnobotanical information were obtained through semi - structured questionnaire featuring the use of medicinal plants and social and economical data. Descriptive statistics was applied for quantitative variables as mean and standard deviation and proportions for qualitative variables in the frequency table format. The results showed that 85.34% of the interviewees used plants for medicinal purposes. As the majority of these were (73.28% females in the age group between 30-60 years of old. Among a total of 45 identified plant species, the highest use frequency were for Boldus Peumus (bilberry, Melissa officinalis (lemon balm, and Mentha piperita (mint. The most widely used plant foliage part was (53.53% prepared as an infusion (55.5%. The use of medicinal plants in Maceió cityis widespread, highlighting the importance of ethnobotanical knowledge for the study of medicinal plants.

  4. Assessment of Genetic Heterogeneity in Structured Plant Populations Using Multivariate Whole-Genome Regression Models.

    Science.gov (United States)

    Lehermeier, Christina; Schön, Chris-Carolin; de Los Campos, Gustavo

    2015-09-01

    Plant breeding populations exhibit varying levels of structure and admixture; these features are likely to induce heterogeneity of marker effects across subpopulations. Traditionally, structure has been dealt with as a potential confounder, and various methods exist to "correct" for population stratification. However, these methods induce a mean correction that does not account for heterogeneity of marker effects. The animal breeding literature offers a few recent studies that consider modeling genetic heterogeneity in multibreed data, using multivariate models. However, these methods have received little attention in plant breeding where population structure can have different forms. In this article we address the problem of analyzing data from heterogeneous plant breeding populations, using three approaches: (a) a model that ignores population structure [A-genome-based best linear unbiased prediction (A-GBLUP)], (b) a stratified (i.e., within-group) analysis (W-GBLUP), and (c) a multivariate approach that uses multigroup data and accounts for heterogeneity (MG-GBLUP). The performance of the three models was assessed on three different data sets: a diversity panel of rice (Oryza sativa), a maize (Zea mays L.) half-sib panel, and a wheat (Triticum aestivum L.) data set that originated from plant breeding programs. The estimated genomic correlations between subpopulations varied from null to moderate, depending on the genetic distance between subpopulations and traits. Our assessment of prediction accuracy features cases where ignoring population structure leads to a parsimonious more powerful model as well as others where the multivariate and stratified approaches have higher predictive power. In general, the multivariate approach appeared slightly more robust than either the A- or the W-GBLUP. Copyright © 2015 by the Genetics Society of America.

  5. Gamma-radiation effect on the parameters of the population recovery of plants

    Directory of Open Access Journals (Sweden)

    N.I. Ivanishvili

    2016-12-01

    Full Text Available Investigation of the effects of different physic-chemical factors on the ecosystems is one of the important scientific tasks. From this perspective, it is to be mentioned an effect of such a strong damaging factor as ionizing radiation. Radiation damage is reflected differently in relation to the levels of organization of living organisms. On the relatively early stage of radiation damage determination of post-irradiation regeneration indicators on population level gives possibility to forecast the sustainability of ecosystems. In order to determine the indicators of post-irradiation regeneration of plant populations we have used as a model water plant – Lemna minor L. During the exposure of radiation on different levels of organization differences are identified not only according to qualitative features but also by the character of direction of the development of the processes of postradiation regeneration. A conclusion is made that if during the acute radiation it is possible to determine radioresistance of certain plants, which is based on the plant potential to post-radiation regeneration, the investigation carried out through chronic irradiation gives the possibility to determine the indicators of the ability of the plant to adapt to the radiation.

  6. Pollination biology of the urban populations of an ancient forest, spring ephemeral plant

    Directory of Open Access Journals (Sweden)

    Maciej A. Ziemiański

    2016-04-01

    Full Text Available Habitat fragmentation, caused by, among all, agriculture and urbanization, is one of the most important drivers of plant biodiversity decline worldwide. One of the signs of deteriorating zoogamous plant reproduction is pollen limitation, often associated with a decline in pollinator diversity and abundance. Various authors predict that the most vulnerable taxa are outbreeding plant species characterized by specialist pollination systems. We have, therefore, focused on self-incompatible Corydalis solida, an ancient forest, spring ephemeral plant, growing in three remnant urban populations in the city of Warsaw (Poland. Over two years, we checked for pollen limitation and recorded insect diversity and abundance for C. solida flowers. Our study populations composed of self-incompatible individuals were mainly visited by generalist pollinators, and produced more seeds when supplementally pollinated. Pollen limitation, however, was greater during 1 year with an early spring onset, when we observed a decline in floral visitors diversity and activity. This was probably an effect of phenological mismatch between plants and their pollinators, in this case, mostly social bees, i.e., over-wintered bumblebee queens and Apis mellifera. We conclude that for outbreeding zoogamous spring ephemerals, such as C. solida serviced by generalist pollinators, changing climatic conditions may override the effects of habitat fragmentation and influence their reproductive success.

  7. Plant Species Restoration: Effects of Different Founding Patterns on Sustaining Future Population Size and Genetic Diversity

    Directory of Open Access Journals (Sweden)

    Stephan Pelikan

    2013-03-01

    Full Text Available Efforts to sustain the earth’s biodiversity will include the establishment and manipulation of isolated rescue populations, derived either via in situ fragmentation, or under ex situ circumstances. For target species, especially those with limited propagation resources, major goals of such projects include both the optimization of population size and the preservation of genetic diversity. Such rescue populations will be founded in a variety of ways, but little is known about how the geometric patterning of founders can affect population growth and genetic diversity retention. We have developed a computer program, NEWGARDEN, to investigate this issue for plant species that vary in life history characteristics. To use NEWGARDEN, input files are created that specify the size and structure of the preserve, the positioning and genetic diversity of the founders, and life history characteristics of the species (e.g., age-specific reproduction and mortality; gene dispersal distances; rates of selfing, etc.. The program conducts matings with consequent offspring establishment such that the virtual population develops through generations as constrained by the input. Output statistics allow comparisons of population development for populations that differ in one or more input conditions. Here, with NEWGARDEN analyses modeling a triennial species, we show that rescue population project managers will often have to carefully consider the geometric placement of founders to minimize effort expended while maximizing population growth and conservation of genetic diversity, such considerations being heavily dependent on the life history characteristics of particular species.

  8. A new approach to the quantification of degree of reciprocity in distylous (sensu lato) plant populations.

    Science.gov (United States)

    Sanchez, Jose M; Ferrero, Victoria; Navarro, Luis

    2008-09-01

    Although evolution of sexual polymorphism has been traditionally analysed using discrete characters, most of these polymorphisms are continuous. This is the case of heterostyly. Heterostyly is a floral polymorphism successfully used as a model to study the evolution of the sexual systems in plants. It involves the reciprocal positioning of anthers and stigmas in flowers of different plants within the same population. Studies of the functioning of heterostyly require the quantification of the degree of reciprocity between morphs of heterostylous species. Some reciprocity indices have been proposed previously, but they show significant limitations that need to be dealt with. This paper analyses these existing indices, and proposes a new index that aims to avoid their main problems (e.g. takes into account population variability and offers a single value per population). The new index is based on the comparison of the position of every single sexual organ in the population with each and every organ of the opposite sex. To carry out all the calculations, a macro was programmed with MS Visual Basic in MS Excel. The behaviour of the index is tested using hypothetical data to simulate different situations of dimorphic populations; the index is also tested with some actual populations of different species of the genus Lithodora. The index of reciprocity proposed here is a sound alternative to previous indices: it compares stigma-stamen height gaps for all potential crosses in the population, it comprises stigma-stamen distance as well as dispersion, it is not skewed by the more frequent sex, and it can be meaningfully compared between populations and species. It has produced solid results for both hypothetical and natural populations.

  9. Managing Natural and Reintroduced Rare Plant Populations within a Large Government Reservation

    Energy Technology Data Exchange (ETDEWEB)

    Carlsen, T M; Paterson, L E; Alfaro, T M

    2009-07-15

    California is home to many large government reservations that have been in existence for decades. Many of these reservations were formed to support various Department of Defense and Department of Energy national defense activities. Often, only a very small percentage of the reservation is actively used for programmatic activities, resulting in large areas of intact habitat. In some cases, this has benefited rare plant populations, as surrounding lands have been developed for residential or industrial use. However, land management activities such as the suppression or active use of fire and other disturbance (such as fire trail grading) can also work to either the detriment or benefit of rare plant populations at these sites. A management regime that is beneficial to the rare plant populations of interest and is at best consistent with existing site programmatic activities, and at a minimum does not impact such activities, has the best potential for a positive outcome. As a result, some species may be 'difficult' while others may be 'easy' to manage in this context, depending on how closely the species biological requirements match the programmatic activities on the reservation. To illustrate, we compare and contrast two rare annual plant species found at Lawrence Livermore National Laboratory's Site 300. Although several populations of Amsinckia grandiflora have been restored on the site, and all populations are intensively managed, this species continues to decline. In contrast, Blepharizonia plumosa appears to take advantage of the annual controlled burns conducted on the site, and is thriving.

  10. Disjunct populations of European vascular plant species keep the same climatic niches

    DEFF Research Database (Denmark)

    Wasof, Safaa; Lenoir, Jonathan; Aarrestad, Per Arild

    2015-01-01

    Aim: Previous research on how climatic niches vary across species ranges has focused on a limited number of species, mostly invasive, and has not, to date, been very conclusive. Here we assess the degree of niche conservatism between distant populations of native alpine plant species that have been...... disjunct populations and 358 species having either a contiguous or a patchy distribution with distant populations. First, we used species distribution modelling to test for a region effect on each species' climatic niche. Second, we quantified niche overlap and shifts in niche width (i.e. ecological...... between populations that are separated between the Alps and Fennoscandia and have probably been so for 10,000-15,000 years. Therefore, the basic assumption of species distribution models that a species' climatic niche is constant in space and time - at least on time scales 104 years or less - seems...

  11. Plant population differentiation and climate change: responses of grassland species along an elevational gradient.

    Science.gov (United States)

    Frei, Esther R; Ghazoul, Jaboury; Matter, Philippe; Heggli, Martin; Pluess, Andrea R

    2014-02-01

    Mountain ecosystems are particularly susceptible to climate change. Characterizing intraspecific variation of alpine plants along elevational gradients is crucial for estimating their vulnerability to predicted changes. Environmental conditions vary with elevation, which might influence plastic responses and affect selection pressures that lead to local adaptation. Thus, local adaptation and phenotypic plasticity among low and high elevation plant populations in response to climate, soil and other factors associated with elevational gradients might underlie different responses of these populations to climate warming. Using a transplant experiment along an elevational gradient, we investigated reproductive phenology, growth and reproduction of the nutrient-poor grassland species Ranunculus bulbosus, Trifolium montanum and Briza media. Seeds were collected from low and high elevation source populations across the Swiss Alps and grown in nine common gardens at three different elevations with two different soil depths. Despite genetic differentiation in some traits, the results revealed no indication of local adaptation to the elevation of population origin. Reproductive phenology was advanced at lower elevation in low and high elevation populations of all three species. Growth and reproduction of T. montanum and B. media were hardly affected by garden elevation and soil depth. In R. bulbosus, however, growth decreased and reproductive investment increased at higher elevation. Furthermore, soil depth influenced growth and reproduction of low elevation R. bulbosus populations. We found no evidence for local adaptation to elevation of origin and hardly any differences in the responses of low and high elevation populations. However, the consistent advanced reproductive phenology observed in all three species shows that they have the potential to plastically respond to environmental variation. We conclude that populations might not be forced to migrate to higher elevations

  12. Assessment of genetic diversity of a native population of Eplingiella fruticosa: a plant with therapeutic potential.

    Science.gov (United States)

    Silva, D C; Diniz, L E C; Blank, A F; Nizio, D A C; Pinto, J A O; Pereira, K L G; Arrigoni-Blank, M F

    2017-08-17

    Eplingiella fruticosa (Salzm. ex Benth.) Harley & J.F.B. Pastore, ex Hyptis fruticosa Salzm. ex Benth. is an aromatic and medicinal plant of the family Lamiaceae, found mainly in regions with intense anthropic activity. Information on the genetic diversity of this species is scarce. However, it can be assessed using molecular markers that identify the level of diversity among phenotypically identical individuals. The present study aimed to characterize the genetic diversity of a native population of E. fruticosa from the State of Sergipe using ISSR molecular markers. Samples of 100 plants were collected in 11 municipalities of the State of Sergipe and analyzed using eight ISSR primers, resulting in 72 informative bands. The cluster analysis obtained using the neighbor joining method resulted in three groups: Group I consisted of 50 plants, mainly from the municipalities of Areia Branca, Estância, Japaratuba, Moita Bonita, Pirambu, and Salgado; Group II was formed by 21 plants, with nine representatives from the municipality of Itaporanga d'Ajuda and 13 representatives from other municipalities; Group III was composed by 29 plants, being represented mainly by the municipalities of Malhada dos Bois and São Cristóvão. The smallest genetic distance occurred between plants EPF94 and EPF96 (0.250), and the greatest distance occurred between plants EPF50 and EPF96 (0.9778). The Shannon index had a mean value of 0.42, and diversity was considered moderate. Heterozygosity had a mean value of 0.267 and was considered low. Polymorphic information content (0.253) was considered moderately informative. Genetic diversity of E. fruticosa plants was intermediate, and the results of the present study can assist in the conservation and use of the genetic resources of this species.

  13. Invasion, disturbance, and competition: modeling the fate of coastal plant populations.

    Science.gov (United States)

    Pathikonda, Sharmila; Ackleh, Azmy S; Hasenstein, Karl H; Mopper, Susan

    2009-02-01

    Wetland habitats are besieged by biotic and abiotic disturbances such as invasive species, hurricanes, habitat fragmentation, and salinization. Predicting how these factors will alter local population dynamics and community structure is a monumental challenge. By examining ecologically similar congeners, such as Iris hexagona and I. pseudacorus (which reproduce clonally and sexually and tolerate a wide range of environmental conditions), one can identify life-history traits that are most influential to population growth and viability. We combined empirical data and stage-structured matrix models to investigate the demographic responses of native (I. hexagona) and invasive (I. pseudacorus) plant populations to hurricanes and salinity stress in freshwater and brackish wetlands. In our models I. hexagona and I. pseudacorus responded differently to salinity stress, and species coexistence was rare. In 82% of computer simulations of freshwater marsh, invasive iris populations excluded the native species within 50 years, whereas native populations excluded the invasive species in 99% of the simulations in brackish marsh. The occurrence of hurricanes allowed the species to coexist, and species persistence was determined by the length of time it took the ecosystem to recover. Rapid recovery (2 years) favored the invasive species, whereas gradual recovery (30 years) favored the native species. Little is known about the effects of hurricanes on competitive interactions between native and invasive plant species in marsh ecosystems. Our models contribute new insight into the relationship between environmental disturbance and invasion and demonstrate how influential abiotic factors such as climate change will be in determining interspecific interactions.

  14. Population history and pathways of spread of the plant pathogen Phytophthora plurivora.

    Science.gov (United States)

    Schoebel, Corine N; Stewart, Jane; Grünwald, Niklaus J; Gruenwald, Niklaus J; Rigling, Daniel; Prospero, Simone

    2014-01-01

    Human activity has been shown to considerably affect the spread of dangerous pests and pathogens worldwide. Therefore, strict regulations of international trade exist for particularly harmful pathogenic organisms. Phytophthora plurivora, which is not subject to regulations, is a plant pathogen frequently found on a broad range of host species, both in natural and artificial environments. It is supposed to be native to Europe while resident populations are also present in the US. We characterized a hierarchical sample of isolates from Europe and the US and conducted coalescent-, migration, and population genetic analysis of sequence and microsatellite data, to determine the pathways of spread and the demographic history of this pathogen. We found P. plurivora populations to be moderately diverse but not geographically structured. High levels of gene flow were observed within Europe and unidirectional from Europe to the US. Coalescent analyses revealed a signal of a recent expansion of the global P. plurivora population. Our study shows that P. plurivora has most likely been spread around the world by nursery trade of diseased plant material. In particular, P. plurivora was introduced into the US from Europe. International trade has allowed the pathogen to colonize new environments and/or hosts, resulting in population growth.

  15. ASSESSMENT OF THE FUKUSIMA NUCLEAR POWER PLANT ACCIDENT CONSEQUENCES BY THE POPULATION IN THE FAR EAST

    Directory of Open Access Journals (Sweden)

    G. V. Arkhangelskaya

    2012-01-01

    Full Text Available The article analyzes the attitude of the population in the five regions of the Far East to the consequences of the accident at the Fukushimai nuclear power plant, as well as the issues of informing about the accident. The analysis of public opinion is based on the data obtained by anonymous questionnaire survey performed in November 2011. In spite of the rather active informing and objective information on the absence of the contamination, most of the population of the Russian Far East believes that radioactive contamination is presented in the areas of their residence, and the main cause of this contamination is the nuclear accident in Japan.

  16. Influence of small hydropower plants on brown trout (Salmo trutta L. population in Mislinja River

    Directory of Open Access Journals (Sweden)

    Blaž Cokan

    2013-12-01

    Full Text Available The brown trout (Salmo trutta L. in the Mislinja River has been endangered for years because of small hydroelectric power plants. To find out how they are affecting the population of the brown trout in the Mislinja River, we conducted a sampling of the brown trout, using a generating set. We measured the length and weight of all caught specimens and analysed the obtained data. The results are presented in this paper, e.g., biomass, estimations of abundance, average weight, average length and number of captured brown trout. We discovered that the population of the brown trout has decreased in all the sections where water has been taken away for small hydroelectric power plants.

  17. Population dose from indoor gamma exposure in the dwellings around Kudankulam nuclear power plant.

    Science.gov (United States)

    Brahmanandhan, G M; Selvasekarapandian, S; Malathi, J; Khanna, D; Jose, M T; Meenakshisundaram, V

    2008-01-01

    To assess the population dose due to the natural background radiation around the upcoming Kudankulam nuclear power plant, a systematic investigation has been carried out by measuring the indoor gamma dose. In total, 159 dwellings have been selected around the Kudankulam nuclear power plant area i.e. in Radhapuram and Nanguneri taluk (sub-districts) for the measurement. The geometric mean value of indoor gamma dose rate is 305 +/- 48 nGy h(-1) and 273 +/- 50 nGy h(-1) in Radhapuram and Nanguneri taluks (sub-districts), respectively. The annual effective dose due to indoor gamma radiation to the population has been found to be 1.5 mSv and 1.36 mSv in Radhapuram and Nanguneri taluks, respectively.

  18. Relative importance of biotic and abiotic soil components to plant growth and insect herbivore population dynamics.

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    Martijn L Vandegehuchte

    Full Text Available BACKGROUND: Plants are affected by several aspects of the soil, which have the potential to exert cascading effects on the performance of herbivorous insects. The effects of biotic and abiotic soil characteristics have however mostly been investigated in isolation, leaving their relative importance largely unexplored. Such is the case for the dune grass Ammophila, whose decline under decreasing sand accretion is argued to be caused by either biotic or abiotic soil properties. METHODOLOGY/PRINCIPAL FINDINGS: By manipulating dune soils from three different regions, we decoupled the contributions of region, the abiotic and biotic soil component to the variation in characteristics of Ammophila arenaria seedlings and Schizaphis rufula aphid populations. Root mass fraction and total dry biomass of plants were affected by soil biota, although the latter effect was not consistent across regions. None of the measured plant properties were significantly affected by the abiotic soil component. Aphid population characteristics all differed between regions, irrespective of whether soil biota were present or absent. Hence these effects were due to differences in abiotic soil properties between regions. Although several chemical properties of the soil mixtures were measured, none of these were consistent with results for plant or aphid traits. CONCLUSIONS/SIGNIFICANCE: Plants were affected more strongly by soil biota than by abiotic soil properties, whereas the opposite was true for aphids. Our results thus demonstrate that the relative importance of the abiotic and biotic component of soils can differ for plants and their herbivores. The fact that not all effects of soil properties could be detected across regions moreover emphasizes the need for spatial replication in order to make sound conclusions about the generality of aboveground-belowground interactions.

  19. How to induce defense responses in wild plant populations? Using bilberry (Vaccinium myrtillus) as example.

    Science.gov (United States)

    Seldal, Tarald; Hegland, Stein Joar; Rydgren, Knut; Rodriguez-Saona, Cesar; Töpper, Joachim Paul

    2017-03-01

    Inducible plant defense is a beneficial strategy for plants, which imply that plants should allocate resources from growth and reproduction to defense when herbivores attack. Plant ecologist has often studied defense responses in wild populations by biomass clipping experiments, whereas laboratory and greenhouse experiments in addition apply chemical elicitors to induce defense responses. To investigate whether field ecologists could benefit from methods used in laboratory and greenhouse studies, we established a randomized block-design in a pine-bilberry forest in Western Norway. We tested whether we could activate defense responses in bilberry ( Vaccinium myrtillus ) by nine different treatments using clipping (leaf tissue or branch removal) with or without chemical treatment by methyljasmonate (MeJA). We subsequently measured consequences of induced defenses through vegetative growth and insect herbivory during one growing season. Our results showed that only MeJA-treated plants showed consistent defense responses through suppressed vegetative growth and reduced herbivory by leaf-chewing insects, suggesting an allocation of resources from growth to defense. Leaf tissue removal reduced insect herbivory equal to the effect of the MeJa treatments, but had no negative impact on growth. Branch removal did not reduce insect herbivory or vegetative growth. MeJa treatment and clipping combined did not give an additional defense response. In this study, we investigated how to induce defense responses in wild plant populations under natural field conditions. Our results show that using the chemical elicitor MeJA, with or without biomass clipping, may be a better method to induce defense response in field experiments than clipping of leaves or branches that often has been used in ecological field studies.

  20. Effects of radiation exposure on plant populations and radiation protection of the environment

    Energy Technology Data Exchange (ETDEWEB)

    Geras' kin, St.A.; Dikarev, V.G.; Oudalova, A.A.; Vasiliev, D.V.; Dikareva, N.S.; Baykova, T.A. [Russian Institute of Agricultural Radiology and Agroecology, Obninsk (Russian Federation); Evseeva, T.I. [Institute of Biology, Komi Scientific Center, Ural Div. RAS, Syktyvkar (Russian Federation)

    2006-07-01

    The results of long-term field experiments in the 30-km Chernobyl NPP zone, In the vicinity of the radioactive wastes storage facility (Leningrad Region), at radium production industry storage cell (the Komi Republic), and in Bryansk Region affected by the ChNPP accident that have been carried out on different species of wild and agricultural plants are discussed. These findings indicate that plant populations growing in areas with relatively low levels of pollution are characterized by the increased level of both cytogenetic disturbances and genetic diversity. The chronic low-dose exposure appears to be an ecological factor creating preconditions for possible changes in the genetic structure of a population. These processes have a genetic basis; therefore, an understanding changes at the genetic level should help in an identifying more complex changes at higher levels. The presented findings add to filling an important gap in our knowledge on remote effects in plant populations and ecosystems from man-made impact. (author)

  1. Effect of Drought on Herbivore-Induced Plant Gene Expression: Population Comparison for Range Limit Inferences

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    Gunbharpur Singh Gill

    2016-03-01

    Full Text Available Low elevation “trailing edge” range margin populations typically face increases in both abiotic and biotic stressors that may contribute to range limit development. We hypothesize that selection may act on ABA and JA signaling pathways for more stable expression needed for range expansion, but that antagonistic crosstalk prevents their simultaneous co-option. To test this hypothesis, we compared high and low elevation populations of Boechera stricta that have diverged with respect to constitutive levels of glucosinolate defenses and root:shoot ratios; neither population has high levels of both traits. If constraints imposed by antagonistic signaling underlie this divergence, one would predict that high constitutive levels of traits would coincide with lower plasticity. To test this prediction, we compared the genetically diverged populations in a double challenge drought-herbivory growth chamber experiment. Although a glucosinolate defense response to the generalist insect herbivore Spodoptera exigua was attenuated under drought conditions, the plastic defense response did not differ significantly between populations. Similarly, although several potential drought tolerance traits were measured, only stomatal aperture behavior, as measured by carbon isotope ratios, was less plastic as predicted in the high elevation population. However, RNAseq results on a small subset of plants indicated differential expression of relevant genes between populations as predicted. We suggest that the ambiguity in our results stems from a weaker link between the pathways and the functional traits compared to transcripts.

  2. Adaptive Transgenerational Plasticity in Plants: Case Studies, Mechanisms, and Implications for Natural Populations

    Science.gov (United States)

    Herman, Jacob J.; Sultan, Sonia E.

    2011-01-01

    Plants respond to environmental conditions not only by plastic changes to their own development and physiology, but also by altering the phenotypes expressed by their offspring. This transgenerational plasticity was initially considered to entail only negative effects of stressful parental environments, such as production of smaller seeds by resource- or temperature-stressed parent plants, and was therefore viewed as environmental noise. Recent evolutionary ecology studies have shown that in some cases, these inherited environmental effects can include specific growth adjustments that are functionally adaptive to the parental conditions that induced them, which can range from contrasting states of controlled laboratory environments to the complex habitat variation encountered by natural plant populations. Preliminary findings suggest that adaptive transgenerational effects can be transmitted by means of diverse mechanisms including changes to seed provisioning and biochemistry, and epigenetic modifications such as DNA methylation that can persist across multiple generations. These non-genetically inherited adaptations can influence the ecological breadth and evolutionary dynamics of plant taxa and promote the spread of invasive plants. Interdisciplinary studies that join mechanistic and evolutionary ecology approaches will be an important source of future insights. PMID:22639624

  3. Adaptive transgenerational plasticity in plants: case studies, mechanisms, and implications for natural populations

    Directory of Open Access Journals (Sweden)

    Jacob J. Herman

    2011-12-01

    Full Text Available Plants respond to environmental conditions not only by plastic changes to their own development and physiology, but also by altering the phenotypes expressed by their offspring. This transgenerational plasticity was initially considered to entail only negative effects of stressful parental environments, such as production of smaller seeds by resource- or temperature-stressed parent plants, and was therefore viewed as environmental noise. Recent evolutionary ecology studies have shown that in some cases, these inherited environmental effects can include specific growth adjustments that are functionally adaptive to the parental conditions that induced them, which can range from contrasting states of controlled laboratory environments to the complex habitat variation encountered by natural plant populations. Preliminary findings suggest that adaptive transgenerational effects can be transmitted by means of diverse mechanisms including changes to seed provisioning and biochemistry, and epigenetic modifications such as DNA methylation that can persist across multiple generations. These non-genetically inherited adaptations can influence the ecological breadth and evolutionary dynamics of plant taxa and promote the spread of invasive plants. Interdisciplinary studies that join mechanistic and evolutionary ecology approaches will be an important source of future insights.

  4. Adaptive transgenerational plasticity in plants: case studies, mechanisms, and implications for natural populations.

    Science.gov (United States)

    Herman, Jacob J; Sultan, Sonia E

    2011-01-01

    Plants respond to environmental conditions not only by plastic changes to their own development and physiology, but also by altering the phenotypes expressed by their offspring. This transgenerational plasticity was initially considered to entail only negative effects of stressful parental environments, such as production of smaller seeds by resource- or temperature-stressed parent plants, and was therefore viewed as environmental noise. Recent evolutionary ecology studies have shown that in some cases, these inherited environmental effects can include specific growth adjustments that are functionally adaptive to the parental conditions that induced them, which can range from contrasting states of controlled laboratory environments to the complex habitat variation encountered by natural plant populations. Preliminary findings suggest that adaptive transgenerational effects can be transmitted by means of diverse mechanisms including changes to seed provisioning and biochemistry, and epigenetic modifications such as DNA methylation that can persist across multiple generations. These non-genetically inherited adaptations can influence the ecological breadth and evolutionary dynamics of plant taxa and promote the spread of invasive plants. Interdisciplinary studies that join mechanistic and evolutionary ecology approaches will be an important source of future insights.

  5. Driving factors of small-scale variability in a savanna plant population after a fire

    Science.gov (United States)

    Dodonov, Pavel; Xavier, Rafael de Oliveira; Tiberio, Fernanda Cristina dos Santos; Lucena, Isabela Codolo de; Zanelli, Carolina Brandão; Silva Matos, Dalva Maria da

    2014-04-01

    The severity of fire impacts on fire-prone vegetation is often spatially heterogeneous, and may lead to small-scale patchiness in the structure of plant populations by affecting mortality, topkill, and reproduction. This patchiness, however, is not usually taken into account in fire ecology studies. We show that a dry-season fire may result in small-scale patchiness in the population structure of the common shrub Miconia albicans, mostly by differential topkill and resprouting. We related fire severity to population structure parameters of the study species and assessed the effects of fire on its soil seed bank. Basal area of non-woody live stems and of dead stems increased with fire severity, whereas that of woody live stems decreased, indicating topkill and resprouting. However, there was no relationship between fire severity and the total number of live or dead plants, showing that mortality in the fire was low. We found very few seedlings, indicating that resprouting, not germination from the soil seed bank, is the main recovery strategy of this species. The fire also affected the soil seed bank, as there were fewer seedlings emerging from soil collected in burned patches. Although this study was performed with a single species, it is likely that other species, especially those with basal resprouting, will show similar patterns of post-fire patchiness in population structure. This patchiness, in turn, may affect the spatial distribution of future fires, and should be taken into account in studies of fire ecology.

  6. Understanding past, contemporary, and future dynamics of plants, populations, and communities using Sonoran Desert winter annuals.

    Science.gov (United States)

    Huxman, Travis E; Kimball, Sarah; Angert, Amy L; Gremer, Jennifer R; Barron-Gafford, Greg A; Venable, D Lawrence

    2013-07-01

    Global change requires plant ecologists to predict future states of biological diversity to aid the management of natural communities, thus introducing a number of significant challenges. One major challenge is considering how the many interacting features of biological systems, including ecophysiological processes, plant life histories, and species interactions, relate to performance in the face of a changing environment. We have employed a functional trait approach to understand the individual, population, and community dynamics of a model system of Sonoran Desert winter annual plants. We have used a comprehensive approach that connects physiological ecology and comparative biology to population and community dynamics, while emphasizing both ecological and evolutionary processes. This approach has led to a fairly robust understanding of past and contemporary dynamics in response to changes in climate. In this community, there is striking variation in physiological and demographic responses to both precipitation and temperature that is described by a trade-off between water-use efficiency (WUE) and relative growth rate (RGR). This community-wide trade-off predicts both the demographic and life history variation that contribute to species coexistence. Our framework has provided a mechanistic explanation to the recent warming, drying, and climate variability that has driven a surprising shift in these communities: cold-adapted species with more buffered population dynamics have increased in relative abundance. These types of comprehensive approaches that acknowledge the hierarchical nature of biology may be especially useful in aiding prediction. The emerging, novel and nonstationary climate constrains our use of simplistic statistical representations of past plant behavior in predicting the future, without understanding the mechanistic basis of change.

  7. FITNESS VARIATION ACROSS A SUBDIVIDED POPULATION OF THE ANNUAL PLANT IMPATIENS CAPENSIS.

    Science.gov (United States)

    Kelly, John K

    1997-08-01

    The evolution of a subdivided population depends on whether subpopulations with high mean fitness make a greater per capita contribution to the next generation than subpopulations with lower mean fitness. I distinguish two different models of ecological population structure, denoted local compensation and global compensation. Local compensation restricts the differential contribution of subpopulations, whereas global compensation allows subpopulations to contribute in direct proportion to their mean fitness. I describe a simple regression-based method that distinguishes these alternatives as points on a continuum of possible population structures. The method is applied to field measurements of local abundance and reproduction in a subdivided population of the annual plant Impatiens capensis. These data suggest that the global compensation model is a more accurate description of the population studied. This result is surprising because local density effects on growth and reproduction occur in I. capensis. The implications of ecological population structure for both geographical variation in selection and kin selection are discussed. © 1997 The Society for the Study of Evolution.

  8. Recent wind-driven change in Subantarctic Mode Water and its impact on ocean heat storage

    Science.gov (United States)

    Gao, Libao; Rintoul, Stephen R.; Yu, Weidong

    2018-01-01

    The subduction and export of Subantarctic Mode Water (SAMW) supplies the upper limb of the overturning circulation and makes an important contribution to global heat, freshwater, carbon and nutrient budgets1-5. Upper ocean heat content has increased since 2006, helping to explain the so-called global warming hiatus between 1998 and 2014, with much of the ocean warming concentrated in extratropical latitudes of the Southern Hemisphere in close association with SAMW and Antarctic Intermediate Water (AAIW)6,7. Here we use Argo observations to assess changes in the thickness, depth and heat content of the SAMW layer. Between 2005 and 2015, SAMW has thickened (3.6 ± 0.3 m yr-1), deepened (2.4 ± 0.2 m yr-1) and warmed (3.9 ± 0.3 W m-2). Wind forcing, rather than buoyancy forcing, is largely responsible for the observed trends in SAMW. Most (84%) of the increase in SAMW heat content is the result of changes in thickness; warming by buoyancy forcing (increased heat flux to the ocean) accounts for the remaining 16%. Projected increases in wind stress curl would drive further deepening of SAMW and increase in heat storage in the Southern Hemisphere oceans.

  9. Assessing Sub-Antarctic Zone primary productivity from fast repetition rate fluorometry

    Science.gov (United States)

    Cheah, Wee; McMinn, Andrew; Griffiths, F. Brian; Westwood, Karen J.; Wright, Simon W.; Molina, Ernesto; Webb, Jason P.; van den Enden, Rick

    2011-11-01

    In situ primary productivity (PP) in the Sub-Antarctic Zone (SAZ) and the Polar Frontal Zone (PFZ) south of Australia was estimated using fast repetition rate fluorometry (FRRF). FRRF-derived PP at Process station 3 (P3) southeast of Tasmania (46°S, 153°E) were higher than P1 in the southwest of Tasmania (46°S, 140°E) and P2 in the Polar Frontal Zone (54°S, 146°E). The FRRF-derived PP rates were well correlated with 14C-uptake rates from one-hour incubations ( r2=0.85, slope=1.23±0.05, plight-limited conditions in deeper waters. Under light-saturated conditions near the surface (0-45 m), the relationship was less clear. This was likely associated with the effects of physiological processes such as cyclic electron flow and the Mehler reaction, which are stimulated at high irradiance. Our results indicate that FRRF can be used to estimate photosynthesis rates in the SAZ and PFZ but to derive an accurate estimation of C-fixation requires a detailed understanding of the physiological properties of the cells and their response to oceanographic parameters under different environmental conditions.

  10. Energy density of sub-Antarctic fishes from the Beagle Channel.

    Science.gov (United States)

    Fernández, D A; Lattuca, M E; Boy, C C; Pérez, A F; Ceballos, S G; Vanella, F A; Morriconi, E R; Malanga, G F; Aureliano, D R; Rimbau, S; Calvo, J

    2009-03-01

    The energy density (ED) of nine species of sub-Antarctic fishes was estimated by calorimetry. The fish, seven notothenioids, one atherinopsid and one galaxiid, represents some of the more abundant species in the ichthyofauna of the Beagle Channel. Principal-components analysis (PCA) of the ED of the different organs/tissues indicated that PC(1) and PC(2) accounted for 87% of the variability. Separation along PC(1) corresponded to differences in muscle and liver energy densities whereas separation along PC(2) corresponded to differences in the ED of the gonads. Differences between species were significant except for P. sima. Inclusion of the gonadosomatic index (GSI) as an explanatory variable enabled us to establish the existence of energy transfer from muscle and liver to the gonads in ripe P. tessellata females. Total ED values varied between 4.21 and 6.26 kJ g(-1), the pelagic Odontesthes sp. being the species with the highest ED. A significant relationship between ED and muscle dry weight (DW(M)) was found for all the species except P. tessellata. These data are the first direct estimates of ED of fishes from the Beagle Channel.

  11. Metagenomic Survey of Viral Diversity Obtained from Feces of Subantarctic and South American Fur Seals.

    Directory of Open Access Journals (Sweden)

    Mariana Kluge

    Full Text Available The Brazilian South coast seasonally hosts numerous marine species, observed particularly during winter months. Some animals, including fur seals, are found dead or debilitated along the shore and may harbor potential pathogens within their microbiota. In the present study, a metagenomic approach was performed to evaluate the viral diversity in feces of fur seals found deceased along the coast of the state of Rio Grande do Sul. The fecal virome of two fur seal species was characterized: the South American fur seal (Arctocephalus australis and the Subantarctic fur seal (Arctocephalus tropicalis. Fecal samples from 10 specimens (A. australis, n = 5; A. tropicalis, n = 5 were collected and viral particles were purified, extracted and amplified with a random PCR. The products were sequenced through Ion Torrent and Illumina platforms and assembled reads were submitted to BLASTx searches. Both viromes were dominated by bacteriophages and included a number of potentially novel virus genomes. Sequences of picobirnaviruses, picornaviruses and a hepevirus-like were identified in A. australis. A rotavirus related to group C, a novel member of the Sakobuvirus and a sapovirus very similar to California sea lion sapovirus 1 were found in A. tropicalis. Additionally, sequences of members of the Anelloviridae and Parvoviridae families were detected in both fur seal species. This is the first metagenomic study to screen the fecal virome of fur seals, contributing to a better understanding of the complexity of the viral community present in the intestinal microbiota of these animals.

  12. [Effects of plant hedgerow on population dynamics of wheat aphid and its natural enemies].

    Science.gov (United States)

    Shi, Guo-Qing; Lin, Chao-Wen; Liu, Zhang-Yong; Li, Chuan-Ren; Chen, Yi-Bing; Ma, Tao; Wang, Qi-Feng; Liu, Zhi-Long; Cai, Qing-Nian

    2011-12-01

    This paper studied the effects of planting different kinds of plant hedgerow (Amorpha fruticosa, Vetiveria zizanioides, Eulaliopsis binata, and Medicago sativa) on the population dynamics of wheat aphid and its natural enemies in the hillside wheat fields in Ziyang City of Sichuan Province, Southwest China. On the 20 degrees hillside, A. fruticosa hedgerow inhibited the occurrence of wheat aphid in the wheat field significantly, and the parasitoid densities were equal to or significantly lower than those in the wheat field with V. zizanioides hedgerow. On the 12 degrees hillside, M. sativa and E. binata hedgerows delayed the peak time of wheat aphid occurrence, and E. binata hedgerow suppressed the wheat aphid population density significantly. In the wheat field with M. sativa hedgerow, the parasitoid densities were significantly higher than those with no hedgerow. An equal or significantly higher ladybird density was observed in the field with M. sativa hedgerow. The olfactory responses showed that E. binata volatiles had repellent effect on both Sitobion avenae and Rhopalosiphum padi, but attracted a spider species of oxyopidae. M. sativa volatiles attracted S. avenae, whereas neither M. sativa nor E. binata volatiles caused obvious behavior response of ladybird adults. Therefore, planting A. fruticosa and E. binata as the hedgerows in hillside wheat fields could not only prevent the soil erosion from seasonal rainfall, but also benefit the control of pest insects.

  13. Evolutionary and plastic responses to climate change in terrestrial plant populations

    Science.gov (United States)

    Franks, Steven J; Weber, Jennifer J; Aitken, Sally N

    2014-01-01

    As climate change progresses, we are observing widespread changes in phenotypes in many plant populations. Whether these phenotypic changes are directly caused by climate change, and whether they result from phenotypic plasticity or evolution, are active areas of investigation. Here, we review terrestrial plant studies addressing these questions. Plastic and evolutionary responses to climate change are clearly occurring. Of the 38 studies that met our criteria for inclusion, all found plastic or evolutionary responses, with 26 studies showing both. These responses, however, may be insufficient to keep pace with climate change, as indicated by eight of 12 studies that examined this directly. There is also mixed evidence for whether evolutionary responses are adaptive, and whether they are directly caused by contemporary climatic changes. We discuss factors that will likely influence the extent of plastic and evolutionary responses, including patterns of environmental changes, species’ life history characteristics including generation time and breeding system, and degree and direction of gene flow. Future studies with standardized methodologies, especially those that use direct approaches assessing responses to climate change over time, and sharing of data through public databases, will facilitate better predictions of the capacity for plant populations to respond to rapid climate change. PMID:24454552

  14. Does the selection of medicinal plants by Brazilian local populations suffer taxonomic influence?

    Science.gov (United States)

    deMedeiros, Patrícia Muniz; Ladio, Ana Haydée; Santos, André Maurício Melo; de Albuquerque, Ulysses Paulino

    2013-04-19

    The analysis of the influence of taxonomic affiliation on the selection of medicinal plants by Brazilian local populations can help elucidate theoretical aspects of medicinal plant selection. Ethnobotanical medicinal plant studies were compiled and the resulting medicinal flora was compared to the total angiosperm flora with a Bayesian approach and the IDM model. A total of 35 families were considered to be overused and six were classified as underused for the Bayesian approach. On the other hand, the IDM model considered 13 families as overused and five as underused (all of them were also highlighted by the Bayesian approach). A high overuse level of Bixaceae, Amaranthaceae, Anacardiaceae and Smilacaceae was recorded for both Bayesian and IDM model, while Orchidaceae, Melastomataceae, Eriocaulaceae, Poaceae and Bromeliaceae were considered as underused for both analyses. The most dissimilar body system in terms of family composition was 'mental and behavioral disorders'. It was also found that the body systems are different from one another in the proportion of taxonomic groups, which could indicate chemical specificity in the treatment of diseases. Results indicate that the chemical specificity of taxonomic groups directly influences medicinal plant selection. Moreover, when data presented here are compared to other studies, there is clearly an overuse pattern for families like Lamiaceae, Rosaceae and Euphorbiaceae and an underuse pattern for Poaceae and Orchidaceae. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  15. Plant species with extremely small populations (PSESP in China: A seed and spore biology perspective

    Directory of Open Access Journals (Sweden)

    Ellie Merrett Wade

    2016-10-01

    Full Text Available Approximately one fifth of the world's plants are at risk of extinction. Of these, a significant number exist as populations of few individuals, with limited distribution ranges and under enormous pressure due to habitat destruction. In China, these most-at-risk species are described as ‘plant species with extremely small populations’ (PSESP. Implementing conservation action for such listed species is urgent. Storing seeds is one of the main means of ex situ conservation for flowering plants. Spore storage could provide a simple and economical method for fern ex situ conservation. Seed and spore germination in nature is a critical step in species regeneration and thus in situ conservation. But what is known about the seed and spore biology (storage and germination of at-risk species? We have used China's PSESP (the first group listing as a case study to understand the gaps in knowledge on propagule biology of threatened plant species. We found that whilst germination information is available for 28 species (23% of PSESP, storage characteristics are only known for 8% of PSESP (10 species. Moreover, we estimate that 60% of the listed species may require cryopreservation for long-term storage. We conclude that comparative biology studies are urgently needed on the world's most threatened taxa so that conservation action can progress beyond species listing.

  16. Population Status of Commercially Important Medicinal Plants in Dehradun Forest Division, Uttarakhand (India

    Directory of Open Access Journals (Sweden)

    Ninad B. RAUT

    2013-05-01

    Full Text Available The objective of forest management in the tropics, in recent decades, has shifted from timber production to biodiversity conservation and maintenance of life support system. However, past forestry practices have greatly influenced the structure of plant communities, preponderance of foreign invasive species, populations of high value medicinal plants as well as other non-wood forest products. We assessed the abundance and distribution of medicinal plants in managed and undisturbed forests of Dehradun Forest Division (DFD, Uttarakhand (India. A total of 80 transects (each 1 km long were laid in various categories of forest types in DFD. This paper deals with distribution, availability and regeneration status of five commercially important species viz., Justicia adhatoda, Aegle marmelos, Phyllanthus emblica, Terminalia bellirica and Terminalia chebula, across different forest types. The study reveals that open canopy forest patches, Lantana infested patches and Acacia catechu-Dalbergia sissoo (Khair -Shisam woodlands in the eastern part of the DFD have excellent potential for the production and sustainable harvest of Justicia adhatoda. Areas those are less suitable for timber production viz., open hill forests, have greater potential for conservation and development of Aegle marmelos, Phyllanthus emblica and Terminalia bellirica. For the production and management of high value medicinal plants in the DFD these ecological considerations need to be kept in mind.

  17. The distribution and spread of alien vascular plants on Prince Edward Island

    NARCIS (Netherlands)

    Ryan, P.G.; Smith, V.; Gremmen, N.J.M.

    2003-01-01

    Surveys of alien plants at subantarctic Prince Edward Island in 2001 show that the ranges of all three introduced species have increased since the last survey in 1998. Poa annua, the longest-established species, increased its range substantially after 1987, prior to which it was confined to a single

  18. Insights from paleogenomic and population studies into the consequences of dosage sensitive gene expression in plants.

    Science.gov (United States)

    Birchler, James A

    2012-11-01

    Classical studies of plant phenotypes of individuals with whole or partial genome dosage changes led to the concept of genomic balance. Subsequent studies of gene expression in ploidy and aneuploidy series showed a greater number of modulations in aneuploid plants than with whole genome changes leading to the idea that gene expression processes were modulated by stoichiometric changes of interacting regulatory factors. Recent studies of genomic sequences and copy number variants in populations reveal different fates of duplicate genes depending on whole genome or segmental duplication. Following polyploidy formation, members of macromolecular complexes persist in the evolutionary lineage longer than random genes and a complementary pattern is found for segmental duplications in that there is an underrepresentation of members of macromolecular complexes. These and other studies described suggest there are negative fitness consequences when an imbalance occurs for members of macromolecular complexes including regulatory functions. Copyright © 2012 Elsevier Ltd. All rights reserved.

  19. Host mating system and the prevalence of a disease in a plant population

    Science.gov (United States)

    Koslow, Jennifer M.; DeAngelis, Donald L.

    2006-01-01

    A modified susceptible–infected–recovered (SIR) host–pathogen model is used to determine the influence of plant mating system on the outcome of a host–pathogen interaction. Unlike previous models describing how interactions between mating system and pathogen infection affect individual fitness, this model considers the potential consequences of varying mating systems on the prevalence of resistance alleles and disease within the population. If a single allele for disease resistance is sufficient to confer complete resistance in an individual and if both homozygote and heterozygote resistant individuals have the same mean birth and death rates, then, for any parameter set, the selfing rate does not affect the proportions of resistant, susceptible or infected individuals at equilibrium. If homozygote and heterozygote individual birth rates differ, however, the mating system can make a difference in these proportions. In that case, depending on other parameters, increased selfing can either increase or decrease the rate of infection in the population. Results from this model also predict higher frequencies of resistance alleles in predominantly selfing compared to predominantly outcrossing populations for most model conditions. In populations that have higher selfing rates, the resistance alleles are concentrated in homozygotes, whereas in more outcrossing populations, there are more resistant heterozygotes.

  20. Host mating system and the prevalence of disease in a plant population

    Science.gov (United States)

    Koslow, Jennifer M; DeAngelis, Donald L

    2006-01-01

    A modified susceptible–infected–recovered (SIR) host–pathogen model is used to determine the influence of plant mating system on the outcome of a host–pathogen interaction. Unlike previous models describing how interactions between mating system and pathogen infection affect individual fitness, this model considers the potential consequences of varying mating systems on the prevalence of resistance alleles and disease within the population. If a single allele for disease resistance is sufficient to confer complete resistance in an individual and if both homozygote and heterozygote resistant individuals have the same mean birth and death rates, then, for any parameter set, the selfing rate does not affect the proportions of resistant, susceptible or infected individuals at equilibrium. If homozygote and heterozygote individual birth rates differ, however, the mating system can make a difference in these proportions. In that case, depending on other parameters, increased selfing can either increase or decrease the rate of infection in the population. Results from this model also predict higher frequencies of resistance alleles in predominantly selfing compared to predominantly outcrossing populations for most model conditions. In populations that have higher selfing rates, the resistance alleles are concentrated in homozygotes, whereas in more outcrossing populations, there are more resistant heterozygotes. PMID:16790417

  1. A population genetic study of Pasqueflower: In situ and Ex situ Conservation Genetics of a Vulnerable UK Plant Species

    OpenAIRE

    Worswick, Gemma

    2016-01-01

    The population genetic structure of the vulnerable UK plant species Anemone pulsatilla L. reflects geographic patterns of historical range fragmentation and the influence of population decline and restoration intervention. Positive spatial auto-correlation of natural in situ populations of A. pulsatilla lends support to a scenario for genetic drift (i.e. random drift of allelic frequencies) driving the emergence of population genetic structure as a consequence of fragmentation. Multivariate a...

  2. Mortality gradients within and among dominant plant populations as barometers of ecosystem change during extreme drought.

    Science.gov (United States)

    Gitlin, Alicyn R; Sthultz, Christopher M; Bowker, Matthew A; Stumpf, Stacy; Paxton, Kristina L; Kennedy, Karla; Muñoz, Axhel; Bailey, Joseph K; Whitham, Thomas G

    2006-10-01

    Understanding patterns of plant population mortality during extreme weather events is important to conservation planners because the frequency of such events is expected to increase, creating the need to integrate climatic uncertainty into management. Dominant plants provide habitat and ecosystem structure, so changes in their distribution can be expected to have cascading effects on entire communities. Observing areas that respond quickly to climate fluctuations provides foresight into future ecological changes and will help prioritize conservation efforts. We investigated patterns of mortality in six dominant plant species during a drought in the southwestern United States. We quantified population mortality for each species across its regional distribution and tested hypotheses to identify ecological stress gradients for each species. Our results revealed three major patterns: (1) dominant species from diverse habitat types (i.e., riparian, chaparral, and low- to high-elevation forests) exhibited significant mortality, indicating that the effects of drought were widespread; (2) average mortality differed among dominant species (one-seed juniper[Juniperus monosperma (Engelm.) Sarg.] 3.3%; manzanita[Arctostaphylos pungens Kunth], 14.6%; quaking aspen[Populus tremuloides Michx.], 15.4%; ponderosa pine[Pinus ponderosa P. & C. Lawson], 15.9%; Fremont cottonwood[Populus fremontii S. Wats.], 20.7%; and pinyon pine[Pinus edulis Engelm.], 41.4%); (3) all dominant species showed localized patterns of very high mortality (24-100%) consistent with water stress gradients. Land managers should plan for climatic uncertainty by promoting tree recruitment in rare habitat types, alleviating unnatural levels of competition on dominant plants, and conserving sites across water stress gradients. High-stress sites, such as those we examined, have conservation value as barometers of change and because they may harbor genotypes that are adapted to climatic extremes.

  3. Distinguishing plant population and variety with UAV-derived vegetation indices

    Science.gov (United States)

    Oakes, Joseph; Balota, Maria

    2017-05-01

    Variety selection and seeding rate are two important choice that a peanut grower must make. High yielding varieties can increase profit with no additional input costs, while seeding rate often determines input cost a grower will incur from seed costs. The overall purpose of this study was to examine the effect that seeding rate has on different peanut varieties. With the advent of new UAV technology, we now have the possibility to use indices collected with the UAV to measure emergence, seeding rate, growth rate, and perhaps make yield predictions. This information could enable growers to make management decisions early in the season based on low plant populations due to poor emergence, and could be a useful tool for growers to use to estimate plant population and growth rate in order to help achieve desired crop stands. Red-Green-Blue (RGB) and near-infrared (NIR) images were collected from a UAV platform starting two weeks after planting and continued weekly for the next six weeks. Ground NDVI was also collected each time aerial images were collected. Vegetation indices were derived from both the RGB and NIR images. Greener area (GGA- the proportion of green pixels with a hue angle from 80° to 120°) and a* (the average red/green color of the image) were derived from the RGB images while Normalized Differential Vegetative Index (NDVI) was derived from NIR images. Aerial indices were successful in distinguishing seeding rates and determining emergence during the first few weeks after planting, but not later in the season. Meanwhile, these aerial indices are not an adequate predictor of yield in peanut at this point.

  4. Mites fluctuation population on peach tree (Prunus persica (L. Batsch and in associated plants

    Directory of Open Access Journals (Sweden)

    Carla Rosana Eichelberger

    2011-09-01

    Full Text Available Despite the importance of peach (Prunus persica (L. Batsch in Rio Grande do Sul, little is known about mites fluctuation population considered important to this crop. The objective of this study was to know the population diversity and fluctuation of mite species associated with Premier and Eldorado varieties in Roca Sales and Venâncio Aires counties, Rio Grande do Sul. The study was conducted from July 2008 to June 2009 when 15 plants were randomly chosen in each area. The plants were divided in quadrants and from each one a branch was chosen from which three leaves were removed: one collected in the apical region, another in the medium and the other in the basal region, totalizing 180 leaves/area. Five of the most abundant associated plants were collected monthly in enough amounts for the screening under the stereoscopic microscope during an hour. A total of 1,124 mites were found belonging to 14 families and 28 species. Tetranychus ludeni Zacher, 1913, Panonychus ulmi (Koch, 1836 and Mononychellus planki (McGregor, 1950 were the most abundant phytophagous mites, whereas Typhlodromalus aripo Deleon, 1967 and Phytoseiulus macropilis (Banks, 1904 the most common predatory mites. The period of one hour under stereoscopic microscope was enough to get a representative sample. In both places evaluated the ecologic indices were low, but little higherin Premier (H' 0.56; EqJ: 0.43 when compared to Eldorado (H' 0.53; EqJ 0.40. In Premier constant species were not observed and accessory only Brevipalpus phoenicis (Geijskes, 1939, T. ludeni and T. aripo. Higher abundance was observed in December and January and bigger amount in April. Already in Eldorado, T. ludeni and P. ulmi were constants. Greater abundance was observed in November and December, whereas grater richness in December and January. In both orchards were not found mites in buds. Tetranychus ludeni is the most abundant phytophagous mites with outbreak population in November, December and

  5. Analysis of genetic diversity of a native population of Myrcia lundiana Kiaersk. plants using ISSR markers.

    Science.gov (United States)

    Alves, M F; Nizio, D A C; Brito, F A; Sampaio, T S; Silva, A V C; Arrigoni-Blank, M F; Carvalho, S V A; Blank, A F

    2016-12-02

    Myrcia lundiana Kiaersk. is a tree of the family Myrtaceae found in tropical and subtropical areas of the southern hemisphere that produces essential oil. The aim of this study was to characterize the genetic diversity of M. lundiana plants from a native population of Parque Nacional de Itabaiana, using inter-simple sequence repeat molecular markers. Thirty-five primers were tested, 20 of which were polymorphic, resulting in 135 polymorphic and informative bands. Results of the cluster analysis, obtained using the unweighted pair group method with arithmetic mean, grouped plants into three clusters: Cluster I - MLU001, MLU002, MLU003, MLU004, MLU005, MLU006, MLU018, MLU019, MLU020, MLU021, MLU022; MLU008, MLU011, MLU012, MLU014, MLU015, MLU017, MLU026, and MLU028; Cluster II - MLU007, MLU009, MLU010, MLU013, and MLU016; and Cluster III - MLU023, MLU024, MLU025, and MLU027. Jaccard similarity coefficients for pair-wise comparisons of plants ranged between 0.15 and 0.87. MLU014 and MLU015 presented low genetic diversity, with a similarity index of 0.87. Conversely, MLU007 and MLU019 presented high diversity, with a similarity index of 0.15. According to the structure analysis, three distinct clusters were formed. Genetic diversity of M. lundiana plants was intermediate, and expansion of its genetic diversity is necessary. MLU026 and MLU028 are the most suitable for selection in breeding programs, since they clearly represent all of the diversity present in these plants. Moreover, these results provide important information on the existing genetic variability, highlighting the importance of Parque Nacional de Itabaiana for the conservation of this species.

  6. High-throughput phenotyping of plant populations using a personal digital assistant.

    Science.gov (United States)

    Vankudavath, Raju Naik; Bodanapu, Reddaiah; Sreelakshmi, Yellamaraju; Sharma, Rameshwar

    2012-01-01

    During many biological experiments voluminous data is acquired, which can be best collected with -portable data acquisition devices and later analyzed with a personal computer (PC). Public domain software catering to data acquisition and analysis is currently limited. The necessity of phenotyping large plant populations led to the development of the application "PHENOME" to manage the data. PHENOME allows acquisition of phenotypic data using a personal digital assistant (PDA) with a built-in barcode scanner. The acquired data can be exported to a customized database on a PC for further analysis and cataloging. PHENOME can be used for a variety of applications, for example high-throughput phenotyping of a mutagenized or mapping population, or phenotyping of several individuals in one or more ecological niches.

  7. Strong Genetic Differentiation of Submerged Plant Populations across Mountain Ranges: Evidence from Potamogeton pectinatus in Iran.

    Science.gov (United States)

    Abbasi, Shabnam; Afsharzadeh, Saeed; Saeidi, Hojjatollah; Triest, Ludwig

    2016-01-01

    Biogeographic barriers for freshwater biota can be effective at various spatial scales. At the largest spatial scale, freshwater organisms can become genetically isolated by their high mountain ranges, vast deserts, and inability to cross oceans. Isolation by distance of aquatic plants is expected to be stronger across than alongside mountain ridges whereas the heterogeneity of habitats among populations and temporary droughts may influence connectivity and hamper dispersal. Suitable aquatic plant habitats became reduced, even for the widespread submerged Potamogeton pectinatus L. (also named Stuckenia pectinata) giving structure to various aquatic habitats. We compared the level of genetic diversity in a heterogeneous series of aquatic habitats across Iran and tested their differentiation over distances and across mountain ranges (Alborz and Zagros) and desert zones (Kavir), with values obtained from temperate region populations. The diversity of aquatic ecosystems across and along large geographic barriers provided a unique ecological situation within Iran. P. pectinatus were considered from thirty-six sites across Iran at direct flight distances ranging from 20 to 1,200 km. Nine microsatellite loci revealed a very high number of alleles over all sites. A PCoA, NJT clustering and STRUCTURE analysis revealed a separate grouping of individuals of southeastern Iranian sites and was confirmed by their different nuclear ITS and cpDNA haplotypes thereby indicating an evolutionary significant unit (ESU). At the level of populations, a positive correlation between allelic differentiation Dest with geographic distance was found. Individual-based STRUCTURE analysis over 36 sites showed 7 genetic clusters. FST and RST values for ten populations reached 0.343 and 0.521, respectively thereby indicating that allele length differences are more important and contain evolutionary information. Overall, higher levels of diversity and a stronger differentiation was revealed among

  8. Strong Genetic Differentiation of Submerged Plant Populations across Mountain Ranges: Evidence from Potamogeton pectinatus in Iran.

    Directory of Open Access Journals (Sweden)

    Shabnam Abbasi

    Full Text Available Biogeographic barriers for freshwater biota can be effective at various spatial scales. At the largest spatial scale, freshwater organisms can become genetically isolated by their high mountain ranges, vast deserts, and inability to cross oceans. Isolation by distance of aquatic plants is expected to be stronger across than alongside mountain ridges whereas the heterogeneity of habitats among populations and temporary droughts may influence connectivity and hamper dispersal. Suitable aquatic plant habitats became reduced, even for the widespread submerged Potamogeton pectinatus L. (also named Stuckenia pectinata giving structure to various aquatic habitats. We compared the level of genetic diversity in a heterogeneous series of aquatic habitats across Iran and tested their differentiation over distances and across mountain ranges (Alborz and Zagros and desert zones (Kavir, with values obtained from temperate region populations. The diversity of aquatic ecosystems across and along large geographic barriers provided a unique ecological situation within Iran. P. pectinatus were considered from thirty-six sites across Iran at direct flight distances ranging from 20 to 1,200 km. Nine microsatellite loci revealed a very high number of alleles over all sites. A PCoA, NJT clustering and STRUCTURE analysis revealed a separate grouping of individuals of southeastern Iranian sites and was confirmed by their different nuclear ITS and cpDNA haplotypes thereby indicating an evolutionary significant unit (ESU. At the level of populations, a positive correlation between allelic differentiation Dest with geographic distance was found. Individual-based STRUCTURE analysis over 36 sites showed 7 genetic clusters. FST and RST values for ten populations reached 0.343 and 0.521, respectively thereby indicating that allele length differences are more important and contain evolutionary information. Overall, higher levels of diversity and a stronger differentiation was

  9. A plant toxin mediated mechanism for the lag in snowshoe hare population recovery following cyclic declines

    Science.gov (United States)

    DeAngelis, Donald L.; Bryant, John P.; Liu, Rongsong; Gourley, Stephen A.; Krebs, Charles J; Reichardt, Paul B

    2015-01-01

    A necessary condition for a snowshoe hare population to cycle is reduced reproduction after the population declines. But the cause of a cyclic snowshoe hare population's reduced reproduction during the low phase of the cycle, when predator density collapses, is not completely understood. We propose that moderate-severe browsing by snowshoe hares upon preferred winter-foods could increase the toxicity of some of the hare's best winter-foods during the following hare low, with the result being a decline in hare nutrition that could reduce hare reproduction. We used a combination of modeling and experiments to explore this hypothesis. Using the shrub birch Betula glandulosa as the plant of interest, the model predicted that browsing by hares during a hare cycle peak, by increasing the toxicity B. glandulosa twigs during the following hare low, could cause a hare population to cycle. The model's assumptions were verified with assays of dammarane triterpenes in segments of B. glandulosa twigs and captive hare feeding experiments conducted in Alaska during February and March 1986. The model's predictions were tested with estimates of hare density and measurements of B. glandulosa twig growth made at Kluane, Yukon from 1988–2008. The empirical tests supported the model's predictions. Thus, we have concluded that a browsing-caused increase in twig toxicity that occurs during the hare cycle's low phase could reduce hare reproduction during the low phase of the hare cycle.

  10. Population dose commitments due to radioactive releases from nuclear power plant sites in 1984

    Energy Technology Data Exchange (ETDEWEB)

    Baker, D.A.

    1988-01-01

    Population radiation dose commitments have been estimated from reported radionuclide releases from commercial power reactors operating during 1984. Fifty-year dose commitments from a one-year exposure were calculated from both liquid and atmospheric releases for four population groups (infant, child, teen-ager and adult) residing between 2 and 80 km from each of 56 sites. This report tabulates the results of these calculations, showing the dose commitments for both liquid and airborne pathways for each age group and organ. Also included for each of the sites is a histogram showing the fraction of the total population within 2 to 80 km around each site receiving various average dose commitments from the airborne pathways. The total dose commitments (from both liquid and airborne pathways) for each site ranged from a high of 110 person-rem to a low of 0.002 person-rem for the sites with plants operating throughout the year with an arithmetic mean of 5 person-rem. The total population dose for all sites was estimated at 280 person-rem for the 100 million people considered at risk. The site average individual dose commitment from all pathways ranged from a low of 6 x 10/sup -6/ mrem to a high of 0.04 mrem. No attempt was made in this study to determine the maximum dose commitment received by any one individual from the radionuclides released at any of the sites.

  11. Influence of Plant Population and Nitrogen-Fertilizer at Various Levels on Growth and Growth Efficiency of Maize

    Directory of Open Access Journals (Sweden)

    M. I. Tajul

    2013-01-01

    Full Text Available Field experiments were conducted to evaluate plant population and N-fertilizer effects on yield and yield components of maize (Zea mays L.. Three levels of plant populations (53000, 66000, and 800000 plants ha−1 corresponding to spacings of 75 × 25, 60 × 25, and 50 × 25 cm and 4 doses of N (100, 140, 180, and 220 kg ha−1 were the treatment variables. Results revealed that plant growth, light interception (LI, yield attributes, and grain yield varied significantly due to the variations in population density and N-rates. Crop growth rate (CGR was the highest with the population of 80,000 ha−1 receiving 220 kg N ha−1, while relative growth rate (RGR showed an opposite trend of CGR. Light absorption was maximum when most of densely populated plant received the highest amount of N (220 kg N ha−1. Response of soil-plant-analysis development (SPAD value as well as N-content to N-rates was found significant. Plant height was the maximum at the lowest plant density with the highest amount of N. Plants that received 180 kg N ha−1 with 80,000 plants ha−1 had larger foliage, greater SPAD value, and higher amount of grains cob−1 that contributed to the maximum yield (5.03 t ha−1 and the maximum harvest index (HI compared to the plants in other treatments.

  12. Millennial-scale variability in dust deposition, marine export production, and nutrient consumption in the glacial subantarctic ocean (Invited)

    Science.gov (United States)

    Martinez-Garcia, A.; Sigman, D. M.; Anderson, R. F.; Ren, H. A.; Hodell, D. A.; Straub, M.; Jaccard, S.; Eglinton, T. I.; Haug, G. H.

    2013-12-01

    Based on the limitation of modern Southern Ocean phytoplankton by iron and the evidence of higher iron-bearing dust fluxes to the ocean during ice ages, it has been proposed that iron fertilization of Southern Ocean phytoplankton contributed to the reduction in atmospheric CO2 during ice ages. In the Subantarctic zone of the Atlantic Southern Ocean, glacial increases in dust flux and export production have been documented, supporting the iron fertilization hypothesis. However, these observations could be interpreted alternatively as resulting from the equatorward migration of Southern Ocean fronts during ice ages if the observed productivity rise was not accompanied by an increase in major nutrient consumption. Here, new 230Th-normalized lithogenic and opal fluxes are combined with high-resolution biomarker measurements to reconstruct millennial-scale changes in dust deposition and marine export production in the subantarctic Atlantic over the last glacial cycle. In the same record foraminifera-bound nitrogen isotopes are used to reconstruct ice age changes in surface nitrate utilization, providing a comprehensive test of the iron fertilization hypothesis. Elevation in foraminifera-bound δ15N, indicating more complete nitrate consumption, coincides with times of surface cooling and greater dust flux and export production. These observations indicate that the ice age Subantarctic was characterized by iron fertilized phytoplankton growth. The resulting strengthening of the Southern Ocean's biological pump can explain the ~40 ppm lowering of CO2 that characterizes the transitions from mid-climate states to full ice age conditions as well as the millennial-scale atmospheric CO2 fluctuations observed within the last ice age

  13. Volatile Constituents of Different Plant Parts and Populations of Malabaila aurea Boiss. from Montenegro

    Directory of Open Access Journals (Sweden)

    Ivan Vučković

    2014-03-01

    Full Text Available The volatile constituents of different plant parts and populations of Malabaila aurea Boiss. from Montenegro were obtained by simultaneous distillation-extraction and analyzed by GC-FID and GC-MS. A total of 12 samples were examined and 45 compounds were identified. The volatile content of different M. aurea populations was very similar, while the volatile fractions obtained from different plant parts showed significant qualitative and quantitative differences. The most abundant compounds found in stems & leaves were apiole (51.0-56.3%, myristicin (16.3-25.4%, and falcarinol (4.1-10.7%. The roots showed the same major components, but with different relative abundances: 30.9-49.1% of apiole, 12.9-34.7% of falcarinol, and 9.9-31.1% of myristicin. The volatile constituents of fruits & flowers were remarkably different, containing up to 71.2-80.5% octyl butyrate, 11.4-18.0% octanol, and 2.7-6.8% octyl hexanoate. The results were discussed as possible indication of relatedness of Malabaila aurea and Pastinacasativa (parsnip .

  14. Hippopotamus (H. amphibius) diet change indicates herbaceous plant encroachment following megaherbivore population collapse.

    Science.gov (United States)

    Chritz, Kendra L; Blumenthal, Scott A; Cerling, Thure E; Klingel, Hans

    2016-09-12

    Megaherbivores (>1000 kg) are critical for ecosystem health and function, but face population collapse and extinction globally. The future of these megaherbivore-impoverished ecosystems is difficult to predict, though many studies have demonstrated increasing representation of C3 woody plants. These studies rely on direct observational data, however, and tools for assessing decadal-scale changes in African ecology without observation are lacking. We use isotopic records of historical common hippopotamus (Hippopotamus amphibius) canines to quantify herbaceous vegetation change in Queen Elizabeth National Park, Uganda following a period of civil unrest and poaching. This poaching event led to population collapse of two threatened African megaherbivore species: hippopotamus and African elephants (Loxodonta africana). Serial carbon isotope ratios (δ(13)C) in canine enamel from individuals that lived between 1960-2000 indicated substantial increases in C3 herbaceous plants in their diet (<20% C3 in the 1960s to 30-45% C3 in the 80s and 90s), supported by other observational and ecological data. These data indicate megaherbivore loss results in succession of both woody and herbaceous C3 vegetation and further reaching effects, such as decreased grazing capacity and herbivore biodiversity in the area. Given multiple lines of evidence, these individuals appear to accurately capture herbaceous vegetation change in Mweya.

  15. Performance of irrigated green corn cultivars in different plant populations at sowing

    Directory of Open Access Journals (Sweden)

    José C. Soares Neto

    Full Text Available ABSTRACT This study aimed to evaluate the yield of green corn hybrids grown under irrigation in different plant populations at sowing. The assay was carried out in the experimental area located in the city of Arapiraca, Alagoas State, Brazil, from November 2015 to January 2016. A randomized complete block design (RCBD was used, in a 2 x 5 factorial scheme with four replicates. A double- and a single-cross hybrid (AG 1051 and BM 3061, which are suitable for green corn production, were cultivated in five spacings between plants at sowing (15.0, 17.5, 20.0, 22.5 and 25.0 cm. The characteristics photosynthetic rate (PR, ear length with rusk (HEL and without husk (UEL, husked ear weight (HEW, unhusked ear weight (UEW, percentage of marketable ears (%ME and weight of husk (HW were evaluated. The double- and single-cross hybrids AG 1051 and BM 3061 showed green ears with commercial standard. The cultivar BM 3061 showed the best results for most of the characteristics related to the performance of green corn (PR, HEL, UEL, UEW, HEW, %ME. The spacing of 17.5 cm between plants at sowing was the most indicated for irrigated green corn cultivation.

  16. Investigation into the impact of storms on sustaining summer primary productivity in the Sub-Antarctic Ocean

    CSIR Research Space (South Africa)

    Nicholson, Sarah-Anne

    2016-09-01

    Full Text Available of such phenomena for ocean-biogeochemical models. 1. Introduction An unexplained peculiarity of phytoplankton blooms in the Southern Ocean (SO) is the regional-scale occur- rence of prolonged blooms into late summer [Swart et al., 2015; Carranza and Gille, 2015...]. Observations of chlorophyll a show that summer blooms are widespread and occur annually [Carranza and Gille, 2015], are prominent within the Sub-Antarctic Zone (SAZ), and may be several months in duration (e.g., ~16weeks in Racault et al. [2012]), typically...

  17. Pseudoisotachis Pocsii Váňa, A New Genus and Species of Liverwort from the Subantarctic Marion Island

    Directory of Open Access Journals (Sweden)

    Váňa Jiří

    2013-07-01

    Full Text Available A new genus and new species of liverwort, Pseudoisotachis Váňa and Pseudoisotachis pocsii Váňa, is described from Marion Island, part of the Prince Edward Islands, a subantarctic archipelago situated in the Kerguelen Province of the southern Indian Ocean. Family placement of the new genus and species is uncertain due to absence of androecia, gynoecia and sporophytes; morphologically it is compared with some genera of Isotachidaceae and with the genus Orthocaulis of Anastrophyllaceae. The new species is described and illustrated.

  18. Species composition and biogeography of diatoms in antarctic and subantarctic (Argentine shelf) waters (37-76°S)

    Science.gov (United States)

    Olguín, Héctor F.; Alder, Viviana A.

    2011-03-01

    A large spatial scale study of the diatom species inhabiting waters from the subantarctic (Argentine shelf) to antarctic was made for the first time in order to understand the relationships between these two regions with regard to the fluctuations in diatom abundances in relation with environmental features, their floristic associations and the effect of the Polar Front as a biogeographic barrier. Species-specific diatom abundance, nutrient and chlorophyll- a concentration were assessed from 64 subsurface oceanographic stations carried out during the austral summer 2002, a period characterized by an anomalous sea-ice coverage corresponding to a "warm year". Significant relationships of both diatom density and biomass with chlorophyll- a (positive) and water temperature (negative) were found for the study area as a whole. Within the Subantarctic region, diatom density and biomass values were more uniform and significantly (in average: 35 and 11 times) lower than those of the Antarctic region, and did not correlate with chlorophyll- a. In antarctic waters, instead, biomass was directly related with chlorophyll- a, thus confirming the important contribution of diatoms to the Antarctic phytoplanktonic stock. A total of 167 taxa were recorded for the entire study area, with Chaetoceros and Thalassiosira being the best represented genera. Species richness was maximum in subantarctic waters (46; Argentine shelf) and minimum in the Antarctic region (21; Antarctic Peninsula), and showed a significant decrease with latitude. Floristic associations were examined both qualitatively (Jaccard Index) and quantitatively (correlation) by cluster analyses and results allowed differentiating a similar number of associations (12 vs. 13, respectively) and two main groups of stations. In the Drake Passage, the former revealed that the main floristic change was found at the Polar Front, while the latter reflected the Southern ACC Front as a main boundary, and yielded a higher number of

  19. Diverse Bacterial Groups Contribute to the Alkane Degradation Potential of Chronically Polluted Subantarctic Coastal Sediments

    Energy Technology Data Exchange (ETDEWEB)

    Guibert, Lilian M.; Loviso, Claudia L.; Borglin, Sharon; Jansson, Janet K.; Dionisi, Hebe M.; Lozada, Mariana

    2015-11-07

    We aimed to gain insight into the alkane degradation potential of microbial communities from chronically polluted sediments of a subantarctic coastal environment using a combination of metagenomic approaches. A total of 6178 sequences annotated as alkane-1-monooxygenases (EC 1.14.15.3) were retrieved from a shotgun metagenomic dataset that included two sites analyzed in triplicate. The majority of the sequences binned with AlkB described in Bacteroidetes (32 ± 13 %) or Proteobacteria (29 ± 7 %), although a large proportion remained unclassified at the phylum level. Operational taxonomic unit (OTU)-based analyses showed small differences in AlkB distribution among samples that could be correlated with alkane concentrations, as well as with site-specific variations in pH and salinity. A number of low-abundance OTUs, mostly affiliated with Actinobacterial sequences, were found to be only present in the most contaminated samples. On the other hand, the molecular screening of a large-insert metagenomic library of intertidal sediments from one of the sampling sites identified two genomic fragments containing novel alkB gene sequences, as well as various contiguous genes related to lipid metabolism. Both genomic fragments were affiliated with the phylum Planctomycetes, and one could be further assigned to the genus Rhodopirellula due to the presence of a partial sequence of the 23S ribosomal RNA (rRNA) gene. This work highlights the diversity of bacterial groups contributing to the alkane degradation potential and reveals patterns of functional diversity in relation with environmental stressors in a chronically polluted, high-latitude coastal environment. In addition, alkane biodegradation genes are described for the first time in members of Planctomycetes.

  20. Hormonal responses to extreme fasting in subantarctic fur seal (Arctocephalus tropicalis) pups.

    Science.gov (United States)

    Verrier, Delphine; Atkinson, Shannon; Guinet, Christophe; Groscolas, René; Arnould, John P Y

    2012-04-15

    Surviving prolonged fasting implies closely regulated alterations in fuel provisioning to meet metabolic requirements, while preserving homeostasis. Little is known, however, of the endocrine regulations governing such metabolic adaptations in naturally fasting free-ranging animals. The hormonal responses to natural prolonged fasting and how they correlate to the metabolic adaptations observed, were investigated in subantarctic fur seal (Arctocephalus tropicalis) pups, which, because of the intermittent pattern of maternal attendance, repeatedly endure exceptionally long fasting episodes throughout their development (1-3 mo). Phase I fasting was characterized by a dramatic decrease in plasma insulin, glucagon, leptin, and total l-thyroxine (T(4)) associated with reductions in mass-specific resting metabolic rate (RMR), plasma triglycerides, glycerol, and urea-to-creatine ratio, while nonesterified fatty acids (NEFA) and β-OHB increased. In contrast, the metabolic steady-state of phase II fasting reached within 6 days was associated with minimal concentrations of insulin, glucagon, and leptin; unchanged cortisol and triiodothyronine (T(3)); and moderately increased T(4). The early fall in insulin and leptin may mediate the shift to the strategy of energy conservation, protein sparing, and primary reliance on body lipids observed in response to the cessation of feeding. In contrast to the typical mammalian starvation response, nonelevated cortisol and minimal glucagon levels may contribute to body protein preservation and downregulation of catabolic pathways, in general. Furthermore, thyroid hormones may be involved in a process of energy conservation, independent of pups' nutritional state. These original hormonal settings might reflect an adaptation to the otariid repeated fasting pattern and emphasize the crucial importance of a tight physiological control over metabolism to survive extreme energetic constraints.

  1. Soil calcium availability influences shell ecophenotype formation in the sub-antarctic land snail, Notodiscus hookeri.

    Directory of Open Access Journals (Sweden)

    Maryvonne Charrier

    Full Text Available Ecophenotypes reflect local matches between organisms and their environment, and show plasticity across generations in response to current living conditions. Plastic responses in shell morphology and shell growth have been widely studied in gastropods and are often related to environmental calcium availability, which influences shell biomineralisation. To date, all of these studies have overlooked micro-scale structure of the shell, in addition to how it is related to species responses in the context of environmental pressure. This study is the first to demonstrate that environmental factors induce a bi-modal variation in the shell micro-scale structure of a land gastropod. Notodiscus hookeri is the only native land snail present in the Crozet Archipelago (sub-Antarctic region. The adults have evolved into two ecophenotypes, which are referred to here as MS (mineral shell and OS (organic shell. The MS-ecophenotype is characterised by a thick mineralised shell. It is primarily distributed along the coastline, and could be associated to the presence of exchangeable calcium in the clay minerals of the soils. The Os-ecophenotype is characterised by a thin organic shell. It is primarily distributed at high altitudes in the mesic and xeric fell-fields in soils with large particles that lack clay and exchangeable calcium. Snails of the Os-ecophenotype are characterised by thinner and larger shell sizes compared to snails of the MS-ecophenotype, indicating a trade-off between mineral thickness and shell size. This pattern increased along a temporal scale; whereby, older adult snails were more clearly separated into two clusters compared to the younger adult snails. The prevalence of glycine-rich proteins in the organic shell layer of N. hookeri, along with the absence of chitin, differs to the organic scaffolds of molluscan biominerals. The present study provides new insights for testing the adaptive value of phenotypic plasticity in response to spatial

  2. Oxidative stress and antioxidant defences generated by solar UV in a Subantarctic marine phytoflagellate

    Directory of Open Access Journals (Sweden)

    Marcelo Pablo Hernando

    2005-12-01

    Full Text Available The reduction of the Antarctic stratospheric ozone resulted in significant increases in ultraviolet B radiation (UV-B, 280-320 nm reaching the surface of the ocean. The main objective of this work was to study long-term (growth rate scale, days stress responses (lipid oxidative damage, TBARS, and lipid soluble antioxidants to UV-B and UV-A of a phytoflagellate species (Asteromonas sp. isolated from a natural phytoplankton community of the Subantarctic Beagle Channel. The growth rate was inhibited by UV-B and UV-A radiation during the exponential phase. A marked increase in the TBARS content was observed on day 1 of the experiment, with significant differences between algae subjected to UV-B and UV-A treatments, thus suggesting high damage to the cell membrane. During the second day of the experiment TBARS in UV-A treatments were higher than under photosynthetically active radiation (PAR. The concentration of TBARS decreased to the level of the PAR control on day 3, remaining low until the end of the experiment. Lipid antioxidant concentrations (?-tocopherol and ?-carotene were delayed with respect to variations in TBARS, showing maximum values on day 3 of the experiment. This coincided with the minimum TBARS concentrations in all treatments. The content of both antioxidants increased significantly in cultures exposed to UV-B and UV-A on days 3 and 4. In Antarctic species (phytoflagellate Asteromonas sp., AP and diatom Thalassiosira sp., AT a-tocopherol was more abundant than b-carotene. The phytoflagellate species showed a lag in reaching the maximum content of both antioxidants in relation to AT, which reached the maximum concentration within a short time scale (3 h suggesting a more rapid response to oxidative stress. AT was more resistant to UVR stress than the phytoflagellate species. Overall, our results show that UVR damage/repair balance involves the combined action of several internal factors in the cell.

  3. Submarine geology and geomorphology of active Sub-Antarctic volcanoes: Heard and McDonald Islands

    Science.gov (United States)

    Watson, S. J.; Coffin, M. F.; Whittaker, J. M.; Lucieer, V.; Fox, J. M.; Carey, R.; Arculus, R. J.; Bowie, A. R.; Chase, Z.; Robertson, R.; Martin, T.; Cooke, F.

    2016-12-01

    Heard and McDonald Islands (HIMI) are World Heritage listed sub-Antarctic active volcanic islands in the Southern Indian Ocean. Built atop the Kerguelen Plateau by Neogene-Quaternary volcanism, HIMI represent subaerial exposures of the second largest submarine Large Igneous Province globally. Onshore, processes influencing island evolution include glaciers, weathering, volcanism, vertical tectonics and mass-wasting (Duncan et al. 2016). Waters surrounding HIMI are largely uncharted, due to their remote location. Hence, the extent to which these same processes shape the submarine environment around HIMI has not been investigated. In early 2016, we conducted marine geophysical and geologic surveys around HIMI aboard RV Investigator (IN2016_V01). Results show that volcanic and sedimentary features prominently trend east-west, likely a result of erosion by the eastward flowing Antarctic Circumpolar Current and tidal currents. However, spatial patterns of submarine volcanism and sediment distribution differ substantially between the islands. >70 sea knolls surround McDonald Island suggesting substantial submarine volcanism. Geophysical data reveals hard volcanic seafloor around McDonald Island, whereas Heard Island is characterised by sedimentary sequences tens of meters or more thick and iceberg scours - indicative of glacial processes. Differences in submarine geomorphology are likely due to the active glaciation of Heard Island and differing rock types (Heard: alkali basalt, McDonald: phonolite), and dominant products (clastics vs. lava). Variations may also reflect different magmatic plumbing systems beneath the two active volcanoes (Heard produces larger volumes of more focused lava, whilst McDonald extrudes smaller volumes of more evolved lavas from multiple vents across the edifice). Using geophysical data, corroborated with new and existing geologic data, we present the first geomorphic map revealing the processes that shape the submarine environment around HIMI.

  4. The spatial distribution of threats to plant species with extremely small populations

    Science.gov (United States)

    Wang, Chunjing; Zhang, Jing; Wan, Jizhong; Qu, Hong; Mu, Xianyun; Zhang, Zhixiang

    2017-03-01

    Many biological conservationists take actions to conserve plant species with extremely small populations (PSESP) in China; however, there have been few studies on the spatial distribution of threats to PSESP. Hence, we selected distribution data of PSESP and made a map of the spatial distribution of threats to PSESP in China. First, we used the weight assignment method to evaluate the threat risk to PSESP at both country and county scales. Second, we used a geographic information system to map the spatial distribution of threats to PSESP, and explored the threat factors based on linear regression analysis. Finally, we suggested some effective conservation options. We found that the PSESP with high values of protection, such as the plants with high scientific research values and ornamental plants, were threatened by over-exploitation and utilization, habitat fragmentation, and a small sized wild population in broad-leaved forests and bush fallows. We also identified some risk hotspots for PSESP in China. Regions with low elevation should be given priority for ex- and in-situ conservation. Moreover, climate change should be considered for conservation of PSESP. To avoid intensive over-exploitation or utilization and habitat fragmentation, in-situ conservation should be practiced in regions with high temperatures and low temperature seasonality, particularly in the high risk hotspots for PSESP that we proposed. Ex-situ conservation should be applied in these same regions, and over-exploitation and utilization of natural resources should be prevented. It is our goal to apply the concept of PSESP to the global scale in the future.

  5. Population Growth Parameters of Tuta absoluta (Lepidoptera: Gelechiidae) on Tomato Plant Using Organic Substrate and Biofertilizers.

    Science.gov (United States)

    Mohamadi, P; Razmjou, J; Naseri, B; Hassanpour, M

    2017-01-01

    The tomato leafminer, Tuta absoluta (Meyrick) is a devastating pest associated with tomato. In this study, effects of tomato plants treated with vermicompost (20, 40, and 60%), humic fertilizer (2, 4 and 6 g/kg soil) and plant growth promoting rhizobacteria (Pseudomonas fluorescens and Bacillus subtilis) were investigated on the life table parameters of T. absoluta in a growth chamber at 25 ± 2 °C, 65 ± 5% RH, and 16:8 (L:D) h. Significant differences were found for the total developmental time, fecundity, and oviposition period of T. absoluta on the treatments tested. The net reproductive rate (R0), intrinsic rate of natural increase (rm), finite rate of increase (λ), mean generation time (T), and doubling time (DT) of T. absoluta were significantly different among treatments tested. We found that in all vermicompost, humic fertilizer and plant growth promoting rhizobacteria treatments, values of R0, rm, and λ were lower than control treatment. However, the lowest values of these parameters were obtained on 2 g/kg humic fertilizer and 40% vermicompost. Furthermore, T. absoluta had longest T and DT values on 2 g/kg humic fertilizer treatment. Data obtained showed that the addition of 2 g/kg humic fertilizer and 40% vermicompost to the growing soil reduced T. absoluta populations in tomato cultures. In addition, these levels of fertilizers improved growth parameters of tomato seedlings (plant height, wet weight, and dry weight) compared with other treatments. These results could be useful in improving the sustainable management of the moth. © The Author 2017. Published by Oxford University Press on behalf of the Entomological Society of America.

  6. A stochastic model of chromatin modification: cell population coding of winter memory in plants.

    Science.gov (United States)

    Satake, Akiko; Iwasa, Yoh

    2012-06-07

    Biological memory, a sustained cellular response to a transient stimulus, has been found in many natural systems. The best example in plants is the winter memory by which plants can flower in favorable conditions in spring. For this winter memory, epigenetic regulation of FLOWERING LOCUS C (FLC), which acts as a floral repressor, plays a key role. Exposure to prolonged periods of cold results in the gradual suppression of FLC, which allows plants to measure the length of cold and to flower only after a sufficiently long winter. Although many genes involved in histone modifications have been isolated, molecular mechanisms of winter memory are not well understood. Here, we develop a model for chromatin modification, in which the dynamics of a single nucleosome are aggregated to on/off behavior of FLC expression at the cellular level and further integrated to a change of FLC expression at the whole-plant level. We propose cell-population coding of winter memory: each cell is described as a bistable system that shows heterogeneous timing of the transition from on to off in FLC expression under cold and measures the length of cold as the proportion of cells in the off state. This mechanism well explains robust FLC regulation and stable inheritance of winter memory after cell division in response to noisy signals. Winter memory lasts longer if deposition of the repressive histone mark occurs faster. A difference in deposition speed would discriminate between stable maintenance of FLC repression in annuals and transient expression in perennials. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Population Growth Parameters of Tuta absoluta (Lepidoptera: Gelechiidae) on Tomato Plant Using Organic Substrate and Biofertilizers

    Science.gov (United States)

    Razmjou, J.; Naseri, B.; Hassanpour, M.

    2017-01-01

    The tomato leafminer, Tuta absoluta (Meyrick) is a devastating pest associated with tomato. In this study, effects of tomato plants treated with vermicompost (20, 40, and 60%), humic fertilizer (2, 4 and 6 g/kg soil) and plant growth promoting rhizobacteria (Pseudomonas fluorescens and Bacillus subtilis) were investigated on the life table parameters of T. absoluta in a growth chamber at 25 ± 2 °C, 65 ± 5% RH, and 16:8 (L:D) h. Significant differences were found for the total developmental time, fecundity, and oviposition period of T. absoluta on the treatments tested. The net reproductive rate (R0), intrinsic rate of natural increase (rm), finite rate of increase (λ), mean generation time (T), and doubling time (DT) of T. absoluta were significantly different among treatments tested. We found that in all vermicompost, humic fertilizer and plant growth promoting rhizobacteria treatments, values of R0, rm, and λ were lower than control treatment. However, the lowest values of these parameters were obtained on 2 g/kg humic fertilizer and 40% vermicompost. Furthermore, T. absoluta had longest T and DT values on 2 g/kg humic fertilizer treatment. Data obtained showed that the addition of 2 g/kg humic fertilizer and 40% vermicompost to the growing soil reduced T. absoluta populations in tomato cultures. In addition, these levels of fertilizers improved growth parameters of tomato seedlings (plant height, wet weight, and dry weight) compared with other treatments. These results could be useful in improving the sustainable management of the moth. PMID:28355477

  8. Population Dynamics of Plant-parasitic Nematodes on Cover Crops of Corn and Sorghum.

    Science.gov (United States)

    McSorley, R; Gallaher, R N

    1993-09-01

    Buildup of plant-parasitic nematode populations on corn (Zea mays), soybean (Glycine max), and sorghum (Sorghum bicolor) were compared in 1991 and 1992. Final population densities (Pf) of Meloidogyne incognita were lower following sorghum than after soybean in both seasons, and Pf after sorghum was lower than Pf after corn in 1992. In both seasons, Pf differed among the sorghum cultivars used. No differences in Pf on corn, sorghum, and soybean were observed for Criconemella spp. (a mixture of C. sphaerocephala and C. ornata) or Paratrichodorus minor in either season. Pf levels of Pratylenchus spp. (a mixture of P. brachyurus and P. scribneri) were greatest after corn in 1992, but no differences with crop treatments were observed in 1991. When data from field tests conducted with corn and sorghum during the past four seasons were pooled, negative linear relationships between ln(Pf/Pi) and ln(Pi) were observed for Criconemella spp. and P. minor on each crop, and for M. incognita on corn (Pi = initial population density). Although ln(Pf/Pi) and ln(Pi) were not related for M. incognita with pooled sorghum data, separate relationships were derived for various sorghum cultivars. Regression equations from pooled data were used to obtain estimates of equilibrium density and maximum reproductive rate, and these estimates were used to construct models expressing nematode Pf across a range of initial densities. Many of these models were robust, encompassing a range of sites, season, crop cultivars, and planting dates. Quadratic models derived from pooled field data provided an alternative method for expressing Pf as a function of Pi.

  9. Extensive lake sediment coring survey on Sub-Antarctic Indian Ocean Kerguelen Archipelago (French Austral and Antarctic Lands)

    Science.gov (United States)

    Arnaud, Fabien; Fanget, Bernard; Malet, Emmanuel; Poulenard, Jérôme; Støren, Eivind; Leloup, Anouk; Bakke, Jostein; Sabatier, Pierre

    2016-04-01

    Recent paleo-studies revealed climatic southern high latitude climate evolution patterns that are crucial to understand the global climate evolution(1,2). Among others the strength and north-south shifts of westerlies wind appeared to be a key parameter(3). However, virtually no lands are located south of the 45th South parallel between Southern Georgia (60°W) and New Zealand (170°E) precluding the establishment of paleoclimate records of past westerlies dynamics. Located around 50°S and 70°E, lost in the middle of the sub-Antarctic Indian Ocean, Kerguelen archipelago is a major, geomorphologically complex, land-mass that is covered by hundreds lakes of various sizes. It hence offers a unique opportunity to reconstruct past climate and environment dynamics in a region where virtually nothing is known about it, except the remarkable recent reconstructions based on a Lateglacial peatbog sequence(4). During the 2014-2015 austral summer, a French-Norwegian team led the very first extensive lake sediment coring survey on Kerguelen Archipelago under the umbrella of the PALAS program supported by the French Polar Institute (IPEV). Two main areas were investigated: i) the southwest of the mainland, so-called Golfe du Morbihan, where glaciers are currently absent and ii) the northernmost Kerguelen mainland peninsula so-called Loranchet, where cirque glaciers are still present. This double-target strategy aims at reconstructing various independent indirect records of precipitation (glacier advance, flood dynamics) and wind speed (marine spray chemical species, wind-borne terrigenous input) to tackle the Holocene climate variability. Despite particularly harsh climate conditions and difficult logistics matters, we were able to core 6 lake sediment sites: 5 in Golfe du Morbihan and one in Loranchet peninsula. Among them two sequences taken in the 4km-long Lake Armor using a UWITEC re-entry piston coring system by 20 and 100m water-depth (6 and 7m-long, respectively). One

  10. The contribution of germination functional traits to population dynamics of a desert plant community.

    Science.gov (United States)

    Huang, Zhenying; Liu, Shuangshuang; Bradford, Kent J; Huxman, Travis E; Venable, D Lawrence

    2016-01-01

    Early life-cycle events play critical roles in determining the population and community dynamics of plants. The ecology of seeds and their germination patterns can determine range limits, adaptation to environmental variation, species diversity, and community responses to climate change. Understanding the adaptive consequences and environmental filtering of such functional traits will allow us to explain and predict ecological dynamics. Here we quantify key functional aspects of germination physiology and relate them to an existing functional ecology framework to explain long-term population dynamics for 13 species of desert annuals near Tucson, Arizona, USA. Our goal was to assess the extent to which germination functional biology contributes to long-term population processes in nature. Some of the species differences in base, optimum, and maximum temperatures for germination, thermal times to germination, and base water potentials for germination were strongly related to 20-yr mean germination fractions, 25-yr average germination dates, seed size, and long-term demographic variation. Comparisons of germination fraction, survival, and fecundity vs. yearly changes in population size found significant roles for all three factors, although in varying proportions for different species. Relationships between species' germination physiologies and relative germination fractions varied across years, with fast-germinating species being favored in years with warm temperatures during rainfall events in the germination season. Species with low germination fractions and high demographic variance have low integrated water-use efficiency, higher vegetative growth rates, and smaller, slower-germinating seeds. We have identified and quantified a number of functional traits associated with germination biology that play critical roles in ecological population dynamics.

  11. Allele Identification for Transcriptome-Based Population Genomics in the Invasive Plant Centaurea solstitialis

    Science.gov (United States)

    Dlugosch, Katrina M.; Lai, Zhao; Bonin, Aurélie; Hierro, José; Rieseberg, Loren H.

    2013-01-01

    Transcriptome sequences are becoming more broadly available for multiple individuals of the same species, providing opportunities to derive population genomic information from these datasets. Using the 454 Life Science Genome Sequencer FLX and FLX-Titanium next-generation platforms, we generated 11−430 Mbp of sequence for normalized cDNA for 40 wild genotypes of the invasive plant Centaurea solstitialis, yellow starthistle, from across its worldwide distribution. We examined the impact of sequencing effort on transcriptome recovery and overlap among individuals. To do this, we developed two novel publicly available software pipelines: SnoWhite for read cleaning before assembly, and AllelePipe for clustering of loci and allele identification in assembled datasets with or without a reference genome. AllelePipe is designed specifically for cases in which read depth information is not appropriate or available to assist with disentangling closely related paralogs from allelic variation, as in transcriptome or previously assembled libraries. We find that modest applications of sequencing effort recover most of the novel sequences present in the transcriptome of this species, including single-copy loci and a representative distribution of functional groups. In contrast, the coverage of variable sites, observation of heterozygosity, and overlap among different libraries are all highly dependent on sequencing effort. Nevertheless, the information gained from overlapping regions was informative regarding coarse population structure and variation across our small number of population samples, providing the first genetic evidence in support of hypothesized invasion scenarios. PMID:23390612

  12. Ways of adaptation of the plant populations to chemical and radioactive contamination

    Energy Technology Data Exchange (ETDEWEB)

    Pozolotina, V.; Bezel' , V.; Zhuykova, T.; Severu' Khina, O.; Ulyanova, E. [Institute of Plant and Animal Ecology, Ural Division of Russian Academy of Sciences, Ekaterinburg (Russian Federation)

    2004-07-01

    Chemical agents (heavy metals, acids, etc.) and radiation render their influence upon biota being clearly distinct in primary mechanisms of action. However, lively organisms demonstrate one and the same set [arsenal] of response reactions, and thus it is important to reveal the ways of their realization caused by different types of techno-genic impacts. Our work was intended to examine the seed progeny of the dandelion, Taraxacum officinale, from radionuclides-contaminated coeno-populations (grown at the territories influenced by Eastern-Ural radioactive trace, in the Techa-river flood plain) and those situated in the nearest impact zone affected by a large metallurgical plant in the Urals. Plots, differently distanced from the enterprise, showed heavy metal contamination loads 8-33 times higher than the control site did. Radionuclides concentrations ({sup 90}Sr and {sup 137}Cs) within the contaminated zone exceeded the background values 4-40 times. The study allowed estimation of the seed progeny vitality level for different coeno-populations, comparison of their adaptive potential in regard to heavy metals tolerance and gamma radiation resistance, estimation of abnormal seedlings [sprouts] frequency values. It was shown [found] that under techno-genic pollution the dandelion coeno-populations usually demonstrate wider variations of different characteristics (vitality, mutability, root and leaf growth rates) as compared to those in the background zone. As a general regularity one can regard the phenomenon, that negative effects were not marked to be increased by heavier pollution loads, irrespectively of the agents nature. (author)

  13. Creating new populations of Apium bermejoi (Apiaceae, a critically endangered endemic plant on Menorca (Balearic Islands

    Directory of Open Access Journals (Sweden)

    Rita, Juan

    2013-06-01

    Full Text Available Apium bermejoi is a stoloniferous plant endemic to the island of Menorca (Balearic Islands. It is found only at one locality, and it is listed as Critically Endangered (according to the IUCN criteria. We describe the main results of population restoration actions undertaken under the Recovery Plan for this species, including the following: 1 introduction at two new localities (2008, 2 reinforcement of the original wild and the introduced populations, and 3 a programme for monitoring population dynamics (including both wild and introduced populations spanning four years (2006-2010. The plant material for the introduction and reinforcement projects was generated from seeds gathered in the wild. We carried out a monthly census of all of the individuals/patches and emerged seedlings, from which we assessed their survival at 3-4months. The survival rates of the planted individuals in the two new localities after three months were found to be 59.0% and 56.3%, and more than 80% of the surviving plants produced fruits. A seasonal pattern was observed based on the minimum cover values recorded in the censuses taken at the end of summer, with an increase detected during autumn, and maximal cover values recorded during May/June. The A. bermejoi populations showed large inter-annual fluctuations in both the number of patches and area of occupancy. The number of seedlings varied across the study years, and their survival was linked to specific meteorological events, such as severe storms and dry and hot spells during autumn. The initial phase of introduction for this species has been overall successful, but a final evaluation can only be made on a longterm basis.Apium bermejoi, planta estolonífera endémica de Menorca (Islas Baleares, de la que se conoce una sola localidad en el medio natural, está considerada en Peligro Crítico de extinción (según criterios UICN. Se presentan los principales resultados de las acciones de restauración de las

  14. Megacopta cribraria (Hemiptera: Plataspidae) Population Dynamics in Soybeans as Influenced by Planting Date, Maturity Group, and Insecticide Use.

    Science.gov (United States)

    Del Pozo-Valdivia, Alejandro I; Seiter, Nicholas J; Reisig, Dominic D; Greene, Jeremy K; Reay-Jones, Francis P F; Bacheler, Jack S

    2016-02-18

    Since its unintentional introduction during 2009, Megacopta cribraria (F.) has spread rapidly throughout the southeastern United States, mainly feeding and reproducing on kudzu, Pueraria montana Loureiro (Merr.) variety lobata (Willdenow), and soybeans, Glycine max (L.) Merr. Megacopta cribraria has become a serious economic pest in soybeans, forcing growers to rely solely on insecticide applications to control this insect. The main objective of this study was to investigate if variation in planting date and maturity group of soybeans had an impact on management of M. cribraria populations. Three experimental fields were located in North Carolina (2) and South Carolina (1), and the tests replicated during 2012 and 2013. Treatments consisted of three planting dates, four maturity groups, and insecticide treated versus untreated, at each location. More M. cribraria were found in untreated early planted soybeans than late planted soybeans. Generally, maturity group did not influence population densities of M. cribraria. Yield was significantly influenced by the interaction between planting date and maturity group. There was a negative linear relationship between M. cribraria populations and soybean yield. Although early planted soybeans may avoid drought conditions and potentially large populations of defoliators, these fields may be at greater risk for infestation by M. cribraria. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America.

  15. The skin of Commerson's dolphins (Cephalorhynchus commersonii) as a biomonitor of mercury and selenium in Subantarctic waters.

    Science.gov (United States)

    Cáceres-Saez, Iris; Goodall, R Natalie P; Dellabianca, Natalia A; Cappozzo, H Luis; Ribeiro Guevara, Sergio

    2015-11-01

    The skin of bycaught Commerson's dolphins was tested for mercury (Hg) and selenium (Se) biomonitoring in Subantarctic environments. The correlation of levels detected in the skin with those found in internal tissues - lung, liver, kidney and muscle - was assessed to evaluate how skin represents internal Hg and Se distribution for monitoring purposes. Mercury in skin had a concentration range of 0.68-3.11 μg g(-1) dry weight (DW), while Se had a higher concentration range of 74.3-124.5 μg g(-1) DW. There was no significant correlation between selenium levels in any of the analyzed tissues. Thus, the skin selenium concentration did not reflect the tissular Se levels and did not provide information for biomonitoring. The lack of correlation is explained by the biological role of Se, provided that each tissue regulates Se levels according to physiological needs. However, the skin Hg level had significant positive correlation with the levels in internal tissues (ANOVA pdolphins for Hg biomonitoring in the waters of the Subantarctic, which is a poorly studied region regarding Hg levels, sources and processes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Morpho-physiological and productive biometry in semi-erect cultivars of the cowpea under different plant populations

    Directory of Open Access Journals (Sweden)

    Antônio Aécio de Carvalho Bezerra

    Full Text Available ABSTRACT The aim of this study was to evaluate morpho-physiological and productive characteristics in four semi-erect cultivars of the cowpea under five plant populations. The experiment was conducted in the experimental area of Embrapa Meio-Norte in Teresina in the State of Piauí, Brazil (PI. The experimental design was of randomised complete blocks with four replications, in a 4 x 5 factorial scheme, for evaluating four cultivars (BRS Guariba, BRS Novaera, BRS Potengi and BRS Tumucumaque and five plant populations (105, 2x105, 3x105, 4x105 and 5x105 plants ha-1. There were significant differences between cultivars for primary branch length (PBL, number of lateral branches (NLB, 100-grain weight (HGW, and dry-grain yield (GY. The maximum PBL of 58.5 cm was obtained with 300 thousand plants ha-1, corresponding to an increase of 11.5% when compared to 100 thousand plants ha-1. However, there was a reduction of 91.2% in NLB when compared to the populations of 100 and 500 thousand plants ha-1. The increases of 188% obtained in the leaf area index (LAI in the range of 100 to 500 thousand plants ha-1 explain the linear increase in the crop growth rate (CGR as being due to the greater production of leaf area; also, the decreases seen in the net assimilation rate (NAR, especially in the range of 100 to 300 thousand plants ha-1, are explained as due to the consequent self-shading, which was intensified in the larger populations. LAI, light interception, and CGR in the cultivars increase in response to higher densities. HGW and GY are not significantly affected by the different populations.

  17. The Effect of Temperature and Host Plant Resistance on Population Growth of the Soybean Aphid Biotype 1 (Hemiptera: Aphididae).

    Science.gov (United States)

    Hough, Ashley R; Nechols, James R; McCornack, Brian P; Margolies, David C; Sandercock, Brett K; Yan, Donglin; Murray, Leigh

    2017-02-01

    A laboratory experiment was conducted to evaluate direct and indirect effects of temperature on demographic traits and population growth of biotype 1 of the soybean aphid, Aphis glycines Matsumura. Our objectives were to better understand how temperature influences the expression of host plant resistance, quantify the individual and interactive effects of plant resistance and temperature on soybean aphid population growth, and generate thermal constants for predicting temperature-dependent development on both susceptible and resistant soybeans. To assess indirect (plant-mediated) effects, soybean aphids were reared under a range of temperatures (15-30 °C) on soybean seedlings from a line expressing a Rag1 gene for resistance, and life history traits were quantified and compared to those obtained for soybean aphids on a susceptible soybean line. Direct effects of temperature were obtained by comparing relative differences in the magnitude of life-history traits among temperatures on susceptible soybeans. We predicted that temperature and host plant resistance would have a combined, but asymmetrical, effect on soybean aphid fitness and population growth. Results showed that temperature and plant resistance influenced preimaginal development and survival, progeny produced, and adult longevity. There also appeared to be a complex interaction between temperature and plant resistance for survival and developmental rate. Evidence suggested that the level of plant resistance increased at higher, but not lower, temperature. Soybean aphids required about the same number of degree-days to develop on resistant and susceptible plants. Our results will be useful for making predictions of soybean aphid population growth on resistant plants under different seasonal temperatures. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  18. Computer simulation model for the striped bass young-of-the-year population in the Hudson River. [Effects of entrainment and impingement at power plants on population dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Eraslan, A.H.; Van Winkle, W.; Sharp, R.D.; Christensen, S.W.; Goodyear, C.P.; Rush, R.M.; Fulkerson, W.

    1975-09-01

    This report presents a daily transient (tidal-averaged), longitudinally one-dimensional (cross-section-averaged) computer simulation model for the assessment of the entrainment and impingement impacts of power plant operations on young-of-the-year populations of the striped bass, Morone saxatilis, in the Hudson River.

  19. Twelve years of repeated wild hog activity promotes population maintenance of an invasive clonal plant in a coastal dune ecosystem.

    Science.gov (United States)

    Oldfield, Callie A; Evans, Jonathan P

    2016-04-01

    Invasive animals can facilitate the success of invasive plant populations through disturbance. We examined the relationship between the repeated foraging disturbance of an invasive animal and the population maintenance of an invasive plant in a coastal dune ecosystem. We hypothesized that feral wild hog (Sus scrofa) populations repeatedly utilized tubers of the clonal perennial, yellow nutsedge (Cyperus esculentus) as a food source and evaluated whether hog activity promoted the long-term maintenance of yellow nutsedge populations on St. Catherine's Island, Georgia, United States. Using generalized linear mixed models, we tested the effect of wild hog disturbance on permanent sites for yellow nutsedge culm density, tuber density, and percent cover of native plant species over a 12-year period. We found that disturbance plots had a higher number of culms and tubers and a lower percentage of native live plant cover than undisturbed control plots. Wild hogs redisturbed the disturbed plots approximately every 5 years. Our research provides demographic evidence that repeated foraging disturbances by an invasive animal promote the long-term population maintenance of an invasive clonal plant. Opportunistic facultative interactions such as we demonstrate in this study are likely to become more commonplace as greater numbers of introduced species are integrated into ecological communities around the world.

  20. Genetic Population Structure of Cacao Plantings within a Young Production Area in Nicaragua

    Science.gov (United States)

    Trognitz, Bodo; Scheldeman, Xavier; Hansel-Hohl, Karin; Kuant, Aldo; Grebe, Hans; Hermann, Michael

    2011-01-01

    Significant cocoa production in the municipality of Waslala, Nicaragua, began in 1961. Since the 1980s, its economic importance to rural smallholders increased, and the region now contributes more than 50% of national cocoa bean production. This research aimed to assist local farmers to develop production of high-value cocoa based on optimal use of cacao biodiversity. Using microsatellite markers, the allelic composition and genetic structure of cacao was assessed from 44 representative plantings and two unmanaged trees. The population at Waslala consists of only three putative founder genotype spectra (lineages). Two (B and R) were introduced during the past 50 years and occur in >95% of all trees sampled, indicating high rates of outcrossing. Based on intermediate allelic diversity, there was large farm-to-farm multilocus genotypic variation. GIS analysis revealed unequal distribution of the genotype spectra, with R being frequent within a 2 km corridor along roads, and B at more remote sites with lower precipitation. The third lineage, Y, was detected in the two forest trees. For explaining the spatial stratification of the genotype spectra, both human intervention and a combination of management and selection driven by environmental conditions, appear responsible. Genotypes of individual trees were highly diverse across plantings, thus enabling selection for farm-specific qualities. On-farm populations can currently be most clearly recognized by the degree of the contribution of the three genotype spectra. Of two possible strategies for future development of cacao in Waslala, i.e. introducing more unrelated germplasm, or working with existing on-site diversity, the latter seems most appropriate. Superior genotypes could be selected by their specific composite genotype spectra as soon as associations with desired quality traits are established, and clonally multiplied. The two Y trees from the forest share a single multilocus genotype, possibly representing the

  1. Plant extracts, metaldehyde and saline solutions on the population control of Bradybaena similaris

    Directory of Open Access Journals (Sweden)

    Junir Antonio Lutinski

    2016-08-01

    Full Text Available ABSTRACT: This study aimed to test the efficiency of plant extracts, metaldehyde and saline solutions, as alternatives to the population control of the snail Bradybaena similaris , and to investigate the effect of the plant extracts in reducing the damage of the snail on Brassica oleracea . The experiments were performed at the Entomology Laboratory of the Universidade Comunitária da Região de Chapecó (Unochapecó, using a random experimental design with nine treatments in triplicate. Five adult individuals of B. similaris were subjected to each trial, totaling 135 snails. The following treatments were tested: cinnamon ( Melia azedarach , timbó ( Ateleia glazioveana , rosemary ( Rosmarinus officinalis , mate herb ( Ilex paraguariensis , two concentrations of metaldehyde (3% and 5%, two concentrations of salt solution (5% and 10 %, and a control treatment (distilled water. To evaluate the survival of B. similaris it was checked the treatments every 24 hours, over four consecutive days. The results revealed that the two concentrations of metaldehyde were fully efficient, that the saline solution (10% had and intermediate efficiency, and that all other treatments were not effective. The treatment with the M. azedarach extract induced a higher consumption of B. oleracea , while the saline solution at 10% and the extracts of R. officinalis and I. paraguariensis inhibited leaf consumption.

  2. Demographic population structure and fungal associations of plants colonizing High Arctic glacier forelands, Petuniabukta, Svalbard

    Directory of Open Access Journals (Sweden)

    Jakub Těšitel

    2014-04-01

    Full Text Available The development of vegetation in Arctic glacier forelands has been described as unidirectional, non-replacement succession characterized by the gradual establishment of species typical for mature tundra with no species turnover. Our study focused on two early colonizers of High Arctic glacier forelands: Saxifraga oppositifolia (Saxifragaceae and Braya purpurascens (Brassicaceae. While the first species is a common generalist also found in mature old growth tundra communities, the second specializes on disturbed substrate. The demographic population structures of the two study species were investigated along four glacier forelands in Petuniabukta, north Billefjorden, in central Spitsbergen, Svalbard. Young plants of both species occurred exclusively on young substrate, implying that soil conditions are favourable for establishment only before soil crusts develop. We show that while S. oppositifolia persists from pioneer successional stages and is characterized by increased size and flowering, B. purpurascens specializes on disturbed young substrate and does not follow the typical unidirectional, non-replacement succession pattern. Plants at two of the forelands were examined for the presence of root-associated fungi. Fungal genus Olpidium (Fungus incertae sedis was found along a whole successional gradient in one of the forelands.

  3. The seasonal cycle of mixed layer dynamics and phytoplankton biomass in the Sub-Antarctic Zone: A high-resolution glider experiment

    CSIR Research Space (South Africa)

    Swart, S

    2014-06-01

    Full Text Available -resolution glider data (3 hourly, 2 km horizontal resolution), from~6 months of sampling (spring through summer) in the Sub-Antarctic Zone, is used to assess 1) the different forcing mechanisms driving variability in upper ocean physics and 2) how thesemay...

  4. Adaptive Potential for the Invasion of Novel Host Plants in the Bean Weevil: Patterns of the Reproductive Behavior in Populations That Used Different Host Plants

    Directory of Open Access Journals (Sweden)

    Dragana Milanović

    2007-01-01

    Full Text Available The goal of this work was to examine interpopulation patterns in the reproductive behavior of populations of bean weevil (Acanthoscelides obtectus Say; Coleoptera: Bruchidae that had different levels of specialization on their native host plant – the bean (Phaseolus vulgaris L., as well as on a novel host plant – the chickpea (Cicer arietinum Thorn. The obtained pattern of interpopulation mating behavior seemed exactly as if the males on chickpea had evolved a specific odor and/or a courtship ritual that females of populationson bean found repulsive. Unlike females, the males of bean populations seemed to be willing to mate with females from the population on chickpea equally as with their own females. Such an asymmetric pattern of reproductive isolation between populations ofa species has been often considered an initial phase of a process of speciation. Thus, our results could be a good starting point for further, thorough examination of both the role of the level of host specialization in females and the role of biochemical characteristics of male pheromone (and/or their cuticular hydrocarbones in the evolution of pre-reproductive isolation between insect populations.As the results of this study, together those of previous studies on A. obtectus, suggest great evolutionary potential for invasions of and fast specialization on novel host plants, they could provide valuable information for the development of long-term strategiesunder the programmes of Integrated Pest Management.

  5. Portfolio effects, climate change, and the persistence of small populations: analyses on the rare plant Saussurea weberi.

    Science.gov (United States)

    Abbott, Ronald E; Doak, Daniel F; Peterson, Megan L

    2017-04-01

    The mechanisms that stabilize small populations in the face of environmental variation are crucial to their long-term persistence. Building from diversity-stability concepts in community ecology, within-population diversity is gaining attention as an important component of population stability. Genetic and microhabitat variation within populations can generate diverse responses to common environmental fluctuations, dampening temporal variability across the population as a whole through portfolio effects. Yet, the potential for portfolio effects to operate at small scales within populations or to change with systematic environmental shifts, such as climate change, remain largely unexplored. We tracked the abundance of a rare alpine perennial plant, Saussurea weberi, in 49 1-m(2) plots within a single population over 20 yr. We estimated among-plot correlations in log annual growth rate to test for population-level synchrony and quantify portfolio effects across the 20-yr study period and also in 5-yr subsets based on June temperature quartiles. Asynchrony among plots, due to different plot-level responses to June temperature, reduced overall fluctuations in abundance and the probability of decline in population models, even when accounting for the effects of density dependence on dynamics. However, plots became more synchronous and portfolio effects decreased during the warmest years of the study, suggesting that future climate warming may erode stabilizing mechanisms in populations of this rare plant. © 2017 by the Ecological Society of America.

  6. Effects of temperature and fertilization on the structure of total versus active bacterial communities from sub-Antarctic seawater exposed to crude oil and diesel fuel

    Directory of Open Access Journals (Sweden)

    Arturo Rodríguez-Blanco

    2013-05-01

    Full Text Available Polar environments are exposed to the risk of oil pollution. However, there is limited knowledge regarding how the variation of physicochemical factors influencing biodegradation may affect bacterial community structure. The effects of temperature (4, 10 and 20°C and organic fertilization (Inipol EAP 22 on community structure and diversity of bacteria inhabiting Kerguelen sub-Antarctic waters were studied in crude- and diesel-amended microcosms. Dynamics of total (i.e., 16S rDNA-based and metabolically active (i.e., 16S rRNA-based bacterial community structure and diversity were monitored using capillary-electrophoresis single-strand conformation polymorphism. Results showed that total and active community structures were differently influenced by temperature and fertilization in the presence of hydrocarbons. Both fertilization and temperature induced changes in total community structure in the presence of crude oil and diesel. However, temperature showed a limited influence on active community structure, and fertilization induced changes in the presence of crude oil only. Simpson's index decreased for total bacterial communities at all temperatures in the presence of crude oil and diesel, whereas a lower reduction was observed for active bacterial populations. In the presence of fertilizer, the diversity of the whole community approached control values after seven incubation weeks; this was not observed for the active bacterial community. This study evidenced qualitative differences in total and active bacterial community structures of Kerguelen seawaters in the presence of hydrocarbons and different responses relative to variation in temperature and fertilization. These factors and hydrocarbons composition have to be taken into account to understand bacterial community dynamics after an oil spill.

  7. A theoretical analysis of population genetics of plants on restored habitats

    Energy Technology Data Exchange (ETDEWEB)

    Bogoliubov, A.G. [Russian Academy of Science, St. Petersburg (Russian Federation). Botanical Inst.; Loehle, C. [Argonne National Lab., IL (United States). Environmental Research Div.

    1997-07-01

    Seed and propagules used for habitat restoration are not likely to be closely adapted to local site conditions. Rapid changes of genotypes frequencies on local microsites and/or microevolution would allow plants to become better adapted to a site. These same factors would help to maintain genetic diversity and ensure the survival of small endangered populations. The authors used population genetics models to examine the selection of genotypes during establishment on restored sites. Vegetative spread was shown to affect selection and significantly reduce genetic diversity. To study general microevolution, the authors linked a model of resource usage with a genetics model and analyzed competition between genotypes. A complex suite of feasible ecogenetic states was shown to result. The state actually resulting would depend strongly on initial conditions. This analysis indicated that genetic structure can vary locally and can produce overall genetic variability that is not simply the result of microsite adaptations. For restoration activities, the implication is that small differences in seed source could lead to large differences in local genetic structure after selection.

  8. A theoretical analysis of population genetics of plants on restored habitats

    Energy Technology Data Exchange (ETDEWEB)

    Bogoliubov, A.G. [Botanical Institute, Russian Academy of Science, St. Petersburg (Russian Federation); Loehle, C. [Argonne National Lab., IL (United States)

    1995-02-01

    Seed and propagules used for habitat restoration are not likely to be closely adapted to local site conditions. Rapid changes of genotypes frequencies on local microsites and/or microevolution would allow plants to become better adapted to a site. These same factors would help to maintain genetic diversity and ensure the survival of small endangered populations. We used population genetics models to examine the selection of genotypes during establishment on restored sites. Vegetative spread was shown to affect selection and significantly reduce genetic diversity. To study general microevolution, we linked a model of resource usage with a genetics model and analyzed competition between genotypes. A complex suite of feasible ecogenetic states was shown to result. The state actually resulting would depend strongly on initial conditions. This analysis indicated that genetic structure can vary locally and can produce overall genetic variability that is not simply the result of microsite adaptations. For restoration activities, the implication is that small differences in seed source could lead to large differences in local genetic structure after selection.

  9. Quantifying how fine-grained environmental heterogeneity and genetic variation affect demography in an annual plant population.

    Science.gov (United States)

    Latimer, Andrew M; Jacobs, Brooke S

    2012-11-01

    The ability of plant species to colonize new habitats and persist in changing environments depends on their ability to respond plastically to environmental variation and on the presence of genetic variation, thus allowing adaptation to new conditions. For invasive species in particular, the relationship between phenotypic trait expression, demography, and the quantitative genetic variation that is available to respond to selection are likely to be important determinants of the successful establishment and persistence of populations. However, the magnitude and sources of individual demographic variation in exotic plant populations remain poorly understood. How important is plasticity versus adaptability in populations of invasive species? Among environmental factors, is temperature, soil nutrients, or competition most influential, and at what scales and life stages do they affect the plants? To investigate these questions we planted seeds of the exotic annual plant Erodium brachycarpum into typical pasture habitat in a spatially nested design. Seeds were drawn from 30 inbred lines to enable quantification of genetic effects. Despite a positive population growth rate, a few plants (0.1 %) produced >50 % of the seeds, suggesting a low effective population size. Emergence and early growth varied by genotype, but as in previous studies on native plants, environmental effects greatly exceeded genetic effects, and survival was unrelated to genotype. Environmental influences shifted from microscale soil compaction and litter depth at emergence through to larger-scale soil nutrient gradients during growth and to competition during later survival and seed production. Temperature had no effect. Most demographic rates were positively correlated, but emergence was negatively correlated with other rates.

  10. Coexistence of trichome variation in a natural plant population: a combined study using ecological and candidate gene approaches.

    Directory of Open Access Journals (Sweden)

    Tetsuhiro Kawagoe

    Full Text Available The coexistence of distinct phenotypes within populations has long been investigated in evolutionary ecology. Recent studies have identified the genetic basis of distinct phenotypes, but it is poorly understood how the variation in candidate loci is maintained in natural environments. In this study, we examined fitness consequences and genetic basis of variation in trichome production in a natural population of Arabidopsis halleri subsp. gemmifera. Half of the individuals in the study population produced trichomes while the other half were glabrous, and the leaf beetle Phaedon brassicae imposed intensive damage to both phenotypes. The fitness of hairy and glabrous plants showed no significant differences in the field during two years. A similar result was obtained when sibling hairy and glabrous plants were transplanted at the same field site, whereas a fitness cost of trichome production was detected under a weak herbivory condition. Thus, equivalent fitness of hairy and glabrous plants under natural herbivory allows their coexistence in the contemporary population. The pattern of polymorphism of the candidate trichome gene GLABROUS1 (GL1 showed no evidence of long-term maintenance of trichome variation within the population. Although balancing selection under fluctuating biotic environments is often proposed to explain the maintenance of defense variation, the lack of clear evidence of balancing selection in the study population suggests that other factors such as gene flow and neutral process may have played relatively large roles in shaping trichome variation at least for the single population level.

  11. Population growth and within-plant distribution of the striped mealybug Ferrisia virgata (Cockerell (Hemiptera, Pseudococcidae on cotton

    Directory of Open Access Journals (Sweden)

    Martin D. Oliveira

    2014-03-01

    Full Text Available Population growth and within-plant distribution of the striped mealybug Ferrisia virgata (Cockerell (Hemiptera, Pseudococcidae on cotton. The striped mealybug, Ferrisia virgata (Cockerell (Hemiptera, Pseudococcidae, is a widely distributed and polyphagous pest species, which naturally occurs on cotton plants in Brazil. This study evaluated the establishment and population growth as well as the within-plant distribution of F. virgata on four cotton cultivars: CNPA 7H (white fibers, BRS Verde, BRS Safira, and BRS Rubi (colored fibers. The experiment was conducted in a complete randomized design with four treatments (cultivars and 18 replications of each. Thus, cotton plants of each cultivar were infested with 100 newly hatched nymphs of F. virgata. The number of adult female mealybugs and the total number of mealybugs per plant were quantified, respectively, at 25 and 50 days after infestation. The developmental and pre-reproductive periods were also determined. Furthermore, we verified the distribution of F. virgata on the plant parts at 25 and 50 days after infestation. Ferrisia virgata showed similar growth of 412-fold in the four cotton cultivars studied. Also, the nymphs were spread on infested leaves; the secondgeneration nymphs were spread and established in all plant parts. Our results characterize F. virgata as having much potential as an important cotton pest in Brazil.

  12. Plant population and habitat characteristics of the endemic Sonoran Desert cactus Peniocereus striatus in Organ Pipe Cactus National Monument, Arizona

    Science.gov (United States)

    Anderson, Greta; Rutman, Sue; Munson, Seth M.

    2010-01-01

    Peniocereus striatus (Brandegee) Buxb. (Cactaceae) is an endemic Sonoran Desert cactus that reaches its northern range limit in southwestern Arizona. One U.S. population occupies a small area of Organ Pipe Cactus National Monument near the U.S./Mexico international boundary, which has been monitored since 1939. An extensive survey conducted in 2002, covering 177 ha, resulted in the discovery of 88 new plants, in addition to the relocation of 57 plants found in previous surveys. Despite potential increases in population size and spatial distribution, mean plant height and number of basal stems has not significantly changed in recent years. Bud scars revealed that a majority of the population was sexually mature. Peniocereus striatus occurrence increased with decreasing slope, spanned every slope aspect, and was highest on rocky soils, but was noticeably low on west and northwest slopes and areas where severe land degradation had previously occurred. Over half of P. striatus plants were nursed by shrubs and subshrubs, while 40% occurred under leguminous trees. A severe frost in January 2002 top-killed 19% of the population, with the greatest damage in drainage bottoms. However, long-term (1944–2002) climate records show that there has been an overall increase in the number of frost free days in the region, which, coupled with land use change, has implications for the future health of this population.

  13. The role of biotic interactions in population biology of meadow plants

    OpenAIRE

    Janovský, Zdeněk

    2015-01-01

    In present thesis, I treat the topic of impacts of plant-animal interactions, namely herbivory and pollination, on plant life cycle and lifetime fitness. First, I identify the components of the impact of plant-animal interactions: i) interaction frequency; ii) per-interaction effect; iii) sensitivity of the plant's life cycle to the changes in vital rate impacted by the animals. Furthermore, I also classify other causes changing the outcome of a plant-animal interaction into two categories: i...

  14. Implications of different population model structures for management of threatened plants.

    Science.gov (United States)

    Regan, Helen M; Bohórquez, Clara I; Keith, David A; Regan, Tracey J; Anderson, Kurt E

    2017-04-01

    Population viability analysis (PVA) is a reliable tool for ranking management options for a range of species despite parameter uncertainty. No one has yet investigated whether this holds true for model uncertainty for species with complex life histories and for responses to multiple threats. We tested whether a range of model structures yielded similar rankings of management and threat scenarios for 2 plant species with complex postfire responses. We examined 2 contrasting species from different plant functional types: an obligate seeding shrub and a facultative resprouting shrub. We exposed each to altered fire regimes and an additional, species-specific threat. Long-term demographic data sets were used to construct an individual-based model (IBM), a complex stage-based model, and a simple matrix model that subsumes all life stages into 2 or 3 stages. Agreement across models was good under some scenarios and poor under others. Results from the simple and complex matrix models were more similar to each other than to the IBM. Results were robust across models when dominant threats are considered but were less so for smaller effects. Robustness also broke down as the scenarios deviated from baseline conditions, likely the result of a number of factors related to the complexity of the species' life history and how it was represented in a model. Although PVA can be an invaluable tool for integrating data and understanding species' responses to threats and management strategies, this is best achieved in the context of decision support for adaptive management alongside multiple lines of evidence and expert critique of model construction and output. © 2016 Society for Conservation Biology.

  15. Plant Population Dynamics of Dodonaea angustifolia and Olea europaea ssp. cuspidata in Dry Afromontane Forests of Ethiopia

    OpenAIRE

    Bekele, Tesfaye

    2000-01-01

    Human disturbance has led to excessive deforestation and to a very limited forest cover in the Afromontane zone of Ethiopia, which forms a large part of the country. Thus urgent conservation measures are required to ameliorate the situation. Understanding the natural regeneration processes and the dynamics of plant populations of tree and shrub species has a practical application in the restoration of these habitats. The present study focuses on the population dynamics and regeneration of an ...

  16. Population size and identity influence the reaction norm of the rare, endemic plant Cochlearia bavarica across a gradient of environmental stress.

    Science.gov (United States)

    Paschke, Melanie; Bernasconi, Giorgina; Schmid, Bernhard

    2003-03-01

    Habitat degradation and loss can result in population decline and genetic erosion, limiting the ability of organisms to cope with environmental change, whether this is through evolutionary genetic response (requiring genetic variation) or through phenotypic plasticity (i.e., the ability of a given genotype to express a variable phenotype across environments). Here we address the question whether plants from small populations are less plastic or more susceptible to environmental stress than plants from large populations. We collected seed families from small (populations (>1,000 flowering plants) of the rare, endemic plant Cochlearia bavarica (Brassicaceae). We exposed the seedlings to a range of environments, created by manipulating water supply and light intensity in a 2 x 2 factorial design in the greenhouse. We monitored plant growth and survival for 300 days. Significant effects of offspring environment on offspring characters demonstrated that there is phenotypic plasticity in the responses to environmental stress in this species. Significant effects of population size group, but mainly of population identity within the population size groups, and of maternal plant identity within populations indicated variation due to genetic (plus potentially maternal) variation for offspring traits. The environment x maternal plant identity interaction was rarely significant, providing little evidence for genetically- (plus potentially maternally-) based variation in plasticity within populations. However, significant environment x population-size-group and environment x population-identity interactions suggested that populations differed in the amount of plasticity, the mean amount being smaller in small populations than in large populations. Whereas on day 210 the differences between small and large populations were largest in the environment in which plants grew biggest (i.e., under benign conditions), on day 270 the difference was largest in stressful environments

  17. Effects of Flavonoid-rich Plant Extracts on Ruminal Methanogenesis, Microbial Populations and Fermentation Characteristics

    Directory of Open Access Journals (Sweden)

    Eun T. Kim

    2015-04-01

    Full Text Available The objective of this study was to evaluate the in vitro effects of flavonoid-rich plant extracts (PE on ruminal fermentation characteristics and methane emission by studying their effectiveness for methanogenesis in the rumen. A fistulated Holstein cow was used as a donor of rumen fluid. The PE (Punica granatum, Betula schmidtii, Ginkgo biloba, Camellia japonica, and Cudrania tricuspidata known to have high concentrations of flavonoid were added to an in vitro fermentation incubated with rumen fluid. Total gas production and microbial growth with all PE was higher than that of the control at 24 h incubation, while the methane emission was significantly lower (p<0.05 than that of the control. The decrease in methane accumulation relative to the control was 47.6%, 39.6%, 46.7%, 47.9%, and 48.8% for Punica, Betula, Ginkgo, Camellia, and Cudrania treatments, respectively. Ciliate populations were reduced by more than 60% in flavonoid-rich PE treatments. The Fibrobacter succinogenes diversity in all added flavonoid-rich PE was shown to increase, while the Ruminoccocus albus and R. flavefaciens populations in all PE decreased as compared with the control. In particular, the F. succinogenes community with the addition of Birch extract increased to a greater extent than that of others. In conclusion, the results of this study showed that flavonoid-rich PE decreased ruminal methane emission without adversely affecting ruminal fermentation characteristics in vitro in 24 h incubation time, suggesting that the flavonoid-rich PE have potential possibility as bio-active regulator for ruminants.

  18. Survey of population health in towns with nuclear and fossil fuel power plants

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, E.; Shubik, V. M.

    2004-07-01

    Comparative assessment of population health in Sosnovy Bor with nuclear power plant and Kirovsk with fossil fuel power station was made for public and administration information. Both towns are located in Leningrad administrative region at 150 km distance from each other. In nuclear power town radiological situation was assessed as normal and in Kirovsk up to 1995 yr. with coal fuel, maximum permissible levels of suspended particle of sulfur oxide in atmosphere were exceeded in 6-9% of samples. After 1995 yr. the natural gas was used as fuel. Demographic data for 1991-2000 yrs indicate that mortality including infants mortality and stillborns was lower in Sosnovy Bor (NOS) then in Kirovsk (fossil fuel) and on average Leningrad administrative region. Birth rate and population growth was higher in Sosnovy Bor at the same time surprisingly the recorded morbidity was higher in Sosnovy Bor which might be explained by extensive medical supervision and improved diagnostics. However, cancer and tuberculosis morbidity was lower in Sosnovy Bor. In Kirovsk in 1997-2000 yrs. oncological morbidity was higher on average comparing to Leningrad administrative region. Oncological mortality in Sosnovy Bor in 1997-2000 yrs. was lower than in Kirovsk and Leningrad region Standardized annual mortality in Sosnovy Bor, Kirovsk and Leningrad administrative region was 128.3, 209.6 and 211.7 on 100 000 respectively. Health state of pregnant women, deliveries, new-born condition were all in normal range in Sosnovy Bor, contrary to higher increased abortion rate and pregnancy complications in Kirovsk. These findings need further studies. (Author)

  19. Permanent colonization of creek sediments, creek water and limnic water plants by four Listeria species in low population densities.

    Science.gov (United States)

    Lang-Halter, Evi; Schober, Steffen; Scherer, Siegfried

    2016-09-01

    During a 1-year longitudinal study, water, sediment and water plants from two creeks and one pond were sampled monthly and analyzed for the presence of Listeria species. A total of 90 % of 30 sediment samples, 84 % of 31 water plant samples and 67 % of 36 water samples were tested positive. Generally, most probable number counts ranged between 1 and 40 g-1, only occasionally >110 cfu g-1 were detected. Species differentiation based on FT-IR spectroscopy and multiplex PCR of a total of 1220 isolates revealed L. innocua (46 %), L. seeligeri (27 %), L. monocytogenes (25 %) and L. ivanovii (2 %). Titers and species compositions were similar during all seasons. While the species distributions in sediments and associated Ranunculus fluitans plants appeared to be similar in both creeks, RAPD typing did not provide conclusive evidence that the populations of these environments were connected. It is concluded that (i) the fresh-water sediments and water plants are year-round populated by Listeria, (ii) no clear preference for growth in habitats as different as sediments and water plants was found and (iii) the RAPD-based intraspecific biodiversity is high compared to the low population density.

  20. Molecular and quantitative trait variation within and among small fragmented populations of the endangered plant species Psilopeganum sinense.

    Science.gov (United States)

    Ye, Qigang; Tang, Feiyan; Wei, Na; Yao, Xiaohong

    2014-01-01

    Natural selection and genetic drift are important evolutionary forces in determining genetic and phenotypic differentiation in plant populations. The extent to which these two distinct evolutionary forces affect locally adaptive quantitative traits has been well studied in common plant and animal species. However, we know less about how quantitative traits respond to selection pressures and drift in endangered species that have small population sizes and fragmented distributions. To address this question, this study assessed the relative strengths of selection and genetic drift in shaping population differentiation of phenotypic traits in Psilopeganum sinense, a naturally rare and recently endangered plant species. Population differentiation at five quantitative traits (QST) obtained from a common garden experiment was compared with differentiation at putatively neutral microsatellite markers (FST) in seven populations of P. sinense. QST estimates were derived using a Bayesian hierarchical variance component method. Trait-specific QST values were equal to or lower than FST. Neutral genetic diversity was not correlated with quantitative genetic variation within the populations of P. sinense. Despite the prevalent empirical evidence for QST > FST, the results instead suggest a definitive role of stabilizing selection and drift leading to phenotypic differentiation among small populations. Three traits exhibited a significantly lower QST relative to FST, suggesting that populations of P. sinense might have experienced stabilizing selection for the same optimal phenotypes despite large geographical distances between populations and habitat fragmentation. For the other two traits, QST estimates were of the same magnitude as FST, indicating that divergence in these traits could have been achieved by genetic drift alone. The lack of correlation between molecular marker and quantitative genetic variation suggests that sophisticated considerations are required for the

  1. Ecology and life history affect different aspects of the population structure of 27 high-alpine plants

    NARCIS (Netherlands)

    Meirmans, P.G.; Goudet, J.; Gaggiotti, O.E.

    2011-01-01

    A plant species’ genetic population structure is the result of a complex combination of its life history, ecological preferences, position in the ecosystem and historical factors. As a result, many different statistical methods exist that measure different aspects of species’ genetic structure.

  2. Genetic Diversity and Population Structure of the Rare and Endangered Plant Species Pulsatilla patens (L.) Mill in East Central Europe

    National Research Council Canada - National Science Library

    Szczecińska, Monika; Sramko, Gabor; Wołosz, Katarzyna; Sawicki, Jakub

    2016-01-01

    Pulsatilla patens s.s. is a one of the most endangered plant species in Europe. The present range of this species in Europe is highly fragmented and the size of the populations has been dramatically reduced in the past 50 years...

  3. Emergence of competitive dominant ammonia-oxidizing bacterial populations in a full-scale industrial wastewater treatment plant.

    Science.gov (United States)

    Layton, Alice C; Dionisi, Hebe; Kuo, H-W; Robinson, Kevin G; Garrett, Victoria M; Meyers, Arthur; Sayler, Gary S

    2005-02-01

    Ammonia-oxidizing bacterial populations in an industrial wastewater treatment plant were investigated with amoA and 16S rRNA gene real-time PCR assays. Nitrosomonas nitrosa initially dominated, but over time RI-27-type ammonia oxidizers, also within the Nitrosomonas communis lineage, increased from below detection to codominance. This shift occurred even though nitrification remained constant.

  4. Emergence of Competitive Dominant Ammonia-Oxidizing Bacterial Populations in a Full-Scale Industrial Wastewater Treatment Plant

    OpenAIRE

    Layton, Alice C.; Dionisi, Hebe; Kuo, H.-W.; Robinson, Kevin G.; Garrett, Victoria M.; Meyers, Arthur; Sayler, Gary S.

    2005-01-01

    Ammonia-oxidizing bacterial populations in an industrial wastewater treatment plant were investigated with amoA and 16S rRNA gene real-time PCR assays. Nitrosomonas nitrosa initially dominated, but over time RI-27-type ammonia oxidizers, also within the Nitrosomonas communis lineage, increased from below detection to codominance. This shift occurred even though nitrification remained constant.

  5. Some remarks on the methods of assessing the population density of higher plants in cases of aggregated spatial structure

    Directory of Open Access Journals (Sweden)

    Anna Justyna Kwiatkowska

    2015-01-01

    Full Text Available This paper presents a comparative analysis of the methods used for. assessing the density of higher plants. The analysis was carried out on natural population (Vaccinium myrtillus L. characterized by aggregated spatial structure. Attention has been paid to the surface methods with high (0.25 m2 and low

  6. Discovery of natural Miscanthus (Poaceae) triploid plants in sympatric populations of Miscanthus sacchariflorus and Miscanthus sinensis in southern Japan.

    Science.gov (United States)

    Nishiwaki, Aya; Mizuguti, Aki; Kuwabara, Shotaro; Toma, Yo; Ishigaki, Genki; Miyashita, Tomomi; Yamada, Toshihiko; Matuura, Hiroya; Yamaguchi, Sachi; Rayburn, A Lane; Akashi, Ryo; Stewart, J Ryan

    2011-01-01

    Looming petroleum shortages and projected negative impacts of human-induced climate change may be partly alleviated by the development and use of bioenergy feedstock crops. Miscanthus ×giganteus, a highly productive sterile triploid hybrid grass that was discovered in Japan several decades ago, has considerable potential as an alternative source of energy. Given the risks, however, involved in the reliance upon production of one clone of this hybrid, which is a natural cross between Miscanthus sacchariflorus and Miscanthus sinensis, for lignocellulosic bioenergy production, natural occurrences of triploidy were investigated in sympatric populations of tetraploid M. sacchariflorus and diploid M. sinensis in Japan. Seeds were counted and DNA content was estimated by flow cytometry for plants of M. sacchariflorus and M. sinensis in several sympatric populations throughout Japan. Chromosomes were also counted for select plants. Based on seed-set data, M. sacchariflorus has significantly lower seed set than M. sinensis in Japan. Putative triploid seeds were found on M. sacchariflorus plants in southern Japan. This is the first report of the natural occurrence of Miscanthus triploid plants in several decades. If found to be sterile and similar in productivity to the commonly cultivated clone of M. ×giganteus, these triploid plants might serve as additional sources of genetic variation for bioenergy production. Seed set data also indicates that other triploid plants might be found in more northern regions of Japan.

  7. Mate Limitation in Fungal Plant Parasites Can Lead to Cyclic Epidemics in Perennial Host Populations.

    Science.gov (United States)

    Ravigné, Virginie; Lemesle, Valérie; Walter, Alicia; Mailleret, Ludovic; Hamelin, Frédéric M

    2017-03-01

    Fungal plant parasites represent a growing concern for biodiversity and food security. Most ascomycete species are capable of producing different types of infectious spores both asexually and sexually. Yet the contributions of both types of spores to epidemiological dynamics have still to been fully researched. Here we studied the effect of mate limitation in parasites which perform both sexual and asexual reproduction in the same host. Since mate limitation implies positive density dependence at low population density, we modeled the dynamics of such species with both density-dependent (sexual) and density-independent (asexual) transmission rates. A first simple SIR model incorporating these two types of transmission from the infected compartment, suggested that combining sexual and asexual spore production can generate persistently cyclic epidemics in a significant part of the parameter space. It was then confirmed that cyclic persistence could occur in realistic situations by parameterizing a more detailed model fitting the biology of the Black Sigatoka disease of banana, for which literature data are available. We discuss the implications of these results for research on and management of Sigatoka diseases of banana.

  8. Specific Effects of Carbofuran on Rice Agrosystem in Yogyakarta Plant Growth and Rice Stem Borer Populations

    Directory of Open Access Journals (Sweden)

    Eddy Mahrub

    1996-12-01

    Full Text Available The effectiveness of carbofuran in controlling lowland rice stem borers in traditional farming systems was studied by looking at its impact on the whole rice agroecosystem. Levels of infestation, rice yield, damage to the plant, parasitism rates, and distribution of damage were compared after medium, high, and no (control dosages were applied to lowland rice fields near Yogyakarta, Indonesia. Although larvae were found to be more numerous in control plots, the damage attributable to them was not significantly different. Their spatial distribution, however, differed radically. The authors concluded that carbofuran might affect pest populations at two different levels: by discouraging or preventing rice stem borers from laying their eggs on rice, and by delaying or eliminating natural enemies attacks on rice stem borers. Both levels were determined by comparing the distribution of damage in treated fields with untreated fields. In the treated fields, distributions of larvae seemed to reflect initial grouping of eggs, producing a random distribution of groups, while in the control fields larvae were found in random distribution of individuals.

  9. The influence of iron and light on net community production in the Subantarctic and Polar Frontal Zones

    Directory of Open Access Journals (Sweden)

    N. Cassar

    2011-02-01

    Full Text Available The roles of iron and light in controlling biomass and primary productivity are clearly established in the Southern Ocean. However, their influence on net community production (NCP and carbon export remains to be quantified. To improve our understanding of NCP and carbon export production in the Subantarctic Zone (SAZ and the northern reaches of the Polar Frontal Zone (PFZ, we conducted continuous onboard determinations of NCP as part of the Sub-Antarctic Sensitivity to Environmental Change (SAZ-Sense study, which occurred in January–February 2007. Biological O2 supersaturation was derived from measuring O2/Ar ratios by equilibrator inlet mass spectrometry. Based on these continuous measurements, NCP during the austral summer 2007 in the Australian SAZ was approximately 43 mmol O2 m−2 d−1. NCP showed significant spatial variability, with larger values near the Subtropical front, and a general southward decrease. For shallower mixed layers (<50 m, dissolved Fe concentrations and Fe sufficiency, estimated from variable fluorescence, correlated strongly with NCP. The strong correlation between NCP and dissolved Fe may be difficult to interpret because of the correlation of dissolved Fe to MLD and because the concentration of iron may not be a good indicator of its availability. At stations with deeper mixed layers, NCP was consistently low, regardless of iron sufficiency, consistent with light availability also being an important control of NCP. Our new observations provide independent evidence for the critical roles of iron and light in mediating carbon export from the Southern Ocean mixed layer.

  10. Effect of plant population density on the growth and yield of sorghum ...

    African Journals Online (AJOL)

    Improvement of resource use efficiency and yields is probably possible through the use of appropriate plant densities. Field trials were therefore conducted to study the effects of four plant densities, varying from 2.0 to 12.5 plants m-2 on water and radiation use and performance of two Masakwa sorghum varieties grown on ...

  11. Plant-soil feedbacks and mycorrhizal type influence temperate forest population dynamics

    Science.gov (United States)

    Feedback with soil biota is a major driver of diversity within terrestrial plant communities. However, little is known about the factors regulating plant-soil feedback, which can vary from positive to negative among plant species. In a large-scale observational and experimental study involving 55 sp...

  12. Population history of the two carnivorous plants Drosera peltata var. nipponica and Drosera rotundifolia (Droseraceae) in Korea.

    Science.gov (United States)

    Chung, Mi Yoon; López-Pujol, Jordi; Chung, Myong Gi

    2013-11-01

    Drosera peltata var. nipponica, an element of the East Asia warm-temperate vegetation, and D. rotundifolia, a widely distributed boreal species, reach one of their northernmost and southernmost limits, respectively, on the Korean Peninsula. Because the Last Glacial Maximum (LGM)-Holocene dynamics of warm-temperate and boreal paleovegetation differed considerably on the Peninsula, the population history of these two sundews is expected to be different, leaving differential imprints in their genetic structure. We investigated population genetic structure of D. peltata var. nipponica and D. rotundifolia in South Korea (10 populations of each for 20 allozyme loci) to infer their population history in this region. In addition, we compared the genetic variation harbored in the two sundews to those reported for other carnivorous and wetland plants. Drosera peltata var. nipponica showed no genetic diversity, whereas D. rotundifolia exhibited extremely low within-population variation (He = 0.005) and considerable among-population divergence (FST = 0.817). Our results suggest that extant populations of D. peltata var. nipponica likely originated from a single ancestral population from southern Japan or southern China through postglacial dispersal. On the contrary, D. rotundifolia probably survived the LGM in situ, with extant populations derived from either one or several small source populations. We argue that separate conservation strategies should be employed, given that the two taxa have different ecological and demographic traits and harbor different levels of genetic diversity.

  13. Mixing Plants from Different Origins to Restore a Declining Population: Ecological Outcomes and Local Perceptions 10 Years Later

    Science.gov (United States)

    Maurice, Anne-Claire; Abdelkrim, Jawad; Cisel, Matthieu; Zavodna, Monika; Bardin, Philippe; Matamoro, Alexis; Dumez, Richard; Machon, Nathalie

    2013-01-01

    Populations of the Large-flowered Sandwort (Arenaria grandiflora L.) in the Fontainebleau forest (France) have declined rapidly during the last century. Despite the initiation of a protection program in 1991, less than twenty individuals remained by the late 1990s. The low fitness of these last plants, which is likely associated with genetic disorders and inbreeding depression, highlighted the need for the introduction of non-local genetic material to increase genetic diversity and thus restore Fontainebleau populations. Consequently, A. grandiflora was introduced at three distant sites in the Fontainebleau forest in 1999. Each of these populations was composed of an identical mix of individuals of both local and non-local origin that were obtained through in vitro multiplication. After establishment, the population status (number of individuals, diameter of the plants, and number of flowers) of the introduced populations was monitored. At present, two populations (one of which is much larger than the other) persist, while the third one became extinct in 2004. Analyses of the ecological parameters of the introduction sites indicated that differences in soil pH and moisture might have contributed to the differences in population dynamics. This introduction plan and its outcome attracted interest of local community, with those who supported the plan and regarded its 10-year result as a biological success (i.e., persistent populations were created), but also those who expressed reservations or disapproval of the plan and its outcome. To understand this controversy, a sociological study involving 27 semi-structured interviews was carried out. From these interviews emerged three areas of controversy: alteration of the identity of the plant, alteration of the identity of its territory, and the biological and ethical consequences of the techniques used for the experimental conservation. PMID:23349668

  14. Mixing plants from different origins to restore a declining population: ecological outcomes and local perceptions 10 years later.

    Directory of Open Access Journals (Sweden)

    Anne-Claire Maurice

    Full Text Available Populations of the Large-flowered Sandwort (Arenaria grandiflora L. in the Fontainebleau forest (France have declined rapidly during the last century. Despite the initiation of a protection program in 1991, less than twenty individuals remained by the late 1990s. The low fitness of these last plants, which is likely associated with genetic disorders and inbreeding depression, highlighted the need for the introduction of non-local genetic material to increase genetic diversity and thus restore Fontainebleau populations. Consequently, A. grandiflora was introduced at three distant sites in the Fontainebleau forest in 1999. Each of these populations was composed of an identical mix of individuals of both local and non-local origin that were obtained through in vitro multiplication. After establishment, the population status (number of individuals, diameter of the plants, and number of flowers of the introduced populations was monitored. At present, two populations (one of which is much larger than the other persist, while the third one became extinct in 2004. Analyses of the ecological parameters of the introduction sites indicated that differences in soil pH and moisture might have contributed to the differences in population dynamics. This introduction plan and its outcome attracted interest of local community, with those who supported the plan and regarded its 10-year result as a biological success (i.e., persistent populations were created, but also those who expressed reservations or disapproval of the plan and its outcome. To understand this controversy, a sociological study involving 27 semi-structured interviews was carried out. From these interviews emerged three areas of controversy: alteration of the identity of the plant, alteration of the identity of its territory, and the biological and ethical consequences of the techniques used for the experimental conservation.

  15. Genetic Diversity and Population Structure of the Rare and Endangered Plant Species Pulsatilla patens (L. Mill in East Central Europe.

    Directory of Open Access Journals (Sweden)

    Monika Szczecińska

    Full Text Available Pulsatilla patens s.s. is a one of the most endangered plant species in Europe. The present range of this species in Europe is highly fragmented and the size of the populations has been dramatically reduced in the past 50 years. The rapid disappearance of P. patens localities in Europe has prompted the European Commission to initiate active protection of this critically endangered species. The aim of this study was to estimate the degree and distribution of genetic diversity within European populations of this endangered species. We screened 29 populations of P. patens using a set of six microsatellite primers. The results of our study indicate that the analyzed populations are characterized by low levels of genetic diversity (Ho = 0.005 and very high levels of inbreeding (FIS = 0.90. These results suggest that genetic erosion could be partially responsible for the lower fitness in smaller populations of this species. Private allelic richness was very low, being as low as 0.00 for most populations. Average genetic diversity over loci and mean number of alleles in P. patens populations were significantly correlated with population size, suggesting severe genetic drift. The results of AMOVA point to higher levels of variation within populations than between populations.The results of Structure and PCoA analyses suggest that the genetic structure of the studied P. patens populations fall into three clusters corresponding to geographical regions. The most isolated populations (mostly from Romania formed a separate group with a homogeneous gene pool located at the southern, steppic part of the distribution range. Baltic, mostly Polish, populations fall into two genetic groups which were not fully compatible with their geographic distribution.Our results indicate the serious genetic depauperation of P. patens in the western part of its range, even hinting at an ongoing extinction vortex. Therefore, special conservation attention is required to

  16. Population dynamics of Scirtothrips dorsalis (Thysanoptera: Thripidae) and other thrips species on two ornamental host plant species in Southern Florida.

    Science.gov (United States)

    Mannion, Catharine M; Derksen, Andrew I; Seal, Dakshina R; Osborne, Lance S; Martin, Cliff G

    2014-08-01

    Since its 2005 introduction into the United States, chilli thrips, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae), has become a problematic pest of agronomic, vegetable, fruit, and ornamental plants. Knowledge of its population dynamics may help managers better monitor and control S. dorsalis. Population estimates were recorded for S. dorsalis and other thrips species on Knock-Out rose (Rosa 'Radrazz') and green buttonwood (Conocarpus erectus L.) from July 2007 to September 2008 in two field plots (one per plant species) in Homestead, FL. Yellow sticky card traps and samples of terminals, flowers, buds, and leaves were collected. S. dorsalis accounted for 95% of all thrips individuals collected from plants and 84% from traps with the remainder including at least 18 other thrips species. More thrips were caught on or flying near rose plants (47,438) than on or near buttonwoods (5,898), and on-plant densities of S. dorsalis appeared higher for rose than for buttonwood. Compared with rose leaves, rose buds, terminals, and flowers each had higher numbers of S. dorsalis, and buds and terminals had higher densities. On each host plant species, S. dorsalis density fluctuated over time with peaks in the late spring, summer, and fall, but populations were consistently low in the late winter and early spring. On roses, increased plant damage ratings correlated with reduced numbers of flowers and buds, reduced mean flower areas, and increased on-plant number and density of S. dorsalis. There were positive correlations over time between S. dorsalis density and plant damage rating for rose flowers (R = 0.78; P = 0.0003) and for buttonwood terminals (R = 0.90; P = 0.0001). Yellow sticky card traps were effective for monitoring S. dorsalis and may be especially useful and economically justified for the most susceptible hosts, but they also work well for less susceptible hosts. A good S. dorsalis scouting program should hence consider trap catches and symptoms such as leaf

  17. Population densities of indigenous Acidobacteria change in the presence of plant growth promoting rhizobacteria (PGPR) in rhizosphere.

    Science.gov (United States)

    Kalam, Sadaf; Das, Subha Narayan; Basu, Anirban; Podile, Appa Rao

    2017-05-01

    Rhizosphere microbial community has diverse metabolic capabilities and plays a crucial role in maintaining plant health. Oligotrophic plant growth promoting rhizobacteria (PGPR), along with difficult-to-culture microbial fractions, might be involved synergistically in microbe-microbe and plant-microbe interactions in the rhizosphere. Among the difficult-to-culture microbial fractions, Acidobacteria constitutes the most dominant phylum thriving in rhizospheric soils. We selected effective PGPR for tomato and black gram and studied their effect on population densities of acidobacterial members. Three facultatively oligotrophic PGPR were identified through 16S rRNA gene sequencing as Sphingobacterium sp. (P3), Variovorax sp. (P4), and Roseomonas sp. (A2); the latter being a new report of PGPR. In presence of selected PGPR strains, the changes in population densities of Acidobacteria were monitored in metagenomic DNA extracted from bulk and rhizospheric soils of tomato and black gram using real time qPCR. A gradual increase in equivalent cell numbers of Acidobacteria members was observed over time along with a simultaneous increase in plant growth promotion by test PGPR. We report characterization of three effective PGPR strains and their effects on indigenous, underexplored difficult-to-culture phylum-Acidobacteria. We suggest that putative interactions between these two bacterial groups thriving in rhizospheric soils could be beneficial for plant growth. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Reproductive isolation between two populations of Diatraea saccharalis (F.) (Lepidoptera: Crambidae) from different host plant species and regions in Argentina.

    Science.gov (United States)

    Fogliata, S V; Vera, A; Gastaminza, G; Cuenya, M I; Zucchi, M I; Willink, E; Castagnaro, A P; Murúa, M G

    2016-10-01

    The sugarcane borer, Diatraea saccharalis (F.), has a widespread distribution throughout the Western Hemisphere and is a pest of many crop plants including sugarcane, corn, sorghum and rice. The use of Bacillus thuringiensis (Bt) corn has been the primary tool for managing this species in corn fields. Sugarcane borer control has been recently threatened by observations of susceptibility and/or resistance to certain varieties of Bt corn and the protein used in many newer varieties. This has led to increased interest in understanding sugarcane borer genetic diversity and gene flow within and among its populations and the consequent exchange of alleles between geographically distant populations. The objective of this study was to examine reproductive compatibility between host-associated geographic populations of D. saccharalis in Argentina and to determine whether this pest represents a complex of host-associated cryptic species rather than a wide ranging generalist species. Intra and inter-population crosses revealed that D. saccharalis populations from the northwestern and Pampas regions presented evidence of prezygotic and postzygotic incompatibility. Such a result is likely to be the product of an interruption of gene flow produced by either geographic or host plant associated isolation, suggesting that Tucumán (northwestern) and Buenos Aires (Pampas) populations of D. saccharalis are a distinct genotype and possibly an incipient species.

  19. THE STRUCTURE OF THE SPIDER POPULATION (ARANEI OF THE DONETSK CITY WOOD PLANTINGS

    Directory of Open Access Journals (Sweden)

    Prokopenko E. V.

    2013-09-01

    Full Text Available The studies of the species composition and structure of the spider population in the Donetsk City wood planting are given. A total of 109 species from 22 families were recorded. Linyphiidae (26,6% of total species in study sites, Lycosidae (11,1% and Gnaphosidae (13,8% were most species-rich. Lycosidae (55,6% individuals were the more abundant. Linyphiidae (19,6% occupied the second position. Gnaphosidae (4,8% were less abundant than Thomisidae (10,8%. The high spider density and significant species richness are typical for country wood, in city parks these parameters have decreased. The maximal species richness (71 species is recorded in suburban bairak wood (Yasinovataya Town. The minimal species richness is recorded in Lenynkiy Komsomol Park (32 species. The average spider density equal to 65,8 individuals to 100 trap-days. The maximal value of this parameter is recorded in suburban bairak wood (103,8 individuals to 100 trap-days. The minimal value of this parameter is recorded in the city parks (40,4 and 31,6 individuals to 100 trap-days in Scherbakova Park and Lenynkiy Komsomol Park respectively. The total percentage of the most abundant species (eudominants in the parks has increased and the the total percent of the rare species has decreased. Location of the biotops in city space (on fringe, in the centre with the spectrum of antropogenous influence has more determinative significance for the araneocomplex similarity, than generality of the origin (artificial wood, natural bairak oak forest.

  20. Analysis of Genetic Variation in Brevipalpus yothersi (Acari: Tenuipalpidae) Populations from Four Species of Citrus Host Plants.

    Science.gov (United States)

    Salinas-Vargas, Delfina; Santillán-Galicia, Ma Teresa; Guzmán-Franco, Ariel W; Hernández-López, Antonio; Ortega-Arenas, Laura D; Mora-Aguilera, Gustavo

    2016-01-01

    We studied species diversity and genetic variation among populations of Brevipalpus mites from four species of citrus host plants. We sampled mites on orange, lime, grapefruit and mandarin trees from orchards at six localities distributed in the five most important citrus producing states in Mexico. Genetic variation among citrus host plants and localities were assessed by analysis of nucleotide sequence data from fragments of the mitochondrial cytochrome oxidase subunit I (COI). Both Brevipalpus yothersi and B. californicus were found at these sites, and B. yothersi was the most abundant species found on all citrus species and in all localities sampled. B. californicus was found mainly on orange and mandarin and only in two of the states sampled. AMOVA and haplotype network analyses revealed no correlation between B. yothersi genetic population structure and geographical origin or citrus host plant species. Considering that a previous study reported greater genetic diversity in B. yothersi populations from Brazil than we observed in Mexico, we discuss the possibility that the Mexican populations may have originated in the southern region of America.

  1. Medicinal plants of Papua New Guinea's Miu speaking population and a focus on their use of plant-slaked lime mixtures.

    Science.gov (United States)

    Prescott, Thomas A K; Briggs, Marie; Kiapranis, Robert; Simmonds, Monique S J

    2015-11-04

    Here we present the results of an ethnobotanical survey of the medicinal plants used by the Miu, a virtually unresearched ethnolinguistic group who live in the mountainous interior of Papua New Guinea's West New Britain Province. We compare the findings for those previously reported for the neighbouring inland Kaulong speaking population. Three species, Trema orientalis, Spondias dulcis and Ficus botryocarpa are used in combination with locally prepared slaked lime to produce intensely coloured mixtures which are applied to dermatological infections. Their effects on dermal fibroblast viability with and without slaked lime are examined. The sap of F. botryocarpa which is used to treat tropical ulcers was examined further with assays relevant to wound healing. Focus groups and semi-structured interviews were used to acquire information on the uses of plants, vouchers of which were collected and identified by comparison with authentic herbarium specimens. LC-MS and NMR were used to identify chemical components. Cell viability assays were used to examine the effects of added slaked lime on dermal fibroblasts. For the sap of F. botryocarpa, fibroblast stimulation assays and antibacterial growth inhibition with Bacillus subtilis were carried out. The survey identified 33 plants and one fungal species, and clear differences with the inland Kaulong group despite their close proximity. Added slaked lime does not greatly increase the cytotoxicity of plant material towards dermal fibroblasts. The sap of F. botryocarpa contains the alkaloid ficuseptine as a single major component and displays antibacterial activity. The results demonstrate the potential for variation in medicinal plant use amongst Papua New Guinea's numerous language groups. The addition of slaked lime to plant material does not appear to present a concern for wound healing in the amounts used. The sap of F. botryocarpa displays antibacterial activity at concentrations that would occur at the wound surface

  2. Population morbidity in the Zaporizhzhia Nuclear Power Plant observation zone as an integral part of public health.

    Science.gov (United States)

    Khomenko, I M; Zakladna, N V; Orlova, N M

    2017-12-01

    To evaluate the health status of adult population living in the Ukrainian nuclear power industry obser vation zone on the example of Zaporizhzhia Nuclear Power Plant. System review, analytic, sociological survey and statistical methods. There was established an increase in the incidence of digestive diseases among adult population in Nikopol of Dnipropetrovsk region, which is included in the Zaporizhzhia NPP observation zone. The highest increase was observed in the incidence of peptic ulcer, gastritis and duodenitis, cholecystitis and cholangitis by 340 %, 305 % and 83 %, respectively. In connection with the residence in industrially developed region and NPP life extension in Ukraine, the possible influence of harmful factors on health status of the population of observation zones, an increase in the incidence of digestive diseases among adult population, there is required continuous monitoring and detailed study of public health. I. M. Khomenko, N. V. Zakladna, N. M. Orlova.

  3. Varying Herbivore Population Structure Correlates with Lack of Local Adaptation in a Geographic Variable Plant-Herbivore Interaction

    Science.gov (United States)

    Cogni, Rodrigo; Trigo, José R.; Futuyma, Douglas J.

    2011-01-01

    Local adaptation of parasites to their hosts due to coevolution is a central prediction of many theories in evolutionary biology. However, empirical studies looking for parasite local adaptation show great variation in outcomes, and the reasons for such variation are largely unknown. In a previous study, we showed adaptive differentiation in the arctiid moth Utetheisa ornatrix to its host plant, the pyrrolizidine alkaloid-bearing legume Crotalaria pallida, at the continental scale, but found no differentiation at the regional scale. In the present study, we sampled the same sites to investigate factors that may contribute to the lack of differentiation at the regional scale. We performed field observations that show that specialist and non-specialist polyphagous herbivore incidence varies among populations at both scales. With a series of common-garden experiments we show that some plant traits that may affect herbivory (pyrrolizidine alkaloids and extrafloral nectaries) vary at the regional scale, while other traits (trichomes and nitrogen content) just vary at the continental scale. These results, combined with our previous evidence for plant population differentiation based on larval performance on fresh fruits, suggest that U. ornatrix is subjected to divergent selection even at the regional scale. Finally, with a microsatellite study we investigated population structure of U. ornatrix. We found that population structure is not stable over time: we found population differentiation at the regional scale in the first year of sampling, but not in the second year. Unstable population structure of the herbivore is the most likely cause of the lack of regional adaptation. PMID:22220208

  4. Directional Analysis of Sub-Antarctic Climate Change on South Georgia 1905-2009

    Science.gov (United States)

    Sakamoto Ferranti, Emma Jayne; Solera Garcia, Maria Angeles; Timmis, Roger James; Gerrard McKenna, Paul; Whyatt, James Duncan

    2010-05-01

    Directional analysis has been used to study changes in the sub-polar climate of the mountainous and glacierised sub-Antarctic island of South Georgia (54-55°S, 36-38°W). Significantly for climate change studies, South Georgia lies in the Scotia Sea between polar and temperate latitudes, and approximately 1000 km northeast and downwind of the Antarctic Peninsula - one of the fastest-warming regions on Earth (Vaughan et al., 2001). South Georgia was chosen for directional analysis because its climate is substantially advected by predominantly westerly circulations, and because it has a long (since 1905) meteorological record from King Edward Point (KEP) on its eastern side. Additional shorter records from Bird Island at the northwest tip of South Georgia allow comparison between windward (Bird Island) and leeward (KEP) climate regimes. The variation of mountain barrier heights with direction from KEP allows climate changes to be studied under different amounts of orographic influence (from ~700 m to ~2200 m). Records of glacier advance and retreat provide further independent evidence of climate change for comparison with the meteorological record. Directional climate analysis is based on a series of monthly-mean pressure fields defining the orientation and strength of synoptic-scale air-mass advection over the Scotia Sea. These fields are used to define directional climatologies for six 30° sectors with bearings from 150-180° to 300-330°; these sectors encompass 99% of recorded months since 1905. The climatologies summarise the frequencies of air masses from each sector, and the accompanying temperatures and precipitation. The 6 sectors can be broadly associated with 4 air-mass types and source regions: (i) sectors 150-210° advect cold polar maritime air that originated over the Antarctic continent before passing over the Weddell Sea, (ii) sectors 210-270° advect warmer, more stable polar maritime air from the Bellingshausen Sea/Antarctic Peninsula region

  5. Woody plants in dry sands : life history traits and population dynamics

    NARCIS (Netherlands)

    Li, S.|info:eu-repo/dai/nl/304849324

    2010-01-01

    Inland dune ecosystems are harsh environment for long-lived woody plants because of poor water and nutrient availability and frequent sand. As a result, long-lived woody plants have a high risk of being killed by sand movement or a long period of drought and this may occur even before they reach

  6. Impact of insect management on population dynamics and insecticide resistance of tarnished plant bug (Lygus lineolaris)

    Science.gov (United States)

    The tarnished plant bug, Lygus lineolaris (Palisot De Beauvois) is a highly polyphagous insect that feeds on numerous wild and cultivated host plants. Although transgenic crops expressing insecticidal toxins have been available for approximately 20 years for some insect crop pests, none have been d...

  7. Nitrogen and plant population change radiation capture and utilization capacity of sunflower in semi-arid environment.

    Science.gov (United States)

    Awais, Muhammad; Wajid, Aftab; Bashir, Muhammad Usman; Habib-Ur-Rahman, Muhammad; Raza, Muhammad Aown Sammar; Ahmad, Ashfaq; Saleem, Muhammad Farrukh; Hammad, Hafiz Mohkum; Mubeen, Muhammad; Saeed, Umer; Arshad, Muhammad Naveed; Fahad, Shah; Nasim, Wajid

    2017-07-01

    The combination of nitrogen and plant population expresses the spatial distribution of crop plants. The spatial distribution influences canopy structure and development, radiation capture, accumulated intercepted radiation (Sa), radiation use efficiency (RUE), and subsequently dry matter production. We hypothesized that the sunflower crop at higher plant populations and nitrogen (N) rates would achieve early canopy cover, capture more radiant energy, utilize radiation energy more efficiently, and ultimately increase economic yield. To investigate the above hypothesis, we examined the influences of leaf area index (LAI) at different plant populations (83,333, 66,666, and 55,555 plants ha -1 ) and N rates (90, 120, and 150 kg ha -1 ) on radiation interception (Fi), photosynthetically active radiation (PAR) accumulation (Sa), total dry matter (TDM), achene yield (AY), and RUE of sunflower. The experimental work was conducted during 2012 and 2013 on sandy loam soil in Punjab, Pakistan. The sunflower crop captured more than 96% of incident radiant energy (mean of all treatments), 98% with a higher plant population (83,333 plants ha -1 ), and 97% with higher N application (150 kg ha -1 ) at the fifth harvest (60 days after sowing) during both study years. The plant population of 83,333 plants ha -1 with 150 kg N ha -1 ominously promoted crop, RUE, and finally productivity of sunflower (AY and TDM). Sunflower canopy (LAI) showed a very close and strong association with Fi (R 2  = 0.99 in both years), PAR (R 2  = 0.74 and 0.79 in 2012 and 2013, respectively), TDM (R 2  = 0.97 in 2012 and 0.91 in 2013), AY (R 2  = 0.95 in both years), RUE for TDM (RUE TDM ) (R 2  = 0.63 and 0.71 in 2012 and 2013, respectively), and RUE for AY (RUE AY ) (R 2  = 0.88 and 0.87 in 2012 and 2013, respectively). Similarly, AY (R 2  = 0.73 in 2012 and 0.79 in 2013) and TDM (R 2  = 0.75 in 2012 and 0.84 in 2013) indicated significant dependence on PAR accumulation of

  8. A preliminary synoptic assessment of soil frost on Marion Island and the possible consequences of climate change in a maritime sub-Antarctic environment

    Directory of Open Access Journals (Sweden)

    Werner Nel

    2012-03-01

    Full Text Available Located in the sub-Antarctic, Marion Island (46° 54′ S, 37° 45′ E has a distinct periglacial environment that is sensitive to climate change. Diurnal soil frost is the most important geomorphic process occurring on the island and this paper aims to understand the synoptic weather circulation pattern associated with summer soil frost occurrence in a sub-Antarctic environment. Preliminary results from automated microclimate measurements in the interior of Marion Island show that summer soil frost is dependent on Antarctic air mass circulation. This occurs exclusively during post-cyclonic airflow after the passage of a cold front connected to a mid-latitudinal cyclone and subsequent ridging in of the South Atlantic Anticyclone behind the cold front, or when a series of low pressure systems passes over the island. The duration and intensity of soil frost cycles are dependent on the duration of post-cyclonic Antarctic air mass circulation. Summer soil frost on Marion Island is driven by a complex interaction between the latitudinal position of the passing cyclone, the latitudinal position of the ridging anticyclone as well as the trajectory of the air mass circulation. The data suggest that predicted trends in synoptic climate change in the sub-Antarctic may lead to non-linear responses in soil frost dynamics.

  9. Plant GABA:proline ratio modulates dissemination of the virulence Ti plasmid within the Agrobacterium tumefaciens hosted population.

    Science.gov (United States)

    Lang, Julien; Faure, Denis

    2016-05-03

    Accumulation of amino acids is a common plant response to several biotic and abiotic stresses, even if the roles of these accumulations remain often poorly understood. In a recent study we measured the levels of different amino acids in tumors of Arabidopsis thaliana induced by the phytopathogen Agrobacterium tumefaciens and correlated these data with changes of gene expressions in both organisms. This led to the demonstration that the non-protein amino acid GABA plays an important role for the adaptation of the bacteria to the plant tumor environment, and especially in the control of the virulent Ti plasmid dissemination. Here we present a model that describes how different GABA:proline ratios in the A. thaliana host may have different impacts on the conjugation of A. tumefaciens Ti plasmid, and advance the view that the amino acid metabolism of plant hosts could be critical for the propagation of the virulence genes in A. tumefaciens populations.

  10. Population survey of phytoseiid mites and spider mites on peach leaves and wild plants in Japanese peach orchard.

    Science.gov (United States)

    Wari, David; Yamashita, Jun; Kataoka, Yoko; Kohara, Yoko; Hinomoto, Norihide; Kishimoto, Hidenari; Toyoshima, Shingo; Sonoda, Shoji

    2014-07-01

    A population survey of phytoseiid mites and spider mites was conducted on peach leaves and wild plants in Japanese peach orchards having different pesticide practices. The phytoseiid mite species composition on peach leaves and wild plants, as estimated using quantitative sequencing, changed during the survey period. Moreover, it varied among study sites. The phytoseiid mite species compositions were similar between peach leaves and some wild plants, such as Veronica persica, Paederia foetida, Persicaria longiseta, and Oxalis corniculata with larger quantities of phytoseiid mites, especially after mid-summer. A PCR-based method to detect the ribosomal ITS sequences of Tetranychus kanzawai and Panonychus mori from phytoseiid mites was developed. Results showed that Euseius sojaensis (specialized pollen feeder/generalist predator) uses both spider mites as prey in the field.

  11. Populism

    OpenAIRE

    Abts, Koenraad; Van Kessel, Stijn

    2015-01-01

    Populism is a concept applied to a wide range of political movements and actors across the globe. There is, at the same time, considerable confusion about the attributes and manifestation of populism, as well as its impact on democracy. This contribution identifies the defining elements of the populist ideology and discusses the varieties in which populism manifests itself, for instance as a component of certain party families. We finally discuss various normative interpretations of populism,...

  12. Plantes médicinales utilisées par les populations Bassa de la région ...

    African Journals Online (AJOL)

    Une enquête ethnobotanique portant sur un échantillon de 90 ménages a été conduite en juin 2010 dans trois villages de la région de Douala, au Cameroun, afin de recenser les plantes médicinales utilisées par les populations rurales. Elle montre que 48 espèces relevant de 44 genres et de 26 familles sont utilisées dans ...

  13. Les plantes à alcaloïdes utilisées par les populations de la ville de ...

    African Journals Online (AJOL)

    SARAH

    30 juin 2014 ... Yinyang et al. J. Appl. Biosci. 2014. Les plantes à alcaloïdes utilisées par les populations de la ville ... Objectif : Une enquête ethnobotanique a été conduite de janvier à février 2013 dans la ville de Douala concernant les différents .... choisi a permis de communiquer et de réaliser sans difficulté majeure les ...

  14. 77 FR 665 - Endangered and Threatened Wildlife and Plants; Listing Two Distinct Population Segments of Broad...

    Science.gov (United States)

    2012-01-05

    ... successful (wild populations are increasing), and broad-snouted caiman production and harvest is increasing... population has increased since the time of the original listing. Technical Corrections This proposed rule... status of the population in two ways: by creating incentives for landowners and by increasing public...

  15. Climate adaptation is not enough: warming does not facilitate success of southern tundra plant populations in the high Arctic.

    Science.gov (United States)

    Bjorkman, Anne D; Vellend, Mark; Frei, Esther R; Henry, Gregory H R

    2017-04-01

    Rapidly rising temperatures are expected to cause latitudinal and elevational range shifts as species track their optimal climate north and upward. However, a lack of adaptation to environmental conditions other than climate - for example photoperiod, biotic interactions, or edaphic conditions - might limit the success of immigrants in a new location despite hospitable climatic conditions. Here, we present one of the first direct experimental tests of the hypothesis that warmer temperatures at northern latitudes will confer a fitness advantage to southern immigrants relative to native populations. As rates of warming in the Arctic are more than double the global average, understanding the impacts of warming in Arctic ecosystems is especially urgent. We established experimentally warmed and nonwarmed common garden plots at Alexandra Fiord, Ellesmere Island in the Canadian High Arctic with seeds of two forb species (Oxyria digyna and Papaver radicatum) originating from three to five populations at different latitudes across the Arctic. We found that plants from the local populations generally had higher survival and obtained a greater maximum size than foreign individuals, regardless of warming treatment. Phenological traits varied with latitude of the source population, such that southern populations demonstrated substantially delayed leaf-out and senescence relative to northern populations. Our results suggest that environmental conditions other than temperature may influence the ability of foreign populations and species to establish at more northerly latitudes as the climate warms, potentially leading to lags in northward range shifts for some species. © 2016 John Wiley & Sons Ltd.

  16. Population growth of Varroa destructor (Acari: Varroidae) in commercial honey bee colonies treated with beta plant acids.

    Science.gov (United States)

    DeGrandi-Hoffman, Gloria; Ahumada, Fabiana; Curry, Robert; Probasco, Gene; Schantz, Lloyd

    2014-10-01

    Varroa (Varroa destuctor Anderson and Trueman) populations in honey bee (Apis mellifera L.) colonies might be kept at low levels by well-timed miticide applications. HopGuard(®) (HG) that contains beta plant acids as the active ingredient was used to reduce mite populations. Schedules for applications of the miticide that could maintain low mite levels were tested in hives started from either package bees or splits of larger colonies. The schedules were developed based on defined parameters for efficacy of the miticide and predictions of varroa population growth generated from a mathematical model of honey bee colony-varroa population dynamics. Colonies started from package bees and treated with HG in the package only or with subsequent HG treatments in the summer had 1.2-2.1 mites per 100 bees in August. Untreated controls averaged significantly more mites than treated colonies (3.3 mites per 100 bees). By October, mite populations ranged from 6.3 to 15.0 mites per 100 bees with the lowest mite numbers in colonies treated with HG in August. HG applications in colonies started from splits in April reduced mite populations to 0.12 mites per 100 bees. In September, the treated colonies had significantly fewer mites than the untreated controls. Subsequent HG applications in September that lasted for 3 weeks reduced mite populations to levels in November that were significantly lower than in colonies that were untreated or had an HG treatment that lasted for 1 week. The model accurately predicted colony population growth and varroa levels until the fall when varroa populations measured in colonies established from package bees or splits were much greater than predicted. Possible explanations for the differences between actual and predicted mite populations are discussed.

  17. Derivation of plant-soil relationships for dose assessment on Bikini Atoll. [Radiation dose to returning population

    Energy Technology Data Exchange (ETDEWEB)

    Colsher, C. S.

    1976-11-01

    A radiological survey of the terrestrial environment of Bikini and Eneu Islands (Bikini Atoll) was conducted in June 1975 to evaluate the potential radiation dose to the returning Bikini population. This report presents measurements of the radionuclide concentration in soil profiles and in dominant species of edible and nonedible indicator plants and describes the use of these data to derive relationships to predict the plant uptake of radionuclides from soil. Soil-plant concentration factors together with leaf-leaf and fruit-leaf concentration ratios for indicator and edible plant species from the same area are calculated to quantitatively assess and compare the uptake of /sup 90/Sr, /sup 137/Cs, and /sup 239/'/sup 240/Pu. In general, the concentration factors for /sup 137/Cs in terrestrial vegetation are greater than those for /sup 90/Sr and the concentration factors for both these nuclides exceed those for /sup 239/'/sup 240/Pu by ten to one hundred-fold. Uptake of /sup 90/Sr and /sup 239/'/sup 240/Pu by fruit is less than that by mature leaves; however, the opposite is true for /sup 137/Cs. The relative contribution of the individual plant species to the internal dose to man varies with the nuclide. The use of concentration factors and concentration ratios to predict nuclide concentrations in fruit from those in soil or leaves is prescribed.

  18. Diversity of endophytic bacterial populations and their interaction with Xylella fastidiosa in citrus plants

    NARCIS (Netherlands)

    Araujo, W.L.; Marcon, J.; jr. Maccheroni, W.; Elsas, van J.D.; Vuurde, van J.W.L.; Azevedo, de J.L.

    2002-01-01

    Citrus variegated chlorosis (CVC) is caused by Xylella fastidiosa, a phytopathogenic bacterium that can infect all Citrus sinensis cultivars. The endophytic bacterial communities of healthy, resistant, and CVC-affected citrus plants were studied by using cultivation as well as

  19. Late Holocene intensification of the westerly winds at the subantarctic Auckland Islands (51° S, New Zealand

    Directory of Open Access Journals (Sweden)

    I. M. Browne

    2017-10-01

    Full Text Available The Southern Hemisphere westerly winds (SHWWs play a major role in controlling wind-driven upwelling of Circumpolar Deep Water (CDW and outgassing of CO2 in the Southern Ocean, on interannual to glacial–interglacial timescales. Despite their significance in the global carbon cycle, our understanding of millennial- and centennial-scale changes in the strength and latitudinal position of the westerlies during the Holocene (especially since 5000 yr BP is limited by a scarcity of palaeoclimate records from comparable latitudes. Here, we reconstruct middle to late Holocene SHWW variability using a fjord sediment core collected from the subantarctic Auckland Islands (51° S, 166° E, located in the modern centre of the westerly wind belt. Changes in drainage basin response to variability in the strength of the SHWW at this latitude are interpreted from downcore variations in magnetic susceptibility (MS and bulk organic δ13C and atomic C ∕ N, which monitor influxes of lithogenous and terrestrial vs. marine organic matter, respectively. The fjord water column response to SHWW variability is evaluated using benthic foraminifer δ18O and δ13C, both of which are influenced by the isotopic composition of shelf water masses entering the fjord. Using these data, we provide marine and terrestrial-based evidence for increased wind strength from  ∼  1600 to 900 yr BP at subantarctic latitudes that is broadly consistent with previous studies of climate-driven vegetation change at the Auckland Islands. Comparison with a SHWW reconstruction using similar proxies from Fiordland suggests a northward migration of the SHWW over New Zealand during the first half of the last millennium. Comparison with palaeoclimate and palaeoceanographic records from southern South America and West Antarctica indicates a late Holocene strengthening of the SHWW after  ∼  1600 yr BP that appears to be broadly symmetrical across the Pacific Basin

  20. Late Holocene intensification of the westerly winds at the subantarctic Auckland Islands (51° S), New Zealand

    Science.gov (United States)

    Browne, Imogen M.; Moy, Christopher M.; Riesselman, Christina R.; Neil, Helen L.; Curtin, Lorelei G.; Gorman, Andrew R.; Wilson, Gary S.

    2017-10-01

    The Southern Hemisphere westerly winds (SHWWs) play a major role in controlling wind-driven upwelling of Circumpolar Deep Water (CDW) and outgassing of CO2 in the Southern Ocean, on interannual to glacial-interglacial timescales. Despite their significance in the global carbon cycle, our understanding of millennial- and centennial-scale changes in the strength and latitudinal position of the westerlies during the Holocene (especially since 5000 yr BP) is limited by a scarcity of palaeoclimate records from comparable latitudes. Here, we reconstruct middle to late Holocene SHWW variability using a fjord sediment core collected from the subantarctic Auckland Islands (51° S, 166° E), located in the modern centre of the westerly wind belt. Changes in drainage basin response to variability in the strength of the SHWW at this latitude are interpreted from downcore variations in magnetic susceptibility (MS) and bulk organic δ13C and atomic C / N, which monitor influxes of lithogenous and terrestrial vs. marine organic matter, respectively. The fjord water column response to SHWW variability is evaluated using benthic foraminifer δ18O and δ13C, both of which are influenced by the isotopic composition of shelf water masses entering the fjord. Using these data, we provide marine and terrestrial-based evidence for increased wind strength from ˜ 1600 to 900 yr BP at subantarctic latitudes that is broadly consistent with previous studies of climate-driven vegetation change at the Auckland Islands. Comparison with a SHWW reconstruction using similar proxies from Fiordland suggests a northward migration of the SHWW over New Zealand during the first half of the last millennium. Comparison with palaeoclimate and palaeoceanographic records from southern South America and West Antarctica indicates a late Holocene strengthening of the SHWW after ˜ 1600 yr BP that appears to be broadly symmetrical across the Pacific Basin. Contemporaneous increases in SHWW at localities on either

  1. Use of traditional plants in management of halitosis in a Moroccan population

    OpenAIRE

    Akkaoui, Sanae; Ennibi, Oum keltoum

    2017-01-01

    Introduction: The use of medicinal plants was a very spread therapeutic way. At present, several studies are moving toward this ancestral option, seen the emergence of several bacterial resistance and for the large number of side effects of some synthetic drugs. Objective: The objective of this study was to collect and evaluate information on medicinal plants commonly used in five Moroccan cities: Rabat, Sal?, T?mara, Kh?misset, and Tiflet for the management of halitosis. Methods: This is a c...

  2. Adaptive Transgenerational Plasticity in Plants: Case Studies, Mechanisms, and Implications for Natural Populations

    OpenAIRE

    Herman, Jacob J.; Sultan, Sonia E

    2011-01-01

    Plants respond to environmental conditions not only by plastic changes to their own development and physiology, but also by altering the phenotypes expressed by their offspring. This transgenerational plasticity was initially considered to entail only negative effects of stressful parental environments, such as production of smaller seeds by resource- or temperature-stressed parent plants, and was therefore viewed as environmental noise. Recent evolutionary ecology studies have shown that in ...

  3. Genetic diversity and differentiation of yellowwood [Cladrastis kentukea (Dum.Cours.) Rudd] growing in the wild and in planted populations outside the natural range

    Science.gov (United States)

    Nicholas LaBonte; Jadelys Tonos; Colleen Hartel; Keith E. Woeste

    2017-01-01

    Yellowwood (Cladrastis kentukea) grows in small, widely scattered populations in the wild, but is also a popular ornamental tree that thrives when planted in urban areas outside its natural range. Since the small native populations of yellowwood in several states are considered at risk of extirpation, the cultivated population could serve as an ex...

  4. The demographic consequences of mutualism: ants increase host-plant fruit production but not population growth

    Science.gov (United States)

    Kevin Ford; Joshua H. Ness; Judith L. Bronstein; William F. Morris

    2015-01-01

    The impact of mutualists on a partner’s demography depends on how they affect the partner’s multiple vital rates and how those vital rates, in turn, affect population growth. However, mutualism studies rarely measure effects on multiple vital rates or integrate them to assess the ultimate impact on population growth. We used vital rate data, population models and...

  5. Effect of Varieties and Plant Population Densities on Dry Matter Production, Radiation Interception and Radiation Energy Conversion in Peanut

    Directory of Open Access Journals (Sweden)

    agus suprapto

    2012-05-01

    Full Text Available The solar radiation is one of the major criteria to obtaining advantages on peanuts (Arachishypogaea L.. Although various combinations of crops have been reported, but variety association and plant population densities (PPD during the periodically stage of growth on peanuts have yet to be analyzed. Dry matter production (DM, radiation energy interception, and radiation energy conversions were monitored over the growth period of two varieties of peanut. An experiment was conducted in Jambegede Research Farm, Indonesian Legume and Tuber Crops Research Institute, Malang, East Java, Indonesia, from July until October 2011. The experiment was arranged in a Split Plot Design with three replications. Peanut varieties, as the main plot consisted of two treatments: Kelinci andKancil variety. In addition, five PPD variations as sub plot consisted of 8.1, 11.1, 16.0, 25.0 and 44.4 plant m-2 were arranged in a square spacing. The results showed that DM production from high PPD increased gradually to lower PPD in all varieties. Interception efficiency (IE increased in all varieties from early sowing. A plant population density of 25.0 m-2 and 44.4 plants m-2 intercepted more radiation over 11.1 or 16.0 plants m-2. Conversion efficiency of radiation energy (CE to total dry matter production on Kelinci variety (1.52% indicated a slight higher percentage than on Kancil variety (1.41%. Moreover, the CE and IE values indicated a decrease as the PPD increased on maximum DM.

  6. A geoprocessing model for the selection of populations most affected by diffuse industrial contamination: the case of oil refinery plants.

    Science.gov (United States)

    Pasetto, Roberto; De Santis, Marco

    2013-01-01

    A method to select populations living in areas affected by diffuse environmental contamination is presented, with particular regard to oil refineries, in the Italian context. The reasons to use municipality instead of census tract populations for environment and health small-area studies of contaminated sites are discussed. Populations most affected by diffuse environmental contamination are identified through a geoprocessing model. Data from the national census 2001 were used to estimate census tract level populations. A geodatabase was developed using the municipality and census tract layers provided by the Italian National Bureau of Statistics (ISTAT). The orthophotos of the Italian territory - year 2006 - available on the geographic information systems (GIS) of the National Cartographic Portal, were considered. The area within 2 km from the plant border was used as an operational definition to identify the area at major contamination. The geoprocessing model architecture is presented. The results of its application to the selection of municipality populations in a case study are shown. The application of the proposed geoprocessing model, the availability of long time series of mortality and morbidity data, and a quali-quantitative estimate of contamination over time, could allow an appraisal of the health status of populations affected by oil refinery emissions.

  7. A geoprocessing model for the selection of populations most affected by diffuse industrial contamination: the case of oil refinery plants

    Directory of Open Access Journals (Sweden)

    Roberto Pasetto

    2013-03-01

    Full Text Available INTRODUCTION. A method to select populations living in areas affected by diffuse environmental contamination is presented, with particular regard to oil refineries, in the Italian context. The reasons to use municipality instead of census tract populations for environment and health small-area studies of contaminated sites are discussed. METHODS. Populations most affected by diffuse environmental contamination are identified through a geoprocessing model. Data from the national census 2001 were used to estimate census tract level populations. A geodatabase was developed using the municipality and census tract layers provided by the Italian National Bureau of Statistics (ISTAT. The orthophotos of the Italian territory - year 2006 - available on the geographic information systems (GIS of the National Cartographic Portal, were considered. The area within 2 km from the plant border was used as an operational definition to identify the area at major contamination. RESULTS. The geoprocessing model architecture is presented. The results of its application to the selection of municipality populations in a case study are shown. CONCLUSIONS. The application of the proposed geoprocessing model, the availability of long time series of mortality and morbidity data, and a quali-quantitative estimate of contamination over time, could allow an appraisal of the health status of populations affected by oil refinery emissions.

  8. From facilitation to competition: temperature-driven shift in dominant plant interactions affects population dynamics in seminatural grasslands.

    Science.gov (United States)

    Olsen, Siri L; Töpper, Joachim P; Skarpaas, Olav; Vandvik, Vigdis; Klanderud, Kari

    2016-05-01

    Biotic interactions are often ignored in assessments of climate change impacts. However, climate-related changes in species interactions, often mediated through increased dominance of certain species or functional groups, may have important implications for how species respond to climate warming and altered precipitation patterns. We examined how a dominant plant functional group affected the population dynamics of four co-occurring forb species by experimentally removing graminoids in seminatural grasslands. Specifically, we explored how the interaction between dominants and subordinates varied with climate by replicating the removal experiment across a climate grid consisting of 12 field sites spanning broad-scale temperature and precipitation gradients in southern Norway. Biotic interactions affected population growth rates of all study species, and the net outcome of interactions between dominants and subordinates switched from facilitation to competition with increasing temperature along the temperature gradient. The impacts of competitive interactions on subordinates in the warmer sites could primarily be attributed to reduced plant survival. Whereas the response to dominant removal varied with temperature, there was no overall effect of precipitation on the balance between competition and facilitation. Our findings suggest that global warming may increase the relative importance of competitive interactions in seminatural grasslands across a wide range of precipitation levels, thereby favouring highly competitive dominant species over subordinate species. As a result, seminatural grasslands may become increasingly dependent on disturbance (i.e. traditional management such as grazing and mowing) to maintain viable populations of subordinate species and thereby biodiversity under future climates. Our study highlights the importance of population-level studies replicated under different climatic conditions for understanding the underlying mechanisms of climate

  9. The Impact of Different Habitat Conditions on the Variability of Wild Populations of a Medicinal Plant Betonica officinalis L.

    Directory of Open Access Journals (Sweden)

    Kinga Kostrakiewicz-Gierałt

    2015-06-01

    Full Text Available Plants are important source of beneficial bioactive compounds which may find various applications as functional ingredients, such as components of food supplements, cosmetics, and pharmaceuticals. One such medicinal plant is Betonica officinalis, populations of which were investigated in 2012‒13. The studies were conducted in patches of Molinietum caeruleae dominated by: small meadow taxa (patch I; the shrub willow Salix repens ssp. rosmarinifolia (patch II; large tussock grasses Deschampsia caespitosa and Molinia caerulaea (patch III; tall-growing macroforbs Filipendula ulmaria and Solidago canadensis (patch IV. Over successive patches, the average height of plant cover increased, as did soil moisture, while light availability at ground level decreased. Much greater abundance and density of the Betonica officinalis population were found in patches I, III and IV, while lower values for these parameters were noted in patch II. Individuals in pre-reproductive stages were absent during whole study period in all study plots, vegetative ramet clusters were observed in plots situated in patches I and III in the first year of observations, while only generative ramet clusters occurred in plots set in patches II and IV. The number of rosettes per ramet cluster, number and dimensions of rosette leaves, height of flowering stems, number of cauline leaves, length of inflorescences, as well as number and length of flowers increased gradually over successive patches, whereas the number of generative stems per ramet cluster did not differ remarkably among populations. On the basis of the performed studies it might be concluded that the condition of populations deteriorated from patches overgrown by large-tussock grasses and characterized by considerable share of native and alien tall-growing macroforbs, via patch dominated by small meadow taxa, to patch prevailed by shrub willows.

  10. Environmental heterogeneity and the evolution of plant-virus interactions: Viruses in wild pepper populations.

    Science.gov (United States)

    Fraile, Aurora; McLeish, Michael J; Pagán, Israel; González-Jara, Pablo; Piñero, Daniel; García-Arenal, Fernando

    2017-09-15

    Understanding host-pathogen interactions requires analyses to address the multiplicity of scales in heterogeneous landscapes. Anthropogenic influence on plant communities, especially cultivation, is a major cause of environmental heterogeneity. We have approached the analysis of how environmental heterogeneity determines plant-virus interactions by studying virus infection in a wild plant currently undergoing incipient domestication, the wild pepper or chiltepin, across its geographical range in Mexico. We have shown previously that anthropogenic disturbance is associated with higher infection and disease risk, and with disrupted patterns of host and virus genetic spatial structure. We now show that anthropogenic factors, species richness, host genetic diversity and density in communities supporting chiltepin differentially affect infection risk according to the virus analysed. We also show that in addition to these factors, a broad range of abiotic and biotic variables meaningful to continental scales, have an important role on the risk of infection depending on the virus. Last, we show that natural virus infection of chiltepin plants in wild communities results in decreased survival and fecundity, hence negatively affecting fitness. This important finding paves the way for future studies on plant-virus co-evolution. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Cultivated Sub-Populations of Soil Microbiomes Retain Early Flowering Plant Trait.

    Science.gov (United States)

    Panke-Buisse, Kevin; Lee, Stacey; Kao-Kniffin, Jenny

    2017-02-01

    The collection of microorganisms found in the root zone of soil, termed the rhizosphere microbiome, has been shown to impact plant growth and development. Here, we tease apart the function of the cultivable portion of the microbiome from the whole microbiome in retaining plant traits modified through artificial selection on flowering time. Specifically, the whole microbiome associated with earlier flowering time of Arabidopsis thaliana was cultivated on four types of solid media to create cultivated fractions of the microbiome. These cultivated microbiomes were subsequently preserved in glycerol, frozen, and revived to yield a portion of the cultivable fraction to compare (1) whole microbiome, (2) cultivable microbiome, and (3) revived, cultivable microbiome controls on early flowering time. Plants grown in soils inoculated with bacteria grown on 25 % Luria broth and 10 % tryptic soy agar retained the early flowering trait. An increase in leaf biomass with two of the cultivated microbiomes (49.4 and 38.5 %) contrasted the lowered biomass effect of the whole microbiome. Inoculation with the cultivated microbiomes that were cryopreserved in glycerol showed no effect on flowering time or leaf biomass. The results indicate that the cultivable portion of a plant's microbiome retains the early flowering effect in A. thaliana, but cryopreservation of the cultivated microbiomes disrupts the microbial effects on flowering time. Furthermore, the contrasting effects on leaf biomass (an indirect response from selection on early flowering time), seen with the whole microbiome versus the cultivable portion, suggests versatility in using cultivation methods to modify multiple traits of plants.

  12. A tale of two islands: contrasting fortunes for Subantarctic skuas at ...

    African Journals Online (AJOL)

    Prince Edward Island (46 km2) remains free of introduced mammals, whereas Marion Island (290 km2) had a feral population of cats from the 1950s to 1980s, and still supports a large population of introduced house mice Mus musculus. Breeding skuas were more widespread, occurred at greater densities and extended to ...

  13. [History of Polish botanical and mycological researches on sheets of land of Antarctic and Sub-Antarctic in the years 1977-2009].

    Science.gov (United States)

    Köhler, Piotr; Olech, Maria

    2011-01-01

    Antarctic from the late Cretaceous period to the beginning of Melville's continental glaciation. One singled out three floristic stages and were reconstructed their peculiarities in the development of flora. There was also described an early Jurassic flora of Hope Bay (Półwysep Antarktyczny - Antarctic Peninsula) that turned out to be the richest Jurassic flora in the world. From that point of view were analyzed new species of mineral plants. Ecological researches concentrated on the problems connected with several issues and, among others, with the processes of settlement and succession, distribution and ecology of land biotopes, changes in their spatial structure, and state of biotopes' biological mass. The second group of issues concerned the anthropogenous impacts. One also analyzed early stages of synanthropization of flora. Another important issue was recognizing an extent of the pollution of the environment, particularly with base metals. In the years 1977-2009 were published, at least, 426 notes, articles and monographs that were a result of botanical and mycological researches on sheets of land of Antarctic and Sub-Antarctic.

  14. Sea-level pressure variability around Antarctica since A.D. 1750 inferred from subantarctic tree-ring records

    Energy Technology Data Exchange (ETDEWEB)

    Villalba, R. [Columbia Univ., Palisades, NY (United States). Lamont-Doherty Earth Observatory]|[Departamento de Dendrocronologia e Historia Ambientol, IANIGLA, CONICET, C.C. 330, 5500 Mena (Argentina); Cook, E.R.; D`Arrigo, R.D.; Jacoby, G.C. [Columbia Univ., Palisades, NY (United States). Lamont-Doherty Earth Observatory; Jones, P.D. [Climatic Research Unit, University of East Anglia, Norwich NR4 7TJ (United Kingdom); Salinger, M.J. [National Institute of Water and Atmospheric Research, P O Box 109-695, New market, Auckland (New Zealand); Palmer, J. [Department of Plant Science, Lincoln University, P O Box 84, Canterbury (New Zealand)

    1997-07-01

    A tree-ring chronology network recently developed from the subantarctic forests provides an opportunity to study long-term climatic variability at higher latitudes in the Southern Hemisphere. Fifty long (1911-1985), homogeneous records of monthly mean sea-level pressure (MSLP) from the southern latitudes (15-65 S) were intercorrelated on a seasonal basis to establish the most consistent, long-term transpolar teleconnections during this century. Variations in summer MSLP between the South America-Antarctic Peninsula and the New Zealand sectors of the Southern Ocean are significantly correlated in a negative sense (r=-0.53, P<0.001). Climatically sensitive chronologies from Tierra del Fuego (54-55 ) and New Zealand (39-47 ) were used to develop verifiable reconstructions of summer (November to February) MSLP for both sectors of the Southern Ocean. These reconstructions, which explain between 37 and 43% of the instrumentally recorded pressure variance, indicate that inverse trends in MSLP from diametrically opposite sides of Antarctica have prevailed during the past two centuries. However, the strength of this relationship varies over time. Differences in normalized MSLP between the New Zealand and the South America-Antarctic Peninsula sectors were used to develop a summer transpolar index (STPI), which represents an index of sea-level pressure wavenumber one in the Southern Hemisphere higher latitudes. Tree-ring based reconstructions of STPI show significant differences in large-scale atmospheric circulation between the nineteenth and the twentieth centuries. (orig.). With 18 figs., 4 tabs.

  15. Response of phytoplankton photophysiology to varying environmental conditions in the Sub-Antarctic and Polar Frontal Zone.

    Directory of Open Access Journals (Sweden)

    Wee Cheah

    Full Text Available Climate-driven changes are expected to alter the hydrography of the Sub-Antarctic Zone (SAZ and Polar Frontal Zone (PFZ south of Australia, in which distinct regional environments are believed to be responsible for the differences in phytoplankton biomass in these regions. Here, we report how the dynamic influences of light, iron and temperature, which are responsible for the photophysiological differences between phytoplankton in the SAZ and PFZ, contribute to the biomass differences in these regions. High effective photochemical efficiency of photosystem II (F'(q/F'(m0.4, maximum photosynthesis rate (P(B(max, light-saturation intensity (E(k, maximum rate of photosynthetic electron transport (1/[Symbol: see text]PSII, and low photoprotective pigment concentrations observed in the SAZ correspond to high chlorophyll a and iron concentrations. In contrast, phytoplankton in the PFZ exhibits low F'(q/F'(M (~ 0.2 and high concentrations of photoprotective pigments under low light environment. Strong negative relationships between iron, temperature, and photoprotective pigments demonstrate that cells were producing more photoprotective pigments under low temperature and iron conditions, and are responsible for the low biomass and low productivity measured in the PFZ. As warming and enhanced iron input is expected in this region, this could probably increase phytoplankton photosynthesis in this region. However, complex interactions between the biogeochemical processes (e.g. stratification caused by warming could prevent mixing of nutrients, which control phytoplankton biomass and productivity, remain uncertain.

  16. Marinomonas polaris sp. nov., a psychrohalotolerant strain isolated from coastal sea water off the subantarctic Kerguelen islands.

    Science.gov (United States)

    Gupta, Pratima; Chaturvedi, Preeti; Pradhan, Suman; Delille, Daniel; Shivaji, Sisinthy

    2006-02-01

    Two aerobic, psychrohalotolerant, motile bacterial isolates, CK13T and CK16, isolated from sea-water samples collected off the subantarctic Kerguelen island, were characterized by using a polyphasic taxonomic approach. On the basis of 16S rRNA gene sequence data, the strains were 99.6% similar and exhibited 93-97% similarity with the seven recognized species of Marinomonas. The most closely related species were Marinomonas pontica and Marinomonas primoryensis, with 97 and 96 % similarity at the 16S rRNA gene sequence level, respectively. DNA-DNA hybridization values between strain CK13T and M. pontica and M. primoryensis were only 58 and 40%, respectively. The major fatty acids present in strain CK13T were iso-C(16:0), C(16:0), C(16:1)omega7c and C(18:1)omega7c. The DNA G+C content of strain CK13T was 41.2 mol%. Phosphatidylethanolamine and phosphatidylglycerol were identified as the predominant phospholipids. All the above characteristics support the affiliation of strain CK13T to the genus Marinomonas. Phylogenetic analysis and phenotypic and genotypic distinctiveness confirmed that strains CK13T and CK16 are members of a novel species of the genus Marinomonas, for which the name Marinomonas polaris sp. nov. is proposed. The type strain is CK13T (=MTCC 6645T=DSM 16579T=JCM 12522T).

  17. Landscape mapping at sub-Antarctic South Georgia provides a protocol for underpinning large-scale marine protected areas

    Science.gov (United States)

    Hogg, Oliver T.; Huvenne, Veerle A. I.; Griffiths, Huw J.; Dorschel, Boris; Linse, Katrin

    2016-10-01

    Global biodiversity is in decline, with the marine environment experiencing significant and increasing anthropogenic pressures. In response marine protected areas (MPAs) have increasingly been adopted as the flagship approach to marine conservation, many covering enormous areas. At present, however, the lack of biological sampling makes prioritising which regions of the ocean to protect, especially over large spatial scales, particularly problematic. Here we present an interdisciplinary approach to marine landscape mapping at the sub-Antarctic island of South Georgia as an effective protocol for underpinning large-scale (105-106  km2) MPA designations. We have developed a new high-resolution (100 m) digital elevation model (DEM) of the region and integrated this DEM with bathymetry-derived parameters, modelled oceanographic data, and satellite primary productivity data. These interdisciplinary datasets were used to apply an objective statistical approach to hierarchically partition and map the benthic environment into physical habitats types. We assess the potential application of physical habitat classifications as proxies for biological structuring and the application of the landscape mapping for informing on marine spatial planning.

  18. Ventilation of the abyssal Southern Ocean during the late Neogene: A new perspective from the subantarctic Pacific

    Science.gov (United States)

    Waddell, Lindsey M.; Hendy, Ingrid L.; Moore, Theodore C.; Lyle, Mitchell W.

    2009-09-01

    Benthic foraminiferal stable carbon isotope records from the South Atlantic show significant declines toward more "Pacific-like" values at ˜7 and ˜2.7 Ma, and it has been posited that these shifts may mark steps toward increased CO2 sequestration in the deep Southern Ocean as climate cooled over the late Neogene. We generated new stable isotope records from abyssal subantarctic Pacific cores MV0502-4JC and ELT 25-11. The record from MV0502-4JC suggests that the Southern Ocean remained well mixed and free of vertical or interbasinal δ13C gradients following the late Miocene carbon shift (LMCS). According to the records from MV0502-4JC and ELT 25-11, however, cold, low δ13C bottom waters developed in the Southern Ocean in the late Pliocene and persisted until ˜1.7 Ma. These new data suggest that while conditions in the abyssal Southern Ocean following the LMCS were comparable to the present day, sequestration of respired CO2 may have increased in the deepest parts of the Southern Ocean during the late Pliocene, a critical period for the growth and establishment of the Northern Hemisphere ice sheets.

  19. Host races of the cotton aphid, Aphis gossypii, in asexual populations from wild plants of taro and brinjal.

    Science.gov (United States)

    Agarwala, B K; Choudhury, Parichita Ray

    2013-01-01

    Worldwide, several studies have shown that adaptation to different host plants in phytophagous insects can promote speciation. The cotton aphid, Aphis gossypii Glover (Homoptera: Aphididae: Aphidini), is a highly polyphagous species, but its populations increase by parthenogenetic reproduction alone in Indian subcontinent. This study showed that genotypes living in wild plants of taro, Colocasia esculenta var. esculenta (L.) Schott (Alismatales: Araceae), and brinjal, Solanum torvum Swartz (Solanales: Solanaceae), behave as distinct host races. Success rates of colonization after reciprocal host transfers were very poor. Clones of A. gossypii from wild taro partly survived in the first generation when transferred to wild brinjal, but nymph mortality was 100% in the second generation. In contrast, brinjal clones, when transferred to taro, could not survive even in the first generation. Significant differences between the clones from two host species were also recorded in development time, generation time, fecundity, intrinsic rate of increase, net reproductive rate, and mean relative growth rate. Morphologically, aphids of wild taro clones possessed longer proboscis and fore-femora than the aphids of the brinjal clones. The results showed that A. gossypii exists as distinct host races with different abilities of colonizing host plants, and its populations appear to have more potential of sympatic evolution than previously regarded.

  20. ACCase mutations in Avena sterilis populations and their impact on plant fitness.

    Science.gov (United States)

    Papapanagiotou, Aristeidis P; Paresidou, Maria I; Kaloumenos, Nikolaos S; Eleftherohorinos, Ilias G

    2015-09-01

    Avena sterilis (sterile oat) populations originating from wheat-growing regions of Greece, developed resistance to fenoxaprop, clodinafop and other herbicides. The partial ACCase gene sequence revealed six point mutations (Ile-1781-Leu, Trp-1999-Cys, Trp-2027-Cys, Ile-2041-Asn, Asp-2078-Gly, and Cys-2088-Arg) in 24 out of the 26 resistant (R) populations, confirming the molecular mechanism of resistance to ACCase-inhibiting herbicides. However, DNA sequence of two R populations did not reveal any known ACCase mutations, suggesting possible presence of unknown mutation or metabolism-based mechanism of resistance. The Cys-2088-Arg mutation is the first record for ACCase mutant conferring target-site resistance in A. sterilis worldwide. The evaluation of 12 R and 6 susceptible (S) populations under non-competitive field conditions did not indicate consistent mean growth rate differences, whereas the pot evaluation of the same (12 R and 6 S) populations grown in competition with wheat or in pure stands showed significant growth (fresh weight and panicle number) differences between six S populations and between six R populations containing the same ACCase mutation (Ile-2041-Asn). Finally, one S and five R (Trp-1999-Cys, Trp-2027-Cys, Ile-2041-Asn, Asp-2078-Gly, and Cys-2088-Arg) populations grown under field competitive conditions indicated fresh weight and panicle number differences in competition with other populations as compared with pure stands. These findings suggest clearly that the inconsistent fitness differences between R and S A. sterilis populations are not related with the ACCase resistance trait but they may result from other non-resistance fitness traits selected in their different geographical locations. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. The demography of climate-driven and density-regulated population dynamics in a perennial plant

    DEFF Research Database (Denmark)

    Dahlgren, Johan; Bengstsson, Karin; Ehrlén, Johan

    2016-01-01

    important aspect of such forecasts. We examined the simultaneous impact of climate and intraspecific density on vital rates of the dwarf shrub Fumana procumbens over 20 yr, using generalized additive mixed models. We then analyzed effects on population dynamics using integral projection models...... to be driven solely by the environment can overestimate extinction risks if there is density dependence. We conclude that density regulation can dampen effects of climate change on Fumana population size, and discuss the need to quantify density dependence in predictions of population responses...

  2. Ecological systems as computer networks: Long distance sea dispersal as a communication medium between island plant populations.

    Science.gov (United States)

    Sanaa, Adnen; Ben Abid, Samir; Boulila, Abdennacer; Messaoud, Chokri; Boussaid, Mohamed; Ben Fadhel, Najeh

    2016-06-01

    Ecological systems are known to exchange genetic material through animal species migration and seed dispersal for plants. Isolated plant populations have developed long distance dispersal as a means of propagation which rely on meteorological such as anemochory and hydrochory for coast, island and river bank dwelling species. Long distance dispersal by water, in particular, in the case of water current bound islands, calls for the analogy with computer networks, where each island and nearby mainland site plays the role of a network node, the water currents play the role of a transmission channel, and water borne seeds as data packets. In this paper we explore this analogy to model long distance dispersal of seeds among island and mainland populations, when traversed with water currents, in order to model and predict their future genetic diversity. The case of Pancratium maritimum L. populations in Tunisia is used as a proof of concept, where their genetic diversity is extrapolated. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  3. Population dynamics of Agriophyllum squarrosum, a pioneer annual plant endemic to mobile sand dunes, in response to global climate change.

    Science.gov (United States)

    Qian, Chaoju; Yin, Hengxia; Shi, Yong; Zhao, Jiecai; Yin, Chengliang; Luo, Wanyin; Dong, Zhibao; Chen, Guoxiong; Yan, Xia; Wang, Xiao-Ru; Ma, Xiao-Fei

    2016-05-23

    Climate change plays an important role in the transition of ecosystems. Stratigraphic investigations have suggested that the Asian interior experienced frequent transitions between grassland and desert ecosystems as a consequence of global climate change. Using maternally and bi-parentally inherited markers, we investigated the population dynamics of Agriophyllum squarrosum (Chenopodiaceae), an annual pioneer plant endemic to mobile sand dunes. Phylogeographic analysis revealed that A. squarrosum could originate from Gurbantunggut desert since ~1.6 Ma, and subsequently underwent three waves of colonisation into other deserts and sandy lands corresponding to several glaciations. The rapid population expansion and distribution range shifts of A. squarrosum from monsoonal climate zones suggested that the development of the monsoonal climate significantly enhanced the population growth and gene flow of A. squarrosum. These data also suggested that desertification of the fragile grassland ecosystems in the Qinghai-Tibetan Plateau was more ancient than previously suggested and will be aggravated under global warming in the future. This study provides new molecular phylogeographic insights into how pioneer annual plant species in desert ecosystems respond to global climate change, and facilitates evaluation of the ecological potential and genetic resources of future crops for non-arable dry lands to mitigate climate change.

  4. Limited genetic exchanges between populations of an insect pest living on uncultivated and related cultivated host plants

    Science.gov (United States)

    Vialatte, Aude; Dedryver, Charles-Antoine; Simon, Jean-Christophe; Galman, Marina; Plantegenest, Manuel

    2005-01-01

    Habitats in agroecosystems are ephemeral, and are characterized by frequent disturbances forcing pest species to successively colonize various hosts belonging either to the cultivated or to the uncultivated part of the agricultural landscape. The role of wild habitats as reservoirs or refuges for the aphid Sitobion avenae that colonize cultivated fields was assessed by investigating the genetic structure of populations collected on both cereal crops (wheat, barley and oat) and uncultivated hosts (Yorkshire fog, cocksfoot, bulbous oatgrass and tall oatgrass) in western France. Classical genetic analyses and Bayesian clustering algorithms indicate that genetic differentiation is high between populations collected on uncultivated hosts and on crops, revealing a relatively limited gene flow between the uncultivated margins and the cultivated part of the agroecosystem. A closer genetic relatedness was observed between populations living on plants belonging to the same tribe (Triticeae, Poeae and Aveneae tribes) where aphid genotypes appeared not to be specialized on a single host, but rather using a group of related plant species. Causes of this ecological differentiation and its implications for integrated pest management of S. avenae as cereals pest are discussed. PMID:16024367

  5. Population structure and association analysis of bolting, plant height, and leaf erectness in spinach

    Science.gov (United States)

    Spinach (Spinacia oleracea L.) is an important vegetable worldwide with high nutritional and health-promoting compounds. Bolting is an important trait to consider in order to grow spinach in different seasons and regions. Plant height and leaf erectness are important traits for machine-harvesting. B...

  6. Life history strategies and biomass allocation : the population dynamics of perennial plants in a regional perspective

    NARCIS (Netherlands)

    Jongejans, E.

    2004-01-01

    This study aims to contribute to the knowledge of how plants respond to adverse influences of intensified land use. In particular, attention was paid to the ways in which life history strategies change in order to buffer environmental variation, and which important parts of the life cycle are

  7. "Antimalarial" medicinal plants and their impact on cell populations in various organs of mice.

    Science.gov (United States)

    Agomo, P U; Idigo, J C; Afolabi, B M

    1992-12-01

    We have investigated the effects of leaf and bark decoctions of Ocimum gratissimum, Azadirachta indica, Morinda lucida and Enantia chlorantha on (a) the course of Plasmodium yoelii nigeriensis malaria (b) reticulocyte and haematocrit values and (c) nucleated cell numbers in the spleen, bone marrow, peritoneum, liver and peripheral blood of Swiss albino mice. Results obtained showed that normal mice infected with the parasite (10(4)/mouse) suffered fulminant parasitaemia which resulted in death, 7-10 days later. All infected mice treated with chloroquine survived. On the other hand all infected mice treated with the medicinal plants exhibited varying percentages of chemosuppression of early parasitaemia which did not lead to their survival. The total number of nucleated cells in the liver, spleen and peripheral blood of malaria-infected mice increased enormously before the animals died. Such increases were maintained in other groups of mice treated with the medicinal plants. In the non-infected mice, O.gratissimum and E. chlorantha administration increased the number of nucleated cells in the spleen, liver and peripheral blood. Chloroquine on the other hand decreased the number of nucleated cells in both the malaria-infected and un-infected mice. There was also a decrease in reticulocyte numbers in the blood of normal mice injected with chloroquine. Conversely reticulocyte numbers increased in normal mice administered with some medicinal plants. Acute and chronic toxicity tests revealed that some of the medicinal plants were much more toxic than others.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. Composition of natural populations of yeast and yeast-like microorganisms in the area of Mochovce nuclear power plant construction

    Energy Technology Data Exchange (ETDEWEB)

    Stollarova, V. (Pedagogical Faculty, Nitra (Czechoslovakia))

    1984-01-01

    In 1982 to 1983, the composition was studied of natural populations of yeasts and yeast-like microorganisms in the area of the construction of the nuclear power plant at Mochovce. Samples were taken from fruits of plum trees (Prunus domestica L.) and grape vine (Vitis vinifera L.). Totally, 394 strains were isolated that were identified and classified according to the monography of Lodder into the following families and genera: Saccharomycetaceae (Saccharomyces, Hanseniaspora, Hansenula, Debaryomyces, Kluyveromyces, Pichia), Spermopthoraceae (Metschnikowia), Cryptococaceae (Torulopsis, Candida, Kloeckera). On plum tree fruits the species Hanseniaspora uvarum and Saccharomyces rosei and on grape vine fruits Hanseniaspora uvarum and Metschnikowia pulcherrima were most abundantly represented. The trees and plants were not treated with pesticides and on both the fruits of plum trees and grape vines the species Pullularia pullulans was frequently present that had never been isolated before from regularly treated vineyards.

  9. Vip3Aa tolerance response of Helicoverpa armigera populations from a Cry1Ac cotton planting region.

    Science.gov (United States)

    An, Jingjie; Gao, Yulin; Wu, Kongming; Gould, Fred; Gao, Jianhua; Shen, Zhicheng; Lei, Chaoliang

    2010-12-01

    Transgenic cotton, Gossypium hirsutum L., that expresses the Bacillus thuringiensis (Bt) Cry1Ac toxin, holds great promise in controlling target insect pests. Evolution of resistance by target pests is the primary threat to the continued efficacy of Bt cotton. To thwart pest resistance evolution, a transgenic cotton culitvar that produces two different Bt toxins, cry1Ac and vip3A genes, was proposed as a successor of cry1Ac cotton. This article reports on levels of Vip3Aa tolerance in Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) populations from the Cry1Ac cotton planting region in China based on bioassays of the F1 generation of isofemale lines. In total, 80 isofemale families of H. armigera from Xiajin county of Shandong Province (an intensive Bt cotton planting area) and 93 families from Anci county of Hebei Province (a multiple-crop system including corn [Zea mays L.] , soybean [Glycine max (L.) Merr.], peanut (Arachis hypogaea L.), and Bt cotton) were screened with a discriminating concentration of both Cry1Ac- and Vip3A-containing diets in 2009. From data on the relative average development rates and percentage of larval weight inhibition of F1 full-sib families tested simultaneously on Cry1Ac and Vip3Aa, results indicate that responses to Cry1Ac and Vip3Aa were not genetically correlated in field population ofH. armigera. This indicates that the threat of cross-resistance between Cry1Ac and Vip3A is low in field populations of H. armigera. Thus, the introduction of Vip3Aa/Cry1Ac-producing lines could delay resistance evolution in H. armigera in Bt cotton planting area of China.

  10. Auxin-mediated relationships between apple plants and root inhabiting fungi: impact on root pathogens and potentialities of growth-promoting populations

    Science.gov (United States)

    Studies were conducted to examine the symbiotic relationship between plant hosts and endophytic fungi recovered in multi-generation replanted apple orchard soils. Based upon results obtained, subsequent studies were oriented toward investigating fungal populations showing a mutualistic symbiotic rel...

  11. Selection for high oridonin yield in the Chinese medicinal plant Isodon (Lamiaceae using a combined phylogenetics and population genetics approach.

    Directory of Open Access Journals (Sweden)

    Eric S J Harris

    Full Text Available Oridonin is a diterpenoid with anti-cancer activity that occurs in the Chinese medicinal plant Isodon rubescens and some related species. While the bioactivity of oridonin has been well studied, the extent of natural variation in the production of this compound is poorly known. This study characterizes natural variation in oridonin production in order to guide selection of populations of Isodon with highest oridonin yield. Different populations of I. rubescens and related species were collected in China, and their offspring were grown in a greenhouse. Samples were examined for oridonin content, genotyped using 11 microsatellites, and representatives were sequenced for three phylogenetic markers (ITS, rps16, trnL-trnF. Oridonin production was mapped on a molecular phylogeny of the genus Isodon using samples from each population as well as previously published Genbank sequences. Oridonin has been reported in 12 out of 74 species of Isodon examined for diterpenoids, and the phylogeny indicates that oridonin production has arisen at least three times in the genus. Oridonin production was surprisingly consistent between wild-collected parents and greenhouse-grown offspring, despite evidence of gene flow between oridonin-producing and non-producing populations of Isodon. Additionally, microsatellite genetic distance between individuals was significantly correlated with chemical distance in both parents and offspring. Neither heritability nor correlation with genetic distance were significant when the comparison was restricted to only populations of I. rubescens, but this result should be corroborated using additional samples. Based on these results, future screening of Isodon populations for oridonin yield should initially prioritize a broad survey of all species known to produce oridonin, rather than focusing on multiple populations of one species, such as I. rubescens. Of the samples examined here, I. rubescens or I. japonicus from Henan province

  12. The presence of significant methylotrophic population in biological activated carbon of a full-scale drinking water plant.

    Science.gov (United States)

    Kim, Tae Gwan; Moon, Kyung-Eun; Cho, Kyung-Suk

    2013-12-01

    Methylotrophs within biological activated carbon (BAC) systems have not received attention although they are a valuable biological resource for degradation of organic pollutants. In this study, methylotrophic populations were monitored for four consecutive seasons in BAC of an actual drinking water plant, using ribosomal tag pyrosequencing. Methylotrophs constituted up to 5.6% of the bacterial community, and the methanotrophs Methylosoma and Methylobacter were most abundant. Community comparison showed that the temperature was an important factor affecting community composition, since it had an impact on the growth of particular methylotrophic genera. These results demonstrated that BAC possesses a substantial methylotrophic activity and harbors the relevant microbes.

  13. Ethnobotanical study of medicinal plants by population of Valley of Juruena Region, Legal Amazon, Mato Grosso, Brazil.

    Science.gov (United States)

    Bieski, Isanete Geraldini Costa; Leonti, Marco; Arnason, John Thor; Ferrier, Jonathan; Rapinski, Michel; Violante, Ivana Maria Povoa; Balogun, Sikiru Olaitan; Pereira, João Filipe Costa Alves; Figueiredo, Rita de Cassia Feguri; Lopes, Célia Regina Araújo Soares; da Silva, Dennis Rodrigues; Pacini, Aloir; Albuquerque, Ulysses Paulino; Martins, Domingos Tabajara de Oliveira

    2015-09-15

    barbadense L. (44), Solidago microglossa DC. (40) and Bauhinia forficata L. (20). And the most cited exotics are: Chenopodium ambrosioides L. (151), Aloe vera (L.) Burm. f., (89) and Rosmarinus officinalis L. (72). In some cases, high ICF values were found, which reflects high degree of homogeneity of consensus among informants in this region on medicinal plants. The population of Valle of Juruena makes use of a wide array of medicinal plants distributed in all use categories with predominance of those use in the treatments of gastrointestinal and respiratory ailments. The therapeutic potential of some of the species of medicinal importance extensively utilized by the population of the region have been scientifically validated, and are therefore promising prototype of new drugs. However, there are some of these species whose ethnomedicinal uses are yet to be scientifically verified and thus constitute an unexplored terrain for future biological/pharmacological studies. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  14. Sclerotia of Rhizoctonia solani, Their Production on Infected Rice Plants and Their Population in Different Soil Types

    Directory of Open Access Journals (Sweden)

    I. Suwanto

    1997-12-01

    Full Text Available Production of sclerotia of Rhizoctonla solani on infected rice plants and their population in different soil types were evaluated during the year of 1992/1993 and 1993/1994. The production of sclerotia was estimated on 20 diseased rice plants and plant debris (rice straw placed on soil surface, in 10 cm depth, and in 20 cm depth. The population of sclerotia in the soil was estimated by separating the sclerotia from soil samples collected from different soil previously planted with different crops. Data indicated that during the rainy season of 1992/1993, the mean sclerotia produced were 14.85 and 10.95 per hill on the variety of IR64 and non-lR64, respectively. While during the dry season of 1993 the mean sclerotia produced on these varieties were 7.50 and 7 .25 per hill. On both varieties, the production of sclerotia was positively correlated with disease  severity of sheath blight, as indicated by the correlation coefficient of 0.90 and 0.70, for the variety of IR64 and non-IR64, reepectively. Their close relationship was estimated by the model of Y=-29.00+1.16x (R^2=0.82 and Y=-2.94+0.35x (R^2=0.45, for the variety of IR64 and non-IR.64, respectively. The production of sclerotia on the infected rice straw was significantly affected by the soil depth where the diseased straw were kept. On the straw of IR64, the sclerotia produced were 7.00, 5.25, and 1.25, when the straw were kept in the depth of 0, 10, and 20 cm, respectively. While on the straw of non-IR.64 variety, the sclerotia produced were 7.75, 5.25, and 0.50. when the straw were kept in the depth of 0, 10, and 20 cm, respectively. Highest number of sclerotia was observed in Ultisol soil previously planted with corn, while the smallest was in Ultisol previously planted with mungbean.

  15. An innovative procedure of genome-wide association analysis fits studies on germplasm population and plant breeding.

    Science.gov (United States)

    He, Jianbo; Meng, Shan; Zhao, Tuanjie; Xing, Guangnan; Yang, Shouping; Li, Yan; Guan, Rongzhan; Lu, Jiangjie; Wang, Yufeng; Xia, Qiuju; Yang, Bing; Gai, Junyi

    2017-11-01

    The innovative RTM-GWAS procedure provides a relatively thorough detection of QTL and their multiple alleles for germplasm population characterization, gene network identification, and genomic selection strategy innovation in plant breeding. The previous genome-wide association studies (GWAS) have been concentrated on finding a handful of major quantitative trait loci (QTL), but plant breeders are interested in revealing the whole-genome QTL-allele constitution in breeding materials/germplasm (in which tremendous historical allelic variation has been accumulated) for genome-wide improvement. To match this requirement, two innovations were suggested for GWAS: first grouping tightly linked sequential SNPs into linkage disequilibrium blocks (SNPLDBs) to form markers with multi-allelic haplotypes, and second utilizing two-stage association analysis for QTL identification, where the markers were preselected by single-locus model followed by multi-locus multi-allele model stepwise regression. Our proposed GWAS procedure is characterized as a novel restricted two-stage multi-locus multi-allele GWAS (RTM-GWAS, https://github.com/njau-sri/rtm-gwas ). The Chinese soybean germplasm population (CSGP) composed of 1024 accessions with 36,952 SNPLDBs (generated from 145,558 SNPs, with reduced linkage disequilibrium decay distance) was used to demonstrate the power and efficiency of RTM-GWAS. Using the CSGP marker information, simulation studies demonstrated that RTM-GWAS achieved the highest QTL detection power and efficiency compared with the previous procedures, especially under large sample size and high trait heritability conditions. A relatively thorough detection of QTL with their multiple alleles was achieved by RTM-GWAS compared with the linear mixed model method on 100-seed weight in CSGP. A QTL-allele matrix (402 alleles of 139 QTL × 1024 accessions) was established as a compact form of the population genetic constitution. The 100-seed weight QTL-allele matrix was

  16. Air-sea interaction regimes in the sub-Antarctic Southern Ocean and Antarctic marginal ice zone revealed by icebreaker measurements

    Science.gov (United States)

    Yu, Lisan; Jin, Xiangze; Schulz, Eric W.; Josey, Simon A.

    2017-08-01

    This study analyzed shipboard air-sea measurements acquired by the icebreaker Aurora Australis during its off-winter operation in December 2010 to May 2012. Mean conditions over 7 months (October-April) were compiled from a total of 22 ship tracks. The icebreaker traversed the water between Hobart, Tasmania, and the Antarctic continent, providing valuable in situ insight into two dynamically important, yet poorly sampled, regimes: the sub-Antarctic Southern Ocean and the Antarctic marginal ice zone (MIZ) in the Indian Ocean sector. The transition from the open water to the ice-covered surface creates sharp changes in albedo, surface roughness, and air temperature, leading to consequential effects on air-sea variables and fluxes. Major effort was made to estimate the air-sea fluxes in the MIZ using the bulk flux algorithms that are tuned specifically for the sea-ice effects, while computing the fluxes over the sub-Antarctic section using the COARE3.0 algorithm. The study evidenced strong sea-ice modulations on winds, with the southerly airflow showing deceleration (convergence) in the MIZ and acceleration (divergence) when moving away from the MIZ. Marked seasonal variations in heat exchanges between the atmosphere and the ice margin were noted. The monotonic increase in turbulent latent and sensible heat fluxes after summer turned the MIZ quickly into a heat loss regime, while at the same time the sub-Antarctic surface water continued to receive heat from the atmosphere. The drastic increase in turbulent heat loss in the MIZ contrasted sharply to the nonsignificant and seasonally invariant turbulent heat loss over the sub-Antarctic open water.Plain Language SummaryThe icebreaker Aurora Australis is a research and supply vessel that is regularly chartered by the Australian Antarctic Division during the southern summer to operate in waters between Hobart, Tasmania, and Antarctica. The vessel serves as the main lifeline to three permanent research stations on the

  17. Prioritizing management actions for invasive populations using cost, efficacy, demography and expert opinion for 14 plant species world-wide.

    Science.gov (United States)

    Kerr, Natalie Z; Baxter, Peter W J; Salguero-Gómez, Roberto; Wardle, Glenda M; Buckley, Yvonne M

    2016-04-01

    Management of invasive populations is typically investigated case-by-case. Comparative approaches have been applied to single aspects of management, such as demography, with cost or efficacy rarely incorporated.We present an analysis of the ranks of management actions for 14 species in five countries that extends beyond the use of demography alone to include multiple metrics for ranking management actions, which integrate cost, efficacy and demography (cost-effectiveness) and managers' expert opinion of ranks. We use content analysis of manager surveys to assess the multiple criteria managers use to rank management strategies.Analysis of the matrix models for managed populations showed that all management actions led to reductions in population growth rate (λ), with a median 48% reduction in λ across all management units; however, only 66% of the actions led to declining populations (λ demography as important. 80% of managers identified off-target effects of management as important, which was not captured using any of the other metrics. Synthesis and applications. A multidimensional view of the benefits and costs of management options provides a range of single and integrated metrics. These rankings, and the relationships between them, can be used to assess management actions for invasive plants. The integrated cost-effectiveness approach goes well 'beyond demography' and provides additional information for managers; however, cost-effectiveness needs to be augmented with information on off-target effects and social impacts of management in order to provide greater benefits for on-the-ground management.

  18. Recurrent Selection and Participatory Plant Breeding for Improvement of Two Organic Open-Pollinated Sweet Corn (Zea mays L. Populations

    Directory of Open Access Journals (Sweden)

    Adrienne C. Shelton

    2015-04-01

    Full Text Available Organic growers face unique challenges when raising sweet corn, and benefit from varieties that maintain high eating quality, germinate consistently, deter insect pests, and resist diseases. Genotype by environment rank changes can occur in the performance of cultivars grown on conventional and organic farms, yet few varieties have been bred specifically for organic systems. The objective of this experiment was to evaluate the changes made to open-pollinated sweet corn populations using recurrent selection and a participatory plant breeding (PPB methodology. From 2008 to 2011, four cycles of two open-pollinated (OP sweet corn populations were selected on a certified organic farm in Minnesota using a modified ear-to-row recurrent selection scheme. Selections were made in collaboration with an organic farmer, with selection criteria based on traits identified by the farmer. In 2012 and 2013, the population cycles were evaluated in a randomized complete block design in two certified organic locations in Wisconsin, with multiple replications in each environment. Significant linear trends were found among cycles of selection for quantitative and qualitative traits, suggesting the changes were due to recurrent selection and PPB methodology for these populations. However, further improvement is necessary to satisfy the requirements for a useful cultivar for organic growers.

  19. Population dose commitments due to radioactive releases from Nuclear-Power-Plant Sites in 1979

    Energy Technology Data Exchange (ETDEWEB)

    Baker, D.A.; Peloquin, R.A.

    1982-12-01

    Population radiation dose commitments have been estimated from reported radionuclide releases from commercial power reactors operating during 1979. Fifty-year dose commitments from a one-year exposure were calculated from both liquid and atmospheric releases for four population groups (infant, child, teen-ager and adult) residing between 2 and 80 km from each site. This report tabulates the results of these calculations, showing the dose commitments for both liquid and airborne pathways for each age group and organ. Also included for each site is a histogram showing the fraction of the total population within 2 to 80 km around each site receiving various average dose commitments from the airborne pathways. The total dose commitment from both liquid and airborne pathways ranged from a high of 1300 person-rem to a low of 0.0002 person-rem with an arithmetic mean of 38 person-rem. The total population dose for all sites was estimated at 1800 person-rem for the 94 million people considered at risk. The average individual dose commitment from all pathways on a site basis ranged from a low of 2 x 10/sup -6/ mrem to a high of 0.7 mrem. No attempt was made in this study to determine the maximum dose commitment received by any one individual from the radionuclides released at any of the sites.

  20. Bottom-up control of water hyacinth weevil populations: Do the plants regulate the insects?

    Science.gov (United States)

    A key measure of dietary sufficiency relates to an insect’s reproductive ability so oögenesis, a nutrient-limited process, can be subject to bottom-up regulation. We hypothesized that aquatic nutrient flux seasonally affects ovarian development thereby controlling population growth of two specialis...

  1. Population Dose Commitments Due to Radioactive Releases from Nuclear Power Plant Sites in 1977

    Energy Technology Data Exchange (ETDEWEB)

    Baker, D. A.

    1980-10-01

    Population radiation dose commitments have been estimated from reported radionuclide releases from commercial power reactors operating during 1977. Fifty-year dose commitments from a one-year exposure were calculated from both liquid and atmospheric releases for four population groups (infant, child, teen-ager and adult) residing between 2 and 80 km from each site. This report tabulates the results of these calculations, showing the dose commitments for both liquid and airborne pathways for each age group and organ, Also included for each site is a histogram showing the fraction of the total population within 2 to 80 km around each site receiving various average dose commitments from the airborne pathways. The total dose commitment from both liquid and airborne pathways ranged from a high of 220 person-rem to a low of 0.003 person-rem with an arithmetic mean of 16 person-rem. The total population dose for all sites was estimated at 700 person-rem for the 92 million people considered at risk. The average individual dose commitment from all pathways on a site basis ranged from a low of 2 x 10{sup -5} mrem to a high of 0.1 mrem. No attempt was made in this study to determine the maximum dose commitment received by any one individual from the radionuclides released at any of the sites.

  2. Climate-associated population declines reverse recovery and threaten future of an iconic high-elevation plant.

    Science.gov (United States)

    Krushelnycky, Paul D; Loope, Lloyd L; Giambelluca, Thomas W; Starr, Forest; Starr, Kim; Drake, Donald R; Taylor, Andrew D; Robichaux, Robert H

    2013-03-01

    Although climate change is predicted to place mountain-top and other narrowly endemic species at severe risk of extinction, the ecological processes involved in such extinctions are still poorly resolved. In addition, much of this biodiversity loss will likely go unobserved, and therefore largely unappreciated. The Haleakalā silversword is restricted to a single volcano summit in Hawai'i, but is a highly charismatic giant rosette plant that is viewed by 1-2 million visitors annually. We link detailed local climate data to a lengthy demographic record, and combine both with a population-wide assessment of recent plant mortality and recruitment, to show that after decades of strong recovery following successful management, this iconic species has entered a period of substantial climate-associated decline. Mortality has been highest at the lower end of the distributional range, where most silverswords occur, and the strong association of annual population growth rates with patterns of precipitation suggests an increasing frequency of lethal water stress. Local climate data confirm trends toward warmer and drier conditions on the mountain, and signify a bleak outlook for silverswords if these trends continue. The silversword example foreshadows trouble for diversity in other biological hotspots, and illustrates how even well-protected and relatively abundant species may succumb to climate-induced stresses. © 2012 Blackwell Publishing Ltd.

  3. Rates of change in climatic niches in plant and animal populations are much slower than projected climate change.

    Science.gov (United States)

    Jezkova, Tereza; Wiens, John J

    2016-11-30

    Climate change may soon threaten much of global biodiversity. A critical question is: can species undergo niche shifts of sufficient speed and magnitude to persist within their current geographic ranges? Here, we analyse niche shifts among populations within 56 plant and animal species using time-calibrated trees from phylogeographic studies. Across 266 phylogeographic groups analysed, rates of niche change were much slower than rates of projected climate change (mean difference > 200 000-fold for temperature variables). Furthermore, the absolute niche divergence among populations was typically lower than the magnitude of projected climate change over the next approximately 55 years for relevant variables, suggesting the amount of change needed to persist may often be too great, even if these niche shifts were instantaneous. Rates were broadly similar between plants and animals, but especially rapid in some arthropods, birds and mammals. Rates for temperature variables were lower at lower latitudes, further suggesting that tropical species may be especially vulnerable to climate change. © 2016 The Author(s).

  4. RADIATION EXPOSURE OF THE POPULATION FROM 222Rn AND OTHER NATURAL RADIONUCLIDES AROUND MOCHOVCE NUCLEAR POWER PLANT, SLOVAKIA.

    Science.gov (United States)

    Bulko, Martin; Holý, Karol; Pohronská, Žofia; Mullerová, Monika; Böhm, Radoslav; Holá, Ol'ga

    2017-09-18

    In this article, the effective dose to the population from natural sources of ionizing radiation in the vicinity of Mochovce nuclear power plant in Slovakia is presented. All major contributions to the effective dose were taken into account, including the contributions from gamma radiation of soil and rocks, cosmic radiation, and indoor and outdoor radon and thoron. On the basis of recent indoor radon measurements in Slovak cities and publicly available data about radon concentration in the soil air, a roughly linear relationship was found between these variables. Consequently, the annual effective dose from indoor radon and thoron was conservatively estimated. For the area of interest, a map of conservatively estimated potential effective doses was created. For the villages in the vicinity of Mochovce, the conservatively estimated effective dose to the population from natural sources ranged from 5.4 to 14.6 mSv, which is four orders of magnitude higher than the contribution of radioactive discharges from Mochovce nuclear power plant. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  5. Mapping the Centimeter-Scale Spatial Variability of PAHs and Microbial Populations in the Rhizosphere of Two Plants.

    Directory of Open Access Journals (Sweden)

    Amélia Bourceret

    Full Text Available Rhizoremediation uses root development and exudation to favor microbial activity. Thus it can enhance polycyclic aromatic hydrocarbon (PAH biodegradation in contaminated soils. Spatial heterogeneity of rhizosphere processes, mainly linked to the root development stage and to the plant species, could explain the contrasted rhizoremediation efficiency levels reported in the literature. Aim of the present study was to test if spatial variability in the whole plant rhizosphere, explored at the centimetre-scale, would influence the abundance of microorganisms (bacteria and fungi, and the abundance and activity of PAH-degrading bacteria, leading to spatial variability in PAH concentrations. Two contrasted rhizospheres were compared after 37 days of alfalfa or ryegrass growth in independent rhizotron devices. Almost all spiked PAHs were degraded, and the density of the PAH-degrading bacterial populations increased in both rhizospheres during the incubation period. Mapping of multiparametric data through geostatistical estimation (kriging revealed that although root biomass was spatially structured, PAH distribution was not. However a greater variability of the PAH content was observed in the rhizosphere of alfalfa. Yet, in the ryegrass-planted rhizotron, the Gram-positive PAH-degraders followed a reverse depth gradient to root biomass, but were positively correlated to the soil pH and carbohydrate concentrations. The two rhizospheres structured the microbial community differently: a fungus-to-bacterium depth gradient similar to the root biomass gradient only formed in the alfalfa rhizotron.

  6. Mapping the Centimeter-Scale Spatial Variability of PAHs and Microbial Populations in the Rhizosphere of Two Plants.

    Science.gov (United States)

    Bourceret, Amélia; Leyval, Corinne; de Fouquet, Chantal; Cébron, Aurélie

    2015-01-01

    Rhizoremediation uses root development and exudation to favor microbial activity. Thus it can enhance polycyclic aromatic hydrocarbon (PAH) biodegradation in contaminated soils. Spatial heterogeneity of rhizosphere processes, mainly linked to the root development stage and to the plant species, could explain the contrasted rhizoremediation efficiency levels reported in the literature. Aim of the present study was to test if spatial variability in the whole plant rhizosphere, explored at the centimetre-scale, would influence the abundance of microorganisms (bacteria and fungi), and the abundance and activity of PAH-degrading bacteria, leading to spatial variability in PAH concentrations. Two contrasted rhizospheres were compared after 37 days of alfalfa or ryegrass growth in independent rhizotron devices. Almost all spiked PAHs were degraded, and the density of the PAH-degrading bacterial populations increased in both rhizospheres during the incubation period. Mapping of multiparametric data through geostatistical estimation (kriging) revealed that although root biomass was spatially structured, PAH distribution was not. However a greater variability of the PAH content was observed in the rhizosphere of alfalfa. Yet, in the ryegrass-planted rhizotron, the Gram-positive PAH-degraders followed a reverse depth gradient to root biomass, but were positively correlated to the soil pH and carbohydrate concentrations. The two rhizospheres structured the microbial community differently: a fungus-to-bacterium depth gradient similar to the root biomass gradient only formed in the alfalfa rhizotron.

  7. Investigating the turbulence response of a 1-D idealized water column located in the sub-Antarctic zone with focus on the upper ocean dynamics

    CSIR Research Space (South Africa)

    Boodhraj, Kirodh

    2017-09-01

    Full Text Available discussed. 40 41 Data and Method 42 This study focussed on the sub-Antarctic zone of the 43 Southern Ocean region off the coast of South Africa (47ºS 44 4.5ºE), chosen due to the availability of in situ glider data. 45 A configuration (named SAZ1D... 107 of glider data (Swart et al. 2015) obtained from the region. 108 The winter deep mixing penetrates down to 150 𝑚 (above 109 the permanent pycnocline) while during the summer 110 stratification, high temperatures penetrate down to 100 𝑚. 111...

  8. Egg masses of the Patagonian squid Doryteuthis (Amerigo gahi attached to giant kelp (Macrocystis pyrifera in the sub-Antarctic ecoregion

    Directory of Open Access Journals (Sweden)

    Sebastián Rosenfeld

    2014-11-01

    Full Text Available Egg masses of the Patagonian squid Doryteuthis (Amerigo gahi attached to giant kelp (Macrocystis pyrifera in the Magellanic channels of the sub-Antarctic ecoregion in southern South America is documented for the first time. Of seven egg masses observed between 2008 and 2011, one was taken to the laboratory to be analysed and photographed. Comprising long transparent capsules containing eggs, the masses were strongly attached to the stipes of M. pyrifera. This macroalgae is a potentially important economic resource due to its multiple industrial uses; this study shows that it also serves an important ecological role as a spawning substrate for D. gahi.

  9. Aspects of reproductive ecology and benthic-pelagic coupling in the sub-antarctic sea cucumber Pseudostichopus mollis (Theel)

    Science.gov (United States)

    Morgan, Andrew; Neal, Lance

    2012-07-01

    For deeper regions of the continental shelf environmental cues entraining reproduction in echinoderms are often absent, which contributes to adoption of continuous reproduction, having larger eggs, and a lecithotrophic mode of larval development. In the present study the sub-Antarctic sea cucumber Pseudostichopus mollis from the family Synallactidae was obtained during June (winter) and September (spring) from a depth of approximately 300 m north of the Auckland Islands in an area abundant in biogenic sediments. Samples were processed for body indices and gonad development. Features characteristic of non-continuous reproduction were exhibited. Although a larger egg size was found (212±14 μm), two distinct winter cohorts of oocytes occurred (41-81 and 161-201 μm) and body wall weight fluctuations (7.6% increase in males and 27.5% reduction in females) coincided with changes in gonad indices between sample dates. For males gonad as a proportion of body wall weight decreased from 3.31±0.9 to 2.11±0.37% and for females it increased from 1.59±0.28 to 2.5±0.30%. For both sample dates the gonad of males maintained mature spermatozoa whereas female gonad shifted from mainly recovery and growth of oocytes to growth and advanced growth of mature oocytes. In habitats with low or variable food availability intermittent reproduction is predicted as resources are too low for a high reproductive effort and too erratic for synchrony. A pattern of reproduction where fluctuations in seasonal organic input into an accumulated benthic food source initiates and synchronises gametogenesis for future spawning is proposed.

  10. Biogeochemical flux and phytoplankton succession: A year-long sediment trap record in the Australian sector of the Subantarctic Zone

    Science.gov (United States)

    Wilks, Jessica V.; Rigual-Hernández, Andrés S.; Trull, Thomas W.; Bray, Stephen G.; Flores, José-Abel; Armand, Leanne K.

    2017-03-01

    The Subantarctic Zone (SAZ) plays a crucial role in global carbon cycling as a significant sink for atmospheric CO2. In the Australian sector, the SAZ exports large quantities of organic carbon from the surface ocean, despite lower algal biomass accumulation in surface waters than other Southern Ocean sectors. We present the first analysis of diatom and coccolithophore assemblages and seasonality, as well as the first annual quantification of bulk organic components of captured material at the base of the mixed layer (500 m depth) in the SAZ. Sediment traps were moored in the SAZ southwest of Tasmania as part of the long-term SAZ Project for one year (September 2003 to September 2004). Annual mass flux at 500 m and 2000 m was composed mainly of calcium carbonate, while biogenic silica made up on average <10% of material captured in the traps. Organic carbon flux was estimated at 1.1 g m-2 y-1 at 500 m, close to the estimated global mean carbon flux. Low diatom fluxes and high fluxes of coccoliths were consistent with low biogenic silica and high calcium carbonate fluxes, respectively. Diatoms and coccoliths were identified to species level. Diatom and coccolithophore sinking assemblages reflected some seasonal ecological succession. A theoretical scheme of diatom succession in live assemblages is compared to successional patterns presented in sediment traps. This study provides a unique, direct measurement of the biogeochemical fluxes and their main biological carbon vectors just below the winter mixed layer depth at which effective sequestration of carbon occurs. Comparison of these results with previous sediment trap deployments at the same site at deeper depths (i.e. 1000, 2000 and 3800 m) documents the changes particle fluxes experience in the lower ;twilight zone; where biological processes and remineralisation of carbon reduce the efficiency of carbon sequestration.

  11. Habitat associations and distribution of the hyperbenthic shrimp, Nauticaris marionis, around the sub-Antarctic Prince Edward Islands

    Science.gov (United States)

    Haley, Craig; von der Meden, Charles; Atkinson, Lara; Reed, Cecile

    2017-09-01

    The association of organisms with particular habitats and habitat-forming organisms, can strongly influence species distributions, interactions and wider ecosystem services. At the sub-Antarctic Prince Edward Islands, the caridean shrimp Nauticaris marionis is a principal part of the benthic ecosystem, occurring between ca. 50 m and 600 m. Its role as a trophic link between the primary productivity and higher predators is established, but little is understood of its in situ habitat usage and associations or of how these structure patterns of abundance. We investigated these aspects directly using a benthic camera sled, sampling 27 stations between 50 m and 500 m. Substratum type was characterised, and estimates of percentage cover of the 13 main groups of habitat-forming epibenthic taxa were made, alongside absolute counts of N. marionis within 'digital quadrats' drawn from 300 m transects. The distribution of N. marionis was influenced by depth, substratum type and overall biogenic cover, being limited to habitats between 50 and 160 m depth on mud or gravel substrata only, and having > 50% biogenic cover. The presence/absence of N. marionis related to significantly different epibenthic assemblages (termed biogenic habitats), but this effect was contingent on depth. Likewise, densities of N. marionis were significantly affected by biogenic habitat type, identifying an association with two biogenic habitat groups, one dominated by red-algae, the other by structurally complex bryozoan species. These associations likely relate to the structural complexity of the two habitat groups, rather than the specific taxa involved. The apparent absence of N. marionis at depths > 160 m contrasts with earlier records and poses questions about the trophic importance of the shrimp in deeper habitats.

  12. Satellite tagging and biopsy sampling of killer whales at subantarctic Marion Island: effectiveness, immediate reactions and long-term responses.

    Directory of Open Access Journals (Sweden)

    Ryan R Reisinger

    Full Text Available Remote tissue biopsy sampling and satellite tagging are becoming widely used in large marine vertebrate studies because they allow the collection of a diverse suite of otherwise difficult-to-obtain data which are critical in understanding the ecology of these species and to their conservation and management. Researchers must carefully consider their methods not only from an animal welfare perspective, but also to ensure the scientific rigour and validity of their results. We report methods for shore-based, remote biopsy sampling and satellite tagging of killer whales Orcinus orca at Subantarctic Marion Island. The performance of these methods is critically assessed using 1 the attachment duration of low-impact minimally percutaneous satellite tags; 2 the immediate behavioural reactions of animals to biopsy sampling and satellite tagging; 3 the effect of researcher experience on biopsy sampling and satellite tagging; and 4 the mid- (1 month and long- (24 month term behavioural consequences. To study mid- and long-term behavioural changes we used multievent capture-recapture models that accommodate imperfect detection and individual heterogeneity. We made 72 biopsy sampling attempts (resulting in 32 tissue samples and 37 satellite tagging attempts (deploying 19 tags. Biopsy sampling success rates were low (43%, but tagging rates were high with improved tag designs (86%. The improved tags remained attached for 26±14 days (mean ± SD. Individuals most often showed no reaction when attempts missed (66% and a slight reaction-defined as a slight flinch, slight shake, short acceleration, or immediate dive-when hit (54%. Severe immediate reactions were never observed. Hit or miss and age-sex class were important predictors of the reaction, but the method (tag or biopsy was unimportant. Multievent trap-dependence modelling revealed considerable variation in individual sighting patterns; however, there were no significant mid- or long-term changes

  13. Satellite tagging and biopsy sampling of killer whales at subantarctic Marion Island: effectiveness, immediate reactions and long-term responses.

    Science.gov (United States)

    Reisinger, Ryan R; Oosthuizen, W Chris; Péron, Guillaume; Cory Toussaint, Dawn; Andrews, Russel D; de Bruyn, P J Nico

    2014-01-01

    Remote tissue biopsy sampling and satellite tagging are becoming widely used in large marine vertebrate studies because they allow the collection of a diverse suite of otherwise difficult-to-obtain data which are critical in understanding the ecology of these species and to their conservation and management. Researchers must carefully consider their methods not only from an animal welfare perspective, but also to ensure the scientific rigour and validity of their results. We report methods for shore-based, remote biopsy sampling and satellite tagging of killer whales Orcinus orca at Subantarctic Marion Island. The performance of these methods is critically assessed using 1) the attachment duration of low-impact minimally percutaneous satellite tags; 2) the immediate behavioural reactions of animals to biopsy sampling and satellite tagging; 3) the effect of researcher experience on biopsy sampling and satellite tagging; and 4) the mid- (1 month) and long- (24 month) term behavioural consequences. To study mid- and long-term behavioural changes we used multievent capture-recapture models that accommodate imperfect detection and individual heterogeneity. We made 72 biopsy sampling attempts (resulting in 32 tissue samples) and 37 satellite tagging attempts (deploying 19 tags). Biopsy sampling success rates were low (43%), but tagging rates were high with improved tag designs (86%). The improved tags remained attached for 26±14 days (mean ± SD). Individuals most often showed no reaction when attempts missed (66%) and a slight reaction-defined as a slight flinch, slight shake, short acceleration, or immediate dive-when hit (54%). Severe immediate reactions were never observed. Hit or miss and age-sex class were important predictors of the reaction, but the method (tag or biopsy) was unimportant. Multievent trap-dependence modelling revealed considerable variation in individual sighting patterns; however, there were no significant mid- or long-term changes following

  14. Thermal preference and performance in a sub-Antarctic caterpillar: A test of the coadaptation hypothesis and its alternatives.

    Science.gov (United States)

    Haupt, Tanya M; Sinclair, Brent J; Chown, Steven L

    2017-04-01

    Physiological ecologists have long assumed that thermoregulatory behaviour will evolve to optimise physiological performance. The coadaptation hypothesis predicts that an animal's preferred body temperature will correspond to the temperature at which its performance is optimal. Here we use a strong inference approach to examine the relationship between thermal preference and locomotor performance in the caterpillars of a wingless sub-Antarctic moth, Pringleophaga marioni Viette (Tineidae). The coadaptation hypothesis and its alternatives (suboptimal is optimal, thermodynamic effect, trait variation) are tested. Compared to the optimal movement temperature (22.5°C for field-fresh caterpillars and 25, 20, 22.5, 25 and 20°C following seven day acclimations to 0, 5, 10, 15 and 5-15°C respectively), caterpillar thermal preference was significantly lower (9.2°C for field-fresh individuals and 9.4, 8.8, 8.1, 5.2 and 4.6°C following acclimation to 0, 5, 10, 15 and 5-15°C, respectively). Together with the low degree of asymmetry observed in the performance curves, and the finding that acclimation to high temperatures did not result in maximal performance, all, but one of the above hypotheses (i.e. 'trait variation') was rejected. The thermal preference of P. marioni caterpillars more closely resembles temperatures at which survival is high (5-10°C), or where feeding is optimal (10°C), than where locomotion speed is maximal, suggesting that thermal preference may be optimised for overall fitness rather than for a given trait. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Variable Isotopic Compositions of Host Plant Populations Preclude Assessment of Aphid Overwintering Sites

    Directory of Open Access Journals (Sweden)

    Michael S. Crossley

    2017-12-01

    Full Text Available Soybean aphid (Aphis glycines Matsumura is a pest of soybean in the northern Midwest whose migratory patterns have been difficult to quantify. Improved knowledge of soybean aphid overwintering sites could facilitate the development of control efforts with exponential impacts on aphid densities on a regional scale. In this preliminary study, we explored the utility of variation in stable isotopes of carbon and nitrogen to distinguish soybean aphid overwintering origins. We compared variation in bulk 13C and 15N content in buckthorn (Rhamnus cathartica L. and soybean aphids in Wisconsin, among known overwintering locations in the northern Midwest. Specifically, we looked for associations between buckthorn and environmental variables that could aid in identifying overwintering habitats. We detected significant evidence of correlation between the bulk 13C and 15N signals of soybean aphids and buckthorn, despite high variability in stable isotope composition within and among buckthorn plants. Further, the 15N signal in buckthorn varied predictably with soil composition. However, lack of sufficient differentiation of geographic areas along axes of isotopic and environmental variation appears to preclude the use of carbon and nitrogen isotopic signals as effective predictors of likely aphid overwintering sites. These preliminary data suggest the need for future work that can further account for variability in 13C and 15N within/among buckthorn plants, and that explores the utility of other stable isotopes in assessing likely aphid overwintering sites.

  16. [Myxomatosis in the sub-antarctic islands of Kerguelen, without vectors, thirty years after its introduction].

    Science.gov (United States)

    Chapuis, J L; Chantal, J; Bijlenga, G

    1994-02-01

    Myxoma virus was introduced into the Kerguelen archipelago in 1955-1956. Thirty years after its introduction, the virus is present in most areas inhabited by rabbits. Rabbit fleas and mosquitoes are absent from this group of islands and the disease is transmitted by contact. The timing of the beginning of new myxomatosis outbreaks, the absence of real epizootics as well as the higher percentage of infected males over females are specific observations in favour of this mode of transmission. The majority of 34 isolates tested between 1984 and 1988 are of intermediate virulence (Grades IIIA-IIIB). In these conditions, the impact of myxomatosis virus on rabbit populations estimated on two sites is low. Myxomatosis therefore plays only a minor role in the regulation of rabbit populations.

  17. Using CA model to obtain insight into mechanism of plant population spread in a controllable system : annual weeds as an example

    NARCIS (Netherlands)

    Wang, J.; Kropff, M.J.; Bastiaans, L.; Christensen, S.; Hansen, P.K.

    2003-01-01

    Using cellular automata (CA) model, in this article, a mechanistic approach has been conducted to help to insight into spread process of plant population such as annual weed population. A controllable CA model with 25 neighbourhood cells has been built, in which seed dispersal, as a key process of

  18. Population level analysis of evolved mutations underlying improvements in plant hemicellulose and cellulose fermentation by Clostridium phytofermentans.

    Directory of Open Access Journals (Sweden)

    Supratim Mukherjee

    Full Text Available The complexity of plant cell walls creates many challenges for microbial decomposition. Clostridium phytofermentans, an anaerobic bacterium isolated from forest soil, directly breaks down and utilizes many plant cell wall carbohydrates. The objective of this research is to understand constraints on rates of plant decomposition by Clostridium phytofermentans and identify molecular mechanisms that may overcome these limitations.Experimental evolution via repeated serial transfers during exponential growth was used to select for C. phytofermentans genotypes that grow more rapidly on cellobiose, cellulose and xylan. To identify the underlying mutations an average of 13,600,000 paired-end reads were generated per population resulting in ∼300 fold coverage of each site in the genome. Mutations with allele frequencies of 5% or greater could be identified with statistical confidence. Many mutations are in carbohydrate-related genes including the promoter regions of glycoside hydrolases and amino acid substitutions in ABC transport proteins involved in carbohydrate uptake, signal transduction sensors that detect specific carbohydrates, proteins that affect the export of extracellular enzymes, and regulators of unknown specificity. Structural modeling of the ABC transporter complex proteins suggests that mutations in these genes may alter the recognition of carbohydrates by substrate-binding proteins and communication between the intercellular face of the transmembrane and the ATPase binding proteins.Experimental evolution was effective in identifying molecular constraints on the rate of hemicellulose and cellulose fermentation and selected for putative gain of function mutations that do not typically appear in traditional molecular genetic screens. The results reveal new strategies for evolving and engineering microorganisms for faster growth on plant carbohydrates.

  19. Phenotypic plasticity despite source-sink population dynamics in a long-lived perennial plant.

    Science.gov (United States)

    Anderson, Jill T; Sparks, Jed P; Geber, Monica A

    2010-11-01

    • Species that exhibit adaptive plasticity alter their phenotypes in response to environmental conditions, thereby maximizing fitness in heterogeneous landscapes. However, under demographic source-sink dynamics, selection should favor traits that enhance fitness in the source habitat at the expense of fitness in the marginal habitat. Consistent with source-sink dynamics, the perennial blueberry, Vaccinium elliottii (Ericaceae), shows substantially higher fitness and population sizes in dry upland forests than in flood-prone bottomland forests, and asymmetrical gene flow occurs from upland populations into bottomland populations. Here, we examined whether this species expresses plasticity to these distinct environments despite source-sink dynamics. • We assessed phenotypic responses to a complex environmental gradient in the field and to water stress in the glasshouse. • Contrary to expectations, V. elliottii exhibited a high degree of plasticity in foliar and root traits (specific leaf area, carbon isotope ratios, foliar nitrogen content, root : shoot ratio, root porosity and root architecture). • We propose that plasticity can be maintained in source-sink systems if it is favored within the source habitat and/or a phylogenetic artifact that is not costly. Additionally, plasticity could be advantageous if habitat-based differences in fitness result from incipient niche expansion. Our results illuminate the importance of evaluating phenotypic traits and fitness components across heterogeneous landscapes. © The Authors (2010). Journal compilation © New Phytologist Trust (2010).

  20. Effects of temperature and resource variation on insect population dynamics: the bordered plant bug as a case study

    Science.gov (United States)

    Johnson, Christopher A.; Coutinho, Renato M.; Berlin, Erin; Dolphin, Kimberly E.; Heyer, Johanna; Kim, Britney; Leung, Alice; Sabellon, Jamie Lou; Amarasekare, Priyanga

    2017-01-01

    Summary In species with complex life cycles, population dynamics result from a combination of intrinsic cycles arising from delays in the operation of negative density-dependent processes (e.g., intraspecific competition) and extrinsic fluctuations arising from seasonal variation in the abiotic environment. Abiotic variation can affect species directly through their life history traits and indirectly by modulating the species’ interactions with resources or natural enemies.We investigate how the interplay between density-dependent dynamics and abiotic variability affects population dynamics of the bordered plant bug (Largus californicus), a Hemipteran herbivore inhabiting the California coastal sage scrub community. Field data show a striking pattern in abundance: adults are extremely abundant or nearly absent during certain periods of the year, leading us to predict that seasonal forcing plays a role in driving observed dynamics.We develop a stage-structured population model with variable developmental delays, in which fecundity is affected by both intra-specific competition and temporal variation in resource availability and all life history traits (reproduction, development, mortality) are temperature-dependent. We parameterize the model with experimental data on temperature-responses of life history and competitive traits and validate the model with independent field census data.We find that intra-specific competition is strongest at temperatures optimal for reproduction, which theory predicts leads to more complex population dynamics. Our model predicts that while temperature or resource variability interact with development-induced delays in self-limitation to generate population fluctuations, it is the interplay between all three factors that drive the observed dynamics. Considering how multiple abiotic factors interact with density-dependent processes is important both for understanding how species persist in variable environments and predicting species

  1. Cadmium exposure pathways in a population living near a battery plant.

    Science.gov (United States)

    Hellström, Lennart; Persson, Bodil; Brudin, Lars; Grawé, Kierstin Petersson; Oborn, Ingrid; Järup, Lars

    2007-02-15

    The objectives of the present study were to assess the relative impact of different pathways of environmental cadmium (Cd) exposure and to evaluate the contribution from locally produced vegetables and root crops to the total dietary intake of Cd. Cadmium in urine was determined for 492 individuals living near a closed down battery factory in Sweden. For each individual we created an environmental exposure-index based on Cd emissions to ambient air and number of years living at various distances from the plant. This information as well as dietary data were collected via questionnaires. Samples of soil, carrots and/or potatoes were collected from 37 gardens and analysed for Cd concentration. Eating home grown vegetables/potatoes, environmental Cd-exposure-index, female gender, age above 30 years and smoking more than one pack of cigarettes daily for at least 10 years were found to be significantly associated with increased urine concentrations of Cd (UCd>1.0 nmol/mmol creatinine). We found a statistically significant relation between Cd in urine and environmental Cd-exposure-index in persons eating home grown vegetables/potatoes regularly. Cd concentrations in home grown carrots, potatoes and in garden soil were highest in the area closest to the factory. Daily consumption of potatoes and vegetables cultivated in the vicinity of the closed battery factory was estimated to increase Cd intake by 18-38%. The present study shows that consumption of locally grown vegetables and root crops was an important exposure pathway, in subjects living near a nickel-cadmium battery plant, whereas direct exposure via ambient air was less important.

  2. Actual and potential use of population viability analyses in recovery of plant species listed under the US endangered species act.

    Science.gov (United States)

    Zeigler, Sara L; Che-Castaldo, Judy P; Neel, Maile C

    2013-12-01

    Use of population viability analyses (PVAs) in endangered species recovery planning has been met with both support and criticism. Previous reviews promote use of PVA for setting scientifically based, measurable, and objective recovery criteria and recommend improvements to increase the framework's utility. However, others have questioned the value of PVA models for setting recovery criteria and assert that PVAs are more appropriate for understanding relative trade-offs between alternative management actions. We reviewed 258 final recovery plans for 642 plants listed under the U.S. Endangered Species Act to determine the number of plans that used or recommended PVA in recovery planning. We also reviewed 223 publications that describe plant PVAs to assess how these models were designed and whether those designs reflected previous recommendations for improvement of PVAs. Twenty-four percent of listed species had recovery plans that used or recommended PVA. In publications, the typical model was a matrix population model parameterized with ≤5 years of demographic data that did not consider stochasticity, genetics, density dependence, seed banks, vegetative reproduction, dormancy, threats, or management strategies. Population growth rates for different populations of the same species or for the same population at different points in time were often statistically different or varied by >10%. Therefore, PVAs parameterized with underlying vital rates that vary to this degree may not accurately predict recovery objectives across a species' entire distribution or over longer time scales. We assert that PVA, although an important tool as part of an adaptive-management program, can help to determine quantitative recovery criteria only if more long-term data sets that capture spatiotemporal variability in vital rates become available. Lacking this, there is a strong need for viable and comprehensive methods for determining quantitative, science-based recovery criteria for

  3. The demography and population genomics of evolutionary transitions to self-fertilization in plants.

    Science.gov (United States)

    Barrett, Spencer C H; Arunkumar, Ramesh; Wright, Stephen I

    2014-08-05

    The evolution of self-fertilization from outcrossing has occurred on numerous occasions in flowering plants. This shift in mating system profoundly influences the morphology, ecology, genetics and evolution of selfing lineages. As a result, there has been sustained interest in understanding the mechanisms driving the evolution of selfing and its environmental context. Recently, patterns of molecular variation have been used to make inferences about the selective mechanisms associated with mating system transitions. However, these inferences can be complicated by the action of linked selection following the transition. Here, using multilocus simulations and comparative molecular data from related selfers and outcrossers, we demonstrate that there is little evidence for strong bottlenecks associated with initial transitions to selfing, and our simulation results cast doubt on whether it is possible to infer the role of bottlenecks associated with reproductive assurance in the evolution of selfing. They indicate that the effects of background selection on the loss of diversity and efficacy of selection occur rapidly following the shift to high selfing. Future comparative studies that integrate explicit ecological and genomic details are necessary for quantifying the independent and joint effects of selection and demography on transitions to selfing and the loss of genetic diversity. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  4. Global urban signatures of phenotypic change in animal and plant populations.

    Science.gov (United States)

    Alberti, Marina; Correa, Cristian; Marzluff, John M; Hendry, Andrew P; Palkovacs, Eric P; Gotanda, Kiyoko M; Hunt, Victoria M; Apgar, Travis M; Zhou, Yuyu

    2017-08-22

    Humans challenge the phenotypic, genetic, and cultural makeup of species by affecting the fitness landscapes on which they evolve. Recent studies show that cities might play a major role in contemporary evolution by accelerating phenotypic changes in wildlife, including animals, plants, fungi, and other organisms. Many studies of ecoevolutionary change have focused on anthropogenic drivers, but none of these studies has specifically examined the role that urbanization plays in ecoevolution or explicitly examined its mechanisms. This paper presents evidence on the mechanisms linking urban development patterns to rapid evolutionary changes for species that play important functional roles in communities and ecosystems. Through a metaanalysis of experimental and observational studies reporting more than 1,600 phenotypic changes in species across multiple regions, we ask whether we can discriminate an urban signature of phenotypic change beyond the established natural baselines and other anthropogenic signals. We then assess the relative impact of five types of urban disturbances including habitat modifications, biotic interactions, habitat heterogeneity, novel disturbances, and social interactions. Our study shows a clear urban signal; rates of phenotypic change are greater in urbanizing systems compared with natural and nonurban anthropogenic systems. By explicitly linking urban development to traits that affect ecosystem function, we can map potential ecoevolutionary implications of emerging patterns of urban agglomerations and uncover insights for maintaining key ecosystem functions upon which the sustainability of human well-being depends.

  5. Nutritional Immunity Triggers the Modulation of Iron Metabolism Genes in the Sub-Antarctic Notothenioid Eleginops maclovinus in Response to Piscirickettsia salmonis

    Directory of Open Access Journals (Sweden)

    Danixa Martínez

    2017-09-01

    Full Text Available Iron deprivation is a nutritional immunity mechanism through which fish can limit the amount of iron available to invading bacteria. The aim of this study was to evaluate the modulation of iron metabolism genes in the liver and brain of sub-Antarctic notothenioid Eleginops maclovinus challenged with Piscirickettsia salmonis. The specimens were inoculated with two P. salmonis strains: LF-89 (ATCC® VR-1361™ and Austral-005 (antibiotic resistant. Hepatic and brain samples were collected at intervals over a period of 35 days. Gene expression (by RT-qPCR of proteins involved in iron storage, transport, and binding were statistically modulated in infected fish when compared with control counterparts. Specifically, the expression profiles of the transferrin and hemopexin genes in the liver, as well as the expression profiles of ferritin-M, ferritin-L, and transferrin in the brain, were similar for both experimental groups. Nevertheless, the remaining genes such as ferritin-H, ceruloplasmin, hepcidin, and haptoglobin presented tissue-specific expression profiles that varied in relation to the injected bacterial strain and sampling time-point. These results suggest that nutritional immunity could be an important immune defense mechanism for E. maclovinus against P. salmonis injection. This study provides relevant information for understanding iron metabolism of a sub-Antarctic notothenioid fish.

  6. On the biogeography of Cumacea (Crustacea, Malacostraca. A comparison between South America, the Subantarctic Islands and Antarctica: present state of the art

    Directory of Open Access Journals (Sweden)

    Ute Mühlenhardt-Siegel

    1999-12-01

    Full Text Available Cumacea (Crustacea were collected during the Joint Magellan expedition in November 1994, by means of an epibenthic sledge from RV Victor Hensen. The cumaceans were well represented, the second abundant order after the amphipods, among the other Peracarida in depth ranges between 25 and 665 m. Twenty-five species were found in the samples mainly from the Beagle Channel, nine of them were already known for this region. 14 species were recorded for the first time for this region, 2 of them were known from the northern Argentinian coast and one from Antarctica. The most important in terms of species richness and abundance were the families Diastylidae, Nannastacidae and Leuconidae. In the Beagle Channel an almost completely different cumacean fauna was found compared to the Subantarctic Islands, the Antarctic Peninsula and eastern Antarctic (Prydz Bay regions. Comparison of published data and the present results show moderate overlap in the cumacean fauna at the species level between the periantarctic South Georgian shelf / Antarctic Peninsula (48%. Little correspondence at the species level was found between Antarctica / Subantarctic Kerguelen (14 %, South Georgia / Kerguelen (13 % and Magellan / Antarctica (11 %. Interestingly, the Magellan region and South Georgia show very little species overlap (5 %. It is concluded that the Antarctic shelf regions were not colonized from the Magellan region via the Scotia Arc.

  7. Identification of QTLs for capsaicinoids, fruit quality, and plant architecture-related traits in an interspecific Capsicum RIL population.

    Science.gov (United States)

    Yarnes, Shawn C; Ashrafi, Hamid; Reyes-Chin-Wo, Sebastian; Hill, Theresa A; Stoffel, Kevin M; Van Deynze, Allen

    2013-01-01

    Quantitative trait loci (QTL) analyses in pepper are common for horticultural, disease resistance, and fruit quality traits; although none of the studies to date have used sequence-based markers associated with genes. In this study we measured plant architectural, phenological, and fruit quality traits in a pepper mapping population consisting of 92 recombinant inbred lines derived from a cross between Capsicum frutescens acc. 2814-6 and C. annuum var. NuMexRNAKY. Phenotypic measurements were correlated to loci in a high-density EST-based genetic map. In total, 96 QTL were identified for 38 traits, including 12 QTL associated with capsaicinoid levels. Twenty-one loci showed correlation among seemingly unrelated phenotypic categories, highlighting tight linkage or shared genetics between previously unassociated traits in pepper.

  8. Pesticide residues in heterogeneous plant populations, a model-based approach applied to nematicides in banana (Musa spp.).

    Science.gov (United States)

    Tixier, Philippe; Chabrier, Christian; Malézieux, Eric

    2007-03-21

    Nematicides are widely used to control plant-parasitic nematodes in intensive export banana (Musa spp.) cropping systems. Data show that the concentration of fosthiazate in banana fruits varies from zero to 0.035 g kg-1, under the maximal residue limit (MRL=0.05 mg kg-1). The fosthiazate concentration in fruit is described by a Gaussian envelope curve function of the interval between pesticide application and fruit harvest (preharvest interval). The heterogeneity of phenological stages in a banana population increases over time, and thus the preharvest interval of fruits harvested after a pesticide application varies over time. A phenological model was used to simulate the long-term harvest dynamics of banana at field scale. Simulations show that the mean fosthiazate concentration in fruits varies according to nematicide application program, climate (temperature), and planting date of the banana field. This method is used to assess the percentage of harvested bunches that exceed a residue threshold and to help farmers minimize fosthiazate residues in bananas.

  9. Population dynamics of iron-oxidizing communities in pilot plants for the treatment of acid mine waters

    Energy Technology Data Exchange (ETDEWEB)

    Elke Heinzel; Eberhard Janneck; Franz Glombitza; Michael Schlmann; Jana Seifert [TU Bergakademie Freiberg, Freiberg (Germany). Interdisciplinary Ecological Center

    2009-08-15

    The iron-oxidizing microbial community in two pilot plants for the treatment of acid mine water was monitored to investigate the influence of different process parameters such as pH, iron concentration, and retention time on the stability of the system to evaluate the applicability of this treatment technology on an industrial scale. The dynamics of the microbial populations were followed using T-RFLP (terminal restriction fragment length polymorphism) over a period of several months. For a more precise quantification, two TaqMan assays specific for the two prominent groups were developed and the relative abundance of these taxa in the iron-oxidizing community was verified by real-time PCR. The investigations revealed that the iron-oxidizing community was clearly dominated by two groups of Betaproteobacteria affiliated with the poorly known and not yet recognized species 'Ferrovum myxofaciens' and with strains related to Gallionella ferruginea, respectively. These taxa dominated the microbial community during the whole investigation period and accelerated the oxidation of ferrous iron despite the changing characteristics of mine waters flowing into the plants. Thus, it is assumed that the treatment technology can also be applied to other mine sites and that these organisms play a crucial role in such treatment systems. 32 refs., 4 figs. 1 tab.

  10. Population dynamics of iron-oxidizing communities in pilot plants for the treatment of acid mine waters.

    Science.gov (United States)

    Heinzel, Elke; Janneck, Eberhard; Glombitza, Franz; Schlömann, Michael; Seifert, Jana

    2009-08-15

    The iron-oxidizing microbial community in two pilot plants for the treatment of acid mine water was monitored to investigate the influence of different process parameters such as pH, iron concentration, and retention time on the stability of the system to evaluate the applicability of this treatment technology on an industrial scale. The dynamics of the microbial populations were followed using T-RFLP (terminal restriction fragment length polymorphism) over a period of several months. For a more precise quantification, two TaqMan assays specific for the two prominent groups were developed and the relative abundance of these taxa in the iron-oxidizing community was verified by real-time PCR. The investigations revealed that the iron-oxidizing community was clearly dominated by two groups of Betaproteobacteria affiliated with the poorly known and not yet recognized species "Ferrovum myxofaciens" and with strains related to Gallionella ferruginea, respectively. These taxa dominated the microbial community during the whole investigation period and accelerated the oxidation of ferrous iron despite the changing characteristics of mine waters flowing into the plants. Thus, it is assumed that the treatment technology can also be applied to other mine sites and that these organisms play a crucial role in such treatment systems.

  11. Rice-straw mulch reduces the green peach aphid, Myzus persicae (Hemiptera: Aphididae) populations on kale, Brassica oleracea var. acephala (Brassicaceae) plants.

    Science.gov (United States)

    Silva-Filho, Reinildes; Santos, Ricardo Henrique Silva; Tavares, Wagner de Souza; Leite, Germano Leão Demolin; Wilcken, Carlos Frederico; Serrão, José Eduardo; Zanuncio, José Cola

    2014-01-01

    Organic mulches, like peel and rice-straw, besides other materials affect the UV and temperature, which cause a reduction in the aphid arrival. The aim was to evaluate the effect of covering the soil with straw on the populations of the green peach aphid, Myzus persicae on the kale, Brassica oleracea var. acephala plants. The first experiment evaluated the direct effect of the rice-straw mulch and the second its indirect effect on aphid immigration, testing the plant characteristics that could lead to the landing preference of this insect. The third experiment evaluated the direct effect of the mulch on the aphid population. In the second and third experiments, four plants, each in a 14 L polyethylene pot with holes at the bottom, were used in areas with and without soil mulching. These pots were changed between areas, after seven days, to evaluate the effects of this change on the arrival of the winged aphids to the plants. Each plant was covered with anti-aphid gauze and inoculated with one winged M. persicae. Winged and apterous adults of this insect were counted per plant after 15 days. The temperature increased in the mulched plots to a maximum of 21-36°C and to 18-32°C in the plots with or without soil covering, respectively. Plant growth reduced the numbers of the winged aphids landing before and after they were moved to the bare soil plots. The nutrient content was similar in plants in both the mulched and no mulched plots. The population growth of M. persicae was higher in the control than in the mulched plots. This was partially due to temperatures close to 30°C in these plots and changes in the plant physiology. The soil mulching with rice-straw decreased the M. persicae landing, increased the plot temperatures and improved the vegetative growth of the kale plants.

  12. Rice-straw mulch reduces the green peach aphid, Myzus persicae (Hemiptera: Aphididae populations on kale, Brassica oleracea var. acephala (Brassicaceae plants.

    Directory of Open Access Journals (Sweden)

    Reinildes Silva-Filho

    Full Text Available Organic mulches, like peel and rice-straw, besides other materials affect the UV and temperature, which cause a reduction in the aphid arrival. The aim was to evaluate the effect of covering the soil with straw on the populations of the green peach aphid, Myzus persicae on the kale, Brassica oleracea var. acephala plants. The first experiment evaluated the direct effect of the rice-straw mulch and the second its indirect effect on aphid immigration, testing the plant characteristics that could lead to the landing preference of this insect. The third experiment evaluated the direct effect of the mulch on the aphid population. In the second and third experiments, four plants, each in a 14 L polyethylene pot with holes at the bottom, were used in areas with and without soil mulching. These pots were changed between areas, after seven days, to evaluate the effects of this change on the arrival of the winged aphids to the plants. Each plant was covered with anti-aphid gauze and inoculated with one winged M. persicae. Winged and apterous adults of this insect were counted per plant after 15 days. The temperature increased in the mulched plots to a maximum of 21-36°C and to 18-32°C in the plots with or without soil covering, respectively. Plant growth reduced the numbers of the winged aphids landing before and after they were moved to the bare soil plots. The nutrient content was similar in plants in both the mulched and no mulched plots. The population growth of M. persicae was higher in the control than in the mulched plots. This was partially due to temperatures close to 30°C in these plots and changes in the plant physiology. The soil mulching with rice-straw decreased the M. persicae landing, increased the plot temperatures and improved the vegetative growth of the kale plants.

  13. Differences in competitive ability between plants from nonnative and native populations of a tropical invader relates to adaptive responses in abiotic and biotic environments.

    Science.gov (United States)

    Liao, Zhi-Yong; Zhang, Ru; Barclay, Gregor F; Feng, Yu-Long

    2013-01-01

    The evolution of competitive ability of invasive plant species is generally studied in the context of adaptive responses to novel biotic environments (enemy release) in introduced ranges. However, invasive plants may also respond to novel abiotic environments. Here we studied differences in competitive ability between Chromolaena odorata plants of populations from nonnative versus native ranges, considering biogeographical differences in both biotic and abiotic environments. An intraspecific competition experiment was conducted at two nutrient levels in a common garden. In both low and high nutrient treatments, C. odorata plants from nonnative ranges showed consistently lower root to shoot ratios than did plants from native ranges grown in both monoculture and competition. In the low nutrient treatment, C. odorata plants from nonnative ranges showed significantly lower competitive ability (competition-driven decreases in plant height and biomass were more), which was associated with their lower root to shoot ratios and higher total leaf phenolic content (defense trait). In the high nutrient treatment, C. odorata plants from nonnative ranges showed lower leaf toughness and cellulosic contents (defense traits) but similar competitive ability compared with plants from native ranges, which was also associated with their lower root to shoot ratios. Our results indicate that genetically based shifts in biomass allocation (responses to abiotic environments) also influence competitive abilities of invasive plants, and provide a first potential mechanism for the interaction between range and environment (environment-dependent difference between ranges).

  14. Natural selection and neutral evolution jointly drive population divergence between alpine and lowland ecotypes of the allopolyploid plant Anemone multifida (Ranunculaceae).

    Science.gov (United States)

    McEwen, Jamie R; Vamosi, Jana C; Rogers, Sean M

    2013-01-01

    Population differentiation can be driven in large part by natural selection, but selectively neutral evolution can play a prominent role in shaping patters of population divergence. The decomposition of the evolutionary history of populations into the relative effects of natural selection and selectively neutral evolution enables an understanding of the causes of population divergence and adaptation. In this study, we examined heterogeneous genomic divergence between alpine and lowland ecotypes of the allopolyploid plant, Anemone multifida. Using peak height and dominant AFLP data, we quantified population differentiation at non-outlier (neutral) and outlier loci to determine the potential contribution of natural selection and selectively neutral evolution to population divergence. We found 13 candidate loci, corresponding to 2.7% of loci, with signatures of divergent natural selection between alpine and lowland populations and between alpine populations (Fst  = 0.074-0.445 at outlier loci), but neutral population differentiation was also evident between alpine populations (FST  = 0.041-0.095 at neutral loci). By examining population structure at both neutral and outlier loci, we determined that the combined effects of selection and neutral evolution are associated with the divergence of alpine populations, which may be linked to extreme abiotic conditions and isolation between alpine sites. The presence of outlier levels of genetic variation in structured populations underscores the importance of separately analyzing neutral and outlier loci to infer the relative role of divergent natural selection and neutral evolution in population divergence.

  15. Natural selection and neutral evolution jointly drive population divergence between alpine and lowland ecotypes of the allopolyploid plant Anemone multifida (Ranunculaceae.

    Directory of Open Access Journals (Sweden)

    Jamie R McEwen

    Full Text Available Population differentiation can be driven in large part by natural selection, but selectively neutral evolution can play a prominent role in shaping patters of population divergence. The decomposition of the evolutionary history of populations into the relative effects of natural selection and selectively neutral evolution enables an understanding of the causes of population divergence and adaptation. In this study, we examined heterogeneous genomic divergence between alpine and lowland ecotypes of the allopolyploid plant, Anemone multifida. Using peak height and dominant AFLP data, we quantified population differentiation at non-outlier (neutral and outlier loci to determine the potential contribution of natural selection and selectively neutral evolution to population divergence. We found 13 candidate loci, corresponding to 2.7% of loci, with signatures of divergent natural selection between alpine and lowland populations and between alpine populations (Fst  = 0.074-0.445 at outlier loci, but neutral population differentiation was also evident between alpine populations (FST  = 0.041-0.095 at neutral loci. By examining population structure at both neutral and outlier loci, we determined that the combined effects of selection and neutral evolution are associated with the divergence of alpine populations, which may be linked to extreme abiotic conditions and isolation between alpine sites. The presence of outlier levels of genetic variation in structured populations underscores the importance of separately analyzing neutral and outlier loci to infer the relative role of divergent natural selection and neutral evolution in population divergence.

  16. Pharmacogenomics Implications of Using Herbal Medicinal Plants on African Populations in Health Transition

    Science.gov (United States)

    Thomford, Nicholas E.; Dzobo, Kevin; Chopera, Denis; Wonkam, Ambroise; Skelton, Michelle; Blackhurst, Dee; Chirikure, Shadreck; Dandara, Collet

    2015-01-01

    The most accessible points of call for most African populations with respect to primary health care are traditional health systems that include spiritual, religious, and herbal medicine. This review focusses only on the use of herbal medicines. Most African people accept herbal medicines as generally safe with no serious adverse effects. However, the overlap between conventional medicine and herbal medicine is a reality among countries in health systems transition. Patients often simultaneously seek treatment from both conventional and traditional health systems for the same condition. Commonly encountered conditions/diseases include malaria, HIV/AIDS, hypertension, tuberculosis, and bleeding disorders. It is therefore imperative to understand the modes of interaction between different drugs from conventional and traditional health care systems when used in treatment combinations. Both conventional and traditional drug entities are metabolized by the same enzyme systems in the human body, resulting in both pharmacokinetics and pharmacodynamics interactions, whose properties remain unknown/unquantified. Thus, it is important that profiles of interaction between different herbal and conventional medicines be evaluated. This review evaluates herbal and conventional drugs in a few African countries and their potential interaction at the pharmacogenomics level. PMID:26402689

  17. Bone-Eating Worms Spread: Insights into Shallow-Water Osedax (Annelida, Siboglinidae) from Antarctic, Subantarctic, and Mediterranean Waters.

    Science.gov (United States)

    Taboada, Sergi; Riesgo, Ana; Bas, Maria; Arnedo, Miquel A; Cristobo, Javier; Rouse, Greg W; Avila, Conxita

    2015-01-01

    Osedax, commonly known as bone-eating worms, are unusual marine annelids belonging to Siboglinidae and represent a remarkable example of evolutionary adaptation to a specialized habitat, namely sunken vertebrate bones. Usually, females of these animals live anchored inside bone owing to a ramified root system from an ovisac, and obtain nutrition via symbiosis with Oceanospirillales gamma-proteobacteria. Since their discovery, 26 Osedax operational taxonomic units (OTUs) have been reported from a wide bathymetric range in the Pacific, the North Atlantic, and the Southern Ocean. Using experimentally deployed and naturally occurring bones we report here the presence of Osedax deceptionensis at very shallow-waters in Deception Island (type locality; Antarctica) and at moderate depths near South Georgia Island (Subantarctic). We present molecular evidence in a new phylogenetic analysis based on five concatenated genes (28S rDNA, Histone H3, 18S rDNA, 16S rDNA, and cytochrome c oxidase I-COI-), using Maximum Likelihood and Bayesian inference, supporting the placement of O. deceptionensis as a separate lineage (Clade VI) although its position still remains uncertain. This phylogenetic analysis includes a new unnamed species (O. 'mediterranea') recently discovered in the shallow-water Mediterranean Sea belonging to Osedax Clade I. A timeframe of the diversification of Osedax inferred using a Bayesian framework further suggests that Osedax diverged from other siboglinids during the Middle Cretaceous (ca. 108 Ma) and also indicates that the most recent common ancestor of Osedax extant lineages dates to the Late Cretaceous (ca. 74.8 Ma) concomitantly with large marine reptiles and teleost fishes. We also provide a phylogenetic framework that assigns newly-sequenced Osedax endosymbionts of O. deceptionensis and O. 'mediterranea' to ribospecies Rs1. Molecular analysis for O. deceptionensis also includes a COI-based haplotype network indicating that individuals from Deception

  18. Bone-Eating Worms Spread: Insights into Shallow-Water Osedax (Annelida, Siboglinidae from Antarctic, Subantarctic, and Mediterranean Waters.

    Directory of Open Access Journals (Sweden)

    Sergi Taboada

    Full Text Available Osedax, commonly known as bone-eating worms, are unusual marine annelids belonging to Siboglinidae and represent a remarkable example of evolutionary adaptation to a specialized habitat, namely sunken vertebrate bones. Usually, females of these animals live anchored inside bone owing to a ramified root system from an ovisac, and obtain nutrition via symbiosis with Oceanospirillales gamma-proteobacteria. Since their discovery, 26 Osedax operational taxonomic units (OTUs have been reported from a wide bathymetric range in the Pacific, the North Atlantic, and the Southern Ocean. Using experimentally deployed and naturally occurring bones we report here the presence of Osedax deceptionensis at very shallow-waters in Deception Island (type locality; Antarctica and at moderate depths near South Georgia Island (Subantarctic. We present molecular evidence in a new phylogenetic analysis based on five concatenated genes (28S rDNA, Histone H3, 18S rDNA, 16S rDNA, and cytochrome c oxidase I-COI-, using Maximum Likelihood and Bayesian inference, supporting the placement of O. deceptionensis as a separate lineage (Clade VI although its position still remains uncertain. This phylogenetic analysis includes a new unnamed species (O. 'mediterranea' recently discovered in the shallow-water Mediterranean Sea belonging to Osedax Clade I. A timeframe of the diversification of Osedax inferred using a Bayesian framework further suggests that Osedax diverged from other siboglinids during the Middle Cretaceous (ca. 108 Ma and also indicates that the most recent common ancestor of Osedax extant lineages dates to the Late Cretaceous (ca. 74.8 Ma concomitantly with large marine reptiles and teleost fishes. We also provide a phylogenetic framework that assigns newly-sequenced Osedax endosymbionts of O. deceptionensis and O. 'mediterranea' to ribospecies Rs1. Molecular analysis for O. deceptionensis also includes a COI-based haplotype network indicating that individuals from

  19. Bone-Eating Worms Spread: Insights into Shallow-Water Osedax (Annelida, Siboglinidae) from Antarctic, Subantarctic, and Mediterranean Waters

    Science.gov (United States)

    Taboada, Sergi; Riesgo, Ana; Bas, Maria; Arnedo, Miquel A.; Cristobo, Javier; Rouse, Greg W.; Avila, Conxita

    2015-01-01

    Osedax, commonly known as bone-eating worms, are unusual marine annelids belonging to Siboglinidae and represent a remarkable example of evolutionary adaptation to a specialized habitat, namely sunken vertebrate bones. Usually, females of these animals live anchored inside bone owing to a ramified root system from an ovisac, and obtain nutrition via symbiosis with Oceanospirillales gamma-proteobacteria. Since their discovery, 26 Osedax operational taxonomic units (OTUs) have been reported from a wide bathymetric range in the Pacific, the North Atlantic, and the Southern Ocean. Using experimentally deployed and naturally occurring bones we report here the presence of Osedax deceptionensis at very shallow-waters in Deception Island (type locality; Antarctica) and at moderate depths near South Georgia Island (Subantarctic). We present molecular evidence in a new phylogenetic analysis based on five concatenated genes (28S rDNA, Histone H3, 18S rDNA, 16S rDNA, and cytochrome c oxidase I–COI–), using Maximum Likelihood and Bayesian inference, supporting the placement of O. deceptionensis as a separate lineage (Clade VI) although its position still remains uncertain. This phylogenetic analysis includes a new unnamed species (O. ‘mediterranea’) recently discovered in the shallow-water Mediterranean Sea belonging to Osedax Clade I. A timeframe of the diversification of Osedax inferred using a Bayesian framework further suggests that Osedax diverged from other siboglinids during the Middle Cretaceous (ca. 108 Ma) and also indicates that the most recent common ancestor of Osedax extant lineages dates to the Late Cretaceous (ca. 74.8 Ma) concomitantly with large marine reptiles and teleost fishes. We also provide a phylogenetic framework that assigns newly-sequenced Osedax endosymbionts of O. deceptionensis and O. ‘mediterranea’ to ribospecies Rs1. Molecular analysis for O. deceptionensis also includes a COI-based haplotype network indicating that individuals from

  20. Ecology and life history affect different aspects of the population structure of 27 high-alpine plants.

    Science.gov (United States)

    Meirmans, Patrick G; Goudet, Jerome; Gaggiotti, Oscar E

    2011-08-01

    A plant species' genetic population structure is the result of a complex combination of its life history, ecological preferences, position in the ecosystem and historical factors. As a result, many different statistical methods exist that measure different aspects of species' genetic structure. However, little is known about how these methods are interrelated and how they are related to a species' ecology and life history. In this study, we used the IntraBioDiv amplified fragment length polymorphisms data set from 27 high-alpine species to calculate eight genetic summary statistics that we jointly correlate to a set of six ecological and life-history traits. We found that there is a large amount of redundancy among the calculated summary statistics and that there is a significant association with the matrix of species traits. In a multivariate analysis, two main aspects of population structure were visible among the 27 species. The first aspect is related to the species' dispersal capacities and the second is most likely related to the species' postglacial recolonization of the Alps. Furthermore, we found that some summary statistics, most importantly Mantel's r and Jost's D, show different behaviour than expected based on theory. We therefore advise caution in drawing too strong conclusions from these statistics. © 2011 Blackwell Publishing Ltd.

  1. Fatty Acid Diversity is Not Associated with Neutral Genetic Diversity in Native Populations of the Biodiesel Plant Jatropha curcas L.

    Science.gov (United States)

    Martínez-Díaz, Yesenia; González-Rodríguez, Antonio; Rico-Ponce, Héctor Rómulo; Rocha-Ramírez, Víctor; Ovando-Medina, Isidro; Espinosa-García, Francisco J

    2017-01-01

    Jatropha curcas L. (Euphorbiaceae) is a shrub native to Mexico and Central America, which produces seeds with a high oil content that can be converted to biodiesel. The genetic diversity of this plant has been widely studied, but it is not known whether the diversity of the seed oil chemical composition correlates with neutral genetic diversity. The total seed oil content, the diversity of profiles of fatty acids and phorbol esters were quantified, also, the genetic diversity obtained from simple sequence repeats was analyzed in native populations of J. curcas in Mexico. Using the fatty acids profiles, a discriminant analysis recognized three groups of individuals according to geographical origin. Bayesian assignment analysis revealed two genetic groups, while the genetic structure of the populations could not be explained by isolation-by-distance. Genetic and fatty acid profile data were not correlated based on Mantel test. Also, phorbol ester content and genetic diversity were not associated. Multiple linear regression analysis showed that total oil content was associated with altitude and seasonality of temperature. The content of unsaturated fatty acids was associated with altitude. Therefore, the cultivation planning of J. curcas should take into account chemical variation related to environmental factors. © 2017 Wiley-VHCA AG, Zurich, Switzerland.

  2. Population structure and dynamics of Gammarus fossarum (Amphipoda) upstream and downstream from effluents of sewage treatment plants.

    Science.gov (United States)

    Ladewig, V; Jungmann, D; Köhler, H-R; Schirling, M; Triebskorn, R; Nagel, R

    2006-04-01

    Two streams in Germany (Körsch and Lockwitzbach), each with two sampling sites above and below a sewage treatment plant (STP) discharging effluent, were investigated. Sampling sites were characterized, and exposure monitoring for chemicals with known or assumed endocrine disrupting potential was carried out. Both the population structure and the population dynamics of Gammarus fossarum were examined. The physicochemical parameters measured at the sampling sites of the Lockwitzbach and Körsch streams were found not to reach levels having an acute toxic impact on the development of gammarids. The calculated estrogenic potential in the stream water was 22- to 35-fold higher at the downstream site of the Körsch compared with the other sampling sites, mainly because of the concentrations of 17alpha-ethinylestradiol on two sampling dates. At both streams, an influence of the respective STP effluent on the sex ratio of G. fossarum was not observed. Moreover, intersexuality was not induced by these effluents. Differences in the structure and dynamics of G. fossarum populations were more pronounced at the Körsch than at the Lockwitzbach. At the downstream sampling site at the Körsch, gammarids reached their highest abundances. Particularly at the downstream sampling site of the Körsch, the proportion of breeding female gammarids and the proportion of juvenile gammarids in the smallest body length class were decreased compared with upstream. Adult gammarids were larger from the Lockwitzbach downstream site, but they were smaller from the Körsch downstream site compared with the respective upstream site. At the Körsch, the earlier onset of the autumnal reproductive resting period could be caused by the influence of the STP effluent.

  3. QTL Analysis and Nested Association Mapping for Adult Plant Resistance to Powdery Mildew in Two Bread Wheat Populations

    Directory of Open Access Journals (Sweden)

    Yan Ren

    2017-07-01

    Full Text Available CIMMYT wheat (Triticum aestivum L. lines Francolin#1 and Quaiu#3 displayed effective and stable adult plant resistance (APR to Chinese Blumeria graminis f. sp. tritici isolates in the field. To elucidate their genetic basis of resistance, two recombinant inbred line (RIL populations of their crosses with Avocet, the susceptible parent, were phenotyped in Zhengzhou and Shangqiu in the 2014–2015 and 2015–2016 cropping seasons. These populations were also genotyped with SSR (simple sequence repeat markers and DArT (diversity arrays technology markers. Two common significant quantitative trait loci (QTL on wheat chromosomes 1BL and 4BL were detected in both populations by joint and individual inclusive composite interval mapping, explaining 20.3–28.7% and 9.6–15.9% of the phenotypic variance in Avocet × Francolin#1 and 4.8–11.5% and 10.8–18.9% in Avocet × Quaiu#3, respectively. Additional QTL were mapped on chromosomes 1DL and 5BL in Avocet × Francolin#1 and on 2DL and 6BS in Avocet × Quaiu#3. Among these, QPm.heau-1DL is probably a novel APR gene contributing 6.1–8.5% of total phenotypic variance. The QTL on 1BL corresponds to the pleiotropic multi-pathogen resistance gene Yr29/Lr46/Pm39, whereas the QTL on 2DL maps to a similar region where stripe rust resistance gene Yr54 is located. The QTL identified can potentially be used for the improvement of powdery mildew and rust resistance in wheat breeding.

  4. Partial replacement of fossil fuel in a cement plant: risk assessment for the population living in the neighborhood.

    Science.gov (United States)

    Rovira, Joaquim; Mari, Montse; Nadal, Martí; Schuhmacher, Marta; Domingo, José L

    2010-10-15

    In cement plants, the substitution of traditional fossil fuels not only allows a reduction of CO(2), but it also means to check-out residual materials, such as sewage sludge or municipal solid wastes (MSW), which should otherwise be disposed somehow/somewhere. In recent months, a cement plant placed in Alcanar (Catalonia, Spain) has been conducting tests to replace fossil fuel by refuse-derived fuel (RDF) from MSW. In July 2009, an operational test was progressively initiated by reaching a maximum of partial substitution of 20% of the required energy. In order to study the influence of the new process, environmental monitoring surveys were performed before and after the RDF implementation. Metals and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were analyzed in soil, herbage, and air samples collected around the facility. In soils, significant decreases of PCDD/F levels, as well as in some metal concentrations were found, while no significant increases in the concentrations of these pollutants were observed. In turn, PM(10) levels remained constant, with a value of 16μgm(-3). In both surveys, the carcinogenic and non-carcinogenic risks derived from exposure to metals and PCDD/Fs for the population living in the vicinity of the facility were within the ranges considered as acceptable according to national and international standards. This means that RDF may be a successful choice in front of classical fossil fuels, being in accordance with the new EU environmental policies, which entail the reduction of CO(2) emissions and the energetic valorization of MSW. However, further long-term environmental studies are necessary to corroborate the harmlessness of RDF, in terms of human health risks. Copyright © 2010 Elsevier B.V. All rights reserved.

  5. The decrease in the population of Gluconacetobacter diazotrophicus in sugarcane after nitrogen fertilization is related to plant physiology in split root experiments.

    Science.gov (United States)

    Rodríguez-Andrade, Osvaldo; Fuentes-Ramírez, Luis E; Morales-García, Yolanda E; Molina-Romero, Dalia; Bustillos-Cristales, María R; Martínez-Contreras, Rebeca D; Muñoz-Rojas, Jesús

    2015-01-01

    It has been established that a decrease in the population of Gluconacetobacter diazotrophicus associated with sugarcane occurs after nitrogen fertilization. This fact could be due to a direct influence of NH(4)NO(3) on bacterial cells or to changes in plant physiology after fertilizer addition, affecting bacterial establishment. In this work, we observed that survival of G. diazotrophicus was directly influenced when 44.8mM of NH(4)NO(3) (640mgN/plant) was used for in vitro experiments. Furthermore, micropropagated sugarcane plantlets were inoculated with G. diazotrophicus and used for split root experiments, in which both ends of the system were fertilized with a basal level of NH(4)NO(3) (0.35mM; 10mgN/plant). Twenty days post inoculation (dpi) one half of the plants were fertilized with a high dose of NH(4)NO(3) (6.3mM; 180 mgN/plant) on one end of the system. This nitrogen level was lower than that directly affecting G. diazotrophicus cells; however, it caused a decrease in the bacterial population in comparison with control plants fertilized with basal nitrogen levels. The decrease in the population of G. diazotrophicus was higher in pots fertilized with a basal nitrogen level when compared with the corresponding end supplied with high levels of NH4NO3 (100dpi; 80 days post fertilization) of the same plant system. These observations suggest that the high nitrogen level added to the plants induce systemic physiological changes that affect the establishment of G. diazotrophicus. Copyright © 2015 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

  6. Fusarium inhibition by wild populations of the medicinal plant Salvia africana-lutea L. linked to metabolomic profiling

    Science.gov (United States)

    2014-01-01

    Background Salvia africana-lutea L., an important medicinal sage used in the Western Cape (South Africa), can be termed a ‘broad-spectrum remedy’ suggesting the presence of a multiplicity of bioactive metabolites. This study aimed at assessing wild S. africana-lutea populations for chemotypic variation and anti-Fusarium properties. Methods Samples were collected from four wild growing population sites (Yzerfontein, Silwerstroomstrand, Koeberg and Brackenfell) and one garden growing location in Stellenbosch. Their antifungal activities against Fusarium verticillioides (strains: MRC 826 and MRC 8267) and F. proliferatum (strains: MRC 6908 and MRC 7140) that are aggressive mycotoxigenic phytopathogens were compared using an in vitro microdilution assay. To correlate antifungal activity to chemical profiles, three techniques viz. Gas chromatography-mass spectrometry (GC-MS); Liquid chromatography-mass spectrometry (LC-MS) and 1H Nuclear Magnetic Resonance (NMR) were employed. Principal Component Analysis (PCA) was applied to the NMR data. The partial least squares-discriminant analysis (PLS-DA) was used to integrate LC-MS and NMR data sets. All statistics were performed with the SIMCA-P + 12.0 software. Results The dichloromethane:methanol (1:1; v/v) extracts of the plant species collected from Stellenbosch demonstrated the strongest inhibition of F. verticillioides and F. proliferatum with minimum inhibitory concentration (MIC) values of 0.031 mg ml-1 and 0.063 mg ml-1 respectively. GC-MS showed four compounds which were unique to the Stellenbosch extracts. By integrating LC-MS and 1H NMR analyses, large chemotype differences leading to samples grouping by site when a multivariate analysis was performed, suggested strong plant-environment interactions as factors influencing metabolite composition. Signals distinguishing the Stellenbosch profile were in the aromatic part of the 1H NMR spectra. Conclusions This study shows the potential of chemotypes of

  7. Benefits of gene flow are mediated by individual variability in self-compatibility in small isolated populations of an endemic plant species.

    Science.gov (United States)

    Frye, Christopher T; Neel, Maile C

    2017-07-01

    Many rare and endemic species experience increased rates of self-fertilization and mating among close relatives as a consequence of existing in small populations within isolated habitat patches. Variability in self-compatibility among individuals within populations may reflect adaptation to local demography and genetic architecture, inbreeding, or drift. We use experimental hand-pollinations under natural field conditions to assess the effects of gene flow in 21 populations of the central Appalachian endemic Trifolium virginicum that varied in population size and degree of isolation. We quantified the effects of distance from pollen source on pollination success and fruit set. Rates of self-compatibility varied dramatically among maternal plants, ranging from 0% to 100%. This variation was unrelated to population size or degree of isolation. Nearly continuous variation in the success of selfing and near-cross-matings via hand pollination suggests that T. virginicum expresses pseudo-self-fertility, whereby plants carrying the same S-allele mate successfully by altering the self-incompatibility reaction. However, outcrossing among populations produced significantly higher fruit set than within populations, an indication of drift load. These results are consistent with strong selection acting to break down self-incompatibility in these small populations and/or early-acting inbreeding depression expressed upon selfing.

  8. Disease status and population origin effects on floral scent: potential consequences for oviposition and fruit predation in a complex interaction between a plant, fungus, and noctuid moth

    NARCIS (Netherlands)

    Dötterl, S.; Jürgens, A.; Wolfe, L.M.; Biere, A.

    2009-01-01

    In the Silene latifolia-Hadena bicruris nursery pollination system, the Hadena moth is both pollinator and seed predator of its host plant. Floral scent, which differs among S. latifolia individuals and populations, is important for adult Hadena to locate its host. However, the success of moth

  9. Population dynamics of plant nematodes in cultivated soil: effect of summer cover crops in newly cleared land.

    Science.gov (United States)

    Brodie, B B; Good, J M; Jaworski, C A

    1970-07-01

    Five nematode species were studied for ability to develop on seven summer cover crops in rotation with tomato transplants grown every third year. Increase of Tylenchorhynchus claytoni, Trichodorus christiei, Pratylenchus brachyurus, Helicotylenchus dihystera, and Xiphinema americanum in newly cleared soil varied with different cover crops. No substantial nematode population increases occurred until the third summer of crop growth. All species except X. americanum and H. dihystera developed best on sudangrass and millet. Crotalaria caused substantial increase of H. dihystera and P. brachyurus but suppressed the other species. Marigold suppressed all species except X. americanum which increased substantially on marigold during the 5th year. Cotton favored rapid increase of T. christiei, and moderate increases of all species except T. claytoni which was suppressed. Beggarweed favored moderate increases of T. christiei and H. dihystera but suppressed the other species. Hairy indigo favored rapid increase of H. dihystera, moderate increases of T. christiei and X. americanum, and suppressed the other species. Number of marketable transplants was reduced after 2 years of sudangrass and cotton; these crops favored increases of T. christiei and T. claytoni. The better cover crops prevented increases of most plant parasitic nematodes in land cropped to tomato, a suitable host.

  10. Studies on Plant Population and Stand Establishment Techniques for Increasing Productivity of Rice in Dera Ismail Khan, Pakistan

    Directory of Open Access Journals (Sweden)

    Mohammad Safdar BALOCH

    2007-06-01

    Full Text Available Rice production in Pakistan is constraint by many factors pertaining to prevalent planting techniques. A research on the feasibility of new planting techniques (direct seeding on flat, transplanting on flat, direct seeding on ridges, transplanting on ridges and parachute planting in transplanted and direct wet-seeded rice was undertaken at Dera Ismail Khan region of Pakistan's North West Frontier Province during 2002 and 2003. Among the planting techniques, the best performance for the yield formation and economic evaluation was noted for transplanting on flat during both years. Chinese parachute planting technology also showed very promising results in most of the parameters. Direct seeding on ridges could not excel transplanting on flat and parachute planting during both cropping seasons. The findings concluded the feasibility of parachute planting technology along with traditional rice transplanting on flat over all other planting techniques being practiced in the area.

  11. Long-term variability of iron supply, marine export production, and sea surface temperature in the subantarctic Atlantic, implications for atmospheric CO2

    Science.gov (United States)

    Martinez-Garcia, A.; Rosell-Mele, A.; Geibert, W.; Gersonde, R.; Masque, P.; Gaspari, V.; Barbante, C.

    2008-12-01

    Paleoclimatic reconstructions have provided a unique dataset to test the sensitivity of climate system to changes in atmospheric CO2 concentrations. However, the mechanisms behind glacial/interglacial (G/IG) variations in atmospheric CO2 concentrations observed in the Antarctic ice cores over the last 800 ky are still not completely understood. Here we present a multiproxy dataset of sea surface temperatures (SST), dust and iron supply, and marine export production, from the marine sediment core PS2489-2/ODP Site 1090 located in the subantarctic Atlantic (SA). This dataset allows us to evaluate various hypotheses focussing on the role of the Southern Ocean (SO) in modulating atmospheric CO2 over the last 800ky, and provides new information on SST, dust, and export production back to the Pliocene. The close correlation observed between iron inputs and marine export production in our record suggests that the process of iron fertilization has been a recurrent process operating in the SA over the G/IG cycles of the last 1.1 My. However, our data indicates that marine productivity in the present Subantarctic Zone can only explain a fraction of atmospheric CO2 changes occurring at glacial maxima in each glacial stage. Moreover, the good correlation of our SST to the EPICA Dome C records (EDC) temperature reconstruction over the last 800ka, suggest that physical processes, possibly related to changes in Antarctic sea-ice extent, surface water stratification and westerly winds position have also played an important role in modulating atmospheric CO2 over the last 800ky. On the long-term, our paleo-SST record reveals a major cooling event around 1.2-1.5 Ma that may have caused a profound impact on atmospheric CO2 and hence in the transition to a 100 kyr world during the Middle Pleistocene Climatic Transition.

  12. Observed Temporal and Spatial Variability in the Marine Environment at the Sub-Antarctic Prince Edward Islands - Evidence of a Changing Climate?

    Science.gov (United States)

    Asdar, S.; Deshayes, J.; Ansorge, I. J.

    2016-02-01

    The sub-Antarctic Prince Edward Islands (PEI) (47°S,38°E) are classified as isolated, hostile, impoverished regions, in which the terrestrial and marine ecosystems are relatively simple and extremely sensitive to perturbations. Their location between the Sub-Antarctic Front (SAF) and the Antarctic Polar Front (APF), bordering the Antarctic Circumpolar Current (ACC) provides an ideal natural laboratory for studying how organisms, ecological processes and ecosystems respond to a changing ocean climate in the Southern Ocean. Recent studies have proposed that climate changes reported at the PEI may correspond in time to a southward shift of the ACC and in particular of the SAF. This southward migration in the geographic position is likely to coincide with dramatic changes in the distribution of species and total productivity of this region. This study focuses on the inter-comparison of observations available at these islands. Using spectral analysis which is a study of the frequency domain characteristics of a process, we first determine the dominant characteristics of both the temporal and spatial variability of physical and biogeochemical properties. In doing so the authors are able to determine whether and how these indices of variability interact with one another in order to understand better the mechanisms underpinning this variability, i.e. the seasonal zonal migrations associated with the SAF. Additionally, we include in our analysis recent data from 2 ADCP moorings deployed between the islands from 2014 to 2015. These in-situ observations of circulation and hydrography in the vicinity of the islands provide a unique opportunity to establish a better understanding of how large scale climatic variability may impact local conditions, and more importantly its influence on the fragile ecosystem surrounding the PEI.

  13. Organic matter characterization and decomposition dynamics in sub-Antarctic streams impacted by invasive beavers Caracterización de la materia orgánica y la dinámica de descomposición en arroyos subantárticos impactados por castores invasores

    OpenAIRE

    Erica Ulloa; Anderson, Christopher B.; Marcelo Ardón; Silvia Murcia; Alejandro E.J Valenzuela

    2012-01-01

    Despite being a relatively remote and well conserved area, the sub-Antarctic ecoregion faces pressing global threats from climate change, the ozone hole and introduced species. Its freshwater ecosystems are one of the least studied components of this biome, but they are known to confront a host of invasive taxa including trout and beavers. We set out to understand the basic characterization and dynamics of organic matter processing and decomposition in sub-Antarctic streams under natural fore...

  14. Esterase polymorphism and the analysis of genetic diversity and structure in cactus populations descended from Cereus peruvianus plants regenerated in vitro.

    Science.gov (United States)

    Sala, Juliana; Mangolin, Claudete Aparecida; Franzoni, Juliana; Machado, Maria de Fátima Pires da Silva

    2011-04-01

    The genetic structure of Cereus peruvianus populations descended from cultivated plants (F(1) populations) and from plants regenerated in vitro (R(1) populations) was analyzed using α- and β-esterase isozymes in native PAGE. The estimated proportion of polymorphic loci was higher (50%) in the R(1) populations than the F(1) populations (42.85%). The mean observed (0.5599) and expected (0.5620) heterozygosity in R(1) descendents was also higher than the rates in F(1) descendents (H (o) = 0.4142; H (e) = 0.4977). A low level of population differentiation was detected in R(1) descendents (F (st) = 0.05). In contrast, population differentiation was high in F(1) descendents (0.2583). Esterase analysis using PAGE showed that artificial selection by silvicultural management provides high genetic diversity and a large genetic basis for C. peruvianus, whereas in vitro selection from callus tissue culture involves an increase of heterozygosity levels in descendents from somaclones and a low level of interpopulational divergence.

  15. Rapid Buildup of Genetic Diversity in Founder Populations of the Gynodioecious Plant Species Origanum vulgare after Semi-Natural Grassland Restoration

    Science.gov (United States)

    Helsen, Kenny; Jacquemyn, Hans; Hermy, Martin; Vandepitte, Katrien; Honnay, Olivier

    2013-01-01

    In most landscapes the success of habitat restoration is largely dependent on spontaneous colonization of plant species. This colonization process, and the outcome of restoration practices, can only be considered successful if the genetic makeup of founding populations is not eroded through founder effects and subsequent genetic drift. Here we used 10 microsatellite markers to investigate the genetic effects of recent colonization of the long-lived gynodioecious species Origanum vulgare in restored semi-natural grassland patches. We compared the genetic diversity and differentiation of fourteen recent populations with that of thirteen old, putative source populations, and we evaluated the effects of spatial configuration of the populations on colonization patterns. We did not observe decreased genetic diversity in recent populations, or inflated genetic differentiation among them. Nevertheless, a significantly higher inbreeding coefficient was observed in recent populations, although this was not associated with negative fitness effects. Overall population genetic differentiation was low (FST = 0.040). Individuals of restored populations were assigned to on average 6.1 different source populations (likely following the ‘migrant pool’ model). Gene flow was, however, affected by the spatial configuration of the grasslands, with gene flow into the recent populations mainly originating from nearby source populations. This study demonstrates how spontaneous colonization after habitat restoration can lead to viable populations in a relatively short time, overcoming pronounced founder effects, when several source populations are nearby. Restored populations can therefore rapidly act as stepping stones and sources of genetic diversity, likely increasing overall metapopulation viability of the study species. PMID:23840642

  16. Regional genetic diversity patterns in Antarctic hairgrass (Deschampsia antartica Desv.)

    NARCIS (Netherlands)

    van de Wouw, M.J.; Van Dijk, P.J.; Huiskes, A.H.L.

    2008-01-01

    Aim To determine patterns in diversity of a major Antarctic plant species, including relationships of Antarctic populations with those outside the Antarctic zone. Location Antarctic Peninsula, Maritime Antarctica, sub-Antarctic islands, Falkland Islands and South America. Methods Amplified fragment

  17. Biomarker of chronic cadmium exposure in a population residing in the vicinity of a zinc producing plant

    Energy Technology Data Exchange (ETDEWEB)

    Bratveit, Magne, E-mail: magne.bratveit@isf.uib.no [Department for Public Health and Primary Health Care, Occupational and Environmental Medicine, University of Bergen, Bergen (Norway); Uni Health, Bergen (Norway); Mageroy, Nils, E-mail: nils.mageroy@isf.uib.no [Uni Health, Bergen (Norway); Gundersen, Hilde, E-mail: hilde.gundersen@isf.uib.no [Department for Public Health and Primary Health Care, Occupational and Environmental Medicine, University of Bergen, Bergen (Norway); Vahter, Marie, E-mail: Marie.Vahter@ki.se [Division of Metals and Health, Institute of Environmental Medicine, Karolinska Institutet, Stockholm (Sweden); Moen, Bente E., E-mail: Bente.Moen@isf.uib.no [Department for Public Health and Primary Health Care, Occupational and Environmental Medicine, University of Bergen, Bergen (Norway)

    2011-09-15

    residential area close to a zinc smelter. {yields} Urinary cadmium did not differ between populations close to the plant and controls. {yields} Positive correlation between cadmium and {alpha}1-microglobulin (ProteinHC) in urine. {yields} No difference in ProteinHC between residents in polluted area and controls. {yields} No indications of elevated cadmium exposure or kidney damage in polluted area.

  18. No Genetic Diversity at Molecular Markers and Strong Phenotypic Plasticity in Populations of Ranunculus nodiflorus, an Endangered Plant Species in France

    Science.gov (United States)

    Noel, Florence; Machon, Nathalie; Porcher, Emmanuelle

    2007-01-01

    Background and Aims Although conservation biology has long focused on population dynamics and genetics, phenotypic plasticity is likely to play a significant role in population viability. Here, an investigation is made into the relative contribution of genetic diversity and phenotypic plasticity to the phenotypic variation in natural populations of Ranunculus nodiflorus, a rare annual plant inhabiting temporary puddles in the Fontainebleau forest (Paris region, France) and exhibiting metapopulation dynamics. Methods The genetic diversity and phenotypic plasticity of quantitative traits (morphological and fitness components) were measured in five populations, using a combination of field measurements, common garden experiments and genotyping at microsatellite loci. Key Results It is shown that populations exhibit almost undetectable genetic diversity at molecular markers, and that the variation in quantitative traits observed among populations is due to a high level of phenotypic plasticity. Despite the lack of genetic diversity, the natural population of R. nodiflorus exhibits large population sizes and does not appear threatened by extinction; this may be attributable to large phenotypic plasticity, enabling the production of numerous seeds under a wide range of environmental conditions. Conclusions Efficient conservation of the populations can only be based on habitat management, to favour the maintenance of microenvironmental variation and the resulting strong phenotypic plasticity. In contrast, classical actions aiming to improve genetic diversity are useless in the present case. PMID:17468109

  19. Experimental and genetic analyses reveal that inbreeding depression declines with increased self-fertilization among populations of a coastal dune plant.

    Science.gov (United States)

    Dart, S; Eckert, C G

    2013-03-01

    Theory predicts that inbreeding depression (ID) should decline via purging in self-fertilizing populations. Yet, intraspecific comparisons between selfing and outcrossing populations are few and provide only mixed support for this key evolutionary process. We estimated ID for large-flowered (LF), predominantly outcrossing vs. small-flowered (SF), predominantly selfing populations of the dune endemic Camissoniopsis cheiranthifolia by comparing selfed and crossed progeny in glasshouse environments differing in soil moisture, and by comparing allozyme-based estimates of the proportion of seeds selfed and inbreeding coefficient of mature plants. Based on lifetime measures of dry mass and flower production, ID was stronger in nine LF populations [mean δ = 1-(fitness of selfed seed/fitness of outcrossed seed) = 0.39] than 16 SF populations (mean δ = 0.03). However, predispersal ID during seed maturation was not stronger for LF populations, and ID was not more pronounced under simulated drought, a pervasive stress in sand dune habitat. Genetic estimates of δ were also higher for four LF (δ = 1.23) than five SF (δ = 0.66) populations; however, broad confidence intervals around these estimates overlapped. These results are consistent with purging, but selective interference among loci may be required to maintain strong ID in partially selfing LF populations, and trade-offs between selfed and outcrossed fitness are likely required to maintain outcrossing in SF populations. © 2013 The Authors. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology.

  20. Genotype composition of populations of grapefruit-cross-protecting citrus tristeza virus strain GFMS12 in different host plants and aphid-transmitted sub-isolates.

    Science.gov (United States)

    Scott, Katherine Anne; Hlela, Quinsile; Zablocki, Olivier; Read, David; van Vuuren, Stephanus; Pietersen, Gerhard

    2013-01-01

    Citrus tristeza virus (CTV) causes severe losses in grapefruit production in South Africa and requires mild-strain cross-protection to maintain production. Unfortunately, cross-protection breakdown of the pre-immunizing CTV grapefruit mild source GFMS12 is prevalent in grapefruit in South Africa. The CTV genotype composition of the GFMS12 population inoculated onto different hosts was determined by sequencing part of ORF1a and the p23 gene of multiple clones from each plant. Analysis of the GFMS12 population in Mexican lime and Marsh and Star Ruby grapefruit varieties revealed that at least four genotypes occur in the GFMS12 population and that genotype compositions differed amongst the populations in different host plants. Single-aphid-transmitted sub-isolates derived from the GFMS12 mother population on Mexican lime appeared to contain three populations of a mixture of VT-like and recombinant B165/VT-like genotypes; a mixture of recombinant RB/VT- and B165/VT-like genotypes; and a single recombinant B165/VT-like genotype. This study underlines the importance of determining the genotype composition of a potential CTV pre-immunizing source on a range of inoculated host species before utilization.

  1. Chloroplast and nuclear DNA variation among homozygous plants in a population of the autogamous annual Microseris douglasii (Asteraceae, Lactuceae)

    NARCIS (Netherlands)

    Roelofs, D.; Bachmann, K

    The autogamous diploid annual Microseris douglasii of California occurs in many isolated populations. The populations consist of one to many highly inbred biotypes. Morphological variation among populations usually is greater than within populations. In spite of the virtual absence of gene flow even

  2. The Microbial Database for Danish wastewater treatment plants with nutrient removal (MiDas-DK) - a tool for understanding activated sludge population dynamics and community stability.

    Science.gov (United States)

    Mielczarek, A T; Saunders, A M; Larsen, P; Albertsen, M; Stevenson, M; Nielsen, J L; Nielsen, P H

    2013-01-01

    Since 2006 more than 50 Danish full-scale wastewater treatment plants with nutrient removal have been investigated in a project called 'The Microbial Database for Danish Activated Sludge Wastewater Treatment Plants with Nutrient Removal (MiDas-DK)'. Comprehensive sets of samples have been collected, analyzed and associated with extensive operational data from the plants. The community composition was analyzed by quantitative fluorescence in situ hybridization (FISH) supported by 16S rRNA amplicon sequencing and deep metagenomics. MiDas-DK has been a powerful tool to study the complex activated sludge ecosystems, and, besides many scientific articles on fundamental issues on mixed communities encompassing nitrifiers, denitrifiers, bacteria involved in P-removal, hydrolysis, fermentation, and foaming, the project has provided results that can be used to optimize the operation of full-scale plants and carry out trouble-shooting. A core microbial community has been defined comprising the majority of microorganisms present in the plants. Time series have been established, providing an overview of temporal variations in the different plants. Interestingly, although most microorganisms were present in all plants, there seemed to be plant-specific factors that controlled the population composition thereby keeping it unique in each plant over time. Statistical analyses of FISH and operational data revealed some correlations, but less than expected. MiDas-DK (www.midasdk.dk) will continue over the next years and we hope the approach can inspire others to make similar projects in other parts of the world to get a more comprehensive understanding of microbial communities in wastewater engineering.

  3. Genetic differentiation among Maruca vitrata F. (Lepidoptera: Crambidae populations on cultivated cowpea and wild host plants: implications for insect resistance management and biological control strategies.

    Directory of Open Access Journals (Sweden)

    Tolulope A Agunbiade

    Full Text Available Maruca vitrata Fabricius (Lepidoptera: Crambidae is a polyphagous insect pest that feeds on a variety of leguminous plants in the tropics and subtropics. The contribution of host-associated genetic variation on population structure was investigated using analysis of mitochondrial cytochrome oxidase 1 (cox1 sequence and microsatellite marker data from M. vitrata collected from cultivated cowpea (Vigna unguiculata L. Walp., and alternative host plants Pueraria phaseoloides (Roxb. Benth. var. javanica (Benth. Baker, Loncocarpus sericeus (Poir, and Tephrosia candida (Roxb.. Analyses of microsatellite data revealed a significant global FST estimate of 0.05 (P≤0.001. The program STRUCTURE estimated 2 genotypic clusters (co-ancestries on the four host plants across 3 geographic locations, but little geographic variation was predicted among genotypes from different geographic locations using analysis of molecular variance (AMOVA; among group variation -0.68% or F-statistics (FSTLoc = -0.01; P = 0.62. These results were corroborated by mitochondrial haplotype data (φSTLoc = 0.05; P = 0.92. In contrast, genotypes obtained from different host plants showed low but significant levels of genetic variation (FSTHost = 0.04; P = 0.01, which accounted for 4.08% of the total genetic variation, but was not congruent with mitochondrial haplotype analyses (φSTHost = 0.06; P = 0.27. Variation among host plants at a location and host plants among locations showed no consistent evidence for M. vitrata population subdivision. These results suggest that host plants do not significantly influence the genetic structure of M. vitrata, and this has implications for biocontrol agent releases as well as insecticide resistance management (IRM for M. vitrata in West Africa.

  4. Description of Pseudingolfiella possessionis n. sp. (Crustacea, Amphipoda) from sub-Antarctic Île de La Possession, Crozet archipelago: the second freshwater amphipod known from the Antarctic biome, a human introduction of Gondwanan ancestry?

    Science.gov (United States)

    Smet, Willem H De

    2015-03-31

    A new species of freshwater amphipod, Pseudingolfiella possessionis n. sp. (Senticaudata, Pseudingolfiellidae), is described from the submerged moss vegetation of small brooklets at sub-Antarctic Île de La Possession, Crozet archipelago. It constitutes the second freshwater amphipod species known for the sub-Antarctic and Antarctic region, and the fourth member of the genus. The main characters distinguishing it from all congeners are: the spine on the posterior margin of the dactylus, incisor and lamina mobilis of mandible each with 5 teeth, the setation of the maxilliped, the vestigial second article of pleopod 3 in the female, the undulate and laterally notched posterolateral margin of the external ramus of uropods 1 and 2 in the male, the spinulate dorsomedian projection of the telson.

  5. Trichome morphology as an indicator of high rubber bearing guayule (Parthenium argentatum gray) plants in native populations

    Energy Technology Data Exchange (ETDEWEB)

    Mehta, I.J.; Dhillon, S.P.; Hanson, G.P.

    1979-01-01

    Parthenium argentatum Gray (guayule) and P. incanum (mariola) grow in close asociations in their native habitat of Mexico. Variation in rubber concentration and morphology of guayule has been known for a long time. Studies of over 75 native guayule plants indicated the presence of at least three prominent forms of guayule plants. Group I guayule plants have oblanceolate leaves and leaf margins are entire to two-toothed. T-shaped leaf trichomes are with centrally attached stalk and cap cell with two blunt ends. Plants in this group are high in rubber, containing on the average 17% rubber. Group II guayule plants have narrow elliptic leaves and leaf margins are entire to four-toothed. T-shaped trichomes have an acentrally attached stalk and a cap cell with short end blunt, long end pointed and straight. Rubber content in these plants averages 10%. Group III guayule plants have ovate leaves and leaf margins are four- to eight-toothed. T-trichomes have an acentrally attached stalk and a cap cell with short end blunt, long end pointed and wavy or curved. These plants on the average contain 6% rubber. Morphological as well as biochemical data indicate the presence of mariola genes in the last two groups of plants and this has resulted in an increase in trichome length and a decrease in the rubber content. Group II guayule plants are of more common occurrence than the others. Based on the data presented here, high rubber bearing guayule plants in native stands can be easily selected by analyzing trichome morphology. 16 figures, 2 tables.

  6. Assessment of reproductive capacity of seeds sampled from natural populations of plants from a territory contaminated with radionuclides and heavy metals

    Energy Technology Data Exchange (ETDEWEB)

    Vakhusheva, O.; Evseeva, T. [Institute of biology Komi SC Ural Branch of RAS (Russian Federation)

    2014-07-01

    Plants are an essential component of any ecosystem and are permanently exposed to soil contamination. Therefore, they are widely used for characterization of ecological situation of the territory. Located at the base of the food chain, plants are exposed to toxic agents before the organisms at higher trophic levels. Kirovo-Chepetsk chemical plant (Kirov, Russia) is one of the biggest chemical enterprises in Europe. Vascular plant communities from surrounding area are exposed to industrial wastes, including uranium production wastes from 1938. The aim of this work was to estimate reproductive capacity of Urtica dioica L., Cirsium setosum (Willd.) Bess and Filipendula ulmaria (L.) Maxim - natural populations inhabiting the chemical plant industrial zone. The plant species studied are common for the meadow communities of south taiga zone, and are characterized by high seed yield and living in wide range of ecological conditions. Plant seeds were collected from two experimental sites with different soil contamination levels, located in the vicinity of the Kirovo-Chepetsk chemical plant, as well as from the reference site, in 2011 and 2012. Soil specific activities of {sup 137}Cs and {sup 90}Sr and concentrations of Ni, Pb, Cd, Zn, Hg and Cu were measured and ecological criteria of the radioactive (C{sub r}) and chemical (C{sub c}) contamination of the soil cover were calculated. Seeds germination, germinative energy and seedling survival rate were used for assessing reproductive capacity. Urtica dioicawas found to be the most sensitive among plant species studied. Germination of seeds from contaminated sites was significantly lower compared with the reference values. Exponential relationship was found between the levels of soil radioactive contamination and seeds germination (R{sup 2}=0.8, p<0.001). Germination of Cirsium setosum seeds, sampled from contaminated sites, exceeded the values obtained for the reference plant population and was linearly dependent (R{sup 2

  7. Food assimilated by two sympatric populations of the brown planthopper Nilaparvata lugens (Delphacidae) feeding on different host plants contaminates insect DNA detected by RAPD-PCR analysis.

    Science.gov (United States)

    Latif, M A; Omar, M Y; Tan, S G; Siraj, S S; Ali, M E; Rafii, M Y

    2012-01-09

    Contamination of insect DNA for RAPD-PCR analysis can be a problem because many primers are non-specific and DNA from parasites or gut contents may be simultaneously extracted along with that of the insect. We measured the quantity of food ingested and assimilated by two sympatric populations of brown planthopper (BPH), Nilaparvata lugens, one from rice and the other from Leersia hexandra (Poaceae), a wetland forage grass, and we also investigated whether host plant DNA contaminates that of herbivore insects in extractions of whole insects. Ingestion and assimilation of food were reduced significantly when individuals derived from one host plant were caged on the other species. The bands, OPA3 (1.25), OPD3 (1.10), OPD3 (0.80), OPD3 (0.60), pUC/M13F (0.35), pUC/M13F (0.20), BOXAIR (0.50), peh#3 (0.50), and peh#3 (0.17) were found in both rice-infesting populations of brown planthopper and its host plant (rice). Similarly, the bands, OPA4 (1.00), OPB10 (0.70), OPD3 (0.90), OPD3 (0.80), OPD3 (0.60), pUC/ M13F (0.35), pUC/M13F (0.20), and BOXAIR (0.50) were found in both Leersia-infesting populations of brown planthopper and the host plant. So, it is clear that the DNA bands amplified in the host plants were also found in the extracts from the insects feeding on them.

  8. Plant planting

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report summarizes planting activities on Neal Smith National Wildlife Refuge (formerly Walnut Creek National Wildlife Refuge) between 1995 and 2009.

  9. Model-based scenario planning to develop climate change adaptation strategies for rare plant populations in grassland reserves

    Science.gov (United States)

    Laura Phillips-Mao; Susan M. Galatowitsch; Stephanie A. Snyder; Robert G. Haight

    2016-01-01

    Incorporating climate change into conservation decision-making at site and population scales is challenging due to uncertainties associated with localized climate change impacts and population responses to multiple interacting impacts and adaptation strategies. We explore the use of spatially explicit population models to facilitate scenario analysis, a conservation...

  10. Morphological, Phenological And Agronomical Characterisation Of Variability Among Common Bean (Phaseolus Vulgaris L. Local Populations From The National Centre For Plant Genetic Resources: Polish Genebank

    Directory of Open Access Journals (Sweden)

    Boros Lech

    2014-12-01

    Full Text Available The main purpose of this work was to analyse the morphological, phenological and agronomical variability among common bean local populations from The National Centre for Plant Genetic Resources, Polish Genebank, in order to know the relation among them, and to identify potentially useful accessions for future production and breeding. A considerable genotypic variation for number of seeds per plant, number of pods per plant and weight of seeds per plant were found. Studied bean accessions differed significantly in terms of thousand seeds weight (TSW as well as severity of bacterial halo blight and anthracnose, the major bean diseases. The lowest genotypic diversity was found for the percentage of protein in the seeds, the length of the vegetation period and lodging. The cluster analysis allowed identification of five groups of bean accessions. Genotypes from the first cluster (POLPOD 98-77, KOS 002 and Raba cv. and from the second cluster (WUKR 06-573a, KRA 4, WUKR 06-0534 together with Prosna cv. are of the highest usefulness for breeding purposes. There was no grouping of local populations depending on region of origin.

  11. Resistance-breaking population of Meloidogyne incognita utilizes plant peroxidase to scavenge reactive oxygen species, thereby promoting parasitism on tomato carrying Mi-1 gene.

    Science.gov (United States)

    Guan, Tinglong; Shen, Jinhua; Fa, Yang; Su, Yishi; Wang, Xuan; Li, Hongmei

    2017-01-01

    Resistance conferred by the Mi-1 gene from Solanum peruvianum is effective and widely used for controlling root-knot nematodes (RKNs, Meloidogyne spp.). However, breakdown of resistance by RKNs seriously threatens the durable application of the resistance resource. Here, a resistance-breaking population of M. incognita was selected from an avirulent population by continuously inoculating on Mi-1-carrying tomato. Histological observations showed the resistance-breaking population would not induce hypersensitive response (HR) when infecting Mi-1-carrying tomato, while avirulent population did. A total of 308 differentially expressed genes (DEGs) were identified from Mi-1-carrying tomato upon infection with resistance-breaking versus avirulent populations by RNA-seq. The expression patterns of 23 selected DEGs were validated by quantitative real-time PCR (qRT-PCR). Subsequently, seven out of nine highly up-regulated DEGs were successfully knocked down in Mi-1-carrying tomato by tobacco rattle virus (TRV) mediated RNAi. The TRV line targeting a peroxidase gene showed a much higher magnitude of reactive oxygen species (ROS) and distinct reduction of pathogenicity upon infection of the resistance-breaking population compared with that of TRV::gfp line. Our results suggested that plant peroxidase might be exploited by resistance-breaking population of M. incognita to scavenge ROS, so as to overcome Mi-1-mediated resistance. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Selective enhancement of the fluorescent pseudomonad population after amending the recirculating nutrient solution of hydroponically grown plants with a nitrogen stabilizer.

    Science.gov (United States)

    Pagliaccia, D; Merhaut, D; Colao, M C; Ruzzi, M; Saccardo, F; Stanghellini, M E

    2008-10-01

    Fluorescent pseudomonads have been associated, via diverse mechanisms, with suppression of root disease caused by numerous fungal and fungal-like pathogens. However, inconsistent performance in disease abatement, after their employment, has been a problem. This has been attributed, in part, to the inability of the biocontrol bacterium to maintain a critical threshold population necessary for sustained biocontrol activity. Our results indicate that a nitrogen stabilizer (N-Serve, Dow Agrosciences) selectively and significantly enhanced, by two to three orders of magnitude, the resident population of fluorescent pseudomonads in the amended (i.e., 25 microg ml(-1) nitrapyrin, the active ingredient) and recycled nutrient solution used in the cultivation of hydroponically grown gerbera and pepper plants. Pseudomonas putida was confirmed as the predominant bacterium selectively enhanced. Terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rDNA suggested that N-Serve selectively increased P. putida and reduced bacterial diversity 72 h after application. In vitro tests revealed that the observed population increases of fluorescent pseudomonads were preceded by an early growth suppression of indigenous aerobic heterotrophic bacteria (AHB) population. Interestingly, the fluorescent pseudomonad population did not undergo this decrease, as shown in competition assays. Xylene and 1,2,4-trimethylbenzene (i.e., the inert ingredients in N-Serve) were responsible for a significant percentage of the fluorescent pseudomonad population increase. Furthermore, those increases were significantly higher when the active ingredient (i.e., nitrapyrin) and the inert ingredients were combined, which suggests a synergistic response. P. putida strains were screened for the ability to produce antifungal compounds and for the antifungal activity against Pythium aphanidermatum and Phytophthora capsici. The results of this study suggest the presence of diverse mechanisms with

  13. Cholesterol lowering effect of a soy drink enriched with plant sterols in a French population with moderate hypercholesterolemia

    Directory of Open Access Journals (Sweden)

    Bard Jean-Marie

    2008-10-01

    Full Text Available Abstract Background Plant sterols are an established non-pharmacological means to reduce total and LDL blood cholesterol concentrations and are therefore recommended for cholesterol management by worldwide-renown health care institutions. Their efficacy has been proven in many types of foods with the majority of trials conducted in spreads or dairy products. As an alternative to dairy products, soy based foods are common throughout the world. Yet, there is little evidence supporting the efficacy of plant sterols in soy-based foods. The objective of this study was to investigate the effect of a soy drink enriched with plant sterols on blood lipid profiles in moderately hypercholesterolemic subjects. Methods In a randomized, placebo-controlled double-blind mono-centric study, 50 subjects were assigned to 200 ml of soy drink either enriched with 2.6 g plant sterol esters (1.6 g/d free plant sterol equivalents or without plant sterols (control for 8 weeks. Subjects were instructed to maintain stable diet pattern and physical activity. Plasma concentrations of lipids were measured at initial visit, after 4 weeks and after 8 weeks. The primary measurement was the change in LDL cholesterol (LDL-C. Secondary measurements were changes in total cholesterol (TC, non-HDL cholesterol (non-HDL-C, HDL cholesterol (HDL-C and triglycerides. Results Regular consumption of the soy drink enriched with plant sterols for 8 weeks significantly reduced LDL- C by 0.29 mmol/l or 7% compared to baseline (p 96%, and products were well tolerated. Conclusion Daily consumption of a plant sterol-enriched soy drink significantly decreased total, non-HDL and LDL cholesterol and is therefore an interesting and convenient aid in managing mild to moderate hypercholesterolemia.

  14. A geoprocessing model for the selection of populations most affected by diffuse industrial contamination: the case of oil refinery plants

    OpenAIRE

    Roberto Pasetto; Marco De Santis

    2013-01-01

    INTRODUCTION. A method to select populations living in areas affected by diffuse environmental contamination is presented, with particular regard to oil refineries, in the Italian context. The reasons to use municipality instead of census tract populations for environment and health small-area studies of contaminated sites are discussed. METHODS. Populations most affected by diffuse environmental contamination are identified through a geoprocessing model. Data from the national census 2001 we...

  15. Genetic Diversity and Demographic History of Wild and Cultivated/Naturalised Plant Populations: Evidence from Dalmatian Sage (Salvia officinalis L., Lamiaceae.

    Directory of Open Access Journals (Sweden)

    Ivana Rešetnik

    Full Text Available Dalmatian sage (Salvia officinalis L., Lamiaceae is a well-known aromatic and medicinal Mediterranean plant that is native in coastal regions of the western Balkan and southern Apennine Peninsulas and is commonly cultivated worldwide. It is widely used in the food, pharmaceutical and cosmetic industries. Knowledge of its genetic diversity and spatiotemporal patterns is important for plant breeding programmes and conservation. We used eight microsatellite markers to investigate evolutionary history of indigenous populations as well as genetic diversity and structure within and among indigenous and cultivated/naturalised populations distributed across the Balkan Peninsula. The results showed a clear separation between the indigenous and cultivated/naturalised groups, with the cultivated material originating from one restricted geographical area. Most of the genetic diversity in both groups was attributable to differences among individuals within populations, although spatial genetic analysis of indigenous populations indicated the existence of isolation by distance. Geographical structuring of indigenous populations was found using clustering analysis, with three sub-clusters of indigenous populations. The highest level of gene diversity and the greatest number of private alleles were found in the central part of the eastern Adriatic coast, while decreases in gene diversity and number of private alleles were evident towards the northwestern Adriatic coast and southern and eastern regions of the Balkan Peninsula. The results of Ecological Niche Modelling during Last Glacial Maximum and Approximate Bayesian Computation suggested two plausible evolutionary trajectories: 1 the species survived in the glacial refugium in southern Adriatic coastal region with subsequent colonization events towards northern, eastern and southern Balkan Peninsula; 2 species survived in several refugia exhibiting concurrent divergence into three genetic groups. The insight

  16. The phloem-sap feeding mealybug (Ferrisia virgata carries 'Candidatus Liberibacter asiaticus' populations that do not cause disease in host plants.

    Directory of Open Access Journals (Sweden)

    Marco Pitino

    Full Text Available 'Candidatus Liberibacter asiaticus' (Las is the primary causal agent of huanglongbing (HLB, the most devastating disease of citrus worldwide. There are three known insect vectors of the HLB-associated bacteria, and all are members of the Hemiptera: Diaphorina citri (Psyllidae, Trioza erytreae (Triozidae, and Cacopsylla (Psylla citrisuga (Psyllidae. In this study, we found that another hemipteran, the striped mealybug Ferrisia virgata (Cockerell (Hemiptera: Pseudococcidae, was able to acquire and retain Las bacteria. The bacterial titers were positively correlated with the feeding acquisition time on Las-infected leaf discs, with a two-weeks feeding period resulting in Ct values ranging from 23.1 to 36.1 (8.24 × 10(7 to 1.07 × 10(4 Las cells per mealybug. We further discovered that the prophage/phage populations of Las in the mealybugs were different from those of Las in psyllids based on Las prophage-specific molecular markers: infected psyllids harbored the Las populations with prophage/phage FP1 and FP2, while infected mealybugs carried the Las populations with the iFP3 being the dominant prophage/phage. As in the psyllids, Las bacteria were shown to move through the insect gut wall to the salivary glands after being ingested by the mealybug based on a time-course quantitative polymerase chain reaction (qPCR assay of the dissected digestive systems. However, Las populations transmitted by the mealybugs did not cause disease in host plants. This is the first evidence of genetic difference among Las populations harbored by different insect vectors and difference among Las populations with respect to whether or not they cause disease in host plants.

  17. Genetic Diversity and Demographic History of Wild and Cultivated/Naturalised Plant Populations: Evidence from Dalmatian Sage (Salvia officinalis L., Lamiaceae).

    Science.gov (United States)

    Rešetnik, Ivana; Baričevič, Dea; Batîr Rusu, Diana; Carović-Stanko, Klaudija; Chatzopoulou, Paschalina; Dajić-Stevanović, Zora; Gonceariuc, Maria; Grdiša, Martina; Greguraš, Danijela; Ibraliu, Alban; Jug-Dujaković, Marija; Krasniqi, Elez; Liber, Zlatko; Murtić, Senad; Pećanac, Dragana; Radosavljević, Ivan; Stefkov, Gjoshe; Stešević, Danijela; Šoštarić, Ivan; Šatović, Zlatko

    2016-01-01

    Dalmatian sage (Salvia officinalis L., Lamiaceae) is a well-known aromatic and medicinal Mediterranean plant that is native in coastal regions of the western Balkan and southern Apennine Peninsulas and is commonly cultivated worldwide. It is widely used in the food, pharmaceutical and cosmetic industries. Knowledge of its genetic diversity and spatiotemporal patterns is important for plant breeding programmes and conservation. We used eight microsatellite markers to investigate evolutionary history of indigenous populations as well as genetic diversity and structure within and among indigenous and cultivated/naturalised populations distributed across the Balkan Peninsula. The results showed a clear separation between the indigenous and cultivated/naturalised groups, with the cultivated material originating from one restricted geographical area. Most of the genetic diversity in both groups was attributable to differences among individuals within populations, although spatial genetic analysis of indigenous populations indicated the existence of isolation by distance. Geographical structuring of indigenous populations was found using clustering analysis, with three sub-clusters of indigenous populations. The highest level of gene diversity and the greatest number of private alleles were found in the central part of the eastern Adriatic coast, while decreases in gene diversity and number of private alleles were evident towards the northwestern Adriatic coast and southern and eastern regions of the Balkan Peninsula. The results of Ecological Niche Modelling during Last Glacial Maximum and Approximate Bayesian Computation suggested two plausible evolutionary trajectories: 1) the species survived in the glacial refugium in southern Adriatic coastal region with subsequent colonization events towards northern, eastern and southern Balkan Peninsula; 2) species survived in several refugia exhibiting concurrent divergence into three genetic groups. The insight into genetic

  18. Effects of Secondary Plant Metabolites on Microbial Populations: Changes in Community Structure and Metabolic Activity in Contaminated Environments.

    Science.gov (United States)

    Musilova, Lucie; Ridl, Jakub; Polivkova, Marketa; Macek, Tomas; Uhlik, Ondrej

    2016-07-29

    Secondary plant metabolites (SPMEs) play an important role in plant survival in the environment and serve to establish ecological relationships between plants and other organisms. Communication between plants and microorganisms via SPMEs contained in root exudates or derived from litter decomposition is an example of this phenomenon. In this review, the general aspects of rhizodeposition together with the significance of terpenes and phenolic compounds are discussed in detail. We focus specifically on the effect of SPMEs on microbial community structure and metabolic activity in environments contaminated by polychlorinated biphenyls (PCBs) and polyaromatic hydrocarbons (PAHs). Furthermore, a section is devoted to a complex effect of plants and/or their metabolites contained in litter on bioremediation of contaminated sites. New insights are introduced from a study evaluating the effects of SPMEs derived during decomposition of grapefruit peel, lemon peel, and pears on bacterial communities and their ability to degrade PCBs in a long-term contaminated soil. The presented review supports the "secondary compound hypothesis" and demonstrates the potential of SPMEs for increasing the effectiveness of bioremediation processes.

  19. Between-population variation in plant performance traits and elemental composition of Colchicum autumnale L. and its relation to edaphic environments

    Directory of Open Access Journals (Sweden)

    Lucyna Mróz

    2011-01-01

    Full Text Available Variation in vegetative and reproductive performance and leaf mineral composition among 25 populations of Colchicum autumnale (meadow saffron from soils derived from six parent materials (limestone, marl, sandstone, greenstone, melaphyre and serpentine in southwestern Poland has been investigated. The plant size (PS, total le-af area (TLA, leaf shape (LS, number of fruits per plant (NFP, number of seeds per plant (NFP, total weight seed per plant (TWSP were estimated, and concentrations of seventeen elements (N, P, K, Ca, Mg, Na, S, Fe, Mn, Cu, Zn, Pb, Cd, Ni, Co, Cr, Mo were analyzed in leaf and soil samples. In soil samples, also soil pH, organic matter content and sand, silt and clay content were determined. All soils (except melaphyre soil contained elevated levels of Cr. Concentrations of soil Ni and Zn, Pb, Cd in serpentinite soil and polluted marl soils (respectively were significantly higher than those of other examined soils. Meadow saffron leaves from all sites (except marl sites contained elevated levels of Cr, Co and Ni. Statistical analysis, carried out with principal component analysis (PCA revealed that a good correlation exists between the element content in leaves and plant performance traits and soil environment. The leaf Ca content and NFP were correlated and were much higher in populations from metal (except Cr and nutrient-poor marl soils than in those from metal (except Ni in serpentine soiland nutrient moderate rich soils derived from melaphyre, greenstones, serpentinite, limestones and sandstones and in those from metal-rich and nutrient-poor polluted marl soils. Meadow saffron plants tended to take up higher amounts of N, P, K, Mn, Cu and Na and lower amounts of S and had much higher TLA in populations from sandstone soils than those in populations from serpentinite, melaphyre, greenstone, marl and limestone soils. The leaf Co, Ni, Cr, Mg concentrations were correlated and were much higher in populations from

  20. Integration of population genetic structure and plant response to climate change: sustaining genetic resources through evaluation of projected threats

    Science.gov (United States)

    Bryce A. Richardson; Marcus V. Warwell; Mee-Sook Kim; Ned B. Klopfenstein; Geral I. McDonald

    2010-01-01

    To assess threats or predict responses to disturbances, or both, it is essential to recognize and characterize the population structures of forest species in relation to changing environments. Appropriate management of these genetic resources in the future will require (1) understanding the existing genetic diversity/variation and population structure of forest trees...

  1. New findings and a new species of the genus Ammothea (Pycnogonida, Ammotheidae), with an updated identification key to all Antarctic and sub-Antarctic species

    Science.gov (United States)

    Cano-Sánchez, E.; López-González, P. J.

    2014-03-01

    Specimens of the pycnogonid genus Ammothea collected during the Polarstern cruise XXIII/8 (23 November 2006-30 January 2007) were studied. Nine species were recognized in this collection: Ammothea bentartica, A. bicorniculata, A. carolinensis, A. clausi, A. longispina, A. minor, A. spinosa, A. striata and A. tibialis. Three of them ( A. bentartica, A. bicorniculata and A. tibialis) are reported for the second time, enlarging their known geographical and bathymetric range. In the present contribution, the observed morphological variability of all collected Ammothea species is described and discussed. For the identification and description of the material, different museum specimens were consulted. Among them, we have consulted part of the Discovery collection housed at the Natural History Museum in London. That material was initially identified by Isabella Gordon, a reputed author in the field of pycnogonid taxonomy. A new species, based on a museum specimen previously highly confused in the literature, is proposed in the present contribution as Ammothea isabellae n. sp. The new taxon is compared with its closest congeners, especially with A. longispina and A. stylirostris. Finally, we propose an updated dichotomous key to species covering all currently known Antarctic and sub-Antarctic Ammothea species.

  2. Recovering greater fungal diversity from pristine and diesel fuel contaminated Sub-Antarctic soil through cultivation using a high and a novel low nutrient approach

    Directory of Open Access Journals (Sweden)

    Belinda Carlene Ferrari

    2011-11-01

    Full Text Available Novel cultivation strategies for bacteria are widespread and are well described for recovering greater diversity from the hitherto unculturable majority. While similar approaches have not been demonstrated for fungi it has been suggested that of the 1.5 million estimated species less than 5% have been recovered into pure culture. Fungi are known to be involved in many degradative processes, including the breakdown of hydrocarbons, and it has been speculated that in Polar Regions they contribute significantly to bioremediation of soils contaminated with hydrocarbons. Given the biotechnological potential of fungi there is a need to increase efforts for greater species recovery, particularly from extreme environments such as sub-Antarctic Macquarie Island. In this study, like the hitherto unculturable bacteria, high concentrations of nutrients selected for predominantly different species to that recovered using low nutrient media. By combining both approaches to cultivation from contaminated and non-contaminated soils, 99 fungal species were recovered, including 42 yet unidentified species, several of which were isolated from soils containing high concentrations of diesel fuel. These novel species will now be characterized for their potential role in hydrocarbon degradation.

  3. Extraction and characterization of collagen from Antarctic and Sub-Antarctic squid and its potential application in hybrid scaffolds for tissue engineering.

    Science.gov (United States)

    Coelho, Rui C G; Marques, Ana L P; Oliveira, Sara M; Diogo, Gabriela S; Pirraco, Rogério P; Moreira-Silva, Joana; Xavier, José C; Reis, Rui L; Silva, Tiago H; Mano, João F

    2017-09-01

    Collagen is the most abundant protein found in mammals and it exhibits a low immunogenicity, high biocompatibility and biodegradability when compared with others natural polymers. For this reason, it has been explored for the development of biologically instructive biomaterials with applications for tissue substitution and regeneration. Marine origin collagen has been pursued as an alternative to the more common bovine and porcine origins. This study focused on squid (Teuthoidea: Cephalopoda), particularly the Antarctic squid Kondakovia longimana and the Sub-Antarctic squid Illex argentinus as potential collagen sources. In this study, collagen has been isolated from the skins of the squids using acid-based and pepsin-based protocols, with the higher yield being obtained from I. argentinus in the presence of pepsin. The produced collagen has been characterized in terms of physicochemical properties, evidencing an amino acid profile similar to the one of calf collagen, but exhibiting a less preserved structure, with hydrolyzed portions and a lower melting temperature. Pepsin-soluble collagen isolated from I. argentinus was selected for further evaluation of biomedical potential, exploring its incorporation on poly-ε-caprolactone (PCL) 3D printed scaffolds for the development of hybrid scaffolds for tissue engineering, exhibiting hierarchical features. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Recovering greater fungal diversity from pristine and diesel fuel contaminated sub-antarctic soil through cultivation using both a high and a low nutrient media approach.

    Science.gov (United States)

    Ferrari, Belinda C; Zhang, Chengdong; van Dorst, Josie

    2011-01-01

    Novel cultivation strategies for bacteria are widespread and well described for recovering greater diversity from the "hitherto" unculturable majority. While similar approaches have not yet been demonstrated for fungi it has been suggested that of the 1.5 million estimated species less than 5% have been recovered into pure culture. Fungi are known to be involved in many degradative processes, including the breakdown of petroleum hydrocarbons, and it has been speculated that in Polar Regions they contribute significantly to bioremediation of contaminated soils. Given the biotechnological potential of fungi there is a need to increase efforts for greater species recovery, particularly from extreme environments such as sub-Antarctic Macquarie Island. In this study, like the yet-to-be cultured bacteria, high concentrations of nutrients selected for predominantly different fungal species to that recovered using a low nutrient media. By combining both media approaches to the cultivation of fungi from contaminated and non-contaminated soils, 91 fungal species were recovered, including 63 unidentified species. A preliminary biodegradation activity assay on a selection of isolates found that a high proportion of novel and described fungal species from a range of soil samples were capable of hydrocarbon degradation and should be characterized further.

  5. Silicic acid enrichment of subantarctic surface water from continental inputs along the Patagonian archipelago interior sea (41-56°S)

    Science.gov (United States)

    Torres, Rodrigo; Silva, Nelson; Reid, Brian; Frangopulos, Máximo

    2014-12-01

    We estimated Si∗, the surplus or deficit of orthosilicic acid (DSi) relative to nitrate available for diatom growth, in the Chilean Patagonian Archipelago Interior Sea (PAIS). Si∗ and salinity were negatively correlated in the PAIS because of the mixing of high nitrate, low DSi subantarctic surface water and high DSi, low nitrate continental freshwater runoff. Both the slope and the intercept of this relationship decreased from northern to southern Patagonia, which was likely a consequence of reduced DSi inputs from several overlapping hydrological, biological and geological drivers along this gradient. In general, lower freshwater DSi concentrations were expected below 46°S, and a lower total DSi load was expected from reduced runoff below 51°S. The north-south decreasing DSi concentration trend may be linked to dilutions from a higher proportion of runoff in latitudes with higher precipitation rates (45-53°S), the transition to more resistant granitic rocks and glacial melt-water from the Northern and Southern Patagonia Ice Fields (46-51°S) and a reduced density of volcanoes active during the Holocene (48-56°S). The intensification of a southward DSi deficit may be a forcing factor involved in the reported southward reductions in plankton biomass and a more frequent occurrence of non-diatom blooms in southern PAIS.

  6. Linking the response of bacterial populations to plant development through analysis of rhizosphere-competence traits of soil bacteria

    Science.gov (United States)

    Cho, H. J.; Karaoz, U.; Zhalnina, K.; Firestone, M. K.; Brodie, E.

    2016-12-01

    A growing plant root exudes changing combinations of compounds including root litter and other detritus throughout its developmental stages, providing a major source of organic C for rhizosphere bacteria. Clear patterns of microbial succession have been observed in the rhizosphere of a number of plants. These patterns of microbial succession are likely key to the processing of soil organic carbon and nutrient recycling. What is less well understood are the microbial traits, or combinations of traits, selected for during plant development. Are these traits or trait-combinations conserved, and is phylogeny a useful integrator of traits? Understanding the mechanisms underlying ecological succession would enable improved prediction of future rhizosphere states and consequences for C and nutrient cycles. In this study, we resolve the responses of rhizosphere bacteria at strain-level during plant (Avena fatua) developmental stages using both isolation and metagenomic approaches. Metagenome reads from bulk and rhizosphere soils were mapped to the genomes of thirty nine bacterial isolates numerically abundant ( 0.5% in relative abundance) and phylogenetically representative of these soils, and also to ninety six metagenome-derived genome bins. Analysis of temporal coverage patterns demonstrate that bacteria can be classified as positive and negative rhizosphere responders, with traits associated with root exudate utilization being important. Significant strain level diversity was observed and variance in the temporal coverage patterns further distinguished closely related strains of the same genera. For example, while a number of strains from the Bradyrhizobia, Mesorhizobia and Mycobacteria all increased in coverage with root growth, suggesting that recently acquired traits are selected for. Candidate traits distinguishing closely related strains included those related to xylose and other plant cell-wall derived sugar utilization, motility and aromatic organic acid

  7. Application of fisheries management techniques to assessing impacts: task I report. [Assessment of chemical, radiological, and thermal impacts of nuclear power plants on fish populations

    Energy Technology Data Exchange (ETDEWEB)

    McKenzie, D.H.; Baker, K.S.; Fickeisen, D.H.; Metzger, R.M.; Skalski, J.R.

    1979-03-01

    Task I efforts examined the available fisheries management techniques and assessed their potential application in a confirmatory monitoring program. The objective of such monitoring programs is to confirm that the prediction of an insignificant impact (usually made in the FES) was correct. Fisheries resource managers have developed several tools for assessing the fish population response to stress (exploitation) and they were thought potentially useful for detecting nuclear power plant impacts. Techniques in three categories were examined; catch removal, population dynamics, and nondestructive censuses, and the report contains their description, examples of application, advantages, and disadvantages. The techniques applied at nuclear power plant sites were examined in detail to provide information on implementation and variability of specific approaches. The most suitable techniques to incorporate into a monitoring program confirming no impact appear to be those based on Catch Per Unity Effort (CPUE) and hydroacoustic data. In some specific cases, age and growth studies and indirect census techniques may be beneficial. Recommendations for task II efforts to incorporate these techniques into monitoring program designs are presented. These include development of guidelines for; (1) designing and implementing a data collection program; (2) interpreting these data and assessing the occurrence of impact, and (3) establishment of the monitoring program's ability to detect changes in the affected populations.

  8. Analysis of the temperature effect on the components of plant digestibility in two populations of perennial ryegrass

    NARCIS (Netherlands)

    Groot, J.C.J.; Lantinga, E.A.; Neuteboom, J.H.; Deinum, B.

    2003-01-01

    For the development of mechanistic models of herbage digestibility, quantitative insight into the effects of age, temperature and cultivar on digestibility characteristics of individual plant parts is needed. Towards that goal, glasshouse experiments were conducted at day/night temperatures of 13/8,

  9. Association of Animal and Plant Proteins Intake with Hypertension in Iranian Adult Population: Isfahan Healthy Heart Program.

    Science.gov (United States)

    Mehrabani, Sanaz; Asemi, Mehdi; Najafian, Jamshid; Sajjadi, Firouzeh; Maghroun, Maryam; Mohammadifard, Noushin

    2017-01-01

    There is evidence regarding the relationship between dietary proteins intake and blood pressure (BP), but they had inconsistent results. Therefore, this study was designed to assess the association between different kinds of protein intake (animal and plant protein) and BP. Data were collected from Isfahan Healthy Heart Program. We performed a cross-sectional study among 9660 randomly selected Iranian adults aged ≥19-year-old that they were selected from three large Iranian regions in 2007. A simplified validated 48-item-food frequency questionnaire was used to assess dietary intake including all kinds of protein. Systolic and diastolic BPs were measured in duplicate by trained personnel using a standard protocol. Multivariable regressions were applied to assess the relationship between protein intake and BP levels and the presence of hypertension (HTN). More frequent consumption of animal, plant, and total protein intake were inversely associated with BP in a crude model (P protein (P = 0.04). The risk of HTN occurrence decreased in the highest quintile of total and plant protein consumption by 19% (odds ratio [OR] = 0.81; confidence interval [CI]: [0.65-0.96]; P for trend = 0.004) and 18% (OR = 0.82; [CI: (0.67-0.94]; P for trend = 0.03), respectively. More frequent protein intake, especially plant protein consumption was inversely associated with BP and risk of HTN among Iranian adults.

  10. Pollination and seed dispersal of Aquilaria sinensis (Lour. Gilg (Thymelaeaceae: An economic plant species with extremely small populations in China

    Directory of Open Access Journals (Sweden)

    Gao Chen

    2016-10-01

    Full Text Available Pollination and seed dispersal in angiosperms have long been investigated in order to understand the coevolution of plants and animals. However, the signals from flowers and/or seeds to attract pollinators and/or seed dispersers have received comparatively little attention. In this study, the pollination biology and seed dispersal of the vulnerable agarwood plant Aquilaria sinensis (Lour. Gilg, a traditional medicinal plant in China, was studied in its natural distribution range. The reproductive tactics of A. sinensis were studied in detail by employing various tests dealing with fruit set and also seed dispersal. Dynamic headspace extraction followed by GC-MS analysis was also performed in order to reveal the composition of floral scent. The results showed that noctuids and pyralids are the most effective pollinators of pollinator-dependent A. sinensis. The main compounds of the floral scent were (E, E-α-Farnesene (61.9 ± 3.2%, trans-Ocimene (16.6 ± 1.2%, and Benzyl salicylate (4.6 ± 1.1%. The results obtained from seed dispersal experiments indicate that hornets are effective seed dispersers and they may play an important role in long-distance seed dispersal of A. sinensis. Based on our findings, we recommend several protection methods for this threatened agarwood plant in China.

  11. Les plantes à alcaloïdes utilisées par les populations de la ville de ...

    African Journals Online (AJOL)

    They were distributed in 62 genera belonging to 40 families. The supply is provided from farms, secondary forests, gardens, fallows and markets. Solanaceae, Apocynaceae and Rubiaceae are rich in various alkaloids. Leaves, barks and roots are the plant parts mostly used in recipes for the treatment of various diseases.

  12. Molecular identification, genetic diversity, population genetics and genomics of Rhizoctonia solani. In:perspective of plant pathology in genomic era

    Science.gov (United States)

    The basidiomycetous soilborne fungus Rhizoctonia (sensu lato) is an economically important pathogen of worldwide distribution and it is known to attack at least 188 species of higher plants, including agronomic crops, vegetables, ornamentals, forest trees and turfgrasses. The pathogenic isolates may...

  13. Genome size, chromosome number, and rDNA organisation in Algerian populations of Artemisia herba-alba (Asteraceae, a basic plant for animal feeding facing overgrazing erosion

    Directory of Open Access Journals (Sweden)

    Youcef Bougoutaia

    2016-11-01

    Full Text Available Artemisia herba-alba is a largely-distributed and often landscape-dominating taxon in arid areas of the Mediterranean and Irano-Turanian regions. In Algeria, in 2010 its communities covered 10% of the steppe territory, but its populations have been subjected to overgrazing. A karyological study based on 22 populations together with a cytogenetic characterisation of this species has been performed for the first time in Algerian materials, through genome size and chromosome number determination. Fluorescence in situ hybridisation (FISH was also used to assess the rDNA loci number and distribution in the two ploidy levels detected. The studied accessions are diploid (2n = 2x = 18 chromosomes, 6 populations or tetraploid (2n = 4x = 36 chromosomes, 15 populations. One population, occupying a more or less central geographic position among the studied area, presented both cytotypes. Genome size reflects well the two ploidy levels, with no evidence of downsizing with polyploidy. The karyotypes are rather symmetric (2A Stebbins’ class. FISH analyses detected four signals (2 loci in diploid and eight signals (4 loci in tetraploid cytotypes for both ribosomal DNA genes, which present an L-type (linked organisation, i.e. with loci from both rDNA genes colocalised. The presence of two ploidy levels suggest a genomic dynamism and even a possible differentiation underlying the morphological uniformity and despite the dramatic decrease experienced by this plant in Algeria in terms of surface coverage.

  14. Within-plant distribution and seasonal population dynamics of flower thrips (Thysanoptera: Thripidae) infesting French beans (Phaseolus vulgaris L.) in Kenya

    Energy Technology Data Exchange (ETDEWEB)

    Kasina, M.; Nderitu, J.; Nyamasyo, G.; Waturu, C.; Olubayo, F.; Obudho, E.; Yobera, D.

    2009-07-01

    The aim of this research was to study spatial distribution of flower thrips on French beans (Phaseolus vulgaris L.) in Kenya. Their build up and seasonal population dynamics was monitored using sticky blue colour traps and sampling of leaves and flowers in two seasons in 2002. Thrips infested French beans from the second week after crop emergence. Their population peaked at peak flowering. The sticky trap catches were linearly related to the actual presence of thrips on the crop and could estimate population build up of adult thrips on leaves and flowers. On the plants, most adults were on flowers. Larvae mainly inhabited leaves, buds and pods. The two thrips species, Frankliniella occidentalis (Pergande) and Megalurothrips sjostedti Trybom were spatially separated. The former colonized lower-canopy leaves and early flowers while the latter inhabited middle-canopy leaves and mature flowers. Overall, M. sjostedti was less than 5% of the total thrips population, implying that F. occidentalis was the main thrips pest of French beans. This study suggests that French bean growers should monitor thrips population before initiating any control measure. In addition, they should commence thrips control early, at pre-flowering, using larvicides to reduce the thrips pool and their migration to flowers. A combination of monitoring with sticky traps and proper sampling would contribute to sustainable thrips management. (Author) 36 refs.

  15. Association of Animal and Plant Proteins Intake with Hypertension in Iranian Adult Population: Isfahan Healthy Heart Program

    Directory of Open Access Journals (Sweden)

    Sanaz Mehrabani

    2017-01-01

    Full Text Available Background: There is evidence regarding the relationship between dietary proteins intake and blood pressure (BP, but they had inconsistent results. Therefore, this study was designed to assess the association between different kinds of protein intake (animal and plant protein and BP. Materials and Methods: Data were collected from Isfahan Healthy Heart Program. We performed a cross-sectional study among 9660 randomly selected Iranian adults aged ≥19-year-old that they were selected from three large Iranian regions in 2007. A simplified validated 48-item-food frequency questionnaire was used to assess dietary intake including all kinds of protein. Systolic and diastolic BPs were measured in duplicate by trained personnel using a standard protocol. Multivariable regressions were applied to assess the relationship between protein intake and BP levels and the presence of hypertension (HTN. Results: More frequent consumption of animal, plant, and total protein intake were inversely associated with BP in a crude model (P < 0.001; however, after adjustment for potential confounders this relationship remained only for plant protein (P = 0.04. The risk of HTN occurrence decreased in the highest quintile of total and plant protein consumption by 19% (odds ratio [OR] = 0.81; confidence interval [CI]: [0.65–0.96]; P for trend = 0.004 and 18% (OR = 0.82; [CI: (0.67–0.94]; P for trend = 0.03, respectively. Conclusions: More frequent protein intake, especially plant protein consumption was inversely associated with BP and risk of HTN among Iranian adults.

  16. Genetic diversity and population structure of two important medicinal plant species Schisandra chinensis and Schisandra sphenanthera revealed by nuclear microsatellites.

    Science.gov (United States)

    Sun, Ye; Wen, Xiangying; Huang, Hongwen

    2011-04-01

    Seven polymorphic and transferable nuclear microsatellites were used to investigate the population structure of genetic diversity of Schisandra chinensis and Schisandra sphenanthera for facilitating their conservation and sustainable utilization. High levels of gene diversity were revealed in these two medicinal species, the majority of genetic diversity was harbored within populations, and population structure was might due to restricted gene flow among populations. Isolation by distance was close to significance in S. chinensis but not in S. sphenanthera. In S. chinensis, null alleles were identified as a cause for excess of homozygotes at loci G24 and WGA60, but inbreeding might also be partly responsible for the positive F ( IS ) values in this species. In contrast, null allele frequencies were high at all the seven loci in S. sphenanthera and resulted in overestimation of fixation index. The strategy for ex situ conservation of these two medicinal species is discussed based on the genetic results.

  17. Phylogeography of two parthenogenetic sawfly species (Hymenoptera: Tenthredinidae): relationship of population genetic differentiation to host plant distribution

    NARCIS (Netherlands)

    Müller, C.; Barker, A.; Boevé, J.L.; Jong, de P.W.; Vos, de H.; Brakefield, P.M.

    2004-01-01

    This study compares the population genetic structure of two obligate parthenogenetic sawfly species, Aneugmenus padi (L.) Zhelochovtsev and Eurhadinoceraea ventralis (Panzer) Enslin (Hymenoptera: Tenthredinidae). Allozymes were used to detect genetic differences in larvae collected at different

  18. THE EFFECTS OF POPULATION-SIZE AND PLANT-DENSITY ON OUTCROSSING RATES IN LOCALLY ENDANGERED SALVIA-PRATENSIS

    NARCIS (Netherlands)

    VANTREUREN, R; BIJLSMA, R; OUBORG, NJ; VANDELDEN, W

    Multilocus outcrossing rates were estimated in natural and experimental populations of Salvia pratensis, an entomophilous, gynodioecious, protandrous perennial. Male steriles were used to check the estimation procedure of outcrossing rates in hermaphrodites. Estimates of outcrossing rates in

  19. Loop-mediated isothermal amplification as a good tool to study changing Leptosphaeria populations in oilseed rape plants and air samples

    Directory of Open Access Journals (Sweden)

    Małgorzata Jędryczka

    2014-01-01

    Full Text Available LAMP is an innovative, simple, rapid, specific and cost-effective nucleic acid amplification method. Due to the use of a special enzyme – GspSSD polymerase, the reaction takes a short time and can be performed at isothermal conditions. The sensitivity and specificity of LAMP technique is significantly higher, than standard PCR techniques, as two or three specific primer pairs are used. The technique is regarded as a useful tool for the detection and identification of plant pathogens. In this work, LAMP was used to study the composition of the population of fungi of the genus Leptosphaeria, causing a damaging disease of oilseed rape, called blackleg or stem canker. The detection concerned DNA present in fungal spores contained in air samples obtained using Hirst-type volumetric trap, in Pomerania (north Poland in 2010. The results achieved using the LAMP technique were similar to these obtained with previously used, highly specific method of Real-time PCR. Conducting LAMP reaction was much easier and less time-and cost-consuming, due to a simplified method of DNA isolation of pathogens from plant tissues. Then, the LAMP technique was used to assess the composition of the population of Leptosphaeria spp. in plants of oil- seed rape collected from the field in the Opole region (south-we- stern part of Poland in 2013. In contrast to studies conducted in 2002–2003, the analysis of leaf symptoms showed a higher pro- portion of L. maculans compared to L. biglobosa, what reflects changes in the composition of pathogen population of fungi causing blackleg on oilseed rape in this part of Poland.

  20. Dispersion pattern interspecific association and population status of threatened plants on submontane and montane zones of Mount Gede-Pangrango National Park

    Directory of Open Access Journals (Sweden)

    WIHERMANTO

    2004-01-01

    Full Text Available The Mount Gede-Pangrango National Park has an attractive landscape view of mount summits with its crater, genuine flora and fauna of tropical rainforest, and a mild weather. Exploitation is forbidden in the area, but in reality encroachments occur, which will lead to changes in plant population status, particularly for threatened species. The aims of the research were investigate the populations status, dispersion pattern and possible interspecific associations of threatened plant species occurred in the sub montane and montane zones of the Mount Gede-Pangrango National Park. Most of the threatened species occurred in the park had clumped distributions and only one of those showed a regular dispersion, namely Symplocos costata. It should be realized that populations with a clumped dispersion tend to provide over or under estima-tion of abundance, indicating the need for a larger sampling unit to cover. Based on the association tests conducted, three species (Antidesma tetrandrum, Pinanga coronata, and Castanopsis javanica were significantly associated with Saurauia bracteosa, while Altingia excelsa and A. tetrandrum with Symplocos costata, as they had association indices more 0.3 using Jaccard Index. Pinanga coronata seems to be relatively closely associated with Saurauia cauliflora, Altingia excelsa with S. bracteosa, and Castanopsis javanica with S. costata. In contrast, Pinanga javana, Calamus adspersus, and Rhododendron album had low degrees of association, indicating their low abundance and co-occurrence with other species. Seven species of threatened plants were recorded in the Mount Gede-Pangrango: 5 of which had been proposed to change in their status. They were Calamus adspersus from vulnerable (V changed into vulnerable (V UD2., Lithocarpus indutus from vulnerable changed into critically endangered, Pinanga javana from endangered changed into vulnerable, Rhododendron album from vulnerable changed into endangered, and Saurauia bracteosa

  1. Host plant resistance to aphids in cultivated crops: genetic and molecular bases, and interactions with aphid populations.

    Science.gov (United States)

    Dogimont, Catherine; Bendahmane, Abdelhafid; Chovelon, Véronique; Boissot, Nathalie

    2010-01-01

    Host plant resistance is an efficient and environmentally friendly means of controlling insects, including aphids, but resistant-breaking biotypes have occurred in several plant-aphid systems. Our review of the genetic and molecular bases of aphid resistance in crop species emphasizes the limited number of aphid resistance genes and alleles. Inheritance of aphid resistance may be monogenic (dominant or recessive genes) or polygenic. Two dominant, aphid resistance genes have been isolated to date. They both encode NBS-LRR proteins involved in the specific recognition of aphids. Strategies to ensure aphid resistance effectiveness and durability are discussed. Innovative research activities are proposed. Copyright 2010 Académie des sciences. Published by Elsevier SAS. All rights reserved.

  2. Cultivation-Independent Characterization of Methylobacterium Populations in the Plant Phyllosphere by Automated Ribosomal Intergenic Spacer Analysis▿ †

    OpenAIRE

    Knief, Claudia; Frances, Lisa; Cantet, Franck; Vorholt, Julia A.

    2008-01-01

    Bacteria of the genus Methylobacterium are widespread in the environment, but their ecological role in ecosystems, such as the plant phyllosphere, is not very well understood. To gain better insight into the distribution of different Methylobacterium species in diverse ecosystems, a rapid and specific cultivation-independent method for detection of these organisms and analysis of their community structure is needed. Therefore, 16S rRNA gene-targeted primers specific for this genus were design...

  3. Scientific Opinion on the risks to plant health posed by European versus non-European populations of the potato cyst nematodes Globodera pallida and Globodera rostochiensis

    DEFF Research Database (Denmark)

    Baker, R.; Candresse, T.; Dormannsné Simon, E.

    2012-01-01

    The Panel on Plant Health has delivered a scientific opinion on the different risks posed by European and non-European populations of the potato cyst nematodes (PCN) Globodera pallida and Globodera rostochiensis to solanaceous plants in the EU and on the effectiveness of current control measures....

  4. Yield and quality of sweet corn at different plant populationsProdutividade e qualidade do milho doce em diferentes populações de plantas

    Directory of Open Access Journals (Sweden)

    Renan Soares de Souza

    2013-06-01

    Full Text Available The objective of this study was to evaluate the plant population density effect upon yield components and the chemical composition of grains in two sweet corn hybrids in “Winter-Spring” cultivation. The experimental design used was the complete randomized blocks with four replications. The treatments were based on the combination between two sweet corn hybrids (Tropical Plus e RB-6324 and five plant populations (40,000, 55.000, 70,000, 85,000 and 100,000 plants ha-1, in a factorial scheme 2 x 5, evaluated in two “winter-spring” growing seasons (2009 and 2010. The increment in the population of 40,000 to 100,000 plants ha-1 resulted in higher husked commercial corn ear productivity in both hybrids, Tropical Plus and RB-6324. The increase of plant population reduced the length and diameter of corn ears in Tropical Plus and RB-6324. The mass of the corn ears from Tropical Plus also reduced; however, it did not affect the commercial standard and industrial use. In larger plant populations the hybrid RB-6324 produced corn ears with grains that were sweeter and with lower starch content. The hybrid Tropical Plus presented higher mass, length, productivity, sugar content and lower diameter of corn ears when compared to RB-6324.O objetivo do presente estudo foi avaliar o efeito da população de plantas sobre os componentes de produção e a composição química de grãos de dois híbridos de milho doce no cultivo de “Inverno – Primavera”. O delineamento experimental utilizado foi o de blocos completos casualizados com quatro repetições. Os tratamentos constituíram-se da combinação entre híbridos de milho doce (Tropical Plus e RB-6324 e populações de plantas (40.000, 55.000, 70.000, 85.000 e 100.000 plantas ha-1, no esquema fatorial 2 x 5, avaliados em dois anos agrícolas (2009 e 2010, em cultivo de Inverno-Primavera. O incremento na população de plantas de 40.000 até 100.000 plantas ha-1 resultou em maiores produtividades de

  5. Effect of temperature (5-25°C) on epiphytic lactic acid bacteria populations and fermentation of whole-plant corn silage.

    Science.gov (United States)

    Zhou, Y; Drouin, P; Lafrenière, C

    2016-09-01

    The objective of this study was to investigate the effect of temperature (5-25°C) on epiphytic lactic acid bacteria (LAB) populations during 60 days of fermentation of whole-plant corn silage. Vacuum bag mini-silos of chopped whole-plant corn were incubated at five different temperatures (5, 10, 15, 20 and 25°C), according to a completely randomized design with four repetitions. The silos were opened and sampled on day 0, 1, 2, 3, 7, 28 and 60. At 20 and 25°C, Lactobacillus plantarum- and Pediococcus  pentosaceus-related operational taxonomic units (OTU) dominated the fermentation within 1 day. After 7 days, the OTU related to the heterofermentative species Lactobacillus buchneri began to appear and it eventually dominated silages incubated at these temperatures. Population dynamic of LAB at 5 and 10°C was different. At these temperatures, Leuconostoc citreum OTU was identified at the beginning of the fermentation. Thereafter, Lactobacillus sakei- and Lactobacillus curvatus-related OTU appeared and quickly prevailed. Corn silage at 15°C acted as a transition between 20-25°C and 5-10°C, in terms of LAB diversity and succession. The conditions of silage incubation temperature affect species diversity of LAB population with notable difference along the temperature gradient. Colder temperature conditions (5 and 10°C) have led to the identification of LAB species never observed in corn silage. This study demonstrated the impact of temperature gradient on the diversity and some important population shift of lactic acid bacteria communities during fermentation of corn silage. © 2016 The Society for Applied Microbiology.

  6. The peculiarities of formation of circulatory system pathology of evacuated adult population exposed to ionizing radiation on thyroid gland after the accident at the Chernobyl Nuclear Power Plant

    Directory of Open Access Journals (Sweden)

    Kapustinskaia O.A.

    2014-11-01

    Full Text Available The aim of the research - analysis of the structure and dynamics of the morbidity among eva¬cuated population, the peculiarities of pathogenesis of the most widespread forms of circulatory system (CS pathology in the remote period after the accident at the Chernobyl Nuclear Power Plant. Materials and methods. Three groups of persons evacuated from Chernobyl zone of alienation were researched: persons aged 10-17 (6517 persons, 18-39 (496 persons, 40-60 (458 persons. The data on the individual radiation doses which affected thyroid gland were selected at the State Register of Ukraine on persons affected by the Chernobyl disaster. Morbidity rate was estimated per 103 man-year for 5-years periods of monitoring. The main results: Time from the moment of Chernobyl accident affected the formation of morbidity structure of evacuated population. It was fixed two peaks of morbidity incidence - initial and in 12 years. The most essential changes in CS morbidity of evacuated population were fixed 26 years later mainly in cere¬brovascular diseases. The coronary artery disease takes the first place in the morbidity structure. Significant dif¬ferences were detected at age-specific aspect. The evacuated adult population aged 18-39 years was the most vulnerable for the development of CS diseases. Adverse health effects confirmed the necessity of further research of CS morbidity with the differentiation of doses affected thyroid gland.

  7. Validation of SNP allele frequencies determined by pooled next-generation sequencing in natural populations of a non-model plant species.

    Directory of Open Access Journals (Sweden)

    Christian Rellstab

    Full Text Available Sequencing of pooled samples (Pool-Seq using next-generation sequencing technologies has become increasingly popular, because it represents a rapid and cost-effective method to determine allele frequencies for single nucleotide polymorphisms (SNPs in population pools. Validation of allele frequencies determined by Pool-Seq has been attempted using an individual genotyping approach, but these studies tend to use samples from existing model organism databases or DNA stores, and do not validate a realistic setup for sampling natural populations. Here we used pyrosequencing to validate allele frequencies determined by Pool-Seq in three natural populations of Arabidopsis halleri (Brassicaceae. The allele frequency estimates of the pooled population samples (consisting of 20 individual plant DNA samples were determined after mapping Illumina reads to (i the publicly available, high-quality reference genome of a closely related species (Arabidopsis thaliana and (ii our own de novo draft genome assembly of A. halleri. We then pyrosequenced nine selected SNPs using the same individuals from each population, resulting in a total of 540 samples. Our results show a highly significant and accurate relationship between pooled and individually determined allele frequencies, irrespective of the reference genome used. Allele frequencies differed on average by less than 4%. There was no tendency that either the Pool-Seq or the individual-based approach resulted in higher or lower estimates of allele frequencies. Moreover, the rather high coverage in the mapping to the two reference genomes, ranging from 55 to 284x, had no significant effect on the accuracy of the Pool-Seq. A resampling analysis showed that only very low coverage values (below 10-20x would substantially reduce the precision of the method. We therefore conclude that a pooled re-sequencing approach is well suited for analyses of genetic variation in natural populations.

  8. Generalized linear dynamics of a plant-parasitic nematode population and the economic evaluation of crop rotations

    NARCIS (Netherlands)

    Berg, van den W.; Rossing, W.A.H.

    2005-01-01

    In 1-year experiments, the final population density of nematodes is usually modeled as a function of initial density. Often, estimation of the parameters is precarious because nematode measurements, although laborious and expensive, are imprecise and the range in initial densities may be small. The

  9. Population structure of the emerging plant pathogen Phytophthora ramorum on the west coast of the United States

    Science.gov (United States)

    S. Prospero; E.M. Hansen; N.J. Grünwald; J. Britt; L.M. Winton.

    2009-01-01

    Phytophthora ramorum is a devastating pathogen in native forests in California and southwestern Oregon and in nursery crops in California, Oregon and Washington. In this study we analyzed the population structure of P. ramorum in the west coast (CA, OR, and WA) of the United States by screening 579 isolates recovered...

  10. Development of a rapid multiplex SSR genotyping method to study populations of the fun-gal plant pathogen Zymoseptoria tritici

    NARCIS (Netherlands)

    Gautier, A.; Marcel, T.C.; Confais, J.; Crane, C.; Kema, G.H.J.; Suffert, F.; Walker, A.S.

    2014-01-01

    Background Zymoseptoria tritici is a hemibiotrophic ascomycete fungus causing leaf blotch of wheat that often decreases yield severely. Populations of the fungus are known to be highly diverse and poorly differentiated from each other. However, a genotyping tool is needed to address further

  11. Development of a rapid multiplex SSR genotyping method to study populations of the fungal plant pathogen Zymoseptoria tritici.

    Science.gov (United States)

    Gautier, Angélique; Marcel, Thierry C; Confais, Johann; Crane, Charles; Kema, Gert; Suffert, Frédéric; Walker, Anne-Sophie

    2014-06-18

    Zymoseptoria tritici is a hemibiotrophic ascomycete fungus causing leaf blotch of wheat that often decreases yield severely. Populations of the fungus are known to be highly diverse and poorly differentiated from each other. However, a genotyping tool is needed to address further questions in large collections of isolates, regarding regional population structure, adaptation to anthropogenic selective pressures, and dynamics of the recently discovered accessory chromosomes. This procedure is limited by costly and time-consuming simplex PCR genotyping. Recent development of genomic approaches and of larger sets of SSRs enabled the optimization of microsatellite multiplexing. We report here a reliable protocol to amplify 24 SSRs organized in three multiplex panels, and covering all Z. tritici chromosomes. We also propose an automatic allele assignment procedure, which allows scoring alleles in a repeatable manner across studies and laboratories. All together, these tools enabled us to characterize local and worldwide populations and to calculate diversity indexes consistent with results reported in the literature. This easy-to-use, accurate, repeatable, economical, and faster technical strategy can provide useful genetic information for evolutionary inferences concerning Z. tritici populations. Moreover, it will facilitate the comparison of studies from different scientific groups.

  12. Development of a mobile game based on virtual reality tools to sensitize the population about the nuclear power plant's emergency plan

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Lucas H.H.; Mol, Antônio C. de A.; Santo, André C. do E.; Legey, Ana Paula [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Centro Universitário Carioca (Unicarioca), Rio de Janeiro, RJ (Brazil)

    2017-07-01

    The Angra dos Reis Nuclear Power Plant's emergency plan, it is the bunch of instructions that every citizen must adopt in case of an emergency situation. It is highly important, that all the people living in the power plant's surroundings truly understand every single step of the plan, because only in this way people will know how to react in case of a necessity. To hit this goals, the Brazil's Electronuclear, made educational booklets, in the shape of comic books, trying to guide the population about the plan. On the other hand, we have an increasingly connected world, making possible that digital games, be very well accepted by the population. So this project has as an objective, developing a digital tool, in form of a mobile game that shows in a playful and interactive way for the user, the emergency plan, complementing the educational process and social actions made by many institutions. With the information taken from the booklets, objects and buildings were modeled in Autodesk 3Ds Max, allied with the Unity 3D Game Engine, to make a city, inspired in Angra do Reis (RJ). The player has to follow all the security protocols giving by the Eletronuclear according with the rules provided by the National Nuclear Energy Commission. Is expected, with this game that will be available for the Eletronuclear that more people have the chance to know and believe in the efficiency of the emergency plan already established. (author)

  13. Ornithological Fauna of the Waste Water Treatment Plants in the Northern Left Bank Ukraine (Chernihiv and Kyiv Regions: Winter Populations and Ecological Structure

    Directory of Open Access Journals (Sweden)

    Fedun О. М.

    2016-12-01

    Full Text Available The article discusses winter bird populations of the waste water treatment plants (WWTP located in the North of Left -bank Ukraine. The said population comprises 12 orders and 29 families. The most numerous are Passeriformes (37 species, Аnsеriformes (16 species and Falconiformes (6 species. Parus major was registered at all types of facilities while most of the others house Passer montanus, Carduelis carduelis, Turdus pilaris, and Parus caeruleus. The largest number of wintering birds was registered at Bortnychi aeration station, Chernihiv municipal WWTP and Chernihiv wool processing factory - 79. 51 and 15 species respectively. The nuclear part of the bird numbers are the species residing at the facilities all year around (65.8 %; species occurring there in winter only account for 34.2 %. Dendrophilous (38 species and hydrophilous (35 species dominate among them. The primary role in forming the winter fauna of the waste water treatment plants belongs to the zones of water bodies and dams.

  14. Sub-Antarctic glacier extensions in the Kerguelen region (49°S, Indian Ocean) over the past 24,000 years constrained by 36Cl moraine dating

    Science.gov (United States)

    Jomelli, Vincent; Mokadem, Fatima; Schimmelpfennig, Irene; Chapron, Emmanuel; Rinterknecht, Vincent; Favier, Vincent; Verfaillie, Deborah; Brunstein, Daniel; Legentil, Claude; Michel, Elisabeth; Swingedouw, Didier; Jaouen, Alain; Aumaitre, Georges; Bourlès, Didier L.; Keddadouche, Karim

    2017-04-01

    Similar to many other regions in the world, glaciers in the southern sub-polar regions are currently retreating. In the Kerguelen Islands (49°S, 69°E), the mass balance of the Cook Ice Cap (CIC), the largest ice cap in this region, experienced dramatic shrinking between 1960 and 2013 with retreat rates among the highest in the world. This observation needs to be evaluated in a long-term context. However, data on the past glacier extents are sparse in the sub-Antarctic regions. To investigate the deglaciation pattern since the Last Glacial Maximum (LGM) period, we present the first 13 cosmogenic 36Cl surface exposure ages from four sites in the Kerguelen Islands. The 36Cl ages from erratic and moraine boulders span from 24.4 ± 2.7 ka to 0.3 ± 0.1 ka. We combined these ages with existing glacio-marine radiocarbon ages and bathymetric data to document the temporal and spatial changes of the island's glacial history. Ice began to retreat on the main island before 24.4 ± 2.7 ka until around the time of the Antarctic Cold Reversal (ACR) period (∼14.5-12.9 ka), during which the Bontemps moraine was formed by the advance of a CIC outlet glacier. Deglaciation continued during the Holocene probably until 3 ka with evidence of minor advances during the last millennium. This chronology is in pace with major changes in δ18O in a recent West Antarctica ice core record, showing that Kerguelen Islands glaciers are particularly sensitive and relevant to document climate change in the southern polar regions.

  15. Euphotic zone variations in bulk and compound-specific δ13C of suspended organic matter in the Subantarctic Ocean, south of Australia

    Science.gov (United States)

    O'Leary, T.; Trull, T. W.; Griffiths, F. B.; Tilbrook, B.; Revill, A. T.

    2001-12-01

    The carbon isotopic compositions of suspended organic matter δ13CPOC collected from Subantarctic Zone surface waters south of Australia in November 1995 decrease southward from -20 to -26‰ and display strong correlations with aqueous carbon dioxide concentration ([CO2]aq), consistent with previous studies. In contrast, vertical profiles through the euphotic zone (top ˜100 m) of δ13CPOC at six stations display decreases with depth of up to 2.4‰. These decreases in δ13CPOC cannot be fully explained by the small vertical variations in [CO2]aq or its 13C content. Carbon 13 analyses of several individual sterols revealed similar isotopic changes with depth, suggesting that they derive from a fundamental depth control on primary production, rather than from algal community variations or remineralization processes. Growth rate μ appears to be the most likely source of the depth variations. The relationship between μ/[CO2]aq and δ13CPOC derived from surface water samples can explain the vertical variations of δ13CPOC within the mixed layer, provided integrated mixed layer growth rates are used. Below the mixed layer, differences between the observed δ13CPOC and the growth rate model can be explained by recent shallowing in mixed layer depth and the subsequent effect on growth rates. These results suggest that δ13CPOC determinations can be used to provide some information on the recent history of mixed layer processes and that interpretation of sedimentary δ13CPOC records should include consideration of possible growth rate and mixed layer depth variations.

  16. Cultivation-Independent Characterization of Methylobacterium Populations in the Plant Phyllosphere by Automated Ribosomal Intergenic Spacer Analysis▿ †

    Science.gov (United States)

    Knief, Claudia; Frances, Lisa; Cantet, Franck; Vorholt, Julia A.

    2008-01-01

    Bacteria of the genus Methylobacterium are widespread in the environment, but their ecological role in ecosystems, such as the plant phyllosphere, is not very well understood. To gain better insight into the distribution of different Methylobacterium species in diverse ecosystems, a rapid and specific cultivation-independent method for detection of these organisms and analysis of their community structure is needed. Therefore, 16S rRNA gene-targeted primers specific for this genus were designed and evaluated. These primers were used in PCR in combination with a reverse primer that binds to the tRNAAla gene, which is located upstream of the 23S rRNA gene in the 16S-23S intergenic spacer (IGS). PCR products that were of different lengths were obtained due to the length heterogeneity of the IGS of different Methylobacterium species. This length variation allowed generation of fingerprints of Methylobacterium communities in environmental samples by automated ribosomal intergenic spacer analysis. The Methylobacterium communities on leaves of different plant species in a natural field were compared using this method. The new method allows rapid comparisons of Methylobacterium communities and is thus a useful tool to study Methylobacterium communities in different ecosystems. PMID:18263752

  17. Cultivation-independent characterization of methylobacterium populations in the plant phyllosphere by automated ribosomal intergenic spacer analysis.

    Science.gov (United States)

    Knief, Claudia; Frances, Lisa; Cantet, Franck; Vorholt, Julia A

    2008-04-01

    Bacteria of the genus Methylobacterium are widespread in the environment, but their ecological role in ecosystems, such as the plant phyllosphere, is not very well understood. To gain better insight into the distribution of different Methylobacterium species in diverse ecosystems, a rapid and specific cultivation-independent method for detection of these organisms and analysis of their community structure is needed. Therefore, 16S rRNA gene-targeted primers specific for this genus were designed and evaluated. These primers were used in PCR in combination with a reverse primer that binds to the tRNA(Ala) gene, which is located upstream of the 23S rRNA gene in the 16S-23S intergenic spacer (IGS). PCR products that were of different lengths were obtained due to the length heterogeneity of the IGS of different Methylobacterium species. This length variation allowed generation of fingerprints of Methylobacterium communities in environmental samples by automated ribosomal intergenic spacer analysis. The Methylobacterium communities on leaves of different plant species in a natural field were compared using this method. The new method allows rapid comparisons of Methylobacterium communities and is thus a useful tool to study Methylobacterium communities in different ecosystems.

  18. Population dynamics of plant nematodes in cultivated soil: effect of summer cover crops in old agricultural land.

    Science.gov (United States)

    Brodie, B B; Good, J M; Jaworski, C A

    1970-04-01

    In a 6-year cover crop sequence study, nematode population densities varied with different cover crops. Millet favored rapid increase of Belonolaimus longicaudatus and supported relatively large numbers of Pratylenchus brachyurus. Beggarweed and 'Coastal' bermudagrass favored rapid increase of B. Iongicaudatus and to a lesser extent P. brachyurus and Trichodorus christiei. Hairy indigo and Crotalaria supported relatively large numbers of P. brachyurus but suppressed B. longicaudatus. Hairy indigo also supported increases of T. christiei and Xiphinema americanum. Marigold did not favor development of any parasitic nematode species present. Tomato transplant yield was inversely related to nematode population, particularly to B. Iongicaudatus. Largest yields were obtained from plots with smallest numbers of B. longicaudatus and smallest yields were from plots with largest numbers of B. longicaudatus.

  19. Prioritizing management actions for invasive populations using cost, efficacy, demography and expert opinion for 14 plant species world?wide

    OpenAIRE

    Kerr, N.Z.; Baxter, P. W. J.; Salguero-Gómez, R.; Wardle, G.M.; Buckley, Y.M.

    2016-01-01

    1. Management of invasive populations is typically investigated case-by-case. Comparative approaches have been applied to single aspects of management, such as demography, with cost or efficacy rarely incorporated.\\ud 2. We present an analysis of the ranks of management actions for 14 species in five countries that extends beyond the use of demography alone to include multiple metrics for ranking management actions, which integrate cost, efficacy and demography (cost-effectiveness) and manage...

  20. Selective analysis of power plant operation on the Hudson River with emphasis on the Bowline Point Generating Station. Volume 1. [Effects on striped bass population

    Energy Technology Data Exchange (ETDEWEB)

    Barnthouse, L. W.; Cannon, J. B.; Christensen, S. G.

    1977-07-01

    A comprehensive study of the effects of power plant operation on the Hudson River was conducted. The study included thermal, biological, and air quality effects of existing and planned electrical generating stations. This section on thermal impacts presents a comprehensive mathematical modeling and computer simulation study of the effects of heat rejection from the plants. The overall study consisted of three major parts: near-field analysis; far-field analysis; and zone-matched near-field/far-field analysis. Near-field analyses were completed for Roseton, Danskammer, and Bowline Point Generating Stations, and near-field dilution ratios range from a low of about 2 for Bowline Point and 3 for Roseton to a maximum of 6 for both plants. The far-field analysis included a critical review of existing studies and a parametric review of operating plants. The maximum thermal load case, based on hypothetical 1974 river conditions, gives the daily maximum cross-section-averaged and 2-mile-segment-averaged water temperatures as 83.80/sup 0/F in the vicinity of the Indian Point Station and 83.25/sup 0/F in the vicinity of the Bowline Station. This maximum case will be significantly modified if cooling towers are used at certain units. A full analysis and discussion of these cases is presented. A study of the Hudson River striped bass population is divided into the following eight subsections: distribution of striped bass eggs, larvae, and juveniles in the Hudson River; entrainment mortality factor; intake factor; impingement; effects of discharges; compensation; model estimates of percent reduction; and Hudson River striped bass stock.

  1. Windpower and grey seals: An impact assessment of potential effects by sea-based windpower plants in a local seal population

    Energy Technology Data Exchange (ETDEWEB)

    Sundberg, Jan; Soederman, Malin [Uppsala Univ. (Sweden). Dept. of Animal Ecology

    2000-05-01

    The impact of five sea-based wind power plants on two haulout sites for grey seals on southwestern Gotland, in the Baltic Sea, was analysed. Data on seal numbers was collected on a regular basis during the initial stages of the project from summer 1996, continuing during the building (autumn 1997) and running of the wind power plants (from spring 1998) until the end of June 1999. Additional observational data from earlier years was also available. Indications of lower occurrence and reduced number of seals in the area was found during periods of time in 1997 and 1998, times of construction and active running of the plants. However, no evidence on the wind power plants, per se, affecting the grey seals was found. Instead, several weather factors were found to affect the number of seals in the area, and periods of low occurrence and number of seals were more likely explained by i.e. unfavourable water levels and hard wind from certain directions. One important, short term, impact factor was however found. Human induced disturbances such as boat and helicopter traffic, some which were directly related to maintenance of the wind power plants, temporarily reduced number of seals and made them more restless. Disturbance thus constitutes a potential threat to seals. A shift from one to the other of the two haulout sites was also noted, a shift which likely is due to disturbances. Future guidelines are given, including some restrictions in movements near the haulout sites. Continued observations and studies are suggested if more off-shore wind power plants will be raised in the area. A call for more stringent use of environmental impact assessments is thus made. Also, suggestions on measures to be taken in order to reduce the effect of human related disturbances are made. In order to create sustainable conditions for a continued population of seals in the area and in order to create opportunities for a reestablishment of the grey seal in the southern Baltic region

  2. Mapping Water Stress Incidence and Intensity, Optimal Plant Populations, and Cultivar Duration for African Groundnut Productivity Enhancement.

    Science.gov (United States)

    Vadez, Vincent; Halilou, Oumarou; Hissene, Halime M; Sibiry-Traore, Pierre; Sinclair, Thomas R; Soltani, Afshin

    2017-01-01

    Groundnut production is limited in Sub-Saharan Africa and water deficit or "drought," is often considered as the main yield-limiting factor. However, no comprehensive study has assessed the extent and intensity of "drought"-related yield decreases, nor has it explored avenues to enhance productivity. Hence, crop simulation modeling with SSM (Simple Simulation Modeling) was used to address these issues. To palliate the lack of reliable weather data as input to the model, the validity of weather data generated by Marksim, a weather generator, was tested. Marksim provided good weather representation across a large gradient of rainfall, representative of the region, and although rainfall generated by Marksim was above observations, run-off from Marksim data was also higher, and consequently simulations using observed or Marksim weather agreed closely across this gradient of weather conditions (root mean square of error = 99 g m-2; R2 = 0.81 for pod yield). More importantly, simulation of yield changes upon agronomic or genetic alterations in the model were equally predicted with Marksim weather. A 1° × 1° grid of weather data was generated. "Drought"-related yield reduction were limited to latitudes above 12-13° North in West Central Africa (WCA) and to the Eastern fringes of Tanzania and Mozambique in East South Africa (ESA). Simulation and experimental trials also showed that doubling the sowing density of Spanish cultivars from 20 to 40 plants m-2 would increase yield dramatically in both WCA and ESA. However, increasing density would require growers to invest in more seeds and likely additional labor. If these trade-offs cannot be alleviated, genetic improvement would then need to re-focus on a plant type that is adapted to the current low sowing density, like a runner rather than a bush plant type, which currently receives most of the genetic attention. Genetic improvement targeting "drought" adaptation should also be restricted to areas where water is indeed

  3. Mapping Water Stress Incidence and Intensity, Optimal Plant Populations, and Cultivar Duration for African Groundnut Productivity Enhancement

    Science.gov (United States)

    Vadez, Vincent; Halilou, Oumarou; Hissene, Halime M.; Sibiry-Traore, Pierre; Sinclair, Thomas R.; Soltani, Afshin

    2017-01-01

    Groundnut production is limited in Sub-Saharan Africa and water deficit or “drought,” is often considered as the main yield-limiting factor. However, no comprehensive study has assessed the extent and intensity of “drought”-related yield decreases, nor has it explored avenues to enhance productivity. Hence, crop simulation modeling with SSM (Simple Simulation Modeling) was used to address these issues. To palliate the lack of reliable weather data as input to the model, the validity of weather data generated by Marksim, a weather generator, was tested. Marksim provided good weather representation across a large gradient of rainfall, representative of the region, and although rainfall generated by Marksim was above observations, run-off from Marksim data was also higher, and consequently simulations using observed or Marksim weather agreed closely across this gradient of weather conditions (root mean square of error = 99 g m-2; R2 = 0.81 for pod yield). More importantly, simulation of yield changes upon agronomic or genetic alterations in the model were equally predicted with Marksim weather. A 1° × 1° grid of weather data was generated. “Drought”-related yield reduction were limited to latitudes above 12–13° North in West Central Africa (WCA) and to the Eastern fringes of Tanzania and Mozambique in East South Africa (ESA). Simulation and experimental trials also showed that doubling the sowing density of Spanish cultivars from 20 to 40 plants m-2 would increase yield dramatically in both WCA and ESA. However, increasing density would require growers to invest in more seeds and likely additional labor. If these trade-offs cannot be alleviated, genetic improvement would then need to re-focus on a plant type that is adapted to the current low sowing density, like a runner rather than a bush plant type, which currently receives most of the genetic attention. Genetic improvement targeting “drought” adaptation should also be restricted to areas

  4. Effects of Feeding on Different Host Plants and Diets on Bradysia Odoriphaga Population Parameters and Tolerance to Heat and Insecticides.

    Science.gov (United States)

    Zhu, Guodong; Luo, Yin; Xue, Ming; Zhao, Haipeng; Sun, Xia; Wang, Xinhui

    2017-10-17

    Bradysia odoriphaga Yang et Zhang, the Chinese chive root maggot, is a devastating pest of agricultural plants causing significant losses in vegetable crops, edible mushrooms, and humus. To determine the effects of feeding on different host plants and diets on the life parameters of B. odoriphaga and its tolerance to stressful conditions, we analyzed the life-table data of B. odoriphaga reared on Chinese chive (Allium hookeri), Welsh onion (Allium fistulosum), garlic (Allium sativum), oyster mushroom (Pleurotus ostreatus), and humus and assayed its tolerance to heat and insecticides. Furthermore, we assayed the physiological responses of B. odoriphaga reared on different hosts. Development from egg to adult was successfully completed on five hosts. Life table indicated that when reared on Chinese chive and oyster mushroom, B. odoriphaga showed better life parameters (shorter development time, higher survival rate, and fecundity) than on humus and garlic. However, B. odoriphaga larvae fed on humus and garlic better tolerated heat and insecticides than those that were fed Chinese chive and oyster mushroom; larvae survived longer at 38 and 40°C heat shock and at higher insecticide doses. Activities of antioxidant and detoxification enzymes varied significantly in larvae fed on different hosts. Catalase, superoxide dismutase, glutathione S-transferase, and carboxylesterase activities were higher in larva reared on garlic and humus than on Chinese chive and oyster mushroom. These findings indicated that B. odoriphaga preferred liliaceous vegetables and mushroom, and their tolerance against stress increased when reared on humus and garlic. Such basic information can promote targeted pest management in different agricultural fields and allow better understanding of the acclimatization strategy of B. odoriphaga. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please email

  5. Sugarcane Aphid Population Growth, Plant Injury, and Natural Enemies on Selected Grain Sorghum Hybrids in Texas and Louisiana.

    Science.gov (United States)

    Brewer, Michael J; Gordy, John W; Kerns, David L; Woolley, James B; Rooney, William L; Bowling, Robert D

    2017-10-01

    In response to the 2013 outbreak of sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae), on sorghum, Sorghum bicolor (L.), in North America, experiments were conducted at three southern U.S. grain sorghum production locations (Corpus Christi, TX; Winnsboro, LA; Rosenberg, TX). The objectives were to authenticate yield decline on susceptible hybrids (2014 and 2015) and to measure aphid population growth and natural enemy prevalence on susceptible and resistant hybrids with similar genetic background (2014). Yield decline on susceptible hybrids (Tx 2752/Tx430 and DKS53-67) was more substantial when aphid population growth accelerated quickly and peaked above 300 aphids per leaf (50 to nearly 100% yield decline). Location and year variation in maximum aphid density and cumulative aphid-days was high, with doubling time values on the susceptible hybrids ranging between 3.9 and 7.9 d. On resistant Tx2752/Tx2783, leaf injury and yield decline were not seen or less severe than on its paired susceptible Tx2752/Tx430. Aphids declined on Tx2752/Tx2783 after initial colony establishment (Corpus Christi) or took about 60% longer to double in population size when compared with Tx2572/Tx430 (Winnsboro). The predominant natural enemy taxa were aphelinid mummies (Hymenoptera: Aphelinidae), ladybird beetles (Coleoptera: Coccinellidae), and sryphid flies (Diptera: Syrphidae), and they were more prevalent during flowering than prior to flowering. They were generally responsive to changes in aphid density of both susceptible and resistant hybrids, but variability points to need for further study. In future research, full season observations should continue as well as more detailed study of potential compatibility of sorghum resistance and biological control. © The Author 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  6. Sarcoma risk and dioxin emissions from incinerators and industrial plants: a population-based case-control study (Italy

    Directory of Open Access Journals (Sweden)

    Fiore Anna

    2007-07-01

    Full Text Available Abstract Background It is not clear whether environmental exposure to dioxin affects the general population. The aim of this research is to evaluate sarcoma risk in relation to the environmental pollution caused by dioxin emitted by waste incinerators and industrial sources of airborne dioxin. The study population lives in a part of the Province of Venice (Italy, where a population-based cancer registry (Veneto Tumour Registry – RTV has been active since 1987. Methods Two hundred and five cases of visceral and extravisceral sarcoma, confirmed by microscopic examination, diagnosed from 01.01.1990 to 31.12.1996, were extracted from the RTV database. Diagnoses were revised using the actual pathology reports and clinical records. For each sarcoma case, three controls of the same age and sex were randomly selected from the population files of the Local Health Units (LHUs. The residential history of each subject, whether case or control, was reconstructed, address by address, from 1960 to the date of diagnosis. All waste incinerators and industrial sources of airborne dioxin in the Province of Venice were taken into account, as was one very large municipal waste incinerator outside the area but close to its boundaries. The Industrial Source Complex Model in Long Term mode, version 3 (ISCLT3, was used to assess the level of atmospheric dispersion. A specific value for exposure was calculated for each point (geo-referenced address and for each calendar year; the exposure value for each subject is expressed as the average of specific time-weighted values. The analysis takes into account 172 cases and 405 controls, aged more than 14 years. Results The risk of developing a sarcoma is 3.3 times higher (95% Confidence Interval – 95% CI: 1.24 – 8.76 among subjects, both sexes, with the longest exposure period and the highest exposure level ; a significant excess of risk was also observed in women (Odds Ratio OR = 2.41, 95% CI: 1.04 – 5.59 and for

  7. The seasonal evolution of shelf water masses around Bouvetøya, a sub-Antarctic island in the mid-Atlantic sector of the Southern Ocean, determined from an instrumented southern elephant seal

    Directory of Open Access Journals (Sweden)

    Andrew D. Lowther

    2016-10-01

    Full Text Available Our study makes use of a fortuitous oceanographic data set collected around the remote sub-Antarctic island of Bouvetøya by a conductivity–temperature–depth recorder (CTD integrated with a satellite-relayed data logger deployed on an adult female southern elephant seal (Mirounga leonina to describe the seasonal evolution of the western shelf waters. The instrumented seal remained in waters over the shelf for 259 days, collecting an average of 2.6 (±0.06 CTD profiles per day, providing hydrographic data encompassing the late austral summer and the entire winter. These data document the thermal stratification of the upper water layer due to summer surface heating of the previous year's Antarctic Surface Water, giving way to a cold subsurface layer at about 100 m as the austral winter progressed, with a concomitant increase in salinity of the upper layer. Upper Circumpolar Deep Water was detected at a depth of approximately 200 m along the western shelf of Bouvetøya throughout the year. These oceanographic data represent the only seasonal time series for this region and the second such animal–instrument oceanographic time series in the sub-Antarctic domain of the Southern Ocean.

  8. Estimating temporal trend in the presence of spatial complexity: a Bayesian hierarchical model for a wetland plant population undergoing restoration.

    Directory of Open Access Journals (Sweden)

    Thomas J Rodhouse

    Full Text Available Monitoring programs that evaluate restoration and inform adaptive management are important for addressing environmental degradation. These efforts may be well served by spatially explicit hierarchical approaches to modeling because of unavoidable spatial structure inherited from past land use patterns and other factors. We developed bayesian hierarchical models to estimate trends from annual density counts observed in a spatially structured wetland forb (Camassia quamash [camas] population following the cessation of grazing and mowing on the study area, and in a separate reference population of camas. The restoration site was bisected by roads and drainage ditches, resulting in distinct subpopulations ("zones" with different land use histories. We modeled this spatial structure by fitting zone-specific intercepts and slopes. We allowed spatial covariance parameters in the model to vary by zone, as in stratified kriging, accommodating anisotropy and improving computation and biological interpretation. Trend estimates provided evidence of a positive effect of passive restoration, and the strength of evidence was influenced by the amount of spatial structure in the model. Allowing trends to vary among zones and accounting for topographic heterogeneity increased precision of trend estimates. Accounting for spatial autocorrelation shifted parameter coefficients in ways that varied among zones depending on strength of statistical shrinkage, autocorrelation and topographic heterogeneity--a phenomenon not widely described. Spatially explicit estimates of trend from hierarchical models will generally be more useful to land managers than pooled regional estimates and provide more realistic assessments of uncertainty. The ability to grapple with historical contingency is an appealing benefit of this approach.

  9. Populations of selected microbial and fungal species growing on the surface of rape seeds following treatment with desiccants or plant growth regulators.

    Science.gov (United States)

    Frac, Magdalena; Jezierska-Tys, Stefania; Tys, Jerzy

    2010-01-01

    The aim of this study was to determine the effects of desiccants and plant growth regulators on selected microbial species affecting rape seeds, with special emphasis on the growth of fungi and identification of the genus and species composition. The experimental material in the study was seeds of winter rape cv. Californium that were collected from the field during combine harvest. The chemical agents applied, both desiccants and growth regulators, generally decreased the populations of bacteria occurring on the surface of rape seeds. The responses of fungi depended upon the type of agent applied and were manifested as either stimulation or inhibition of the growth of the fungal species. The fungi isolated from the surface of rape seeds were characteristic of those found in the field environment (Cladosporium and Penicillium) and typical for those present on the surface of rape seeds (Alternaria).

  10. Identification of a human erythroid progenitor cell population which expresses the CD34 antigen and binds the plant lectin Ulex europaeus I.

    Science.gov (United States)

    Unverzagt, K L; Martinson, J; Lee, W; Stiff, P J; Williams, S; Bender, J G

    1996-01-01

    Two and three color flow cytometry of normal human bone marrow was used to identify CD34+ progenitor cells and examine their binding to the plant lectin Ulex europaeus I (Ulex). In normal bone marrow, 48.48 +/- 17.4% of the CD34+ cells bind to Ulex. Two color flow cytometry was used to sort CD34 + cells, and subsets of CD34+ cells, CD34+ Ulex+ and CD34+ Ulex-. These populations were sorted into colony assays to assess myeloid (CFU-GM) and erythroid (BFU-E) progenitors. The CD34+ Ulex+ subset was 84 +/- 14% BFU-E colonies (mean +/- S.D.) and had the highest cloning efficiency of 28 +/- 13%. Three color analysis of CD34+ Ulex+ cells showed staining with other erythroid (CD71, GlyA) antibodies and lack of stain. ing with myeloid (CD13, CD45RA) antibodies. These studies confirmed the erythroid characteristics of this subpopulation.

  11. Effect of Bolax gummifera rhizosphere on the mobility of soil nutrients in a subantarctic environment (Mont Martial, Ushuaia-Argentina)

    Science.gov (United States)

    Otero, Xosé Luis; Pérez-Alberti, Augusto; Gónzalez, Adrián; Macias, Felipe

    2013-04-01

    The study area, Mount Martial, is located in the South of Argentina, in the Tierra de Fuego province (54°S, 68°W). The climate in Tierra del Fuego is temperate-cold and humid, with a strong and markedly seasonal oceanic influence. The mean air temperature that we recorded in the study zone, at 1050 m above sea level, between February 2005 and January 2010 was -1.9° C, with an absolute maximum of 12.5° C and an absolute minimum of -12.8° C. Although we have no rainfall data, in Ushuaia, which is close to sea level, the mean annual rainfall for 1961-1970 was 550 mm; however, it would be inaccurate to extrapolate this value given the marked variability in precipitation favoured by the relief. Biogeographically, the area is included in the so-called "Andean Desert", which is almost barren of large plants and with poor vegetable cover. At 800 a.s.l., the vegetation consists of shrubs of specialised taxons such as Bolax gummifera, Moschopsis rosulata and Saxifraga magellanica. In the present study, samples of Bolax gummifera rhizosphere (Umbelliferae), bulk soil and subsurface soils (>5 cm to rock layer) were collected from a small homogeneous area (≈500m2). The soils were characterized by analysis of pH (H2O and KCl), electrical conductivity, total organic carbon, total nitrogen, organic carbon, iron extracted with sodium pyrophosphate, and particle size. Sequential extraction of Fe in the samples was also carried out to determine the following fractions: F1: exchangeable fraction (extracted with 1M MgCl2), F2: amorphous Fe oxyhydroxides (extracted with sodium ascorbate-citrate buffering to pH 8 with sodium bicarbonate), F3: crystalline Fe oxyhydroxides (extracted with 0.11 sodium citrate+ sodium bicarbonate +3 g of sodium dithionite), and F4: organic Fe (extracted with 0.02M HNO3+30%H2O2 at 85°C) and bioavailability nutrients (soluble in Mehlich 3 extratant). The results obtained for the basic physicochemical characteristics of the soils revealed some

  12. Quantitative Trait Loci Mapping of Western Corn Rootworm (Coleoptera: Chrysomelidae) Host Plant Resistance in Two Populations of Doubled Haploid Lines in Maize (Zea mays L.).

    Science.gov (United States)

    Bohn, Martin O; Marroquin, Juan J; Flint-Garcia, Sherry; Dashiell, Kenton; Willmot, David B; Hibbard, Bruce E

    2018-02-09

    Over the last 70 yr, more than 12,000 maize accessions have been screened for their level of resistance to western corn rootworm, Diabrotica virgifera virgifera (LeConte; Coleoptera: Chrysomelidae), larval feeding. Less than 1% of this germplasm was selected for initiating recurrent selection or other breeding programs. Selected genotypes were mostly characterized by large root systems and superior root regrowth after root damage caused by western corn rootworm larvae. However, no hybrids claiming native (i.e., host plant) resistance to western corn rootworm larval feeding are currently commercially available. We investigated the genetic basis of western corn rootworm resistance in maize materials with improved levels of resistance using linkage disequilibrium mapping approaches. Two populations of topcrossed doubled haploid maize lines (DHLs) derived from crosses between resistant and susceptible maize lines were evaluated for their level of resistance in three to four different environments. For each DHL topcross an average root damage score was estimated and used for quantitative trait loci (QTL) analysis. We found genomic regions contributing to western corn rootworm resistance on all maize chromosomes, except for chromosome 4. Models fitting all QTL simultaneously explained about 30 to 50% of the genotypic variance for root damage scores in both mapping populations. Our findings confirm the complex genetic structure of host plant resistance against western corn rootworm larval feeding in maize. Interestingly, three of these QTL regions also carry genes involved in ascorbate biosynthesis, a key compound we hypothesize is involved in the expression of western corn rootworm resistance. © The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  13. Changes in grass plant populations and temporal soil seed bank dynamics in a semi-arid African savanna: Implications for restoration.

    Science.gov (United States)

    Tessema, Zewdu K; de Boer, Willem F; Prins, Herbert H T

    2016-11-01

    The re-colonization or recovery of grass species after disappearance due to heavy grazing depends on the presence of persistent soil seed banks that might be accumulated over time from the aboveground vegetation. Moreover, successful plant recruitment is a function of seed production, seed germination and seedling survival, which can be mechanistically understood through studying the life cycle processes of grass species populations under field conditions. Therefore, we studied the number of germinable seeds, species richness and life-forms in the soil seed banks under light and heavy grazing conditions, and the changes in grass species populations in a semi-arid savanna of Ethiopia. Accordingly, a total of 103 species (15 perennial and 29 annual grasses, 6 legumes, 52 forbs and 1 woody species) emerged from the soil samples collected. Lightly grazed sites had a higher seed density compared with heavily grazed sites. The seed density increased over the first three months of soil sampling and decreased thereafter. Perennial grasses dominated the light grazing sites, whereas annual species dominated the heavily grazed sites, indicating that perennial grasses were replaced by annual species in the soil seed bank through grazing. The mean mortality rate from the seedling stage to adult plants was 65%. The seed-to-seedling stage was found to be the most critical transitional stage for grass survival. High seedling mortality in the aboveground vegetation and depletion of seeds in the soil seed banks as a result of sustained heavy grazing can lead to local extinction and disappearance of perennial grasses in semi-arid Ethiopian savannas. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Synergism between demethylation inhibitor fungicides or gibberellin inhibitor plant growth regulators and bifenthrin in a pyrethroid-resistant population of Listronotus maculicollis (Coleoptera: Curculionidae).

    Science.gov (United States)

    Ramoutar, D; Cowles, R S; Requintina, E; Alm, S R

    2010-10-01

    In 2007-2008, the "annual bluegrass weevil," Listronotus maculicollis Kirby (Coleoptera: Curculionidae), a serious pest of Poa annua L. (Poales: Poaceae) on U.S. golf courses, was shown to be resistant to two pyrethroids, bifenthrin and lambda-cyhalothrin. In 2008, we showed that bifenthrin resistance was principally mediated by oxidase detoxification (cytochrome P450 [P450]). P450s can be inhibited by demethylation inhibitor fungicides and gibberellin inhibitor plant growth regulators, both of which are commonly used on golf courses. We tested these compounds for synergistic activity with bifenthin against a pyrethroid-resistant population of L. maculicollis. The LD50 value for bifenthrin was significantly reduced from 87 ng per insect (without synergists) to 9.6-40 ng per insect after exposure to the fungicides fenarimol, fenpropimorph, prochloraz, propiconazole, and pyrifenox and the plant growth regulators flurprimidol, paclobutrazol, and trinexapac-ethyl. Simulated field exposure with formulated products registered for use on turf revealed enhanced mortality when adult weevils were exposed to bifenthrin (25% mortality, presented alone) combined with field dosages of propiconizole, fenarimol, flurprimidol, or trinexapac-ethyl (range, 49-70% mortality).

  15. The effects of a spillage of diesel fuel on a rocky shore in the sub-Antarctic region (Macquarie Island)

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, R.D.; Smith, S.D.A.; Pople, A.R. [University of New England, Armidale (Australia). Dept. of Zoology

    1995-04-01

    On 3 December 1987, the supply ship Nella Dan ran aground at Macquarie island (54{sup o}29`S. 158{sup o}58`E) releasing about 270 000 1 of oil, mostly light marine diesel, into the sea. At the time of the incident, many marine invertebrates were washed up dead along 2 km of shoreline. Twelve months later, the shore community was investigated using (1) algal and invertebrate populations of the littoral and sublittoral rocky shore, and (2) the invertebrate communities living in the holdfasts of the giant kelp Durvillaea antarctica, which were collected for later examination. Investigations were undertaken at both affected and control locations. Analyses of differences in community structure involved nested ANOVA and multi-dimensional scaling techniques. On the rocky substrate, the effect of the spill was restricted to some biota of the lower littoral and sublittoral zones -particularly echinoderms and the patellid limpet Nacella macquariensis. There were differences in cover for some algal species between locations. Within the kelp holdfasts, communities were dominated by peracarid crustaceans at control locations and by polychaetes (particularly the opportunistic groups - capitellids, cirratulids and spionids) at oil-affected locations. The communities have recently been re-surveyed (in the summer of 1994-95) to assist in the interpretation of the results and to gauge the extent of recovery of the affected biota. (author)

  16. A role for oxygen delivery and extracellular magnesium in limiting cold tolerance of the sub-antarctic stone crab Paralomis granulosa?

    Science.gov (United States)

    Wittmann, Astrid C; Pörtner, Hans O; Sartoris, Franz J

    2012-01-01

    A low capacity for regulation of extracellular Mg(2+) has been proposed to exclude reptant marine decapod crustaceans from temperatures below 0°C and thus to exclude them from the high Antarctic. To test this hypothesis and to elaborate the underlying mechanisms in the most cold-tolerant reptant decapod family of the sub-Antarctic, the Lithodidae, thermal tolerance was determined in the crab Paralomis granulosa (Decapoda, Anomura, Lithodidae) using an acute stepwise temperature protocol (-1°, 1°, 4°, 7°, 10°, and 13°C). Arterial and venous oxygen partial pressures (Po(2)) in hemolymph, heartbeat and ventilation beat frequencies, and hemolymph cation composition were measured at rest and after a forced activity (righting) trial. Scopes for heartbeat and ventilation beat frequencies and intermittent heartbeat and scaphognathite beat rates at rest were evaluated. Hemolymph [Mg(2+)] was experimentally reduced from 30 mmol L(-1) to a level naturally observed in Antarctic caridean shrimps (12 mmol L(-1)) to investigate whether the animals remain more active and tolerant to cold (-1°, 1°, and 4°C). In natural seawater, righting speed was significantly slower at -1° and 13°C, compared with acclimation temperature (4°C). Arterial and venous hemolymph Po(2) increased in response to cooling even though heartbeat and ventilation beat frequencies as well as scopes decreased. At rest, ionic composition of the hemolymph was not affected by temperature. Activity induced a significant increase in hemolymph [K(+)] at -1° and 1°C. Reduction of hemolymph [Mg(2+)] did not result in an increase in activity, an increase in heartbeat and ventilation beat frequencies, or a shift in thermal tolerance to lower temperatures. In conclusion, oxygen delivery in this cold-water crustacean was not acutely limiting cold tolerance, and animals may have been constrained more by their functional capacity and motility. In contrast to earlier findings in temperate and subpolar brachyuran