Reproductive protein evolution in two cryptic species of marine chordate

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Harrison Richard G

2011-01-01

Full Text Available Abstract Background Reproductive character displacement (RCD is a common and taxonomically widespread pattern. In marine broadcast spawning organisms, behavioral and mechanical isolation are absent and prezygotic barriers between species often operate only during the fertilization process. Such barriers are usually a consequence of differences in the way in which sperm and egg proteins interact, so RCD can be manifest as faster evolution of these proteins between species in sympatry than allopatry. Rapid evolution of these proteins often appears to be a consequence of positive (directional selection. Here, we identify a set of candidate gamete recognition proteins (GRPs in the ascidian Ciona intestinalis and showed that these GRPs evolve more rapidly than control proteins (those not involved in gamete recognition. Choosing a subset of these gamete recognition proteins that show evidence of positive selection (CIPRO37.40.1, CIPRO60.5.1, CIPRO100.7.1, we then directly test the RCD hypothesis by comparing divergence (omega and polymorphism (McDonald-Kreitman, Tajima's D, Fu and Li's D and F, Fay and Wu's H statistics in sympatric and allopatric populations of two distinct forms of C. intestinalis (Types A and B between which there are strong post-zygotic barriers. Results Candidate gamete recognition proteins from two lineages of C. intestinalis (Type A and B are evolving more rapidly than control proteins, consistent with patterns seen in insects and mammals. However, ω (dN/dS is not significantly different between the sympatric and allopatric populations, and none of the polymorphism statistics show significant differences between sympatric and allopatric populations. Conclusions Enhanced prezygotic isolation in sympatry has become a well-known feature of gamete recognition proteins in marine broadcast spawners. But in most cases the evolutionary process or processes responsible for this pattern have not been identified. Although gamete

Multiple factors contribute to reproductive isolation between two co-existing Habenaria species (Orchidaceae.

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Wenliu Zhang

Full Text Available Reproductive isolation is a key feature that forms barriers to gene flow between distinct plants. In orchids, prezygotic reproductive isolation has been considered to be strong, because their associations with highly specific pollinators. In this study, the reproductive ecology and reproductive isolation of two sympatric Habenaria species, H. davidii and H. fordii, was investigated by floral phenology and morphology, hand-pollination experiments and visitor observation in southwest China. The two species were dependent on insects for pollination and completely self-compatible. A number of factors have been identified to limit gene flow between the two species and achieved full reproductive isolation. Ecogeographic isolation was a weak barrier. H. fordii and H. davidii had completely overlapped flowering periods, and floral morphology plays an important role in floral isolation. The two species shared the same hawkmoth pollinator, Cechenena lineosa, but the pollinaria of the two orchids were attached on different body parts of pollinators. Prezygotic isolation was not complete, but the interspecific pollination treatments of each species resulted in no seed sets, indicating that unlike many other orchid species, in which the postzygotic reproductive isolation is very weak or complete absence, the post-zygotic isolation strongly acted in the stage of seed production between two species. The results illustrate the reproductive isolation between two species involves multiple plant life-history stages and a variety of reproductive barriers can contribute to overall isolation.

Natural hybridization and reproductive isolation between two Primula speciesFA

Institute of Scientific and Technical Information of China (English)

Yanping Xie; Xingfu Zhu; Yongpeng Ma; Jianli Zhao; Li Li; Qingjun Li

2017-01-01

Natural hybridization frequently occurs in plants and can facilitate gene flow between species,possibly resulting in species refusion.However,various reproductive barriers block the formation of hybrids and maintain species integrity.Here,we conducted a field survey to examine natural hybridization and reproductive isolation (RI) between sympatric populations of Primula secundiflora and P.poissonii using ten nuclear simple sequence repeat (SSR) loci.Although introgressive hybridization occurred,species boundaries between P.secundiflora and P.poissonii were maintained through nearly complete reproductive isolation.These interfertile species provide an excellent model for studying the RI mechanisms and evolutionary forces that maintain species boundaries.

The relationship between intraspecific assortative mating and reproductive isolation between divergent populations

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Daniel I. BOLNICK, Mark KIRKPATRICK

2012-06-01

Full Text Available The term 'assortative mating' has been applied to describe two very different phenomena: (1 the tendency for individuals to choose phenotypically similar mates from among conspecifics; or (2 the tendency to prefer conspecific over hete- rospecific mates (behavioral reproductive isolation. Both forms of assortative mating are widespread in nature, but the relationship between these behaviors remains unclear. Namely, it is plausible that a preference for phenotypically similar conspecifics incidentally reduces the probability of mating with phenotypically divergent heterospecifics. We present a model to calculate how the level of reproductive isolation depends on intraspecific assortative mating and the phenotypic divergence between species. For empirically reasonable levels of intraspecific assortment on a single trait axis, we show that strong reproductive isolation requires very substantial phenotypic divergence. We illustrate this point by applying our model to empirical data from threespine stickleback Gasterosteus aculeatus and Darwin’s Finches (Geospiza spp. We conclude that typical levels of intraspecific assortment cannot generally be extrapolated to explain levels of interspecific reproductive isolation. Instead, reproductive isolation between species likely arises from different mate choice behaviors, or multivariate assortative mating [Current Zoology 58 (3: 481–489, 2012].

Postmating Reproductive isolation between strains of Drosophila willistoni.

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Mardiros, Xian B; Park, Ronni; Clifton, Bryan; Grewal, Gurman; Khizar, Amina K; Markow, Therese A; Ranz, José M; Civetta, Alberto

2016-10-01

Speciation can occur through the presence of reproductive isolation barriers that impede mating, restrict cross-fertilization, or render inviable/sterile hybrid progeny. The D. willistoni subgroup is ideally suited for studies of speciation, with examples of both allopatry and sympatry, a range of isolation barriers, and the availability of one species complete genome sequence to facilitate genetic studies of divergence. D. w. willistoni has the largest geographic distribution among members of the Drosophila willistoni subgroup, spanning from Argentina to the southern United States, including the Caribbean islands. A subspecies of D. w. willistoni, D. w. quechua, is geographically separated by the Andes mountain range and has evolved unidirectional sterility, in that only male offspring of D. w. quechua females × D. w. willistoni males are sterile. Whether D. w. willistoni flies residing east of the Andes belong to one or more D. willistoni subspecies remains unresolved. Here we perform fecundity assays and show that F1 hybrid males produced from crosses between different strains found in Central America, North America, and northern Caribbean islands are reproductively isolated from South American and southern Caribbean island strains as a result of unidirectional hybrid male sterility. Our results show the existence of a reproductive isolation barrier between the northern and southern strains and suggest a subdivision of the previously identified D. willistoni willistoni species into 2 new subspecies.

The rate test of speciation: estimating the likelihood of non-allopatric speciation from reproductive isolation rates in Drosophila.

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Yukilevich, Roman

2014-04-01

Among the most debated subjects in speciation is the question of its mode. Although allopatric (geographical) speciation is assumed the null model, the importance of parapatric and sympatric speciation is extremely difficult to assess and remains controversial. Here I develop a novel approach to distinguish these modes of speciation by studying the evolution of reproductive isolation (RI) among taxa. I focus on the Drosophila genus, for which measures of RI are known. First, I incorporate RI into age-range correlations. Plots show that almost all cases of weak RI are between allopatric taxa whereas sympatric taxa have strong RI. This either implies that most reproductive isolation (RI) was initiated in allopatry or that RI evolves too rapidly in sympatry to be captured at incipient stages. To distinguish between these explanations, I develop a new "rate test of speciation" that estimates the likelihood of non-allopatric speciation given the distribution of RI rates in allopatry versus sympatry. Most sympatric taxa were found to have likely initiated RI in allopatry. However, two putative candidate species pairs for non-allopatric speciation were identified (5% of known Drosophila). In total, this study shows how using RI measures can greatly inform us about the geographical mode of speciation in nature. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

Maladaptive learning and memory in hybrids as a reproductive isolating barrier.

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Rice, Amber M; McQuillan, Michael A

2018-05-30

Selection against hybrid offspring, or postzygotic reproductive isolation, maintains species boundaries in the face of gene flow from hybridization. In this review, we propose that maladaptive learning and memory in hybrids is an important, but overlooked form of postzygotic reproductive isolation. Although a role for learning in premating isolation has been supported, whether learning deficiencies can contribute to postzygotic isolation has rarely been tested. We argue that the novel genetic combinations created by hybridization have the potential to impact learning and memory abilities through multiple possible mechanisms, and that any displacement from optima in these traits is likely to have fitness consequences. We review evidence supporting the potential for hybridization to affect learning and memory, and evidence of links between learning abilities and fitness. Finally, we suggest several avenues for future research. Given the importance of learning for fitness, especially in novel and unpredictable environments, maladaptive learning and memory in hybrids may be an increasingly important source of postzygotic reproductive isolation. © 2018 The Author(s).

Germination failure is not a critical stage of reproductive isolation between three congeneric orchid species.

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De Hert, Koen; Honnay, Olivier; Jacquemyn, Hans

2012-11-01

In food-deceptive orchid species, postmating reproductive barriers (fruit set and embryo mortality) have been shown to be more important for reproductive isolation than premating barriers (pollinator isolation). However, currently there is very little knowledge about whether germination failure acts as a reproductive barrier in hybridizing orchid species. In this study, we investigated germination and protocorm development of pure and hybrid seeds of three species of the orchid genus Dactylorhiza. To test the hypothesis that germination failure contributed to total reproductive isolation, reproductive barriers based on germination were combined with already available data on early acting barriers (fruit set and embryo mortality) to calculate the relative and absolute contributions of these barriers to reproductive isolation. Protocorms were formed in all crosses, indicating that both hybrid and pure seeds were able to germinate and grow into protocorms. Also, the number of protocorms per seed packet was not significantly different between hybrid and pure seeds. High fruit set, high seed viability, and substantial seed germination resulted in very low reproductive isolation (average RI = 0.05). In two of six interspecific crosses, hybrids performed even better than the intraspecific crosses. Very weak postmating reproductive barriers were observed between our study species and may explain the frequent occurrence of first-generation hybrids in mixed Dactylorhiza populations. Germination failure, which is regarded as one of the most important bottlenecks in the orchid life cycle, was not important for reproductive isolation.

Gene duplication and adaptive evolution of digestive proteases in Drosophila arizonae female reproductive tracts.

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Erin S Kelleher

2007-08-01

Full Text Available It frequently has been postulated that intersexual coevolution between the male ejaculate and the female reproductive tract is a driving force in the rapid evolution of reproductive proteins. The dearth of research on female tracts, however, presents a major obstacle to empirical tests of this hypothesis. Here, we employ a comparative EST approach to identify 241 candidate female reproductive proteins in Drosophila arizonae, a repleta group species in which physiological ejaculate-female coevolution has been documented. Thirty-one of these proteins exhibit elevated amino acid substitution rates, making them candidates for molecular coevolution with the male ejaculate. Strikingly, we also discovered 12 unique digestive proteases whose expression is specific to the D. arizonae lower female reproductive tract. These enzymes belong to classes most commonly found in the gastrointestinal tracts of a diverse array of organisms. We show that these proteases are associated with recent, lineage-specific gene duplications in the Drosophila repleta species group, and exhibit strong signatures of positive selection. Observation of adaptive evolution in several female reproductive tract proteins indicates they are active players in the evolution of reproductive tract interactions. Additionally, pervasive gene duplication, adaptive evolution, and rapid acquisition of a novel digestive function by the female reproductive tract points to a novel coevolutionary mechanism of ejaculate-female interaction.

Asymmetric reproductive isolation between two sympatric annual killifish with extremely short lifespans.

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Matej Polačik

Full Text Available BACKGROUND: Interspecific reproductive isolation is typically achieved by a combination of intrinsic and extrinsic barriers. Behavioural isolating barriers between sympatric, closely related species are often of primary importance and frequently aided by extrinsic factors causing spatial and temporal interspecific separation. Study systems with a severely limited role of extrinsic factors on reproductive isolation may provide valuable insights into how reproductive isolation between sympatric species is maintained. We used no-choice experimental set-up to study reproductive barriers between two closely related sympatric African killifish species, Nothobranchius furzeri and Nothobranchius orthonotus. These fish live in small temporary savannah pools and have complete spatial and temporal overlap in reproductive activities and share a similar ecology. PRINCIPAL FINDINGS: We found that the two species display largely incomplete and asymmetric reproductive isolation. Mating between N. furzeri males and N. orthonotus females was absent under standard experimental conditions and eggs were not viable when fish were forced to mate in a modified experimental setup. In contrast, male N. orthonotus indiscriminately mated with N. furzeri females, the eggs were viable, and offspring successfully hatched. Most spawnings, however, were achieved by male coercion and egg production and embryo survival were low. Behavioural asymmetry was likely facilitated by mating coercion from larger males of N. orthonotus and at relatively low cost to females. Interestingly, the direction of asymmetry was positively associated with asymmetry in post-mating reproductive barriers. SIGNIFICANCE: We showed that, in fish species with a promiscuous mating system and multiple matings each day, selection for strong mate preferences was relaxed. This effect was likely due to the small proportion of resources allocated to each single mating and the high potential cost to females from

Divergent Selection and Then What Not: The Conundrum of Missing Reproductive Isolation in Misty Lake and Stream Stickleback

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Katja Räsänen

2012-01-01

Full Text Available In ecological speciation, reproductive isolation evolves as a consequence of adaptation to different selective environments. A frequent contributor to this process is the evolution of positive assortative mate choice between ecotypes. We tested this expectation for lake and inlet stream threespine stickleback (Gasterosteus aculeatus from the Misty system (Vancouver Island, Canada, which show strong genetically based adaptive divergence and little genetic exchange in nature. This, and work on other stickleback systems, led us to expect positive assortative mating. Yet, our standard “no-choice” laboratory experiment on common-garden fish revealed no evidence for this—despite divergence in traits typically mediating assortative mating in stickleback. These results remind us that divergent natural selection may not inevitably lead to the evolution of positive assortative mate choice. The apparent lack of strong and symmetric reproductive barriers in this system presents a conundrum: why are such barriers not evident despite strong adaptive divergence and low gene flow in nature?

The evolution of reproductive diversity in Afrobatrachia: A phylogenetic comparative analysis of an extensive radiation of African frogs

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Portik, Daniel M.; Blackburn, David C.

2016-01-01

The reproductive modes of anurans (frogs and toads) are the most diverse of terrestrial vertebrates, and a major challenge is identifying selective factors that promote the evolution or retention of reproductive modes across clades. Terrestrialized anuran breeding strategies have evolved repeatedly from the plesiomorphic fully aquatic reproductive mode, a process thought to occur through intermediate reproductive stages. Several selective forces have been proposed for the evolution of terrestrialized reproductive traits, but factors such as water systems and co‐evolution with ecomorphologies have not been investigated. We examined these topics in a comparative phylogenetic framework using Afrobatrachian frogs, an ecologically and reproductively diverse clade representing more than half of the total frog diversity found in Africa (∼400 species). We infer direct development has evolved twice independently from terrestrialized reproductive modes involving subterranean or terrestrial oviposition, supporting evolution through intermediate stages. We also detect associations between specific ecomorphologies and oviposition sites, and demonstrate arboreal species exhibit an overall shift toward using lentic water systems for breeding. These results indicate that changes in microhabitat use associated with ecomorphology, which allow access to novel sites for reproductive behavior, oviposition, or larval development, may also promote reproductive mode diversity in anurans. PMID:27402182

Low reproductive isolation and highly variable levels of gene flow reveal limited progress towards speciation between European river and brook lampreys.

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Rougemont, Q; Gaigher, A; Lasne, E; Côte, J; Coke, M; Besnard, A-L; Launey, S; Evanno, G

2015-12-01

Ecologically based divergent selection is a factor that could drive reproductive isolation even in the presence of gene flow. Population pairs arrayed along a continuum of divergence provide a good opportunity to address this issue. Here, we used a combination of mating trials, experimental crosses and population genetic analyses to investigate the evolution of reproductive isolation between two closely related species of lampreys with distinct life histories. We used microsatellite markers to genotype over 1000 individuals of the migratory parasitic river lamprey (Lampetra fluviatilis) and freshwater-resident nonparasitic brook lamprey (Lampetra planeri) distributed in 10 sympatric and parapatric population pairs in France. Mating trials, parentage analyses and artificial fertilizations demonstrated a low level of reproductive isolation between species even though size-assortative mating may contribute to isolation. Most parapatric population pairs were strongly differentiated due to the joint effects of geographic distance and barriers to migration. In contrast, we found variable levels of gene flow between sympatric populations ranging from panmixia to moderate differentiation, which indicates a gradient of divergence with some population pairs that may correspond to alternative morphs or ecotypes of a single species and others that remain partially isolated. Ecologically based divergent selection may explain these variable levels of divergence among sympatric population pairs, but incomplete genome swamping following secondary contact could have also played a role. Overall, this study illustrates how highly differentiated phenotypes can be maintained despite high levels of gene flow that limit the progress towards speciation. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology.

Human evolution, life history theory, and the end of biological reproduction.

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Last, Cadell

2014-01-01

Throughout primate history there have been three major life history transitions towards increasingly delayed sexual maturation and biological reproduction, as well as towards extended life expectancy. Monkeys reproduce later and live longer than do prosimians, apes reproduce later and live longer than do monkeys, and humans reproduce later and live longer than do apes. These life history transitions are connected to increased encephalization. During the last life history transition from apes to humans, increased encephalization co-evolved with increased dependence on cultural knowledge for energy acquisition. This led to a dramatic pressure for more energy investment in growth over current biological reproduction. Since the industrial revolution socioeconomic development has led to even more energy being devoted to growth over current biological reproduction. I propose that this is the beginning of an ongoing fourth major primate life history transition towards completely delayed biological reproduction and an extension of the evolved human life expectancy. I argue that the only fundamental difference between this primate life history transition and previous life history transitions is that this transition is being driven solely by cultural evolution, which may suggest some deeper evolutionary transition away from biological evolution is already in the process of occurring.

PARTIAL REPRODUCTIVE ISOLATION OF A RECENTLY DERIVED RESIDENT-FRESHWATER POPULATION OF THREESPINE STICKLEBACK (GASTEROSTEUS ACULEATUS) FROM ITS PUTATIVE ANADROMOUS ANCESTOR

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Furin, Christoff G.; Von Hippel, Frank A.; Bell, Michael A.

2012-01-01

We used no-choice mating trials to test for assortative mating between a newly derived resident-freshwater population (8 – 22 generations since founding) of threespine stickleback (Gasterosteus aculeatus) in Loberg Lake, Alaska and its putative anadromous ancestor as well as a morphologically convergent but distantly related resident-freshwater population. Partial reproductive isolation has evolved between the Loberg Lake population and its ancestor within a remarkably short time period. However, Loberg stickleback readily mate with morphologically similar, but distantly related resident-freshwater stickleback. Partial pre-mating isolation is asymmetrical; anadromous females and smaller, resident-freshwater males from Loberg Lake readily mate, but the anadromous males and smaller Loberg females do not. Our results indicate that pre-mating isolation can begin to evolve in allopatry within a few generations after isolation as a correlated effect of evolution of reduced body size. PMID:23025615

Evolution of plant reproduction: from fusion and dispersal to interaction and communication

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Willemse, M.T.M.

2009-01-01

Based on the existing data concerning the evolution of the sexual reproduction, it is argued that the processes of sex differentiation and interactions play a key role in evolution. From the beginning environment and organism are unified. In a changing dynamic environment life originates and the

Unisexual reproduction of Cryptococcus gattii.

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Sujal S Phadke

Full Text Available Cryptococcus gattii is a basidiomycetous human fungal pathogen that typically causes infection in tropical and subtropical regions and is responsible for an ongoing outbreak in immunocompetent individuals on Vancouver Island and in the Pacific Northwest of the US. Pathogenesis of this species may be linked to its sexual cycle that generates infectious propagules called basidiospores. A marked predominance of only one mating type (α in clinical and environmental isolates suggests that a-α opposite-sex reproduction may be infrequent or geographically restricted, raising the possibility of an alternative unisexual cycle involving cells of only α mating type, as discovered previously in the related pathogenic species Cryptococcus neoformans. Here we report observation of hallmark features of unisexual reproduction in a clinical isolate of C. gattii (isolate 97/433 and describe genetic and environmental factors conducive to this sexual cycle. Our results are consistent with population genetic evidence of recombination in the largely unisexual populations of C. gattii and provide a useful genetic model for understanding how novel modes of sexual reproduction may contribute to evolution and virulence in this species.

Linkage Map of Lissotriton Newts Provides Insight into the Genetic Basis of Reproductive Isolation

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Marta Niedzicka

2017-07-01

Full Text Available Linkage maps are widely used to investigate structure, function, and evolution of genomes. In speciation research, maps facilitate the study of the genetic architecture of reproductive isolation by allowing identification of genomic regions underlying reduced fitness of hybrids. Here we present a linkage map for European newts of the Lissotriton vulgaris species complex, constructed using two families of F2 L. montandoni × L. vulgaris hybrids. The map consists of 1146 protein-coding genes on 12 linkage groups, equal to the haploid chromosome number, with a total length of 1484 cM (1.29 cM per marker. It is notably shorter than two other maps available for salamanders, but the differences in map length are consistent with cytogenetic estimates of the number of chiasmata per chromosomal arm. Thus, large salamander genomes do not necessarily translate into long linkage maps, as previously suggested. Consequently, salamanders are an excellent model to study evolutionary consequences of recombination rate variation in taxa with large genomes and a similar number of chromosomes. A complex pattern of transmission ratio distortion (TRD was detected: TRD occurred mostly in one family, in one breeding season, and was clustered in two genomic segments. This is consistent with environment-dependent mortality of individuals carrying L. montandoni alleles in these two segments and suggests a role of TRD blocks in reproductive isolation. The reported linkage map will empower studies on the genomic architecture of divergence and interactions between the genomes of hybridizing newts.

Evolution of viviparous reproduction in Paleozoic and Mesozoic reptiles.

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Blackburn, Daniel G; Sidor, Christian A

2014-01-01

Although viviparity (live-bearing reproduction) is widely distributed among lizards and snakes, it is entirely absent from other extant Reptilia and many extinct forms. However, paleontological evidence reveals that viviparity was present in at least nine nominal groups of pre-Cenozoic reptiles, representing a minimum of six separate evolutionary origins of this reproductive mode. Two viviparous clades (sauropterygians and ichthyopterygians) lasted more than 155 million years, a figure that rivals the duration of mammalian viviparity. Circumstantial evidence indicates that extinct viviparous reptiles had internal fertilization, amniotic fetal membranes, and placentas that sustained developing embryos via provision of respiratory gases, water, calcium, and possibly organic nutrients. Production of offspring via viviparity facilitated the invasion of marine habitats in at least five reptilian lineages. Thus, this pattern of embryonic development and reproduction was central to the ecology and evolution of these ancient animals, much as it is to numerous extant species of vertebrates.

Evolution of Isolated Neutron Stars

OpenAIRE

Popov, S. B.

2001-01-01

In this paper we briefly review our recent results on evolution and properties of isolated neutron stars (INSs) in the Galaxy. As the first step we discuss stochastic period evolution of INSs. We briefly discuss how an INS's spin period evolves under influence of interaction with turbulized interstellar medium. To investigate statistical properties of the INS population we calculate a {\\it census} of INSs in our Galaxy. Then we show that for exponential field decay the range of minimum value ...

Hybridization experiments indicate incomplete reproductive isolating mechanism between Fasciola hepatica and Fasciola gigantica.

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Itagaki, T; Ichinomiya, M; Fukuda, K; Fusyuku, S; Carmona, C

2011-09-01

Experiments on hybridization between Fasciola hepatica and Fasciola gigantica were carried out to clarify whether a reproductive isolating mechanism appears between the two Fasciola species. Molecular evidence for hybridization was based on the DNA sequence of the internal transcribed spacer 1 (ITS1) region in nuclear ribosomal DNA, which differs between the species. The results suggested that there were not pre-mating but post-mating isolating mechanisms between the two species. However, viable adults of the hybrids F1 and F2 were produced from both parental F. hepatica and F. gigantica. The hybrids inherited phenotypic characteristics such as ratio of body length and width and infectivity to rats from parental Fasciola hepatica and F. gigantica. These findings suggest that reproductive isolation is incomplete between Fasciola hepatica and F. gigantica. Adults of the hybrids F1 and F2 were completely different in mode of reproduction from aspermic Fasciola forms that occur in Asia and seem to be offspring originated from hybridization between F. hepatica and F. gigantica and to reproduce parthenogenetically.

Patterns of reproductive isolation in the Drosophila subquinaria complex: can reinforced premating isolation cascade to other species?

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Humphreys, Devon P.; Rundle, Howard D.; Dyer, Kelly A.

2016-01-01

Abstract The reinforcement of premating barriers due to reduced hybrid fitness in sympatry may cause secondary sexual isolation within a species as a by-product. Consistent with this, in the fly Drosophila subquinaria, females that are sympatric with D. recens mate at very low rates not only with D. recens, but also with conspecific D. subquinaria males from allopatry. Here, we ask if these effects of reinforcement cascade more broadly to affect sexual isolation with other closely related species. We assay reproductive isolation of these species with D. transversa and find that choosy D. subquinaria females from the region sympatric with D. recens discriminate strongly against male D. transversa, whereas D. subquinaria from the allopatric region do not. This increased sexual isolation cannot be explained by natural selection to avoid mating with this species, as they are allopatric in geographic range and we do not identify any intrinsic postzygotic isolation between D. subquinaria and D. transversa. Variation in epicuticular hydrocarbons, which are used as mating signals in D. subquinaria, follow patterns of premating isolation: D. transversa and allopatric D. subquinaria are most similar to each other and differ from sympatric D. subquinaria, and those of D. recens are distinct from the other two species. We suggest that the secondary effects of reinforcement may cascade to strengthen reproductive isolation with other species that were not a target of selection. These effects may enhance the divergence that occurs in allopatry to help explain why some species are already sexually isolated upon secondary contact. PMID:29491905

Reproductive isolation and the expansion of an invasive hybrid swarm

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Blum, Michael J.; Walters, David M.; Burkhead, Noel M.; Freeman, Byron J.; Porter, Brady A.

2010-01-01

Biological invasions involving hybridization proceed according to prezygotic and postzygotic reproductive isolating mechanisms. Yet few comparisons of reproductive isolation have been carried out to understand how different mechanisms prevent or promote invasions involving hybridization. Here we present a study of prezygotic and postzygotic isolation between non-native red shiner (Cyprinella lutrensis) and native blacktail shiner (C. venusta stigmatura) from the Coosa River basin (USA) to better understand the formation and expansion of invasive hybrid swarms. We conducted spawning trials to measure mating preferences and raised broods from crosses to assay hybrid viability through early juvenile development. Females of both species were more responsive to conspecific mates, although blacktail shiner females responded more often to heterospecific mates than did red shiner females. Fecundity of red shiner females was also higher than blacktail shiner females. Heterospecific crosses resulted in lower fertilization and egg hatching rates, but we found no other evidence of inviability. Rather, we found comparatively low larval mortality of F1 hybrids, which is suggestive of heterosis. These findings support prior inferences of assortative mating from genetic descriptions of hybridization, and that the invasion in the Coosa River is likely proceeding due to interspecific competition and intrinsic hybrid viability.

Rapid neo-sex chromosome evolution and incipient speciation in a major forest pest.

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Bracewell, Ryan R; Bentz, Barbara J; Sullivan, Brian T; Good, Jeffrey M

2017-11-17

Genome evolution is predicted to be rapid following the establishment of new (neo) sex chromosomes, but it is not known if neo-sex chromosome evolution plays an important role in speciation. Here we combine extensive crossing experiments with population and functional genomic data to examine neo-XY chromosome evolution and incipient speciation in the mountain pine beetle. We find a broad continuum of intrinsic incompatibilities in hybrid males that increase in strength with geographic distance between reproductively isolated populations. This striking progression of reproductive isolation is coupled with extensive gene specialization, natural selection, and elevated genetic differentiation on both sex chromosomes. Closely related populations isolated by hybrid male sterility also show fixation of alternative neo-Y haplotypes that differ in structure and male-specific gene content. Our results suggest that neo-sex chromosome evolution can drive rapid functional divergence between closely related populations irrespective of ecological drivers of divergence.

No boundaries: genomes, organisms, and ecological interactions responsible for divergence and reproductive isolation.

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Etges, William J

2014-01-01

Revealing the genetic basis of traits that cause reproductive isolation, particularly premating or sexual isolation, usually involves the same challenges as most attempts at genotype-phenotype mapping and so requires knowledge of how these traits are expressed in different individuals, populations, and environments, particularly under natural conditions. Genetic dissection of speciation phenotypes thus requires understanding of the internal and external contexts in which underlying genetic elements are expressed. Gene expression is a product of complex interacting factors internal and external to the organism including developmental programs, the genetic background including nuclear-cytotype interactions, epistatic relationships, interactions among individuals or social effects, stochasticity, and prevailing variation in ecological conditions. Understanding of genomic divergence associated with reproductive isolation will be facilitated by functional expression analysis of annotated genomes in organisms with well-studied evolutionary histories, phylogenetic affinities, and known patterns of ecological variation throughout their life cycles. I review progress and prospects for understanding the pervasive role of host plant use on genetic and phenotypic expression of reproductive isolating mechanisms in cactophilic Drosophila mojavensis and suggest how this system can be used as a model for revealing the genetic basis for species formation in organisms where speciation phenotypes are under the joint influences of genetic and environmental factors. © The American Genetic Association. 2014. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The Evolution of Reproduction within Testudinata as Evidenced by the Fossil Record

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Lawver, Daniel Ryan

Although known from every continent except Antarctica and having a fossil record ranging from the Middle Jurassic to the Pleistocene, fossil turtle eggs are relatively understudied. In this dissertation I describe four fossil specimens, interpret paleoecology and conduct cladistic analyses in order to investigate the evolution of turtle reproduction. Fossil eggshell descriptions primarily involve analysis by scanning electron and polarized light microscopy, as well as cathodoluminescence to determine the degree of diagenetic alteration. Carapace lengths and gas conductance are estimated in order to investigate the ecology of the adults that produced fossil turtle eggs and clutches, as well as their incubation environments, respectively. Cladistic analyses of turtle egg and reproductive characters permit assessment of the usefulness of these characters for determining phylogenetic relationships of fossil specimens and the evolution of reproduction in turtles. Specimens described here include 1) Testudoolithus oosp. from the Late Cretaceous of Madagascar, 2) a clutch of eggs (some containing late stage embryos and at least one exhibiting multilayer eggshell) from the Late Cretaceous Judith River Formation of Montana and named Testudoolithus zelenitskyae oosp. nov., 3) an egg contained within an adult Basilemys nobilis from the Late Cretaceous Kaiparowits Formation of Utah, and 4) a clutch of Meiolania platyceps eggs from the Pleistocene of Lord Howe Island, Australia. Meiolania platyceps eggs are named Testudoolithus lordhowensis oosp. nov. and provide valuable information on the origin of aragonite eggshell composition and nesting behaviors. Cladistic analyses utilizing egg and reproductive characters are rarely performed on taxa outside of Dinosauria. My analyses demonstrate that morphological data produces poorly resolved trees in which only the clades Adocia and Trionychia are resolved and all other turtles form a large polytomy. However, when combined with

Biannual Spawning and Temporal Reproductive Isolation in Acropora Corals.

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James P Gilmour

Full Text Available Coral spawning on the oceanic reef systems of north-western Australia was recently discovered during autumn and spring, but the degree to which species and particularly colonies participated in one or both of these spawnings was unknown. At the largest of the oceanic reef systems, the participation by colonies in the two discrete spawning events was investigated over three years in 13 species of Acropora corals (n = 1,855 colonies. Seven species spawned during both seasons; five only in autumn and one only in spring. The majority of tagged colonies (n = 218 spawned once a year in the same season, but five colonies from three species spawned during spring and autumn during a single year. Reproductive seasonality was not influenced by spatial variation in habitat conditions, or by Symbiodinium partners in the biannual spawner Acropora tenuis. Colonies of A. tenuis spawning during different seasons separated into two distinct yet cryptic groups, in a bayesian clustering analysis based on multiple microsatellite markers. These groups were associated with a major genetic divergence (G"ST = 0.469, despite evidence of mixed ancestry in a small proportion of individuals. Our results confirm that temporal reproductive isolation is a common feature of Acropora populations at Scott Reef and indicate that spawning season is a genetically determined trait in at least A. tenuis. This reproductive isolation may be punctuated occasionally by interbreeding between genetic groups following favourable environmental conditions, when autumn spawners undergo a second annual gametogenic cycle and spawn during spring.

Batesian mimicry promotes pre- and postmating isolation in a snake mimicry complex.

Science.gov (United States)

Pfennig, David W; Akcali, Christopher K; Kikuchi, David W

2015-04-01

We evaluated whether Batesian mimicry promotes early-stage reproductive isolation. Many Batesian mimics occur not only in sympatry with their model (as expected), but also in allopatry. As a consequence of local adaptation within both sympatry (where mimetic traits are favored) and allopatry (where nonmimetic traits are favored), divergent, predator-mediated natural selection should disfavor immigrants between these selective environments as well as any between-environment hybrids. This selection might form the basis for both pre- and postmating isolation, respectively. We tested for such selection in a snake mimicry complex by placing clay replicas of sympatric, allopatric, or hybrid phenotypes in both sympatry and allopatry and measuring predation attempts. As predicted, replicas with immigrant phenotypes were disfavored in both selective environments. Replicas with hybrid phenotypes were also disfavored, but only in a region of sympatry where previous studies have detected strong selection favoring precise mimicry. By fostering immigrant inviability and ecologically dependent selection against hybrids (at least in some habitats), Batesian mimicry might therefore promote reproductive isolation. Thus, although Batesian mimicry has long been viewed as a mechanism for convergent evolution, it might play an underappreciated role in fueling divergent evolution and possibly even the evolution of reproductive isolation and speciation. © 2015 The Author(s).

Reproductive isolation between sympatric and allopatric Brazilian populations of Lutzomyia longipalpis s.l. (Diptera: Psychodidae).

Science.gov (United States)

Souza, Nataly A; Andrade-Coelho, Claudia A; Vigoder, Felipe M; Ward, Richard D; Peixoto, Alexandre A

2008-03-01

Lutzomyia longipalpis s.l., the main vector of Leishmania chagasi in Latin America, is a species complex although the exact number of siblings is yet unknown. In Brazil, the siblings differ in male copulatory courtship songs and pheromones that most certainly act as pre-zygotic reproductive barriers. Here we analysed the reproductive isolation between three allopatric and two sympatric populations of Lu. longipalpis s.l. from Brazil. The results indicate a strong copulatory and pre-mating isolation between the three allopatric populations. In addition, the results also indicate a stronger pre-mating isolation between the two sympatric siblings than between the three allopatric ones, suggesting a role for reinforcement in the speciation of the Lu. longipalpis s.l. complex.

A widespread chromosomal inversion polymorphism contributes to a major life-history transition, local adaptation, and reproductive isolation.

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David B Lowry

2010-09-01

Full Text Available The role of chromosomal inversions in adaptation and speciation is controversial. Historically, inversions were thought to contribute to these processes either by directly causing hybrid sterility or by facilitating the maintenance of co-adapted gene complexes. Because inversions suppress recombination when heterozygous, a recently proposed local adaptation mechanism predicts that they will spread if they capture alleles at multiple loci involved in divergent adaptation to contrasting environments. Many empirical studies have found inversion polymorphisms linked to putatively adaptive phenotypes or distributed along environmental clines. However, direct involvement of an inversion in local adaptation and consequent ecological reproductive isolation has not to our knowledge been demonstrated in nature. In this study, we discovered that a chromosomal inversion polymorphism is geographically widespread, and we test the extent to which it contributes to adaptation and reproductive isolation under natural field conditions. Replicated crosses between the prezygotically reproductively isolated annual and perennial ecotypes of the yellow monkeyflower, Mimulus guttatus, revealed that alternative chromosomal inversion arrangements are associated with life-history divergence over thousands of kilometers across North America. The inversion polymorphism affected adaptive flowering time divergence and other morphological traits in all replicated crosses between four pairs of annual and perennial populations. To determine if the inversion contributes to adaptation and reproductive isolation in natural populations, we conducted a novel reciprocal transplant experiment involving outbred lines, where alternative arrangements of the inversion were reciprocally introgressed into the genetic backgrounds of each ecotype. Our results demonstrate for the first time in nature the contribution of an inversion to adaptation, an annual/perennial life-history shift, and

Genetic Linkage Map Construction and QTL Analysis of Two Interspecific Reproductive Isolation Traits in Sponge Gourd

OpenAIRE

Wu, Haibin; He, Xiaoli; Gong, Hao; Luo, Shaobo; Li, Mingzhu; Chen, Junqiu; Zhang, Changyuan; Yu, Ting; Huang, Wangping; Luo, Jianning

2016-01-01

The hybrids between Luffa acutangula (L.) Roxb. and L.cylindrica (L.) Roem. have strong heterosis effects. However, some reproductive isolation traits hindered their normal hybridization and fructification, which was mainly caused by the flowering time and hybrid pollen sterility. In order to study the genetic basis of two interspecific reproductive isolation traits, we constructed a genetic linkage map using an F2 population derived from a cross between S1174 [L. acutangula (L.) Roxb.] and 9...

Whole genome characterization of a novel porcine reproductive and respiratory syndrome virus 1 isolate: Genetic evidence for recombination between Amervac vaccine and circulating strains in mainland China.

Science.gov (United States)

Chen, Nanhua; Liu, Qiaorong; Qiao, Mingming; Deng, Xiaoyu; Chen, Xizhao; Sun, Ming

2017-10-01

Genotype 1 porcine reproductive and respiratory syndrome virus (PRRSV 1) have been continuously isolated in China in recent years. Complete genome sequences of these isolates are important to investigate the prevalence and evolution of Chinese PRRSV 1. Herein, we describe the isolation of a novel PRRSV 1 isolate, denominated HLJB1, in the Heilongjiang province of China. Complete genome sequencing of HLJB1 showed that it shares 90.66% and 58.21% nucleotide identities with PRRSV 1 and 2 prototypic strains Lelystad virus and ATCC VR-2332, respectively. HLJB1 has a unique 5-amino-acid insertion in nsp2, which has never been described in other PRRSV 1 isolates. Whole genome-based phylogenetic analysis revealed that all Chinese PRRSV 1 isolates are clustered in pan-European subtype 1 and can be divided into four subgroups. HLJB1 resides in the subgroup of BJEU06-1-like isolates but is also closely related to the Amervac-like isolates. Additionally, recombination analyses suggested that HLJB1 is a recombinant from the Amervac vaccine and the BJEU06-1 isolate. To our best knowledge, our results provide the first genetic evidence for recombination between Amervac vaccine and circulating strains. These findings are also beneficial for studying the origin and evolution of PRRSV 1 in China. Copyright © 2017. Published by Elsevier B.V.

The uncharacterized gene 1700093K21Rik and flanking regions are correlated with reproductive isolation in the house mouse, Mus musculus.

Science.gov (United States)

Kass, David H; Janoušek, Václav; Wang, Liuyang; Tucker, Priscilla K

2014-06-01

Reproductive barriers exist between the house mouse subspecies, Mus musculus musculus and M. m. domesticus, members of the Mus musculus species complex, primarily as a result of hybrid male infertility, and a hybrid zone exists where their ranges intersect in Europe. Using single nucleotide polymorphisms (SNPs) diagnostic for the two taxa, the extent of introgression across the genome was previously compared in these hybrid populations. Sixty-nine of 1316 autosomal SNPs exhibited reduced introgression in two hybrid zone transects suggesting maladaptive interactions among certain loci. One of these markers is within a region on chromosome 11 that, in other studies, has been associated with hybrid male sterility of these subspecies. We assessed sequence variation in a 20 Mb region on chromosome 11 flanking this marker, and observed its inclusion within a roughly 150 kb stretch of DNA showing elevated sequence differentiation between the two subspecies. Four genes are associated with this genomic subregion, with two entirely encompassed. One of the two genes, the uncharacterized 1700093K21Rik gene, displays distinguishing features consistent with a potential role in reproductive isolation between these subspecies. Along with its expression specifically within spermatogenic cells, we present various sequence analyses that demonstrate a high rate of molecular evolution of this gene, as well as identify a subspecies amino acid variant resulting in a structural difference. Taken together, the data suggest a role for this gene in reproductive isolation.

Predictors for reproductive isolation in a ring species complex following genetic and ecological divergence.

Science.gov (United States)

Pereira, Ricardo J; Monahan, William B; Wake, David B

2011-07-06

Reproductive isolation (RI) is widely accepted as an important "check point" in the diversification process, since it defines irreversible evolutionary trajectories. Much less consensus exists about the processes that might drive RI. Here, we employ a formal quantitative analysis of genetic interactions at several stages of divergence within the ring species complex Ensatina eschscholtzii in order to assess the relative contribution of genetic and ecological divergence for the development of RI. By augmenting previous genetic datasets and adding new ecological data, we quantify levels of genetic and ecological divergence between populations and test how they correlate with a restriction of genetic admixture upon secondary contact. Our results indicate that the isolated effect of ecological divergence between parental populations does not result in reproductively isolated taxa, even when genetic transitions between parental taxa are narrow. Instead, processes associated with overall genetic divergence are the best predictors of reproductive isolation, and when parental taxa diverge in nuclear markers we observe a complete cessation of hybridization, even to sympatric occurrence of distinct evolutionary lineages. Although every parental population has diverged in mitochondrial DNA, its degree of divergence does not predict the extent of RI. These results show that in Ensatina, the evolutionary outcomes of ecological divergence differ from those of genetic divergence. While evident properties of taxa may emerge via ecological divergence, such as adaptation to local environment, RI is likely to be a byproduct of processes that contribute to overall genetic divergence, such as time in geographic isolation, rather than being a direct outcome of local adaptation.

Floral traits driving reproductive isolation of two co-flowering taxa that share vertebrate pollinators

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Queiroz, Joel A.; Quirino, Zelma G. M.; Machado, Isabel C.

2015-01-01

Floral attributes evolve in response to frequent and efficient pollinators, which are potentially important drivers of floral diversification and reproductive isolation. In this context, we asked, how do flowers evolve in a bat–hummingbird pollination system? Hence, we investigated the pollination ecology of two co-flowering Ipomoea taxa (I. marcellia and I. aff. marcellia) pollinated by bats and hummingbirds, and factors favouring reproductive isolation and pollinator sharing in these plants. To identify the most important drivers of reproductive isolation, we compared the flowers of the two Ipomoea taxa in terms of morphometry, anthesis and nectar production. Pollinator services were assessed using frequency of visits, fruit set and the number of seeds per fruit after visits. The studied Ipomoea taxa differed in corolla size and width, beginning and duration of anthesis, and nectar attributes. However, they shared the same diurnal and nocturnal visitors. The hummingbird Heliomaster squamosus was more frequent in I. marcellia (1.90 visits h−1) than in I. aff. marcellia (0.57 visits h−1), whereas glossophagine bats showed similar visit rates in both taxa (I. marcellia: 0.57 visits h−1 and I. aff. marcellia: 0.64 visits h−1). Bat pollination was more efficient in I. aff. marcellia, whereas pollination by hummingbirds was more efficient in I. marcellia. Differences in floral attributes between Ipomoea taxa, especially related to the anthesis period, length of floral parts and floral arrangement in the inflorescence, favour reproductive isolation from congeners through differential pollen placement on pollinators. This bat–hummingbird pollination system seems to be advantageous in the study area, where the availability of pollinators and floral resources changes considerably throughout the year, mainly as a result of rainfall seasonality. This interaction is beneficial for both sides, as it maximizes the number of potential pollen vectors for plants and

Living in isolation - population structure, reproduction, and genetic variation of the endangered plant species Dianthus gratianopolitanus (Cheddar pink).

Science.gov (United States)

Putz, Christina M; Schmid, Christoph; Reisch, Christoph

2015-09-01

The endangered plant species Dianthus gratianopolitanus exhibits a highly fragmented distribution range comprising many isolated populations. Based upon this pattern of distribution, we selected a study region in Switzerland with a lower magnitude of isolation (Swiss Jura) and another study region in Germany with a higher degree of isolation (Franconian Jura). In each region, we chose ten populations to analyze population structure, reproduction, and genetic variation in a comparative approach. Therefore, we determined population density, cushion size, and cushion density to analyze population structure, investigated reproductive traits, including number of flowers, capsules, and germination rate, and analyzed amplified fragment length polymorphisms to study genetic variation. Population and cushion density were credibly higher in German than in Swiss populations, whereas reproductive traits and genetic variation within populations were similar in both study regions. However, genetic variation among populations and isolation by distance were stronger in Germany than in Switzerland. Generally, cushion size and density as well as flower and capsule production increased with population size and density, whereas genetic variation decreased with population density. In contrast to our assumptions, we observed denser populations and cushions in the region with the higher magnitude of isolation, whereas reproductive traits and genetic variation within populations were comparable in both regions. This corroborates the assumption that stronger isolation must not necessarily result in the loss of fitness and genetic variation. Furthermore, it supports our conclusion that the protection of strongly isolated populations contributes essentially to the conservation of a species' full evolutionary potential.

The Evolution of Diapsid Reproductive Strategy with Inferences about Extinct Taxa.

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Jason R Moore

Full Text Available Diapsids show an extremely wide range of reproductive strategies. Offspring may receive no parental care, care from only one sex, care from both parents, or care under more complex regimes. Young may vary from independent, super-precocial hatchlings to altricial neonates needing much care before leaving the nest. Parents can invest heavily in a few young, or less so in a larger number. Here we examine the evolution of these traits across a composite phylogeny spanning the extant diapsids and including the limited number of extinct taxa for which reproductive strategies can be well constrained. Generalized estimating equation(GEE-based phylogenetic comparative methods demonstrate the influences of body mass, parental care strategy and hatchling maturity on clutch volume across the diapsids. The influence of polygamous reproduction is not important despite a large sample size. Applying the results of these models to the dinosaurs supports the hypothesis of paternal care (male only in derived non-avian theropods, previously suggested based on simpler analyses. These data also suggest that sauropodomorphs did not care for their young. The evolution of parental-care occurs in an almost linear series of transitions. Paternal care rarely gives rise to other care strategies. Where hatchling condition changes, diapsids show an almost unidirectional tendency of evolution towards increased altriciality. Transitions to social monogamy from the ancestral state in diapsids, where both sexes are polygamous, are common. In contrast, once evolved, polygyny and polyandry are very evolutionarily stable. Polygyny and maternal care correlate, as do polyandry and paternal care. Ancestral-character estimation (ACE of these care strategies with the character transition likelihoods estimated from the original data gives good confidence at most important nodes. These analyses suggest that the basalmost diapsids had no parental care. Crocodilians independently evolved

Genetic Linkage Map Construction and QTL Analysis of Two Interspecific Reproductive Isolation Traits in Sponge Gourd.

Science.gov (United States)

Wu, Haibin; He, Xiaoli; Gong, Hao; Luo, Shaobo; Li, Mingzhu; Chen, Junqiu; Zhang, Changyuan; Yu, Ting; Huang, Wangping; Luo, Jianning

2016-01-01

The hybrids between Luffa acutangula (L.) Roxb. and L.cylindrica (L.) Roem. have strong heterosis effects. However, some reproductive isolation traits hindered their normal hybridization and fructification, which was mainly caused by the flowering time and hybrid pollen sterility. In order to study the genetic basis of two interspecific reproductive isolation traits, we constructed a genetic linkage map using an F2 population derived from a cross between S1174 [L. acutangula (L.) Roxb.] and 93075 [L. cylindrica (L.) Roem.]. The map spans 1436.12 CentiMorgans (cM), with an average of 8.11 cM among markers, and consists of 177 EST-SSR markers distributed in 14 linkage groups (LG) with an average of 102.58 cM per LG. Meanwhile, we conducted colinearity analysis between the sequences of EST-SSR markers and the genomic sequences of cucumber, melon and watermelon. On the basis of genetic linkage map, we conducted QTL mapping of two reproductive isolation traits in sponge gourd, which were the flowering time and hybrid male sterility. Two putative QTLs associated with flowering time (FT) were both detected on LG 1. The accumulated contribution of these two QTLs explained 38.07% of the total phenotypic variance (PV), and each QTL explained 15.36 and 22.71% of the PV respectively. Four QTLs for pollen fertility (PF) were identified on LG 1 (qPF1.1 and qPF1.2), LG 3 (qPF3) and LG 7 (qPF7), respectively. The percentage of PF explained by these QTLs varied from 2.91 to 16.79%, and all together the four QTLs accounted for 39.98% of the total PV. Our newly developed EST-SSR markers and linkage map are very useful for gene mapping, comparative genomics and molecular marker-assisted breeding. These QTLs for interspecific reproductive isolation will also contribute to the cloning of genes relating to interspecific reproductive isolation and the utilization of interspecific heterosis in sponge gourd in further studies.

Multiple Genes Cause Postmating Prezygotic Reproductive Isolation in the Drosophila virilis Group.

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Ahmed-Braimah, Yasir H

2016-12-07

Understanding the genetic basis of speciation is a central problem in evolutionary biology. Studies of reproductive isolation have provided several insights into the genetic causes of speciation, especially in taxa that lend themselves to detailed genetic scrutiny. Reproductive barriers have usually been divided into those that occur before zygote formation (prezygotic) and after (postzygotic), with the latter receiving a great deal of attention over several decades. Reproductive barriers that occur after mating but before zygote formation [postmating prezygotic (PMPZ)] are especially understudied at the genetic level. Here, I present a phenotypic and genetic analysis of a PMPZ reproductive barrier between two species of the Drosophila virilis group: D. americana and D. virilis This species pair shows strong PMPZ isolation, especially when D. americana males mate with D. virilis females: ∼99% of eggs laid after these heterospecific copulations are not fertilized. Previous work has shown that the paternal loci contributing to this incompatibility reside on two chromosomes, one of which (chromosome 5) likely carries multiple factors. The other (chromosome 2) is fixed for a paracentric inversion that encompasses nearly half the chromosome. Here, I present two results. First, I show that PMPZ in this species cross is largely due to defective sperm storage in heterospecific copulations. Second, using advanced intercross and backcross mapping approaches, I identify genomic regions that carry genes capable of rescuing heterospecific fertilization. I conclude that paternal incompatibility between D. americana males and D. virilis females is underlain by four or more genes on chromosomes 2 and 5. Copyright © 2016 Ahmed-Braimah.

Lack of reproductive isolation between the Western and Eastern phylogroups of the tench

Czech Academy of Sciences Publication Activity Database

Lajbner, Zdeněk; Kohlmann, K.; Linhart, O.; Kotlík, Petr

2010-01-01

Roč. 2010, č. 3 (2010), s. 289-300 ISSN 0960-3166 R&D Projects: GA MŠk LC06073 Institutional research plan: CEZ:AV0Z50450515 Keywords : Tench * Phylogroups * Reproductive isolation Subject RIV: EG - Zoology Impact factor: 3.609, year: 2010

Experimental inoculation of late term pregnant sows with a field isolate of porcine reproductive and respiratory syndrome vaccine-derived virus

DEFF Research Database (Denmark)

Nielsen, Jens; Bøtner, Anette; Bille-Hansen, Vivi

2002-01-01

The use of a live attenuated porcine reproductive and respiratory syndrome virus (PRRSV) vaccine in piglets has been associated with reproductive disorders in non-vaccinated sows. Vaccine-derived virus (VDV) has been isolated from foctuses, stillborn pigs, and dead: piglets, indicating that the l......The use of a live attenuated porcine reproductive and respiratory syndrome virus (PRRSV) vaccine in piglets has been associated with reproductive disorders in non-vaccinated sows. Vaccine-derived virus (VDV) has been isolated from foctuses, stillborn pigs, and dead: piglets, indicating...... than 99.6% identity to the attenuated vaccine virus, originated from the lungs of a stillborn pig from a swine herd with a sudden high level of stillborn pigs and increased piglet mortality in the nursing period. Intranasal inoculation of sows with the virus isolate resulted in congenital infection......, foetal death, and preweaning pig mortality. As such, the present study showed that vaccine-derived PRRSV can cause disease in swine consistent with PRRS....

Failed sperm development as a reproductive isolating barrier between species.

Science.gov (United States)

Wünsch, Lisa K; Pfennig, Karin S

2013-01-01

Hybrid male sterility is a common reproductive isolating barrier between species. Yet, little is known about the actual developmental causes of this phenomenon, especially in naturally hybridizing species. We sought to evaluate the developmental causes of hybrid male sterility, using spadefoot toads as our study system. Plains spadefoot toads (Spea bombifrons) and Mexican spadefoot toads (S. multiplicata) hybridize where they co-occur in the southwestern USA. Hybrids are viable, but hybrid males suffer reduced fertility. We compared testes size and developmental stages of sperm cell maturation between hybrid males and males of each species. We found that testes of hybrid males did not differ in mean size from pure-species males. However, hybrids showed a greater range of within-individual variation in testes size than pure-species males. Moreover, although hybrids produced similar numbers of early stage sperm cells, hybrids produced significantly fewer mature spermatozoids than pure-species males. Interestingly, an introgressed individual produced numbers of live sperm comparable to pure-species males, but the majority of these sperm cells were abnormally shaped and non-motile. These results indicate that hybrid incompatibilities in late sperm development serve as a reproductive isolating barrier between species. The nature of this breakdown highlights the possibilities that hybrid males may vary in fertility and that fertility could possibly be recovered in introgressed males. © 2013 Wiley Periodicals, Inc.

Role of seed germination in adaptation and reproductive isolation in Arabidopsis lyrata.

Science.gov (United States)

Hämälä, Tuomas; Mattila, Tiina M; Leinonen, Päivi H; Kuittinen, Helmi; Savolainen, Outi

2017-07-01

Seed germination is an important developmental and life history stage. Yet, the evolutionary impact of germination has mainly been studied in the context of dormancy, or for its role in reproductive isolation between species. Here, we aim to examine multiple consequences of genetic divergence on germination traits between two Arabidopsis lyrata subspecies: ssp. petraea (Eurasia) and ssp. lyrata (North America). Postdormancy germination time, a potentially adaptive trait, showed differentiation between the populations, and quantitative trait loci (QTL) mapping revealed that the trait variation is mainly controlled by two antagonistic loci. These QTL areas contain several candidate genes with known function in postdormancy germination in A. thaliana. The sequence variation of three genes was consistent with differential selection, and they also included fixed nonsynonymous substitutions with potential to account for the phenotypic differentiation. We further show that the divergence between the subspecies has led to a slight but significant reduction in hybrid germination proportions, indicating incipient reproductive isolation. Comparison of reciprocal F 1 and F 2 progenies suggests that Bateson-Dobzhansky-Muller incompatibilities likely act through uniparentally inherited factors. Examination of genomewide transmission ratio distortion further revealed that cytonuclear interactions cause substantial pregermination inviability in the hybrids. These results confirm that seed germination has adaptive potential beyond the dormancy stage and that hybrid seed inviability can be one of the first reproductive barriers to arise during divergence. © 2017 John Wiley & Sons Ltd.

Genetics and evolution of hybrid male sterility in house mice.

Science.gov (United States)

White, Michael A; Stubbings, Maria; Dumont, Beth L; Payseur, Bret A

2012-07-01

Comparative genetic mapping provides insights into the evolution of the reproductive barriers that separate closely related species. This approach has been used to document the accumulation of reproductive incompatibilities over time, but has only been applied to a few taxa. House mice offer a powerful system to reconstruct the evolution of reproductive isolation between multiple subspecies pairs. However, studies of the primary reproductive barrier in house mice-hybrid male sterility-have been restricted to a single subspecies pair: Mus musculus musculus and Mus musculus domesticus. To provide a more complete characterization of reproductive isolation in house mice, we conducted an F(2) intercross between wild-derived inbred strains from Mus musculus castaneus and M. m. domesticus. We identified autosomal and X-linked QTL associated with a range of hybrid male sterility phenotypes, including testis weight, sperm density, and sperm morphology. The pseudoautosomal region (PAR) was strongly associated with hybrid sterility phenotypes when heterozygous. We compared QTL found in this cross with QTL identified in a previous F(2) intercross between M. m. musculus and M. m. domesticus and found three shared autosomal QTL. Most QTL were not shared, demonstrating that the genetic basis of hybrid male sterility largely differs between these closely related subspecies pairs. These results lay the groundwork for identifying genes responsible for the early stages of speciation in house mice.

Kin selection and the evolution of plant reproductive traits.

Science.gov (United States)

Bawa, Kamaljit S

2016-11-16

Competition among developing seeds and sibling rivalry within multiovulated ovaries can be deleterious for both the maternal parent and the siblings. Increased genetic relatedness of seeds within the ovary may foster kin selection and reduce the deleterious consequences of sibling competition. The pollen parent may also be selected for siring all progeny within a fruit. I propose a series of hypotheses to explain the evolution of a number of reproductive traits in angiosperms in the context of kin selection and sibling rivalry within the ovaries of angiosperms. I present evidence to show that a single-pollen parent, indeed, often sires seeds within multiovulated ovaries. Various types of pollen aggregations and transfer of such pollen masses to the stigmas of flowers by specialized pollinators make this increased genetic relatedness possible. An alternative mode to reduce sibling rivalry may be the reduction of ovule number to one, an evolutionary trend that has independently occurred many times in flowering plants. Finally, I build on previously established correlations to predict two sets of correlations among reproductive traits. In the first case, large showy flowers, transfer of pollen en masse by specialized pollinators, and multiovulated ovaries and multisided fruits seem to be correlated. In the second case, the previously established correlations among small and inconspicuous flowers, pollination by wind, water or generalist insects, flowers and fruits with few or single ovules and seeds, respectively, may also include monoecy or dioecy. Although correlations among many of these traits have been established in the past, I invoke kin selection and sibling competition to explain the evolution of correlated traits as two distinct evolutionary pathways in angiosperms. © 2016 The Authors.

Reproductive isolation between sympatric and allopatric Brazilian populations of Lutzomyia longipalpis s.l. (Diptera: Psychodidae)

OpenAIRE

Souza, Nataly A; Andrade-Coelho, Claudia A; Vigoder, Felipe M; Ward, Richard D; Peixoto, Alexandre A

2008-01-01

Lutzomyia longipalpis s.l., the main vector of Leishmania chagasi in Latin America, is a species complex although the exact number of siblings is yet unknown. In Brazil, the siblings differ in male copulatory courtship songs and pheromones that most certainly act as pre-zygotic reproductive barriers. Here we analysed the reproductive isolation between three allopatric and two sympatric populations of Lu. longipalpis s.l. from Brazil. The results indicate a strong copulatory and pre-mating iso...

Isolation barriers between petunia axillaris and Petunia integrifolia (Solanaceae).

Science.gov (United States)

Dell'olivo, Alexandre; Hoballah, Maria Elena; Gübitz, Thomas; Kuhlemeier, Cris

2011-07-01

The isolation barriers restricting gene flow between populations or species are of crucial interest for understanding how biological species arise and how they are maintained. Few studies have examined the entire range of possible isolation barriers from geographic isolation to next generation hybrid viability. Here, we present a detailed analysis of isolation barriers between two flowering plant species of the genus Petunia (Solanaceae). Petunia integrifolia and P. axillaris feature divergent pollination syndromes but can produce fertile hybrids when crossed in the laboratory. Both Petunia species are primarily isolated in space but appear not to hybridize in sympatry. Our experiments demonstrate that pollinator isolation is very high but not strong enough to explain the absence of hybrids in nature. However, pollinator isolation in conjunction with male gametic isolation (i.e., pollen-pistil interaction) can explain the lack of natural hybridization, while postzygotic isolation barriers are low or nonexistent. Our study supports the notion that reproductive isolation in flowering plants is mainly caused by pre- rather than postzygotic isolation mechanisms. © 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.

Asexual reproduction induces a rapid and permanent loss of sexual reproduction capacity in the rice fungal pathogen Magnaporthe oryzae: results of in vitro experimental evolution assays

Directory of Open Access Journals (Sweden)

Saleh Dounia

2012-03-01

Full Text Available Abstract Background Sexual reproduction is common in eukaryotic microorganisms, with few species reproducing exclusively asexually. However, in some organisms, such as fungi, asexual reproduction alternates with episodic sexual reproduction events. Fungi are thus appropriate organisms for studies of the reasons for the selection of sexuality or clonality and of the mechanisms underlying this selection. Magnaporthe oryzae, an Ascomycete causing blast disease on rice, reproduces mostly asexually in natura. Sexual reproduction is possible in vitro and requires (i two strains of opposite mating types including (ii at least one female-fertile strain (i.e. a strain able to produce perithecia, the female organs in which meiosis occurs. Female-fertile strains are found only in limited areas of Asia, in which evidence for contemporary recombination has recently been obtained. We induced the forced evolution of four Chinese female-fertile strains in vitro by the weekly transfer of asexual spores (conidia between Petri dishes. We aimed to determine whether female fertility was rapidly lost in the absence of sexual reproduction and whether this loss was controlled genetically or epigenetically. Results All the strains became female-sterile after 10 to 19 rounds of selection under asexual conditions. As no single-spore isolation was carried out, the observed decrease in the production of perithecia reflected the emergence and the invasion of female-sterile mutants. The female-sterile phenotype segregated in the offspring of crosses between female-sterile evolved strains and female-fertile wild-type strains. This segregation was maintained in the second generation in backcrosses. Female-sterile evolved strains were subjected to several stresses, but none induced the restoration of female fertility. This loss of fertility was therefore probably due to genetic rather than epigenetic mechanisms. In competition experiments, female-sterile mutants produced similar

Isolation and identification of porcine reproductive and respiratory syndrome virus in cell cultures.

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Valícek, L; Psikal, I; Smíd, B; Rodák, L; Kubalíková, R; Kosinová, E

1997-10-01

Three strains of porcine reproductive and respiratory syndrome virus (PRRSV) were isolated in porcine lung macrophage (PLM) cultures from three swine herds. This has been the first successful isolation of PRRSV in the Czech Republic and the strains received the designations CAPM V-501, CAPM V-502 and CAPM V-503, respectively. All the three isolates in PLM were identified by immunofluorescence and immunoperoxidase tests and the strain CAPM V-502 also by electron microscopy using the ultrathin section technique. The strain CAPM V-502 has been adapted to the cell line MARC-145. Viral RNA in PLM cultures infected with any of the isolated PRRSV strains was demonstrated by RT-PCR targeted to the more conserved ORF 7 genomic region encoding the nucleocapsid protein. The assessment of PCR products in agarose gel revealed a uniform size of 394 bp in all the three isolates and the European prototype strain Lelystad used as positive control.

Testing Wallace's intuition: water type, reproductive isolation and divergence in an Amazonian fish.

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Pires, Tiago H S; Borghezan, Elio A; Machado, Valeria N; Powell, Daniel L; Röpke, Cristhiana P; Oliveira, Claudio; Zuanon, Jansen; Farias, Izeni P

2018-06-01

Alfred Russel Wallace proposed classifying Amazon rivers based on their colour and clarity: white, black and clear water. Wallace also proposed that black waters could mediate diversification and yield distinct fish species. Here, we bring evidence of speciation mediated by water type in the sailfin tetra (Crenuchus spilurus), a fish whose range encompasses rivers of very distinct hydrochemical conditions. Distribution of the two main lineages concords with Wallace's water types: one restricted to the acidic and nutrient-poor waters of the Negro River (herein Rio Negro lineage) and a second widespread throughout the remaining of the species' distribution (herein Amazonas lineage). These lineages occur over a very broad geographical range, suggesting that despite occurring in regions separated by thousands of kilometres, individuals of the distinct lineages fail to occupy each other's habitats, hundreds of metres apart and not separated by physical barrier. Reproductive isolation was assessed in isolated pairs exposed to black-water conditions. All pairs with at least one individual of the lineage not native to black waters showed significantly lower spawning success, suggesting that the water type affected the fitness and contributed to reproductive isolation. Our results endorse Wallace's intuition and highlight the importance of ecological factors in shaping diversity of the Amazon fish fauna. © 2018 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2018 European Society For Evolutionary Biology.

THE LESSONIA NIGRESCENS SPECIES COMPLEX (LAMINARIALES, PHAEOPHYCEAE) SHOWS STRICT PARAPATRY AND COMPLETE REPRODUCTIVE ISOLATION IN A SECONDARY CONTACT ZONE(1).

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Tellier, Florence; Tapia, Javier; Faugeron, Sylvain; Destombe, Christophe; Valero, Myriam

2011-08-01

During secondary contact between phylogenetically closely related species (sibling species) having diverged in allopatry, the maintenance of species integrity depends on intrinsic and extrinsic reproductive barriers. In kelps (Phaeophyceae), the observations of hybrids in laboratory conditions suggest that reproductive isolation is incomplete. However, not all interspecific crosses are successful, and very few hybrids have been observed in nature, despite the co-occurrence of many kelp species in sympatry. This suggests that there are reproductive barriers that maintain species integrity. In this study, we characterized the fine genetic structure of a secondary contact zone to clarify the extent of reproductive isolation between two sister species. In Lessonia nigrescens Bory (Laminariales, Phaeophyta) species complex, two cryptic species have been recently found out from gene phylogenies, and-waiting for a formal taxonomic description-we used their geographic distribution to name them (northern and southern species). We studied 12 populations, distributed along 50 km of coastline, and employed two molecular approaches, assigning individuals to phylogenetic species according to a diagnostic mitochondrial marker (351 individuals analyzed) and quantifying interspecific gene flow with four microsatellite markers (248 individuals analyzed). No hybridization or introgression was revealed, indicating complete reproductive isolation in natural conditions. Unexpectedly, our study demonstrated that the two species were strictly segregated in space. This absence of co-occurrence along the contact zone can partially explain the lack of hybridization, raising new interesting questions as to the mechanisms that limit sympatry at small spatial scales. © 2011 Phycological Society of America.

Along the speciation continuum: Quantifying intrinsic and extrinsic isolating barriers across five million years of evolutionary divergence in California jewelflowers.

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Christie, Kyle; Strauss, Sharon Y

2018-05-01

Understanding the relative roles of intrinsic and extrinsic reproductive barriers, and their interplay within the geographic context of diverging taxa, remains an outstanding challenge in the study of speciation. We conducted a comparative analysis of reproductive isolation in California Jewelflowers (Streptanthus, s.l., Brassicaceae) by quantifying potential barriers to gene flow at multiple life history stages in 39 species pairs spanning five million years of evolutionary divergence. We quantified nine potential pre- and postzygotic barriers and explored patterns of reproductive isolation in relation to genetic distance. Intrinsic postzygotic isolation was initially weak, increased at intermediate genetic distances, and reached a threshold characterized by complete genetic incompatibility. Climatic niche differences were strong at shallow genetic distances, and species pairs with overlapping ranges showed slight but appreciable phenological isolation, highlighting the potential for ecological barriers to contribute to speciation. Geographic analyses suggest that speciation is not regionally allopatric in the California Jewelflowers, as recently diverged taxa occur in relatively close proximity and display substantial range overlap. Young pairs are characterized by incomplete intrinsic postzygotic isolation, suggesting that extrinsic barriers or fine-scale spatial segregation are more important early in the divergence process than genetic incompatibilities. © 2018 The Author(s). Evolution © 2018 The Society for the Study of Evolution.

Rapid Evolution of Assortative Fertilization between Recently Allopatric Species of Drosophila.

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Ahmed-Braimah, Yasir H; McAllister, Bryant F

2012-01-01

The virilis group of Drosophila represents a relatively unexplored but potentially useful model to investigate the genetics of speciation. Good resolution of phylogenetic relationships and the ability to obtain fertile hybrid offspring make the group especially promising for analysis of genetic changes underlying reproductive isolation separate from hybrid sterility and inviability. Phylogenetic analyses reveal a close relationship between the sister species, Drosophila americana and D. novamexicana, yet excepting their contemporary allopatric distributions, factors that contribute to reproductive isolation between this species pair remain uncharacterized. A previous report has shown reduced progeny numbers in laboratory crosses between the two species, especially when female D. novamexicana are crossed with male D. americana. We show that the hatch rate of eggs produced from heterospecific matings is reduced relative to conspecific matings. Failure of eggs to hatch, and consequent reduction in hybrid progeny number, is caused by low fertilization success of heterospecific sperm, thus representing a postmating, prezygotic incompatibility. Following insemination, storage and motility of heterospecific sperm is visibly compromised in female D. novamexicana. Our results provide evidence for a mechanism of reproductive isolation that is seldom reported for Drosophila species, and indicate the rapid evolution of postmating, prezygotic reproductive barriers in allopatry.

What shapes the continuum of reproductive isolation? Lessons from Heliconius butterflies.

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Mérot, C; Salazar, C; Merrill, R M; Jiggins, C D; Joron, M

2017-06-14

The process by which species evolve can be illuminated by investigating barriers that limit gene flow between taxa. Recent radiations, such as Heliconius butterflies, offer the opportunity to compare isolation between pairs of taxa at different stages of ecological, geographical, and phylogenetic divergence. Here, we report a comparative analysis of existing and novel data in order to quantify the strength and direction of isolating barriers within a well-studied clade of Heliconius Our results highlight that increased divergence is associated with the accumulation of stronger and more numerous barriers to gene flow. Wing pattern is both under natural selection for Müllerian mimicry and involved in mate choice, and therefore underlies several isolating barriers. However, pairs which share a similar wing pattern also display strong reproductive isolation mediated by traits other than wing pattern. This suggests that, while wing pattern is a key factor for early stages of divergence, it may become facultative at later stages of divergence. Additional factors including habitat partitioning, hybrid sterility, and chemically mediated mate choice are associated with complete speciation. Therefore, although most previous work has emphasized the role of wing pattern, our comparative results highlight that speciation is a multi-dimensional process, whose completion is stabilized by many factors. © 2017 The Author(s).

Antimicrobial resistance and molecular characteristics of Streptococcus agalactiae isolated from women of reproductive age

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Magdalena Musiorska

2016-12-01

Full Text Available Introduction. Streptococcus agalactiae infections are among the most significant causes of neonatal invasive diseases. Proper screening and detection of pregnant women carrying GBS allows intrapartum administration of antibiotic prophylaxis and is an effective measure in preventing transmission of bacteria from mother to newborns. Material and methods. Sixty three bacterial strains were isolated from vaginal swabs from pregnant and nonpregnant women of reproductive age. Species were identified by colony morphology, haemolysis type, Gram staining and SLIDEX® Strepto Plus latex test. Antimicrobial resistance of 56 strains was determined using disk-diffusion method. The presence of molecular resistance determinants was assessed using PCR with specific primers, and capsular types were identified using multiplex PCR. Results. None of the strains were resistant to the first drug of choice, penicillin. A large percentage of isolates (78.6% were resistant to doxycycline. The prevalence of resistance to macrolides and lincosamides, antibiotics used in women allergic to penicillin, was high. Those results corresponded with PCR tests, as tetM and ermA1 were most frequently detected genes (98.4 and 87.3%, respectively. 7.94% of strains possessed 7 different out of 13 tested genes determining resistance to different groups of antimicrobials. Among the capsular types, Ia, which proved to be associated with the most severe and invasive infections in mothers and neonates, was the most prevalent (65.08%. Conclusions. Even though they are susceptible to penicillin, multidrug resistance is common among S. agalactiae strains isolated from women of reproductive age and this resistance can be caused by more than one gene per single isolate

Effects of range-wide variation in climate and isolation on floral traits and reproductive output of Clarkia pulchella.

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Bontrager, Megan; Angert, Amy L

2016-01-01

Plant mating systems and geographic range limits are conceptually linked by shared underlying drivers, including landscape-level heterogeneity in climate and in species' abundance. Studies of how geography and climate interact to affect plant traits that influence mating system and population dynamics can lend insight to ecological and evolutionary processes shaping ranges. Here, we examined how spatiotemporal variation in climate affects reproductive output of a mixed-mating annual, Clarkia pulchella. We also tested the effects of population isolation and climate on mating-system-related floral traits across the range. We measured reproductive output and floral traits on herbarium specimens collected across the range of C. pulchella. We extracted climate data associated with specimens and derived a population isolation metric from a species distribution model. We then examined how predictors of reproductive output and floral traits vary among populations of increasing distance from the range center. Finally, we tested whether reproductive output and floral traits vary with increasing distance from the center of the range. Reproductive output decreased as summer precipitation decreased, and low precipitation may contribute to limiting the southern and western range edges of C. pulchella. High spring and summer temperatures are correlated with low herkogamy, but these climatic factors show contrasting spatial patterns in different quadrants of the range. Limiting factors differ among different parts of the range. Due to the partial decoupling of geography and environment, examining relationships between climate, reproductive output, and mating-system-related floral traits reveals spatial patterns that might be missed when focusing solely on geographic position. © 2016 Botanical Society of America.

An adaptive left–right eigenvector evolution algorithm for vibration isolation control

International Nuclear Information System (INIS)

Wu, T Y

2009-01-01

The purpose of this research is to investigate the feasibility of utilizing an adaptive left and right eigenvector evolution (ALREE) algorithm for active vibration isolation. As depicted in the previous paper presented by Wu and Wang (2008 Smart Mater. Struct. 17 015048), the structural vibration behavior depends on both the disturbance rejection capability and mode shape distributions, which correspond to the left and right eigenvector distributions of the system, respectively. In this paper, a novel adaptive evolution algorithm is developed for finding the optimal combination of left–right eigenvectors of the vibration isolator, which is an improvement over the simultaneous left–right eigenvector assignment (SLREA) method proposed by Wu and Wang (2008 Smart Mater. Struct. 17 015048). The isolation performance index used in the proposed algorithm is defined by combining the orthogonality index of left eigenvectors and the modal energy ratio index of right eigenvectors. Through the proposed ALREE algorithm, both the left and right eigenvectors evolve such that the isolation performance index decreases, and therefore one can find the optimal combination of left–right eigenvectors of the closed-loop system for vibration isolation purposes. The optimal combination of left–right eigenvectors is then synthesized to determine the feedback gain matrix of the closed-loop system. The result of the active isolation control shows that the proposed method can be utilized to improve the vibration isolation performance compared with the previous approaches

Reproductive ecology and isolation of Psittacanthus calyculatus and P. auriculatus mistletoes (Loranthaceae

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Sergio Díaz Infante

2016-09-01

Full Text Available Background Relationships between floral biology and pollinator behavior are important to understanding species diversity of hemiparasitic Psittacanthus mistletoes (c. 120 species. We aimed to investigate trait divergence linked to pollinator attraction and reproductive isolation (RI in two hummingbird-pollinated and bird-dispersed Psittacanthus species with range overlap. Methods We investigated the phylogenetic relationships, floral biology, pollinator assemblages, seed dispersers and host usage, and the breeding system and female reproductive success of two sympatric populations of P. calyculatus and P. auriculatus, and one allopatric population of P. calyculatus. Flowers in sympatry were also reciprocally pollinated to assess a post-mating component of RI. Results Hummingbird assemblages differed between calyculatus populations, while allopatric plants of calyculatus opened more but smaller flowers with longer lifespans and produced less nectar than those in sympatry. Bayesian-based phylogenetic analysis indicated monophyly for calyculatus populations (i.e. both populations belong to the same species. In sympatry, calyculatus plants opened more and larger flowers with longer lifespans and produced same nectar volume than those of auriculatus; populations shared pollinators but seed dispersers and host usage differed between species. Nectar standing crops differed between sympatric populations, with lower visitation in calyculatus. Hand pollination experiments indicated a predominant outcrossing breeding system, with fruit set after interspecific pollination two times higher from calyculatus to auriculatus than in the opposite direction. Conclusions Given the low genetic differentiation between calyculatus populations, observed trait divergence could have resulted from changes regarding the local communities of pollinators and, therefore, expected divergence for peripheral, allopatric populations. Using RI estimates, there were fewer

Reproductive isolating barriers between colour-differentiated populations of an African annual killifish, Nothobranchius korthausae (Cyprinodontiformes)

Czech Academy of Sciences Publication Activity Database

Reichard, Martin; Polačik, Matej

2010-01-01

Roč. 100, č. 1 (2010), s. 62-72 ISSN 0024-4066 R&D Projects: GA ČR GP206/06/P152 Institutional research plan: CEZ:AV0Z60930519 Keywords : allopatric divergence * assortative mating * colour polymorphism * mating experience * premating barriers * reproductive isolation Subject RIV: EG - Zoology Impact factor: 2.166, year: 2010

An evolutionary concept of polycystic ovarian disease: does evolution favour reproductive success over survival?

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Gleicher, Norbert; Barad, David

2006-05-01

Polycystic ovarian disease (PCOD) is currently considered as possibly the most frequent cause of female infertility. It is also closely associated with syndrome XX, which, in turn, is closely linked with premature and excessive mortality. Considering these adverse effects on reproductive success and human survival, the evolutionary survival of PCOD, itself considered by many to be a genetically transmitted condition, would, on first glance, appear surprising, since evolution usually discriminates against both of these traits. However, an analysis of some recently reported characteristics of the condition calls for the reconsideration of PCOD as a condition which, from an evolutionary viewpoint, favours decreased reproductive success. Indeed, the reported observations that patients with PCOD will resume spontaneous ovulation with even relatively minor weight loss, and experience later menopause than controls, suggests exactly the opposite. Under an evolutionary concept, PCOD can thus be seen as a 'fertility storage condition' which in fact favours human reproductive success and allows the human species to maintain fertility even during adverse environmental circumstances, such as famines.

THE DISCOUNTED REPRODUCTIVE NUMBER FOR EPIDEMIOLOGY

OpenAIRE

Reluga, Timothy C.; Medlock, Jan; Galvani, Alison

2009-01-01

The basic reproductive number, , and the effective reproductive number, , are commonly used in mathematical epidemiology as summary statistics for the size and controllability of epidemics. However, these commonly used reproductive numbers can be misleading when applied to predict pathogen evolution because they do not incorporate the impact of the timing of events in the life-history cycle of the pathogen. To study evolution problems where the host population size is changing, measur...

Reproductive isolation between host races of Phytomyza glabricola on Ilex coriacea and I. glabra.

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Julie B Hebert

Full Text Available Recently diverged taxa often show discordance in genetic divergence among genomic loci, where some loci show strong divergence and others show none at all. Genetic studies alone cannot distinguish among the possible mechanisms but experimental studies on other aspects of divergence may provide guidance in the inference of causes of observed discordances. In this study, we used no-choice mating trials to test for the presence of reproductive isolation between host races of the leaf-mining fly, Phytomyza glabricola on its two holly host species, Ilex coriacea and I. glabra. These trials inform our effort to determine the cause of significant differences in the degree of divergence of nuclear and mitochondrial loci of flies collected from the two host plants. We present evidence of reproductive isolation between host races in a controlled greenhouse setting: significantly more mate pairs consisting of flies from the same host plant species produced offspring than inter-host mate pairs, which produced no offspring. We also tested whether the presence of the natal or non-natal host plant affects reproductive success. Flies collected from I. coriacea were more likely to produce offspring when in the presence of the natal host, whereas the presence or absence of either the natal or non-natal host had no effect on flies collected from I. glabra. The results indicate discordant patterns of nuclear and mitochondrial divergence among host races of P. glabricola are likely due to incomplete lineage sorting, and the host races may be well on their way to becoming biological species.

Evaluating the interacting influences of pollination, seed predation, invasive species and isolation on reproductive success in a threatened alpine plant.

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Krushelnycky, Paul D

2014-01-01

Reproduction in rare plants may be influenced and limited by a complex combination of factors. External threats such as invasive species and landscape characteristics such as isolation may impinge on both pollination and seed predation dynamics, which in turn can strongly affect reproduction. I assessed how patterns in floral visitation, seed predation, invasive ant presence, and plant isolation influenced one another and ultimately affected viable seed production in Haleakalā silverswords (Argyroxiphium sandwicense subsp. macrocephalum) of Hawai'i. Floral visitation was dominated by endemic Hylaeus bees, and patterns of visitation were influenced by floral display size and number of plants clustered together, but not by floral herbivory or nearest flowering neighbor distance. There was also some indication that Argentine ant presence impacted floral visitation, but contradictory evidence and limitations of the study design make this result uncertain. Degree of seed predation was associated only with plant isolation, with the two main herbivores partitioning resources such that one preferentially attacked isolated plants while the other attacked clumped plants; total seed predation was greater in more isolated plants. Net viable seed production was highly variable among individuals (0-55% seed set), and was affected mainly by nearest neighbor distance, apparently owing to low cross-pollination among plants separated by even short distances (>10-20 m). This isolation effect dominated net seed set, with no apparent influence from floral visitation rates, percent seed predation, or invasive ant presence. The measured steep decline in seed set with isolation distance may not be typical of the entire silversword range, and may indicate that pollinators in addition to Hylaeus bees could be important for greater gene flow. Management aimed at maintaining or maximizing silversword reproduction should focus on the spatial context of field populations and outplanting

Tropics accelerate the evolution of hybrid male sterility in Drosophila.

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Yukilevich, Roman

2013-06-01

Understanding the evolutionary mechanisms that facilitate speciation and explain global patterns of species diversity has remained a challenge for decades. The most general pattern of species biodiversity is the latitudinal gradient, whereby species richness increases toward the tropics. Although such a global pattern probably has a multitude of causes, recent attention has focused on the hypothesis that speciation and the evolution of reproductive isolation occur faster in the tropics. Here, I tested this prediction using a dataset on premating and postzygotic isolation between recently diverged Drosophila species. Results showed that while the evolution of premating isolation was not greater between tropical Drosophila relative to nontropical species, postzygotic isolation evolved faster in the tropics. In particular, hybrid male sterility was much greater among tropical Drosophila compared to nontropical species pairs of similar genetic age. Several testable explanations for the novel pattern are discussed, including greater role for sterility-inducing bacterial endosymbionts in the tropics and more intense sperm-sperm competition or sperm-egg sexual conflict in the tropics. The results imply that processes of speciation in the tropics may evolve at different rates or may even be somewhat different from those at higher latitudes. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

Ecological context of the evolution of self-pollination in Clarkia xantiana: population size, plant communities, and reproductive assurance.

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Moeller, David A; Geber, Monica A

2005-04-01

The repeated evolutionary transition from outcrossing to self-pollination in flowering plants has been suggested to occur because selfing provides reproductive assurance. Reports from biogeographical and ecological surveys indicate that selfing taxa are often associated with stressful and ephemeral environments, situations in which plant abundance is low (e.g., Baker's law) and with novel plant communities, however experimental tests of ecological hypotheses are few. In this study, we examined the ecological context of selection on mating system traits (herkogamy and protandry) in a California annual, Clarkia xantiana, where natural selfing populations differ from outcrossing populations in that they are often of small size or low density and occur mainly outside the range of pollinator-sharing congeners. We constructed artificial populations of plants with broad genetic variation in floral traits and manipulated two ecological factors, plant population size, and the presence versus absence of pollinator-sharing congeners, in the center of the geographic range of outcrossing populations. We found evidence for context-dependent selection on herkogamy and protandry via female fitness in which reduced traits, which promote autonomous selfing, were favored in small populations isolated from congeners whereas selection was comparatively weak in large populations or when congeners were present. In small, isolated populations, the fertility of plants with low herkogamy or protandry was elevated by 66% and 58%, respectively, compared to those with high herkogamy or protandry. The presence of pollinator-sharing congeners augmented bee visitation rates to C. xantiana flowers by 47% for all bees and by 93% for pollen specialists. By facilitating pollinator visitation, congeners mitigated selection on mating system traits in small populations, where outcross mating success is often low (the Allee effect). We also found support for the hypothesis that pollinator availability

Testing for adaptive evolution of the female reproductive protein ZPC in mammals, birds and fishes reveals problems with the M7-M8 likelihood ratio test.

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Berlin, Sofia; Smith, Nick G C

2005-11-10

Adaptive evolution appears to be a common feature of reproductive proteins across a very wide range of organisms. A promising way of addressing the evolutionary forces responsible for this general phenomenon is to test for adaptive evolution in the same gene but among groups of species, which differ in their reproductive biology. One can then test evolutionary hypotheses by asking whether the variation in adaptive evolution is consistent with the variation in reproductive biology. We have attempted to apply this approach to the study of a female reproductive protein, zona pellucida C (ZPC), which has been previously shown by the use of likelihood ratio tests (LRTs) to be under positive selection in mammals. We tested for evidence of adaptive evolution of ZPC in 15 mammalian species, in 11 avian species and in six fish species using three different LRTs (M1a-M2a, M7-M8, and M8a-M8). The only significant findings of adaptive evolution came from the M7-M8 test in mammals and fishes. Since LRTs of adaptive evolution may yield false positives in some situations, we examined the properties of the LRTs by several different simulation methods. When we simulated data to test the robustness of the LRTs, we found that the pattern of evolution in ZPC generates an excess of false positives for the M7-M8 LRT but not for the M1a-M2a or M8a-M8 LRTs. This bias is strong enough to have generated the significant M7-M8 results for mammals and fishes. We conclude that there is no strong evidence for adaptive evolution of ZPC in any of the vertebrate groups we studied, and that the M7-M8 LRT can be biased towards false inference of adaptive evolution by certain patterns of non-adaptive evolution.

Life span and reproductive cost explain interspecific variation in the optimal onset of reproduction.

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Mourocq, Emeline; Bize, Pierre; Bouwhuis, Sandra; Bradley, Russell; Charmantier, Anne; de la Cruz, Carlos; Drobniak, Szymon M; Espie, Richard H M; Herényi, Márton; Hötker, Hermann; Krüger, Oliver; Marzluff, John; Møller, Anders P; Nakagawa, Shinichi; Phillips, Richard A; Radford, Andrew N; Roulin, Alexandre; Török, János; Valencia, Juliana; van de Pol, Martijn; Warkentin, Ian G; Winney, Isabel S; Wood, Andrew G; Griesser, Michael

2016-02-01

Fitness can be profoundly influenced by the age at first reproduction (AFR), but to date the AFR-fitness relationship only has been investigated intraspecifically. Here, we investigated the relationship between AFR and average lifetime reproductive success (LRS) across 34 bird species. We assessed differences in the deviation of the Optimal AFR (i.e., the species-specific AFR associated with the highest LRS) from the age at sexual maturity, considering potential effects of life history as well as social and ecological factors. Most individuals adopted the species-specific Optimal AFR and both the mean and Optimal AFR of species correlated positively with life span. Interspecific deviations of the Optimal AFR were associated with indices reflecting a change in LRS or survival as a function of AFR: a delayed AFR was beneficial in species where early AFR was associated with a decrease in subsequent survival or reproductive output. Overall, our results suggest that a delayed onset of reproduction beyond maturity is an optimal strategy explained by a long life span and costs of early reproduction. By providing the first empirical confirmations of key predictions of life-history theory across species, this study contributes to a better understanding of life-history evolution. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

Neutral Evolution in a Biological Population as Diffusion in Phenotype Space: Reproduction with Local Mutation but without Selection

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Lawson, Daniel John; Jensen, Henrik Jeldtoft

2007-03-01

The process of “evolutionary diffusion,” i.e., reproduction with local mutation but without selection in a biological population, resembles standard diffusion in many ways. However, evolutionary diffusion allows the formation of localized peaks that undergo drift, even in the infinite population limit. We relate a microscopic evolution model to a stochastic model which we solve fully. This allows us to understand the large population limit, relates evolution to diffusion, and shows that independent local mutations act as a diffusion of interacting particles taking larger steps.

Maternal reproductive history and the risk of isolated congenital malformations.

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Materna-Kiryluk, A; Więckowska, B; Wiśniewska, K; Borszewska-Kornacka, M K; Godula-Stuglik, U; Limon, J; Rusin, J; Sawulicka-Oleszczuk, H; Szwałkiewicz-Warowicka, E; Walczak, M

2011-03-01

We examined the relationship between maternal reproductive history and the newborn's risk of isolated congenital malformations in a large case-control cohort from the Polish Registry of Congenital Malformations. Congenital malformations were classified into four categories: isolated congenital heart defects (n=1673), isolated cleft palate (n=255), cleft lip with or without cleft palate (n=448) and renal agenesis (n=103). The case groups were compared with a shared group of 2068 controls recruited in the same time period and geographic area. Multivariable logistic regression was used to assess the risk associated with maternal gravidity and of previous miscarriages after accounting for maternal age and other potential risk factors. In unadjusted analyses, maternal gravidity was significantly associated with increased risk of all four classes of congenital malformations. After adjustment, a significant association persisted for congenital heart defects [odds ratio (OR)=1.22, [95% confidence interval (CI) 1.09, 1.36], P=0.0007] and cleft lip with or without cleft palate (OR=1.21, [95% CI 1.09, 1.36], P=0.0005). A similar trend existed for isolated cleft palate (OR=1.18, [95% CI 1.02, 1.37], P=0.03). There was no appreciable increase in the risk of congenital malformations associated with a maternal history of miscarriages, but a trend for a protective effect on the occurrence of cleft lip with or without cleft palate was observed (OR=0.72, [95% CI 0.52, 0.99], P=0.045). Based on our data, maternal gravidity represents a significant risk factor for congenital heart defects and cleft lip with or without cleft palate in the newborn infant. Our data do not support an increase in risk because of past history of miscarriages. © 2011 Blackwell Publishing Ltd.

Natural and sexual selection giveth and taketh away reproductive barriers: models of population divergence in guppies.

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Labonne, Jacques; Hendry, Andrew P

2010-07-01

The standard predictions of ecological speciation might be nuanced by the interaction between natural and sexual selection. We investigated this hypothesis with an individual-based model tailored to the biology of guppies (Poecilia reticulata). We specifically modeled the situation where a high-predation population below a waterfall colonizes a low-predation population above a waterfall. Focusing on the evolution of male color, we confirm that divergent selection causes the appreciable evolution of male color within 20 generations. The rate and magnitude of this divergence were reduced when dispersal rates were high and when female choice did not differ between environments. Adaptive divergence was always coupled to the evolution of two reproductive barriers: viability selection against immigrants and hybrids. Different types of sexual selection, however, led to contrasting results for another potential reproductive barrier: mating success of immigrants. In some cases, the effects of natural and sexual selection offset each other, leading to no overall reproductive isolation despite strong adaptive divergence. Sexual selection acting through female choice can thus strongly modify the effects of divergent natural selection and thereby alter the standard predictions of ecological speciation. We also found that under no circumstances did divergent selection cause appreciable divergence in neutral genetic markers.

Changing reproductive effort within a semelparous reproductive episode.

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Hughes, P William; Simons, Andrew M

2014-08-01

• Life-history theory predicts a trade-off between current and future reproduction for iteroparous organisms-as individuals age, the expected value of future reproduction declines, and thus reproductive effort is expected to be higher in later clutches than in earlier. In contrast, models explaining the evolution of semelparity treat semelparous reproduction as instantaneous, with no scope for intraindividual variation. However, semelparous reproduction is also extended, but over shorter time scales; whether there are similar age- or stage-specific changes in reproductive effort within a semelparous episode is unclear. In this study, we assessed whether semelparous individuals increase reproductive effort as residual reproductive value declines by comparing the reproductive phenotype of flowers at five different floral positions along a main inflorescence.• Using the herbaceous monocarp Lobelia inflata, we conducted a longitudinal study of 409 individuals including both laboratory and field populations over three seasons. We recorded six reproductive traits-including the length of three phenological intervals as well as fruit size, seed size, and seed number-for all plants across floral positions produced throughout the reproductive episode.• We found that while the rate of flower initiation did not change, flowers at distal (late) floral positions developed more quickly and contained larger seed than flowers at basal (early) floral positions did.• Our results were consistent with the hypothesis that, like iteroparous organisms, L. inflata increases reproductive effort in response to low residual reproductive value. © 2014 Botanical Society of America, Inc.

Morphological and molecular characterization, sexual reproduction, and pathogenicity of Setosphaeria rostrata isolates from rice leaf spot.

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Kusai, Nor Azizah; Azmi, Madihah Mior Zakuan; Zainudin, Nur Ain Izzati Mohd; Yusof, Mohd Termizi; Razak, Azmi Abd

2016-09-01

Setosphaeria rostrata, a common plant pathogen causing leaf spot disease, affects a wide range of plant species, mainly grasses. Fungi were isolated from brown spots on rice leaves throughout Peninsular Malaysia, and 45 isolates were identified as Setosphaeria rostrata The isolates were then characterized using morphological and molecular approaches. The mating type was determined using PCR amplification of the mating type alleles, and isolates of opposite mating types were crossed to examine sexual reproduction. Based on nuclear ribosomal DNA ITS1-5.8S-ITS2 region (ITS) and beta-tubulin (BT2) sequences, two phylogenetic trees were constructed using the maximum likelihood method; S. rostrata was clustered in one well-supported clade. Pathogenicity tests showed that S. rostrata isolates are pathogenic, suggesting that it is the cause of the symptoms. Mating-type analyses indicated that three isolates carried the MAT1-1 allele, and the other 42 isolates carried MAT1-2 After isolates with opposite mating types were crossed on Sach's medium and incubated for 3 wk, six crosses produced pseudothecia that contained eight mature ascospores, and 12 other crosses produced numerous pseudothecia with no ascospores. To our knowledge, this is the first report on S. rostrata isolated from leaf spots on rice. © 2016 by The Mycological Society of America.

Molecular characterization of ureaplasmas isolated from reproductive tract of goats and sheep from Brazil

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Rosângela C. Oliveira

Full Text Available Abstract Ovine/caprine ureaplasmas have not yet been assigned a species designation, but they have been classified into nine serotypes. Herein ureaplasmas were searched for in 120 samples of vulvo vaginal mucous from sheep and 98 samples from goats at 17 farms. In addition, semen samples were collected from 11 sheep and 23 goats. The recovered ureaplasma were from sheep and goats from animals without any reproductive disorder symptoms, but not all animals presented positive cultures. In sheep, 17 (68% cultures of vulvovaginal mucous were positive for ureaplasma and 11 (27% samples of semen presented positive cultures in animals with clinical signs of orchitis, balanoposthitis or low sperm motility. In goats four ureaplasma isolates were obtained from vulvovaginal mucus, but the semen samples were all negative. The isolates were submitted to Pulsed-field gel electrophoresis methodology and their 16S rRNA genes were sequenced. Fifty percent of ureaplasma recovered from sheep allowed for PFGE typing. Eleven isolates showed eight profiles genetically close to the bovine ureaplasmas. The 16S rRNA gene sequencing showed differences or similarities of isolates from sheep and goats, and the reference strains of bovine and human ureaplasma. Four clinical isolates from sheep were grouped separately. The studied ureaplasma isolates showed to be a diverse group of mollicutes.

40 Years of Pulsars: The Birth and Evolution of Isolated Radio Pulsars

OpenAIRE

Faucher-Giguere, C. -A.; Kaspi, V. M.

2007-01-01

We investigate the birth and evolution of isolated radio pulsars using a population synthesis method, modeling the birth properties of the pulsars, their time evolution, and their detection in the Parkes and Swinburne Multibeam (MB) surveys. Together, the Parkes and Swinburne MB surveys have detected nearly 2/3 of the known pulsars and provide a remarkably homogeneous sample to compare with simulations. New proper motion measurements and an improved model of the distribution of free electrons...

Perspectives on the Evolution of Porcine Parvovirus.

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Oh, Woo-Taek; Kim, Ri-Yeon; Nguyen, Van-Giap; Chung, Hee-Chun; Park, Bong-Kyun

2017-07-26

Porcine parvovirus (PPV) is one of the main causes of porcine reproductive failure. It is important for swine industries to understand the recent trends in PPV evolution. Previous data show that PPV has two genetic lineages originating in Germany. In this study, two more genetic lineages were defined, one of which was distinctly Asian. Additionally, amino acid substitutions in European strains and Asian strains showed distinct differences in several regions of the VP2 gene. The VP1 gene of the recent PPV isolate (T142_South Korea) was identical to that of Kresse strain isolated in the USA in 1985, indicating that modern PPV strains now resemble the original strains (Kresse and NADL-2). In this study, we compared strains isolated in the 20th century to recent isolates and confirmed the trend that modern strains are becoming more similar to previous strains.

POLLINATOR-MEDIATED COMPETITION, REPRODUCTIVE CHARACTER DISPLACEMENT, AND THE EVOLUTION OF SELFING IN ARENARIA UNIFLORA (CARYOPHYLLACEAE).

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Fishman, Lila; Wyatt, Robert

1999-12-01

Ecological factors that reduce the effectiveness of cross-pollination are likely to play a role in the frequent evolution of routine self-fertilization in flowering plants. However, we lack empirical evidence linking the reproductive assurance value of selfing in poor pollination environments to evolutionary shifts in mating system. Here, we investigated the adaptive significance of prior selfing in the polymorphic annual plant Arenaria uniflora (Caryophyllaceae), in which selfer populations occur only in areas of range overlap with congener A. glabra. To examine the hypothesis that secondary contact between the two species contributed to the evolution and maintenance of selfing, we used field competition experiments and controlled hand-pollinations to measure the female fitness consequences of pollinator-mediated interspecific interactions. Uniformly high fruit set by selfers in the naturally pollinated field arrays confirmed the reproductive assurance value of selfing, whereas substantial reductions in outcrosser fruit set (15%) and total seed production (20-35%) in the presence of A. glabra demonstrated that pollinator-mediated interactions can provide strong selection for self-pollination. Heterospecific pollen transfer, rather than competition for pollinator service, appears to be the primary mechanism of pollinator-mediated competition in Arenaria. Premating barriers to hybridization between outcrossers and A. glabra are extremely weak. The production of a few inviable hybrid seeds after heterospecific pollination and intermediate seed set after mixed pollinations indicates that A. glabra pollen can usurp A. uniflora ovules. Thus, any visit to A. uniflora by shared pollinators carries a potential female fitness cost. Moreover, patterns of fruit set and seed set in the competition arrays relative to controls were consistent with the receipt of mixed pollen loads, rather than a lack of pollinator visits. Competition through pollen transfer favors preemptive

Social roles and the evolution of networks in extreme and isolated environments

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Johnson, Jeffrey C.; Boster, James S.; Palinkas, Lawrence A.

2003-01-01

This article reports on the evolution of network structure as it relates to formal and informal social roles in well-bounded, isolated groups. Research was conducted at the Amundsen-Scott South Pole Station. Data were collected on crewmembers' networks of social interaction over each of three winter-over periods, when the station is completely isolated. In addition, data were collected on the informal roles played by crewmembers (e.g., instrumental leadership, expressive leadership). The study found that globally coherent networks in winter-over groups were associated with group consensus on the presence of critically important informal social roles (e.g., expressive leadership) where global coherence is the extent to which a network forms a single group composed of a unitary core and periphery as opposed to being factionalized into two or more subgroups. Conversely, the evolution of multiple subgroups was associated with the absence of consensus on critical informal social roles, above all the critically important role of instrumental leader.

Sexual reproduction and the evolution of microbial pathogens.

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Heitman, Joseph

2006-09-05

Three common systemic human fungal pathogens--Cryptococcus neoformans, Candida albicans and Aspergillus fumigatus--have retained all the machinery to engage in sexual reproduction, and yet their populations are often clonal with limited evidence for recombination. Striking parallels have emerged with four protozoan parasites that infect humans: Toxoplasma gondii, Trypanosoma brucei, Trypanosoma cruzi and Plasmodium falciparum. Limiting sexual reproduction appears to be a common virulence strategy, enabling generation of clonal populations well adapted to host and environmental niches, yet retaining the ability to engage in sexual or parasexual reproduction and respond to selective pressure. Continued investigation of the sexual nature of microbial pathogens should facilitate both laboratory investigation and an understanding of the complex interplay between pathogens, hosts, vectors, and their environments.

Full-Genome Characterization and Genetic Evolution of West African Isolates of Bagaza Virus

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Martin Faye

2018-04-01

Full Text Available Bagaza virus is a mosquito-borne flavivirus, first isolated in 1966 in Central African Republic. It has currently been identified in mosquito pools collected in the field in West and Central Africa. Emergence in wild birds in Europe and serological evidence in encephalitis patients in India raise questions on its genetic evolution and the diversity of isolates circulating in Africa. To better understand genetic diversity and evolution of Bagaza virus, we describe the full-genome characterization of 11 West African isolates, sampled from 1988 to 2014. Parameters such as genetic distances, N-glycosylation patterns, recombination events, selective pressures, and its codon adaptation to human genes are assessed. Our study is noteworthy for the observation of N-glycosylation and recombination in Bagaza virus and provides insight into its Indian origin from the 13th century. Interestingly, evidence of Bagaza virus codon adaptation to human house-keeping genes is also observed to be higher than those of other flaviviruses well known in human infections. Genetic variations on genome of West African Bagaza virus could play an important role in generating diversity and may promote Bagaza virus adaptation to other vertebrates and become an important threat in human health.

Florally rich habitats reduce insect pollination and the reproductive success of isolated plants.

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Evans, Tracie M; Cavers, Stephen; Ennos, Richard; Vanbergen, Adam J; Heard, Matthew S

2017-08-01

Landscape heterogeneity in floral communities has the potential to modify pollinator behavior. Pollinator foraging varies with the diversity, abundance, and spatial configuration of floral resources. However, the implications of this variation for pollen transfer and ultimately the reproductive success of insect pollinated plants remains unclear, especially for species which are rare or isolated in the landscape. We used a landscape-scale experiment, coupled with microsatellite genotyping, to explore how the floral richness of habitats affected pollinator behavior and pollination effectiveness. Small arrays of the partially self-compatible plant Californian poppy ( Eschscholzia californica) were introduced across a landscape gradient to simulate rare, spatially isolated populations. The effects on pollinator activity, outcrossing, and plant reproduction were measured. In florally rich habitats, we found reduced pollen movement between plants, leading to fewer long-distance pollination events, lower plant outcrossing, and a higher incidence of pollen limitation. This pattern indicates a potential reduction in per capita pollinator visitation, as suggested by the lower activity densities and richness of pollinators observed within florally rich habitats. In addition, seed production reduced by a factor of 1.8 in plants within florally rich habitats and progeny germination reduced by a factor of 1.2. We show this to be a consequence of self-fertilization within the partially self-compatible plant, E. californica . These findings indicate that locally rare plants are at a competitive disadvantage within florally rich habitats because neighboring plant species disrupt conspecific mating by co-opting pollinators. Ultimately, this Allee effect may play an important role in determining the long-term persistence of rarer plants in the landscape, both in terms of seed production and viability. Community context therefore requires consideration when designing and

Maternal Lipid Provisioning Mirrors Evolution of Reproductive Strategies in Direct-Developing Whelks.

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Carrasco, Sergio A; Phillips, Nicole E; Sewell, Mary A

2016-06-01

The energetic input that offspring receive from their mothers is a well-studied maternal effect that can influence the evolution of life histories. Using the offspring of three sympatric whelks: Cominella virgata (one embryo per capsule); Cominella maculosa (multiple embryos per capsule); and Haustrum scobina (multiple embryos per capsule and nurse-embryo consumption), we examined how contrasting reproductive strategies mediate inter- and intraspecific differences in hatchling provisioning. Total lipid content (as measured in μg hatchling(-1) ± SE) was unrelated to size among the 3 species; the hatchlings of H. scobina were the smallest but had the highest lipid content (33.8 ± 8.1 μg hatchling(-1)). In offspring of C. maculosa, lipid content was 6.6 ± 0.4 μg hatchling(-1), and in offspring of C. virgata, it was 21.7 ± 3.2 μg hatchling(-1) The multi-encapsulated hatchlings of C. maculosa and H. scobina were the only species that contained the energetic lipids, wax ester (WE) and methyl ester (ME). However, the overall composition of energetic lipid between hatchlings of the two Cominella species reflected strong affinities of taxonomy, suggesting a phylogenetic evolution of the non-adelphophagic development strategy. Inter- and intracapsular variability in sibling provisioning was highest in H. scobina, a finding that implies less control of allocation to individual hatchlings in this adelphophagic developer. We suggest that interspecific variability of lipids offers a useful approach to understanding the evolution of maternal provisioning in direct-developing species. © 2016 Marine Biological Laboratory.

Isolation of Hox cluster genes from insects reveals an accelerated sequence evolution rate.

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Heike Hadrys

Full Text Available Among gene families it is the Hox genes and among metazoan animals it is the insects (Hexapoda that have attracted particular attention for studying the evolution of development. Surprisingly though, no Hox genes have been isolated from 26 out of 35 insect orders yet, and the existing sequences derive mainly from only two orders (61% from Hymenoptera and 22% from Diptera. We have designed insect specific primers and isolated 37 new partial homeobox sequences of Hox cluster genes (lab, pb, Hox3, ftz, Antp, Scr, abd-a, Abd-B, Dfd, and Ubx from six insect orders, which are crucial to insect phylogenetics. These new gene sequences provide a first step towards comparative Hox gene studies in insects. Furthermore, comparative distance analyses of homeobox sequences reveal a correlation between gene divergence rate and species radiation success with insects showing the highest rate of homeobox sequence evolution.

Reproduction alters oxidative status when it is traded-off against longevity.

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Beaulieu, Michaël; Geiger, Rina E; Reim, Elisabeth; Zielke, Luisa; Fischer, Klaus

2015-07-01

Oxidative stress has been proposed to mediate one of the most important aspects of life-history evolution: the trade-off between reproduction and self-maintenance. However, empirical studies have cast doubt on the generality of this intriguing notion. Here, we hypothesize that reproduction alters oxidative status only when a trade-off between reproduction and self-maintenance occurs. Accordingly, in female Bicyclus anynana butterflies, we found that reproduction affected oxidative markers only under challenging thermal conditions that made the trade-off between reproduction and longevity emerge. Interestingly, under such conditions, butterflies favored longevity over reproduction, suggesting that self-maintenance mechanisms were activated. Accordingly, butterflies reproducing under challenging thermal conditions exhibited enhanced antioxidant defenses and stable oxidative damage. Altogether, our results indicate that a trade-off between reproduction and self-maintenance is indeed a necessary condition for reproduction to alter oxidative status, and that the effects of such a trade-off on oxidative status depend on whether priority is given to self-maintenance or reproduction. Assessing the existence of the trade-off between self-maintenance and reproduction, and whether self-maintenance is prioritized relative to reproduction is therefore crucial for understanding variation in oxidative status in reproducing animals, which may clarify the general implication of oxidative stress in the resolution of life-history trade-offs. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

An X chromosome effect responsible for asymmetric reproductive isolation between male Drosophila virilis and heterospecific females.

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Nickel, Desirée; Civetta, Alberto

2009-01-01

Reproductive isolation between closely related species is expressed through uncoordinated courtship, failed fertilization, and (or) postzygotic barriers. Behavioural components of mating often form an initial barrier to hybridization between species. In many animals, females are responsible for mating discrimination in both intra- and interspecific crosses; males of Drosophila virilis group represent an exception to this trend. Using overall productivity tests, we show that a lower proportion of D. virilis males sire progeny when paired with a heterospecific female (Drosophila novamexicana or Drosophila americana texana) for 2 weeks. This suggests male mate discrimination or some other kind of asymmetrical incompatibility in courtship and mating or early zygote mortality. We used males from D. virilis-D. novamexicana and from D. virilis-D. a. texana backcross populations to map chromosome effects responsible for male reproductive isolation. Results from the analysis of both backcross male populations indicate a major X chromosome effect. Further, we conduct a male behavioural analysis to show that D. virilis males significantly fail to continue courtship after the first step of courtship, when they tap heterospecific females. The combined results of a major X chromosome effect and the observation that D. virilis males walk away from females after tapping suggest that future studies should concentrate on the identification of X-linked genes affecting the ability of males to recognize conspecific females.

The effect of isolation on reproduction and growth of Pseudosuccinea columella (Pulmonata: Lymnaeidae: a snail-conditioned water experiment

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Gutiérrez Alfredo

2002-01-01

Full Text Available A snail-conditioned water experiment was conducted in Pseudosuccinea columella to test the possible role of a chemical interaction between snails on the diminished growth and fecundity rates found for snails raised in pairs compared to those raised in complete isolation. The results permit to discard the hypothesis of an inhibition of growth and reproduction between snails due to factors released into the water.

Sexual reproduction and genetic exchange in parasitic protists.

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Weedall, Gareth D; Hall, Neil

2015-02-01

A key part of the life cycle of an organism is reproduction. For a number of important protist parasites that cause human and animal disease, their sexuality has been a topic of debate for many years. Traditionally, protists were considered to be primitive relatives of the 'higher' eukaryotes, which may have diverged prior to the evolution of sex and to reproduce by binary fission. More recent views of eukaryotic evolution suggest that sex, and meiosis, evolved early, possibly in the common ancestor of all eukaryotes. However, detecting sex in these parasites is not straightforward. Recent advances, particularly in genome sequencing technology, have allowed new insights into parasite reproduction. Here, we review the evidence on reproduction in parasitic protists. We discuss protist reproduction in the light of parasitic life cycles and routes of transmission among hosts.

Rapid evolution and copy number variation of primate RHOXF2, an X-linked homeobox gene involved in male reproduction and possibly brain function.

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Niu, Ao-lei; Wang, Yin-qiu; Zhang, Hui; Liao, Cheng-hong; Wang, Jin-kai; Zhang, Rui; Che, Jun; Su, Bing

2011-10-12

Homeobox genes are the key regulators during development, and they are in general highly conserved with only a few reported cases of rapid evolution. RHOXF2 is an X-linked homeobox gene in primates. It is highly expressed in the testicle and may play an important role in spermatogenesis. As male reproductive system is often the target of natural and/or sexual selection during evolution, in this study, we aim to dissect the pattern of molecular evolution of RHOXF2 in primates and its potential functional consequence. We studied sequences and copy number variation of RHOXF2 in humans and 16 nonhuman primate species as well as the expression patterns in human, chimpanzee, white-browed gibbon and rhesus macaque. The gene copy number analysis showed that there had been parallel gene duplications/losses in multiple primate lineages. Our evidence suggests that 11 nonhuman primate species have one RHOXF2 copy, and two copies are present in humans and four Old World monkey species, and at least 6 copies in chimpanzees. Further analysis indicated that the gene duplications in primates had likely been mediated by endogenous retrovirus (ERV) sequences flanking the gene regions. In striking contrast to non-human primates, humans appear to have homogenized their two RHOXF2 copies by the ERV-mediated non-allelic recombination mechanism. Coding sequence and phylogenetic analysis suggested multi-lineage strong positive selection on RHOXF2 during primate evolution, especially during the origins of humans and chimpanzees. All the 8 coding region polymorphic sites in human populations are non-synonymous, implying on-going selection. Gene expression analysis demonstrated that besides the preferential expression in the reproductive system, RHOXF2 is also expressed in the brain. The quantitative data suggests expression pattern divergence among primate species. RHOXF2 is a fast-evolving homeobox gene in primates. The rapid evolution and copy number changes of RHOXF2 had been driven by

Rapid evolution and copy number variation of primate RHOXF2, an X-linked homeobox gene involved in male reproduction and possibly brain function

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Zhang Rui

2011-10-01

Full Text Available Abstract Background Homeobox genes are the key regulators during development, and they are in general highly conserved with only a few reported cases of rapid evolution. RHOXF2 is an X-linked homeobox gene in primates. It is highly expressed in the testicle and may play an important role in spermatogenesis. As male reproductive system is often the target of natural and/or sexual selection during evolution, in this study, we aim to dissect the pattern of molecular evolution of RHOXF2 in primates and its potential functional consequence. Results We studied sequences and copy number variation of RHOXF2 in humans and 16 nonhuman primate species as well as the expression patterns in human, chimpanzee, white-browed gibbon and rhesus macaque. The gene copy number analysis showed that there had been parallel gene duplications/losses in multiple primate lineages. Our evidence suggests that 11 nonhuman primate species have one RHOXF2 copy, and two copies are present in humans and four Old World monkey species, and at least 6 copies in chimpanzees. Further analysis indicated that the gene duplications in primates had likely been mediated by endogenous retrovirus (ERV sequences flanking the gene regions. In striking contrast to non-human primates, humans appear to have homogenized their two RHOXF2 copies by the ERV-mediated non-allelic recombination mechanism. Coding sequence and phylogenetic analysis suggested multi-lineage strong positive selection on RHOXF2 during primate evolution, especially during the origins of humans and chimpanzees. All the 8 coding region polymorphic sites in human populations are non-synonymous, implying on-going selection. Gene expression analysis demonstrated that besides the preferential expression in the reproductive system, RHOXF2 is also expressed in the brain. The quantitative data suggests expression pattern divergence among primate species. Conclusions RHOXF2 is a fast-evolving homeobox gene in primates. The rapid

Reproductive activities of Heliotropium indicum isolate against Helopeltis theivora and toxicity evaluation in mice.

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Dolui, A K; Debnath, Manabendra; De, B; Kumar, Atul

2012-05-01

A new compound E was isolated from the methanolic extract of the leaves of Heliotropium indicum by chromatographic fractionation. In the present study, the effect of the compound E on reproduction of Helopeltis theivora has been evaluated. The acute toxicity study (LD50) and sub-acute toxicity studies (haematological, biochemical and histopathological parameters) in albino Swiss mice were carried out to evaluate the safety aspect of the compound E. The compound showed significant inhibitory effect on the reproductive life of H. theivora. The oviposition period, fecundity and hatching percentage of H. theivora were found to be 15.67 days, 39.33 and 28.00% respectively after treatment with 2% compound E, whereas the control value were found to be 20.33 days, 77.67 and 77.33% respectively. The LD50 of the compound was found to be 780 mg kg(-1) in Swiss albino female mice. The compound did not show any toxicity in mice at sub-lethal dose treatment (78 mg kg(-1) b. wt., once daily) for 21 days as evident from different haematological, biochemical and histopathological parameters in compound E treated group when compared with control.

Postmating-prezygotic isolation between two allopatric populations of Drosophila montana: fertilisation success differs under sperm competition.

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Ala-Honkola, Outi; Ritchie, Michael G; Veltsos, Paris

2016-03-01

Postmating but prezygotic (PMPZ) interactions are increasingly recognized as a potentially important early-stage barrier in the evolution of reproductive isolation. A recent study described a potential example between populations of the same species: single matings between Drosophila montana populations resulted in differential fertilisation success because of the inability of sperm from one population (Vancouver) to penetrate the eggs of the other population (Colorado). As the natural mating system of D. montana is polyandrous (females remate rapidly), we set up double matings of all possible crosses between the same populations to test whether competitive effects between ejaculates influence this PMPZ isolation. We measured premating isolation in no-choice tests, female fecundity, fertility and egg-to-adult viability after single and double matings as well as second-male paternity success (P2). Surprisingly, we found no PMPZ reproductive isolation between the two populations under a competitive setting, indicating no difficulty of sperm from Vancouver males to fertilize Colorado eggs after double matings. While there were subtle differences in how P2 changed over time, suggesting that Vancouver males' sperm are somewhat less competitive in a first-male role within Colorado females, these effects did not translate into differences in overall P2. Fertilisation success can thus differ dramatically between competitive and noncompetitive conditions, perhaps because the males that mate second produce higher quality ejaculates in response to sperm competition. We suggest that unlike in more divergent species comparisons, where sperm competition typically increases reproductive isolation, ejaculate tailoring can reduce the potential for PMPZ isolation when recently diverged populations interbreed.

Why cellular communication during plant reproduction is particularly mediated by CRP signalling.

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Bircheneder, Susanne; Dresselhaus, Thomas

2016-08-01

Secreted cysteine-rich peptides (CRPs) represent one of the main classes of signalling peptides in plants. Whereas post-translationally modified small non-CRP peptides (psNCRPs) are mostly involved in signalling events during vegetative development and interactions with the environment, CRPs are overrepresented in reproductive processes including pollen germination and growth, self-incompatibility, gamete activation and fusion as well as seed development. In this opinion paper we compare the involvement of both types of peptides in vegetative and reproductive phases of the plant lifecycle. Besides their conserved cysteine pattern defining structural features, CRPs exhibit hypervariable primary sequences and a rapid evolution rate. As a result, CRPs represent a pool of highly polymorphic signalling peptides involved in species-specific functions during reproduction and thus likely represent key players to trigger speciation in plants by supporting reproductive isolation. In contrast, precursers of psNCRPs are proteolytically processed into small functional domains with high sequence conservation and act in more general processes. We discuss parallels in downstream processes of CRP signalling in both reproduction and defence against pathogenic fungi and alien pollen tubes, with special emphasis on the role of ROS and ion channels. In conclusion we suggest that CRP signalling during reproduction in plants has evolved from ancient defence mechanisms. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Reproductive Conflict and the Evolution of Menopause in Killer Whales.

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Croft, Darren P; Johnstone, Rufus A; Ellis, Samuel; Nattrass, Stuart; Franks, Daniel W; Brent, Lauren J N; Mazzi, Sonia; Balcomb, Kenneth C; Ford, John K B; Cant, Michael A

2017-01-23

Why females of some species cease ovulation prior to the end of their natural lifespan is a long-standing evolutionary puzzle [1-4]. The fitness benefits of post-reproductive helping could in principle select for menopause [1, 2, 5], but the magnitude of these benefits appears insufficient to explain the timing of menopause [6-8]. Recent theory suggests that the cost of inter-generational reproductive conflict between younger and older females of the same social unit is a critical missing term in classical inclusive fitness calculations (the "reproductive conflict hypothesis" [6, 9]). Using a unique long-term dataset on wild resident killer whales, where females can live decades after their final parturition, we provide the first test of this hypothesis in a non-human animal. First, we confirm previous theoretical predictions that local relatedness increases with female age up to the end of reproduction. Second, we construct a new evolutionary model and show that given these kinship dynamics, selection will favor younger females that invest more in competition, and thus have greater reproductive success, than older females (their mothers) when breeding at the same time. Third, we test this prediction using 43 years of individual-based demographic data in resident killer whales and show that when mothers and daughters co-breed, the mortality hazard of calves from older-generation females is 1.7 times that of calves from younger-generation females. Intergenerational conflict combined with the known benefits conveyed to kin by post-reproductive females can explain why killer whales have evolved the longest post-reproductive lifespan of all non-human animals. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Evolution and molecular control of hybrid incompatibility in plants

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Chen Chen

2016-08-01

Full Text Available Postzygotic reproductive isolation (RI plays an important role in speciation. According to the stage at which it functions and the symptoms it displays, postzygotic RI can be called hybrid inviability, hybrid weakness or necrosis, hybrid sterility, or hybrid breakdown. In this review, we summarized new findings about hybrid incompatibilities in plants, most of which are from studies on Arabidopsis and rice. Recent progress suggests that hybrid incompatibility is a by-product of co-evolution either with parasitic selfish elements in the genome or with invasive microbes in the natural environment. We discuss the environmental influences on the expression of hybrid incompatibility and the possible effects of environment-dependent hybrid incompatibility on sympatric speciation. We also discuss the role of domestication on the evolution of hybrid incompatibilities.

Multiple reproductive strategies in a tropical hover wasp

DEFF Research Database (Denmark)

Fanelli, D.; Boomsma, Jacobus Jan; Turillazzi, S.

2005-01-01

Reproductive skew theory has been an important component of efforts to design a unifying theory of social evolution, as it aims to explain patterns of reproductive partitioning in animal societies as a function of relatedness, group productivity, fighting ability and ecological constraints on ind...

Evolution of reproductive life histories in island birds worldwide.

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Covas, Rita

2012-04-22

Island environments typically share characteristics such as impoverished biotas and less-seasonal climates, which should be conducive to specific adaptations by organisms. However, with the exception of morphological studies, broad-scale tests of patterns of adaptation on islands are rare. Here, I examine reproductive patterns in island birds worldwide. Reproductive life histories are influenced by latitude, which could affect the response to insularity; therefore, I additionally test this hypothesis. Island colonizers showed mostly bi-parental care, but there was a significant increase in cooperative breeding on islands. Additionally, I found support for previous suggestions of reduced fecundity, longer developmental periods and increased investment in young on islands. However, clutch size increased with latitude at a rate nearly five times faster on the mainland than on the islands revealing a substantially stronger effect of insularity at higher latitudes. Latitude and insularity may also interact to determine egg volume and incubation periods, but these effects were less clear. Analyses of reproductive success did not support an effect of reduced nest predation as a driver of reproductive change, but this requires further study. The effect of latitude detected here suggests that the evolutionary changes associated with insularity relate to environmental stability and improved adult survival.

Associations between intrauterine bacterial infection, reproductive tract inflammation, and reproductive performance in pasture-based dairy cows.

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de Boer, Melvin; Buddle, Bryce M; Heuer, Cord; Hussein, Hassan; Zheng, Tao; LeBlanc, Stephen J; McDougall, Scott

2015-06-01

Reproductive tract bacterial infections, particularly those caused by Escherichia coli and Trueperella pyogenes, can have a negative impact on reproductive performance. It has been hypothesized that the presence of E coli early postpartum may increase the risk of isolation of T pyogenes later postpartum. The objective of the present study was to examine associations between intrauterine bacterial infections with E coli and T pyogenes and any bacterial growth (irrespective of bacterial species), purulent vaginal discharge (PVD), cytologic evidence of endometritis (an increased proportion of polymorphonuclear cells [PMNs]), and reproductive performance. Dairy cows (n = 272) from six herds were examined at Days 0 (median, 2 days in milk), 21 and 42 postpartum. From each cow two intrauterine samples were collected via triple-guarded cytobrush at Days 0 and 21. The first cytobrush was used for bacteriologic culture. Escherichia coli and T pyogenes were isolated by culture, and E coli isolates were assigned to one of four phylogenetic groups using a two-step triplex polymerase chain reaction. In addition, T pyogenes was confirmed by polymerase chain reaction. The second cytobrush was used to prepare a cytology slide. Nucleated cells (n = 200) were categorized as epithelial cells, PMNs, or macrophages. Cows were also assessed for body condition score, PVD score, the presence of a CL, and pregnancy. Statistical analysis was performed using multivariable models. There was no association between the presence of E coli at Day 0 and probability of isolation of T pyogenes 3 weeks later; however, E coli positive cows at Day 0 were more likely to be diagnosed with E coli at Day 21 (relative risk [RR] = 2.0, P bacterial growth at Day 21, irrespective of species, were less likely to conceive within 3 weeks after the start of the seasonal breeding program (RR = 0.8; P = 0.05). Interestingly, cows with 25% PMNs or greater at Day 0 had shorter time to pregnancy (hazard ratio = 1.32; P

Evolution of CRISPs associated with toxicoferan-reptilian venom and mammalian reproduction.

Science.gov (United States)

Sunagar, Kartik; Johnson, Warren E; O'Brien, Stephen J; Vasconcelos, Vítor; Antunes, Agostinho

2012-07-01

Cysteine-rich secretory proteins (CRISPs) are glycoproteins found exclusively in vertebrates and have broad diversified functions. They are hypothesized to play important roles in mammalian reproduction and in reptilian venom, where they disrupt homeostasis of the prey through several mechanisms, including among others, blockage of cyclic nucleotide-gated and voltage-gated ion channels and inhibition of smooth muscle contraction. We evaluated the molecular evolution of CRISPs in toxicoferan reptiles at both nucleotide and protein levels relative to their nonvenomous mammalian homologs. We show that the evolution of CRISP gene in these reptiles is significantly influenced by positive selection and in snakes (ω = 3.84) more than in lizards (ω = 2.33), whereas mammalian CRISPs were under strong negative selection (CRISP1 = 0.55, CRISP2 = 0.40, and CRISP3 = 0.68). The use of ancestral sequence reconstruction, mapping of mutations on the three-dimensional structure, and detailed evaluation of selection pressures suggests that the toxicoferan CRISPs underwent accelerated evolution aided by strong positive selection and directional mutagenesis, whereas their mammalian homologs are constrained by negative selection. Gene and protein-level selection analyses identified 41 positively selected sites in snakes and 14 sites in lizards. Most of these sites are located on the molecular surface (nearly 76% in snakes and 79% in lizards), whereas the backbone of the protein retains a highly conserved structural scaffold. Nearly 46% of the positively selected sites occur in the cysteine-rich domain of the protein. This directional mutagenesis, where the hotspots of mutations are found on the molecular surface and functional domains of the protein, acts as a diversifying mechanism for the exquisite biological targeting of CRISPs in toxicoferan reptiles. Finally, our analyses suggest that the evolution of toxicoferan-CRISP venoms might have been influenced by the specific predatory

Quantifying inbreeding avoidance through extra-pair reproduction.

Science.gov (United States)

Reid, Jane M; Arcese, Peter; Keller, Lukas F; Germain, Ryan R; Duthie, A Bradley; Losdat, Sylvain; Wolak, Matthew E; Nietlisbach, Pirmin

2015-01-01

Extra-pair reproduction is widely hypothesized to allow females to avoid inbreeding with related socially paired males. Consequently, numerous field studies have tested the key predictions that extra-pair offspring are less inbred than females' alternative within-pair offspring, and that the probability of extra-pair reproduction increases with a female's relatedness to her socially paired male. However, such studies rarely measure inbreeding or relatedness sufficiently precisely to detect subtle effects, or consider biases stemming from failure to observe inbred offspring that die during early development. Analyses of multigenerational song sparrow (Melospiza melodia) pedigree data showed that most females had opportunity to increase or decrease the coefficient of inbreeding of their offspring through extra-pair reproduction with neighboring males. In practice, observed extra-pair offspring had lower inbreeding coefficients than females' within-pair offspring on average, while the probability of extra-pair reproduction increased substantially with the coefficient of kinship between a female and her socially paired male. However, simulations showed that such effects could simply reflect bias stemming from inbreeding depression in early offspring survival. The null hypothesis that extra-pair reproduction is random with respect to kinship therefore cannot be definitively rejected in song sparrows, and existing general evidence that females avoid inbreeding through extra-pair reproduction requires reevaluation given such biases. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

Lifetime reproductive success in the solitary endoparasitoid, Venturia canescens

NARCIS (Netherlands)

Harvey, J.A.; Harvey, I.F.; Thompson, D.J.

2001-01-01

Parasitoid wasps have long been considered excellent organisms in studies examining the evolution of reproductive and life- history strategies. In examining the lifetime reproductive success of parasitoids in the laboratory, most investigations have provided the insects with excess hosts and food,

Genome size evolution at the speciation level: the cryptic species complex Brachionus plicatilis (Rotifera).

Science.gov (United States)

Stelzer, Claus-Peter; Riss, Simone; Stadler, Peter

2011-04-07

Studies on genome size variation in animals are rarely done at lower taxonomic levels, e.g., slightly above/below the species level. Yet, such variation might provide important clues on the tempo and mode of genome size evolution. In this study we used the flow-cytometry method to study the evolution of genome size in the rotifer Brachionus plicatilis, a cryptic species complex consisting of at least 14 closely related species. We found an unexpectedly high variation in this species complex, with genome sizes ranging approximately seven-fold (haploid '1C' genome sizes: 0.056-0.416 pg). Most of this variation (67%) could be ascribed to the major clades of the species complex, i.e. clades that are well separated according to most species definitions. However, we also found substantial variation (32%) at lower taxonomic levels--within and among genealogical species--and, interestingly, among species pairs that are not completely reproductively isolated. In one genealogical species, called B. 'Austria', we found greatly enlarged genome sizes that could roughly be approximated as multiples of the genomes of its closest relatives, which suggests that whole-genome duplications have occurred early during separation of this lineage. Overall, genome size was significantly correlated to egg size and body size, even though the latter became non-significant after controlling for phylogenetic non-independence. Our study suggests that substantial genome size variation can build up early during speciation, potentially even among isolated populations. An alternative, but not mutually exclusive interpretation might be that reproductive isolation tends to build up unusually slow in this species complex.

Where the lake meets the sea: strong reproductive isolation is associated with adaptive divergence between lake resident and anadromous three-spined sticklebacks.

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Mark Ravinet

Full Text Available Contact zones between divergent forms of the same species are often characterised by high levels of phenotypic diversity over small geographic distances. What processes are involved in generating such high phenotypic diversity? One possibility is that introgression and recombination between divergent forms in contact zones results in greater phenotypic and genetic polymorphism. Alternatively, strong reproductive isolation between forms may maintain distinct phenotypes, preventing homogenisation by gene flow. Contact zones between divergent freshwater-resident and anadromous stickleback (Gasterosteus aculeatus L. forms are numerous and common throughout the species distribution, offering an opportunity to examine these contrasting hypotheses in greater detail. This study reports on an interesting new contact zone located in a tidally influenced lake catchment in western Ireland, characterised by high polymorphism for lateral plate phenotypes. Using neutral and QTL-linked microsatellite markers, we tested whether the high diversity observed in this contact zone arose as a result of introgression or reproductive isolation between divergent forms: we found strong support for the latter hypothesis. Three phenotypic and genetic clusters were identified, consistent with two divergent resident forms and a distinct anadromous completely plated population that migrates in and out of the system. Given the strong neutral differentiation detected between all three morphotypes (mean FST = 0.12, we hypothesised that divergent selection between forms maintains reproductive isolation. We found a correlation between neutral genetic and adaptive genetic differentiation that support this. While strong associations between QTL linked markers and phenotypes were also observed in this wild population, our results support the suggestion that such associations may be more complex in some Atlantic populations compared to those in the Pacific. These findings provide an

[Mobile genetic elements in plant sex evolution].

Science.gov (United States)

Gerashchenkov, G A; Rozhnova, N A

2010-11-01

The most significant theories of the appearance and maintenance of sex are presented. However, in the overwhelming majority of existing theories, the problem of sex, which is the central problem of evolutionary biology, is considered primarily through the prism of reproductive features of living organisms, whereas the issue of molecular driving forces of sexual reproduction id restricted to the possible role of mobile genetic elements (MGEs) in the appearance of sexual reproduction. The structural and functional significance of MGEs in the genomic organization of plants is illustrated. It is shown that MGEs could act as important molecular drivers of sex evolution in plants. The involvement of MGEs in the formation of sex chromosomes and possible participation in seeds-without-sex reproduction (apomixis) is discussed. Thus, the hypothesis on the active MGE participation in sex evolution is in good agreement with the modern views on pathways and directions of sex evolution in plants.

Reproduction, symbiosis, and the eukaryotic cell

Science.gov (United States)

Godfrey-Smith, Peter

2015-01-01

This paper develops a conceptual framework for addressing questions about reproduction, individuality, and the units of selection in symbiotic associations, with special attention to the origin of the eukaryotic cell. Three kinds of reproduction are distinguished, and a possible evolutionary sequence giving rise to a mitochondrion-containing eukaryotic cell from an endosymbiotic partnership is analyzed as a series of transitions between each of the three forms of reproduction. The sequence of changes seen in this “egalitarian” evolutionary transition is compared with those that apply in “fraternal” transitions, such as the evolution of multicellularity in animals. PMID:26286983

Clusters of incompatible genotypes evolve with limited dispersal

Science.gov (United States)

Erin L. Landguth; Norman A. Johnson; Samuel A. Cushman

2015-01-01

Theoretical and empirical studies have shown heterogeneous selection to be the primary driver for the evolution of reproductively isolated genotypes in the absence of geographic barriers. Here, we ask whether limited dispersal alone can lead to the evolution of reproductively isolated genotypes despite the absence of any geographic barriers or heterogeneous...

Independent evolution of the sexes promotes amphibian diversification

Science.gov (United States)

De Lisle, Stephen P.; Rowe, Locke

2015-01-01

Classic ecological theory predicts that the evolution of sexual dimorphism constrains diversification by limiting morphospace available for speciation. Alternatively, sexual selection may lead to the evolution of reproductive isolation and increased diversification. We test contrasting predictions of these hypotheses by examining the relationship between sexual dimorphism and diversification in amphibians. Our analysis shows that the evolution of sexual size dimorphism (SSD) is associated with increased diversification and speciation, contrary to the ecological theory. Further, this result is unlikely to be explained by traditional sexual selection models because variation in amphibian SSD is unlikely to be driven entirely by sexual selection. We suggest that relaxing a central assumption of classic ecological models—that the sexes share a common adaptive landscape—leads to the alternative hypothesis that independent evolution of the sexes may promote diversification. Once the constraints of sexual conflict are relaxed, the sexes can explore morphospace that would otherwise be inaccessible. Consistent with this novel hypothesis, the evolution of SSD in amphibians is associated with reduced current extinction threat status, and an historical reduction in extinction rate. Our work reconciles conflicting predictions from ecological and evolutionary theory and illustrates that the ability of the sexes to evolve independently is associated with a spectacular vertebrate radiation. PMID:25694616

Genome structure and reproductive behaviour influence the evolutionary potential of a fungal phytopathogen.

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Guillaume Daverdin

Full Text Available Modern agriculture favours the selection and spread of novel plant diseases. Furthermore, crop genetic resistance against pathogens is often rendered ineffective within a few years of its commercial deployment. Leptosphaeria maculans, the cause of phoma stem canker of oilseed rape, develops gene-for-gene interactions with its host plant, and has a high evolutionary potential to render ineffective novel sources of resistance in crops. Here, we established a four-year field experiment to monitor the evolution of populations confronted with the newly released Rlm7 resistance and to investigate the nature of the mutations responsible for virulence against Rlm7. A total of 2551 fungal isolates were collected from experimental crops of a Rlm7 cultivar or a cultivar without Rlm7. All isolates were phenotyped for virulence and a subset was genotyped with neutral genetic markers. Virulent isolates were investigated for molecular events at the AvrLm4-7 locus. Whilst virulent isolates were not found in neighbouring crops, their frequency had reached 36% in the experimental field after four years. An extreme diversity of independent molecular events leading to virulence was identified in populations, with large-scale Repeat Induced Point mutations or complete deletion of AvrLm4-7 being the most frequent. Our data suggest that increased mutability of fungal genes involved in the interactions with plants is directly related to their genomic environment and reproductive system. Thus, rapid allelic diversification of avirulence genes can be generated in L. maculans populations in a single field provided that large population sizes and sexual reproduction are favoured by agricultural practices.

Reproductive endocrinology and infertility fellowships: is the 'reproductive endocrinology' portion obsolete?

Science.gov (United States)

Omurtag, Kenan; Lebovic, Dan I

2015-08-01

To take inventory of the past and present and project the future direction of our field to help train the next generation of providers. Review the history of the subspecialty and factors contributing to its evolution. Reproductive endocrinology and infertility's in-vitro fertilization future is shaping the intellectual priorities and surgical skill requirements of the next generation.

Reproductive adaptations to reduce locomotor costs in viviparous fish (Poeciliidae)

NARCIS (Netherlands)

Fleuren, Mike

2017-01-01

Viviparity, a live-bearing mode of reproduction, has evolved over 100 times independently in vertebrate animals. Despite its frequent evolution, viviparity has a number of hypothesised disadvantages compared to the ancestral mode of reproduction, oviparity (egg-laying). One of these disadvantages

Genome size evolution at the speciation level: The cryptic species complex Brachionus plicatilis (Rotifera

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Riss Simone

2011-04-01

Full Text Available Abstract Background Studies on genome size variation in animals are rarely done at lower taxonomic levels, e.g., slightly above/below the species level. Yet, such variation might provide important clues on the tempo and mode of genome size evolution. In this study we used the flow-cytometry method to study the evolution of genome size in the rotifer Brachionus plicatilis, a cryptic species complex consisting of at least 14 closely related species. Results We found an unexpectedly high variation in this species complex, with genome sizes ranging approximately seven-fold (haploid '1C' genome sizes: 0.056-0.416 pg. Most of this variation (67% could be ascribed to the major clades of the species complex, i.e. clades that are well separated according to most species definitions. However, we also found substantial variation (32% at lower taxonomic levels - within and among genealogical species - and, interestingly, among species pairs that are not completely reproductively isolated. In one genealogical species, called B. 'Austria', we found greatly enlarged genome sizes that could roughly be approximated as multiples of the genomes of its closest relatives, which suggests that whole-genome duplications have occurred early during separation of this lineage. Overall, genome size was significantly correlated to egg size and body size, even though the latter became non-significant after controlling for phylogenetic non-independence. Conclusions Our study suggests that substantial genome size variation can build up early during speciation, potentially even among isolated populations. An alternative, but not mutually exclusive interpretation might be that reproductive isolation tends to build up unusually slow in this species complex.

Isolamento reprodutivo entre Australorbis glabratus e A. nigricans Reproductive isolation between Australorbis glabratus and A. nigricans

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W. Lobato Paraense

1955-12-01

Full Text Available Foram feitas provas de cruzamento entre espécimes de uma população de A. glabratus e de outra de A. nigricans, utilizando o fator de albinismo como mercador genético. O resultado dessas provas revelou completo isolamento reprodutivo entre ambas, permitindo separá-las como boas espécies de acôrdo com o critério biológico.Crossing experiments were made between specimens from one population of A. glabratus and another of A. nigricans, the factor of albinism having been used as genetic marker. The results of those experiments revealed a complete reproductive isolation between both population, thus indicating their specific distinctness according to the biological criterion.

Evolution of complex asexual reproductive strategies in jellyfish

DEFF Research Database (Denmark)

Schnedler-Meyer, Nicolas Azaña; Pigolotti, Simone; Mariani, Patrizio

2018-01-01

Many living organisms in terrestrial and aquatic ecosystems rely on multiple reproductive strategies to reduce the risk of extinction in variable environments. Examples are provided by the polyp stage of several bloom-forming jellyfish species, which can reproduce asexually using different buddin...

Isolated self-assembled InAs/InP(001) quantum wires obtained by controlling the growth front evolution

International Nuclear Information System (INIS)

Fuster, David; Alen, Benito; Gonzalez, Luisa; Gonzalez, Yolanda; Martinez-Pastor, Juan; Gonzalez, Maria Ujue; GarcIa, Jorge M

2007-01-01

In this work we explore the first stages of quantum wire (QWR) formation studying the evolution of the growth front for InAs coverages below the critical thickness, θ c , determined by reflection high energy electron diffraction (RHEED). Our results obtained by in situ measurement of the accumulated stress evolution during InAs growth on InP(001) show that the relaxation process starts at a certain InAs coverage θ R c . At this θ R , the spontaneous formation of isolated quantum wires takes place. For θ>θ R this ensemble of isolated nanostructures progressively evolves towards QWRs that cover the whole surface for θ θ c . These results allow for a better understanding of the self-assembling process of QWRs and enable the study of the individual properties of InAs/InP self-assembled single quantum wires

Society for Assisted Reproductive Technology and assisted reproductive technology in the United States: a 2016 update.

Science.gov (United States)

Toner, James P; Coddington, Charles C; Doody, Kevin; Van Voorhis, Brad; Seifer, David B; Ball, G David; Luke, Barbara; Wantman, Ethan

2016-09-01

The Society for Assisted Reproductive Technology (SART) was established within a few years of assisted reproductive technology (ART) in the United States, and has not only reported on the evolution of infertility care, but also guided it toward improved success and safety. Moving beyond its initial role as a registry, SART has expanded its role to include quality assurance, data validation, practice and advertising guidelines, research, patient education and advocacy, and membership support. The success of ART in this country has greatly benefited from SART's role, as highlighted by a series of graphs. SART continues to set the standard and lead the way. Copyright © 2016 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Molecular Characterization of the First Bovine Herpesvirus 4 (BoHV-4 Strains Isolated from In Vitro Bovine Embryos production in Argentina.

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Erika González Altamiranda

Full Text Available Bovine herpesvirus 4 (BoHV-4 is increasingly considered as responsible for various problems of the reproductive tract. The virus infects mainly blood mononuclear cells and displays specific tropism for vascular endothelia, reproductive and fetal tissues. Epidemiological studies suggest its impact on reproductive performance, and its presence in various sites in the reproductive tract highlights its potential transmission in transfer-stage embryos. This work describes the biological and genetic characterization of BoHV-4 strains isolated from an in vitro bovine embryo production system. BoHV-4 strains were isolated in 2011 and 2013 from granulosa cells and bovine oocytes from ovary batches collected at a local abattoir, used as "starting material" for in vitro production of bovine embryos. Compatible BoHV-4-CPE was observed in the co-culture of granulosa cells and oocytes with MDBK cells. The identity of the isolates was confirmed by PCR assays targeting three ORFs of the viral genome. The phylogenetic analyses of the strains suggest that they were evolutionary unlinked. Therefore it is possible that BoHV-4 ovary infections occurred regularly along the evolution of the virus, at least in Argentina, which can have implications in the systems of in vitro embryo production. Thus, although BoHV-4 does not appear to be a frequent risk factor for in vitro embryo production, data are still limited. This study reveals the potential of BoHV-4 transmission via embryo transfer. Moreover, the high variability among the BoHV-4 strains isolated from aborted cows in Argentina highlights the importance of further research on the role of this virus as an agent with the potential to cause reproductive disease in cattle. The genetic characterization of the isolated strains provides data to better understand the pathogenesis of BoHV-4 infections. Furthermore, it will lead to fundamental insights into the molecular aspects of the virus and the means by which these

Evolution: sociality as a driver of unorthodox reproduction.

Science.gov (United States)

Schwander, Tanja; Keller, Laurent

2012-07-10

An unusual reproductive system was discovered in desert ants, in which daughter queens are produced asexually via parthenogenesis, whereas workers develop from hybrid crosses between genetically divergent lineages. The system appears to be doomed to extinction. Copyright © 2012 Elsevier Ltd. All rights reserved.

Antiherbivore defenses alter natural selection on plant reproductive traits.

Science.gov (United States)

Thompson, Ken A; Johnson, Marc T J

2016-04-01

While many studies demonstrate that herbivores alter selection on plant reproductive traits, little is known about whether antiherbivore defenses affect selection on these traits. We hypothesized that antiherbivore defenses could alter selection on reproductive traits by altering trait expression through allocation trade-offs, or by altering interactions with mutualists and/or antagonists. To test our hypothesis, we used white clover, Trifolium repens, which has a Mendelian polymorphism for the production of hydrogen cyanide-a potent antiherbivore defense. We conducted a common garden experiment with 185 clonal families of T. repens that included cyanogenic and acyanogenic genotypes. We quantified resistance to herbivores, and selection on six floral traits and phenology via male and female fitness. Cyanogenesis reduced herbivory but did not alter the expression of reproductive traits through allocation trade-offs. However, the presence of cyanogenic defenses altered natural selection on petal morphology and the number of flowers within inflorescences via female fitness. Herbivory influenced selection on flowers and phenology via female fitness independently of cyanogenesis. Our results demonstrate that both herbivory and antiherbivore defenses alter natural selection on plant reproductive traits. We discuss the significance of these results for understanding how antiherbivore defenses interact with herbivores and pollinators to shape floral evolution. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

Whole-Genome Scans Provide Evidence of Adaptive Evolution in Malawian Plasmodium falciparum Isolates

DEFF Research Database (Denmark)

Ocholla, Harold; Preston, Mark D; Mipando, Mwapatsa

2014-01-01

BACKGROUND:  Selection by host immunity and antimalarial drugs has driven extensive adaptive evolution in Plasmodium falciparum and continues to produce ever-changing landscapes of genetic variation. METHODS:  We performed whole-genome sequencing of 69 P. falciparum isolates from Malawi and used......, an area of high malaria transmission. Allele frequency-based tests provided evidence of recent population growth in Malawi and detected potential targets of host immunity and candidate vaccine antigens. Comparison of the sequence variation between isolates from Malawi and those from 5 geographically...... dispersed countries (Kenya, Burkina Faso, Mali, Cambodia, and Thailand) detected population genetic differences between Africa and Asia, within Southeast Asia, and within Africa. Haplotype-based tests of selection to sequence data from all 6 populations identified signals of directional selection at known...

The Reproduction Trajectories of Institutions of Social Isolation of Individual Population Groups in the Regions of Russia

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Boris Yuryevich Berzin

2015-09-01

Full Text Available The article deals with the spatial socio-demographic isolation as a factor of the current system of settlement in Russia’s regions. In theory, the phenomena of loneliness and social isolation have their demographic, socio-economic and psychological roots. Conceptually, they are expressed in the theories of nuclearization of family structure of society and the family’s loss of its core functions, deprivation of a person (of friends and relatives, in the paradigm of the second demographic transition. In fact, the trend towards the abandonment of birth, growth of cohabitations and divorces, premature mortality as the cause of widowhood are complemented by the institutional factors strengthening the foundations of a singular way of life, including various forms of isolation of an individual from the social environment in a post-industrial society. The main reasons of the socio-demographic isolation are following: the tendency of increasing a number of private households represented by lonely people, both elderly and young; as well as the prevalence of the institute of widowhood (mortality risks influencing the marriage and the family; the impact of flows of labour, academic, self-preservation, consumer migration (both returned and irretrievable types on the reproduction of the population. Psychologically, the demographic isolation of certain local communities contributes to the feelings of loneliness as a regulator of the communication intensity and interaction between individuals. In the socioeconomic aspects, the isolation of local communities is associated with the factor of remote location of families from the centers of communication and real markets, with the development of new Russian and global logistics systems, with are deprivation of traditional sources of household income as a specific form of survival in the vast expanses of life of the Russian society.

Coexistence of sexual individuals and genetically isolated asexual counterparts in a thrips.

Science.gov (United States)

Kobayashi, Kazuya; Yoshimura, Jin; Hasegawa, Eisuke

2013-11-21

Sex is a paradoxical phenomenon because it is less efficient compared with asexual reproduction. To resolve this paradox we need a direct comparison between sexual and asexual forms. In many organisms, however, sexual and asexual forms do not occur in the same habitat, or at the same time. In a few cases where sexual and asexual forms are found in a single population, some (though rare) genetic exchange is usually detected between the two forms. When genetic exchange occurs a direct comparison is impossible. Here we investigate a thrips exhibiting both sexual and asexual forms (lineages) that are morphologically indistinguishable. We examine if the two forms are genetically isolated. Phylogeny based on nuclear genes confirms that the sexual and asexual lineages are genetically differentiated. Thus we demonstrate that the current system has certain advantages over existing and previously used model systems in the evolution of sexual reproduction.

Reproductive isolation in hybrid mice due to spermatogenesis defects at three meiotic stages.

Science.gov (United States)

Oka, Ayako; Mita, Akihiko; Takada, Yuki; Koseki, Haruhiko; Shiroishi, Toshihiko

2010-09-01

Early in the process of speciation, reproductive failures occur in hybrid animals between genetically diverged populations. The sterile hybrid animals are often males in mammals and they exhibit spermatogenic disruptions, resulting in decreased number and/or malformation of mature sperms. Despite the generality of this phenomenon, comparative study of phenotypes in hybrid males from various crosses has not been done, and therefore the comprehensive genetic basis of the disruption is still elusive. In this study, we characterized the spermatogenic phenotype especially during meiosis in four different cases of reproductive isolation: B6-ChrX(MSM), PGN-ChrX(MSM), (B6 × Mus musculus musculus-NJL/Ms) F(1), and (B6 × Mus spretus) F(1). The first two are consomic strains, both bearing the X chromosome of M. m. molossinus; in B6-ChrX(MSM), the genetic background is the laboratory strain C57BL/6J (predominantly M. m. domesticus), while in PGN-ChrX(MSM) the background is the PGN2/Ms strain purely derived from wild M. m. domesticus. The last two cases are F(1) hybrids between mouse subspecies or species. Each of the hybrid males exhibited cell-cycle arrest and/or apoptosis at either one or two of three distinct meiotic stages: premeiotic stage, zygotene-to-pachytene stage of prophase I, and metaphase I. This study shows that the sterility in hybrid males is caused by spermatogenic disruptions at multiple stages, suggesting that the responsible genes function in different cellular processes. Furthermore, the stages with disruptions are not correlated with the genetic distance between the respective parental strains.

Reproductive isolation revealed in preliminary crossbreeding experiments using field collected Triatoma dimidiata (Hemiptera: Reduviidae) from three ITS–2 defined groups

OpenAIRE

García, Mauricio; Menes, Marianela; Dorn, Patricia L.; Monroy, Carlota; Richards, Bethany; Panzera, Francisco; Bustamante, Dulce María

2013-01-01

Triatoma dimidiata, a Chagas disease vector distributed in Mexico, Central America, Colombia, Venezuela, Peru and Ecuador, has been studied using genetic markers and four groups have been defined by ITS–2 sequences: 1A, 1B, 2 and 3. To gather evidence on the divergence and reproductive isolation among T. dimidiata ITS–2 groups, we carried out 15 crossbreeding experiments with field–collected sylvan and domestic T. dimidiata from Guatemala where three groups are found: 1A, 2 and 3. Reciprocal ...

Costs of reproduction can explain the correlated evolution of semelparity and egg size: theory and a test with salmon.

Science.gov (United States)

Kindsvater, Holly K; Braun, Douglas C; Otto, Sarah P; Reynolds, John D

2016-06-01

Species' life history traits, including maturation age, number of reproductive bouts, offspring size and number, reflect adaptations to diverse biotic and abiotic selection pressures. A striking example of divergent life histories is the evolution of either iteroparity (breeding multiple times) or semelparity (breed once and die). We analysed published data on salmonid fishes and found that semelparous species produce larger eggs, that egg size and number increase with salmonid body size among populations and species and that migratory behaviour and parity interact. We developed three hypotheses that might explain the patterns in our data and evaluated them in a stage-structured modelling framework accounting for different growth and survival scenarios. Our models predict the observation of small eggs in iteroparous species when egg size is costly to maternal survival or egg number is constrained. By exploring trait co-variation in salmonids, we generate new hypotheses for the evolution of trade-offs among life history traits. © 2016 John Wiley & Sons Ltd/CNRS.

Diversification and reproductive isolation: cryptic species in the only New World high-duty cycle bat, Pteronotus parnellii

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Clare Elizabeth L

2013-01-01

Full Text Available Abstract Background Molecular techniques are increasingly employed to recognize the presence of cryptic species, even among commonly observed taxa. Previous studies have demonstrated that bats using high-duty cycle echolocation may be more likely to speciate quickly. Pteronotus parnellii is a widespread Neotropical bat and the only New World species to use high-duty cycle echolocation, a trait otherwise restricted to Old World taxa. Here we analyze morphological and acoustic variation and genetic divergence at the mitochondrial COI gene, the 7th intron region of the y-linked Dby gene and the nuclear recombination-activating gene 2, and provide extensive evidence that P. parnellii is actually a cryptic species complex. Results Central American populations form a single species while three additional species exist in northern South America: one in Venezuela, Trinidad and western Guyana and two occupying sympatric ranges in Guyana and Suriname. Reproductive isolation appears nearly complete (only one potential hybrid individual found. The complex likely arose within the last ~6 million years with all taxa diverging quickly within the last ~1-2 million years, following a pattern consistent with the geological history of Central and northern South America. Significant variation in cranial measures and forearm length exists between three of the four groups, although no individual morphological character can discriminate these in the field. Acoustic analysis reveals small differences (5–10 kHz in echolocation calls between allopatric cryptic taxa that are unlikely to provide access to different prey resources but are consistent with divergence by drift in allopatric species or through selection for social recognition. Conclusions This unique approach, considering morphological, acoustic and multi-locus genetic information inherited maternally, paternally and bi-parentally, provides strong support to conclusions about the cessation of gene flow and

A selfish gene governing pollen-pistil compatibility confers reproductive isolation between maize relatives.

Science.gov (United States)

Kermicle, Jerry L

2006-01-01

Some populations of maize's closest relatives, the annual teosintes of Mexico, are unreceptive to maize pollen. When present in the pistil (silk and ovary) a number of maize genes discriminate against or exclude pollen not carrying the same allele. An analogous gene Tcb1-s was found in some teosinte populations but not in sympatric or parapatric maize. It was polymorphic among populations of teosinte growing wild, but regularly present in populations growing in intimate association with maize as a weed. Introduction of Tcb1-s into maize substantially to fully restored compatibility with Tcb1-s carrying teosintes. Although Tcb1-s pollen can fertilize tcb1 tcb1 maize, it is at a competitive disadvantage relative to tcb1 pollen. Hence, the influence of Tcb1-s on crossability is bidirectional. In the absence of maize, Tcb1-s can increase in teosinte populations without improving their fitness. In the presence of maize, Tcb1-s appears to have been co-opted to provide reproductive isolation for adaptation to a cultivated habitat.

Common causes of vaginal infections and antibiotic susceptibility of aerobic bacterial isolates in women of reproductive age attending at Felegehiwot Referral Hospital, Ethiopia: a cross sectional study.

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Mulu, Wondemagegn; Yimer, Mulat; Zenebe, Yohannes; Abera, Bayeh

2015-05-13

Bacterial vaginosis, candidal, trichomonal and Gonococcal vaginal infections are a major health problems associated with gynecologic complications and increase in replication, shedding and transmission of HIV and other STIs in women of reproductive age. The study aimed at determining the prevalence of common vaginal infections and antimicrobial susceptibility profiles of aerobic bacterial isolates in women of reproductive age, attending Felegehiwot referral Hospital. A hospital based cross sectional study was conducted from May to November, 2013. Simple random sampling technique was used. Demographic variables were collected using a structured questionnaire. Clinical data were collected by physicians. Two vaginal swab specimens were collected from each participant. Wet mount and Gram staining were carried out to identify motile T.vaginalis, budding yeast and clue cells. All vaginal specimens were cultured for aerobic bacterial isolates using standard microbiology methods. Antimicrobial susceptibility was performed using disc diffusion technique as per the standard by Kirby-Bauer method. The results were analyzed using descriptive, chi-square and fisher's exact test as appropriate. A total of 409 women in reproductive age (15 - 49 years) participated in the study. The median age of the women was 28 years. Overall, 63 (15.4 %) of women had vaginal infections. The proportion of vaginal infection was higher in non-pregnant (17.3 %) than pregnant women (13.3 %) (P = 0.002). The most common identified vaginal infections were candidiasis (8.3 %) and bacterial vaginosis (2.8 %) followed by trichomoniasis (2.1 %). The isolation rate of N. gonorrhoeae and group B Streptococcus colonization was 4 (1 %) and 6 (1.2 %), respectively. Bacterial vaginosis was higher in non-pregnant (5.6 %) than pregnant women (0.5 %) (P = 0.002). Religion, age, living in rural area and having lower abdominal pain were significantly associated with bacterial vaginosis and

Cancer susceptibility and reproductive trade-offs: a model of the evolution of cancer defences.

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Boddy, Amy M; Kokko, Hanna; Breden, Felix; Wilkinson, Gerald S; Aktipis, C Athena

2015-07-19

The factors influencing cancer susceptibility and why it varies across species are major open questions in the field of cancer biology. One underexplored source of variation in cancer susceptibility may arise from trade-offs between reproductive competitiveness (e.g. sexually selected traits, earlier reproduction and higher fertility) and cancer defence. We build a model that contrasts the probabilistic onset of cancer with other, extrinsic causes of mortality and use it to predict that intense reproductive competition will lower cancer defences and increase cancer incidence. We explore the trade-off between cancer defences and intraspecific competition across different extrinsic mortality conditions and different levels of trade-off intensity, and find the largest effect of competition on cancer in species where low extrinsic mortality combines with strong trade-offs. In such species, selection to delay cancer and selection to outcompete conspecifics are both strong, and the latter conflicts with the former. We discuss evidence for the assumed trade-off between reproductive competitiveness and cancer susceptibility. Sexually selected traits such as ornaments or large body size require high levels of cell proliferation and appear to be associated with greater cancer susceptibility. Similar associations exist for female traits such as continuous egg-laying in domestic hens and earlier reproductive maturity. Trade-offs between reproduction and cancer defences may be instantiated by a variety of mechanisms, including higher levels of growth factors and hormones, less efficient cell-cycle control and less DNA repair, or simply a larger number of cell divisions (relevant when reproductive success requires large body size or rapid reproductive cycles). These mechanisms can affect intra- and interspecific variation in cancer susceptibility arising from rapid cell proliferation during reproductive maturation, intrasexual competition and reproduction. © 2015 The Author

Felsenstein's“one-allele model”of speciation: The role of philopatry in the initial stages of host plant mediated reproductive isolation in Enchenopa binotata

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Frank W. STEARNS, Kelley J. TILMON, Thomas K. WOOD

2013-10-01

Full Text Available The study of speciation genetics is primarily concerned with identifying the genetic traits that allow divergent selection to overcome the homogenizing effects of gene flow. Felsenstein reviewed this race between gene flow and selection, concluding that speciation with gene flow was unlikely under a “two-allele model” (where two traits were necessary for reproductive isolation but that divergence could occur quite easily under a “one-allele model.” Despite this finding, much of the sympatric speciation research involving phytophagous insects has relied on a two-trait model, where insects evolve both preferences for and increased performance on novel host plants. Philopatry (a tendency to remain where one was born is known to occur in phytophagous insects and is a single trait isolation mechanism. However, it is traditionally invoked as simply augmenting reproductive isolation. Species in the Enchenopa binotata complex are believed to have speciated in sympatry. They exhibit host plant prefe­rences, host specific performance advantages and strong philopatry. We experimentally shifted E. binotata to evolutionarily novel host plants. Previous research has demonstrated that the experimental population of insects possesses genetic variation in prefe­rence and performance to the novel host. The degree of philopatry at mating and egg-laying was assayed for the first four years under full choice conditions. Host plant preference and performance was assayed after eight years. Philopatry was an immediate and strong isolating mechanism, while preference for and performance on the novel host lagged. We therefore suggest that philopatry may be a more important mechanism in the early stages of a host shift than previously believed [Current Zoology 59 (5: 658-666, 2013].

Testing the Role of Habitat Isolation among Ecologically Divergent Gall Wasp Populations

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Scott P. Egan

2012-01-01

Full Text Available Habitat isolation occurs when habitat preferences lower the probability of mating between individuals associated with differing habitats. While a potential barrier to gene flow during ecological speciation, the effect of habitat isolation on reproductive isolation has rarely been directly tested. Herein, we first estimated habitat preference for each of six populations of the gall wasp Belonocnema treatae inhabiting either Quercus virginiana or Q. geminata. We then estimated the importance of habitat isolation in generating reproductive isolation between B. treatae populations that were host specific to either Q. virginiana or Q. geminata by measuring mate preference in the presence and absence of the respective host plants. All populations exhibited host preference for their native plant, and assortative mating increased significantly in the presence of the respective host plants. This host-plant-mediated assortative mating demonstrates that habitat isolation likely plays an important role in promoting reproductive isolation among populations of this host-specific gall former.

Heterospecific mating and partial prezygotic reproductive isolation in the planktonic marine copepods Centropages typicus and Centropages hamatus

DEFF Research Database (Denmark)

Goetze, Erica

2008-01-01

Using three-dimensional (3D) video observations in laboratory experiments, I describe interspecific and intergeneric mating behaviors and motility patterns of the common planktonic marine copepods Centropages typicus, Centropages hamatus, and Temora longicornis. These observations are then used...... to estimate heterospecific and conspecific male mate-search volume rates and mate encounter rates in North Sea Centropages populations. Behavioral prezygotic reproductive isolation between Centropages species is incomplete, since males of each species pursued, contacted, captured, and, in rare cases, placed...... a spermatophore on the urosome of heterospecific females. T. longicornis males also detected the diffusible pheromone trail and pursued C. typicus females to the point of mate contact. Male mate-search tracking behavior was equally effective on diffusible pheromone trails of heterospecific and conspecific females...

Adaptive evolution of simian immunodeficiency viruses isolated from two conventional progressor macaques with neuroaids

Energy Technology Data Exchange (ETDEWEB)

Foley, Brian T [Los Alamos National Laboratory; Korber, Bette T [Los Alamos National Laboratory

2008-01-01

Simian immunodeficiency virus infection of macaques may result in neuroAIDS, a feature more commonly observed in macaques with rapid progressive disease than in those with conventional disease. This is the first report of two conventional progressors (H631 and H636) with encephalitis in rhesus macaques inoculated with a derivative of SIVsmES43-3. Phylogenetic analyses of viruses isolated from the cerebral spinal fluid (CSF) and plasma from both animals demonstrated tissue compartmentalization. Additionally, virus from the central nervous system (CNS) was able to infect primary macaque monocyte-derived macrophages more efficiently than virus from plasma. Conversely, virus isolated from plasma was able to replicate better in peripheral blood mononuclear cells than virus from CNS. We speculate that these viruses were under different selective pressures in their separate compartments. Furthermore, these viruses appear to have undergone adaptive evolution to preferentially replicate in their respective cell targets. Analysis of the number of potential N-linked glycosylation sites (PNGS) in gp160 showed that there was a statistically significant loss of PNGS in viruses isolated from CNS in both macaques compared to SIVsmE543-3. Moreover, virus isolated from the brain in H631, had statistically significant loss of PNGS compared to virus isolated from CSF and plasma of the same animal. It is possible that the brain isolate may have adapted to decrease the number of PNGS given that humoral immune selection pressure is less likely to be encountered in the brain. These viruses provide a relevant model to study the adaptations required for SIV to induce encephalitis.

Widespread presence of human BOULE homologs among animals and conservation of their ancient reproductive function.

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Chirag Shah

2010-07-01

Full Text Available Sex-specific traits that lead to the production of dimorphic gametes, sperm in males and eggs in females, are fundamental for sexual reproduction and accordingly widespread among animals. Yet the sex-biased genes that underlie these sex-specific traits are under strong selective pressure, and as a result of adaptive evolution they often become divergent. Indeed out of hundreds of male or female fertility genes identified in diverse organisms, only a very small number of them are implicated specifically in reproduction in more than one lineage. Few genes have exhibited a sex-biased, reproductive-specific requirement beyond a given phylum, raising the question of whether any sex-specific gametogenesis factors could be conserved and whether gametogenesis might have evolved multiple times. Here we describe a metazoan origin of a conserved human reproductive protein, BOULE, and its prevalence from primitive basal metazoans to chordates. We found that BOULE homologs are present in the genomes of representative species of each of the major lineages of metazoans and exhibit reproductive-specific expression in all species examined, with a preponderance of male-biased expression. Examination of Boule evolution within insect and mammalian lineages revealed little evidence for accelerated evolution, unlike most reproductive genes. Instead, purifying selection was the major force behind Boule evolution. Furthermore, loss of function of mammalian Boule resulted in male-specific infertility and a global arrest of sperm development remarkably similar to the phenotype in an insect boule mutation. This work demonstrates the conservation of a reproductive protein throughout eumetazoa, its predominant testis-biased expression in diverse bilaterian species, and conservation of a male gametogenic requirement in mice. This shows an ancient gametogenesis requirement for Boule among Bilateria and supports a model of a common origin of spermatogenesis.

Primates and the Evolution of Long-Slow Life Histories

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Jones, James Holland

2011-01-01

Summary Primates are characterized by relatively late ages at first reproduction, long lives and low fertility. Together, these traits define a life-history of reduced reproductive effort. Understanding the optimal allocation of reproductive effort, and specifically reduced reproductive effort, has been one of the key problems motivating the development of life history theory. Because of their unusual constellation of life-history traits, primates play an important role in the continued development of life history theory. In this review, I present the evidence for the reduced reproductive effort life histories of primates and discuss the ways that such life-history tactics are understood in contemporary theory. Such tactics are particularly consistent with the predictions of stochastic demographic models, suggesting a key role for environmental variability in the evolution of primate life histories. The tendency for primates to specialize in high-quality, high-variability food items may make them particularly susceptible to environmental variability and explain their low reproductive-effort tactics. I discuss recent applications of life history theory to human evolution and emphasize the continuity between models used to explain peculiarities of human reproduction and senescence with the long, slow life histories of primates more generally. PMID:21959161

Reticulate evolution in stick insects: the case of Clonopsis (Insecta Phasmida).

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Milani, Liliana; Ghiselli, Fabrizio; Pellecchia, Marco; Scali, Valerio; Passamonti, Marco

2010-08-25

Phasmids show noteworthy abilities to overcome species-specific reproductive isolation mechanisms, including hybridization, polyploidy, parthenogenesis, hybridogenesis and androgenesis. From an evolutionary standpoint, such tangled reproductive interactions lead to the complex phyletic relationships known as "reticulate evolution". Moroccan stick insects of the genus Clonopsis include one bisexual (C. felicitatis) and two closely related parthenogenetic forms (C. gallica, C. soumiae), which represent a polyploid series in chromosome number, but with apparent diploid karyotypes. Moreover, two Clonopsis strains of ameiotic males have been described, C. androgenes-35 and C. androgenes-53. As a consequence, Clonopsis stick insects may have experienced complex micro-evolutionary events, which we try to disentangle in this study. Mitochondrial cox2 analysis supports a recent divergence of Clonopsis, while AFLPs evidence genetic differentiation not linked to karyotypes, so that parthenogenetic C. gallica and C. soumiae appear to be a mix of strains of polyphyletic origin rather than single parthenogenetic species. Moreover, an admixed hybrid origin seems to be confirmed for C. androgenes. On the whole, Clonopsis is an intriguing case of reticulate evolution. Actually, complex cladogenetic events should be taken into account to explain the observed genetic structure, including diploidization of polyploid karyotypes, possibly coupled with hybridization and androgenesis. We also proposed a "working hypothesis" to account for the observed data, which deserves further studies, but fits the observed data very well.

Reproductive traits and evolutionary divergence between Mediterranean crops and their wild relatives.

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Iriondo, J M; Milla, R; Volis, S; Rubio de Casas, R

2018-01-01

Changes in reproductive traits associated with domestication critically determine the evolutionary divergence between crops and their wild relatives, as well as the potential of crop plants to become feral. In this review, we examine the genetic mechanisms of plant domestication and the different types of selection involved, and describe the particularities of domestication of Mediterranean field crops with regard to their reproductive traits, showing illustrative examples. We also explore gene flow patterns between Mediterranean field crops and their wild relatives, along with their ecological, evolutionary and economic implications. Domestication entails multiple selective processes, including direct selection, environmental adaptation and developmental constraints. In contrast to clonal propagation in perennials, sexual reproduction and seed propagation in annuals and biennials have led to a distinct pathway of evolution of reproductive traits. Thus, the initial domestication and further breeding of Mediterranean field crops has brought about changes in reproductive traits, such as higher mean values and variance of seed and fruit sizes, reduced fruit and seed toxicity, non-shattering seeds and loss of seed dormancy. Evolution under domestication is not a linear process, and bi-directional gene flow between wild and crop taxa is a frequent phenomenon. Thus, hybridisation and introgression have played a very important role in determining the genetics of current cultivars. In turn, gene flow from crops to wild relatives can lead to introgression of crop genes into wild populations and potentially alter the characteristics of natural communities. In conclusion, plant evolution under domestication has not only changed the reproductive biology of cultivated taxa, its effects are multifaceted and have implications beyond agriculture. © 2017 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.

Rapid parallel evolution overcomes global honey bee parasite.

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Oddie, Melissa; Büchler, Ralph; Dahle, Bjørn; Kovacic, Marin; Le Conte, Yves; Locke, Barbara; de Miranda, Joachim R; Mondet, Fanny; Neumann, Peter

2018-05-16

In eusocial insect colonies nestmates cooperate to combat parasites, a trait called social immunity. However, social immunity failed for Western honey bees (Apis mellifera) when the ectoparasitic mite Varroa destructor switched hosts from Eastern honey bees (Apis cerana). This mite has since become the most severe threat to A. mellifera world-wide. Despite this, some isolated A. mellifera populations are known to survive infestations by means of natural selection, largely by supressing mite reproduction, but the underlying mechanisms of this are poorly understood. Here, we show that a cost-effective social immunity mechanism has evolved rapidly and independently in four naturally V. destructor-surviving A. mellifera populations. Worker bees of all four 'surviving' populations uncapped/recapped worker brood cells more frequently and targeted mite-infested cells more effectively than workers in local susceptible colonies. Direct experiments confirmed the ability of uncapping/recapping to reduce mite reproductive success without sacrificing nestmates. Our results provide striking evidence that honey bees can overcome exotic parasites with simple qualitative and quantitative adaptive shifts in behaviour. Due to rapid, parallel evolution in four host populations this appears to be a key mechanism explaining survival of mite infested colonies.

Horizontal Gene Transfer Contributes to the Evolution of Arthropod Herbivory.

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Wybouw, Nicky; Pauchet, Yannick; Heckel, David G; Van Leeuwen, Thomas

2016-06-27

Within animals, evolutionary transition toward herbivory is severely limited by the hostile characteristics of plants. Arthropods have nonetheless counteracted many nutritional and defensive barriers imposed by plants and are currently considered as the most successful animal herbivores in terrestrial ecosystems. We gather a body of evidence showing that genomes of various plant feeding insects and mites possess genes whose presence can only be explained by horizontal gene transfer (HGT). HGT is the asexual transmission of genetic information between reproductively isolated species. Although HGT is known to have great adaptive significance in prokaryotes, its impact on eukaryotic evolution remains obscure. Here, we show that laterally transferred genes into arthropods underpin many adaptations to phytophagy, including efficient assimilation and detoxification of plant produced metabolites. Horizontally acquired genes and the traits they encode often functionally diversify within arthropod recipients, enabling the colonization of more host plant species and organs. We demonstrate that HGT can drive metazoan evolution by uncovering its prominent role in the adaptations of arthropods to exploit plants. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Unisexual and heterosexual meiotic reproduction generate aneuploidy and phenotypic diversity de novo in the yeast Cryptococcus neoformans.

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Min Ni

2013-09-01

Full Text Available Aneuploidy is known to be deleterious and underlies several common human diseases, including cancer and genetic disorders such as trisomy 21 in Down's syndrome. In contrast, aneuploidy can also be advantageous and in fungi confers antifungal drug resistance and enables rapid adaptive evolution. We report here that sexual reproduction generates phenotypic and genotypic diversity in the human pathogenic yeast Cryptococcus neoformans, which is globally distributed and commonly infects individuals with compromised immunity, such as HIV/AIDS patients, causing life-threatening meningoencephalitis. C. neoformans has a defined a-α opposite sexual cycle; however, >99% of isolates are of the α mating type. Interestingly, α cells can undergo α-α unisexual reproduction, even involving genotypically identical cells. A central question is: Why would cells mate with themselves given that sex is costly and typically serves to admix preexisting genetic diversity from genetically divergent parents? In this study, we demonstrate that α-α unisexual reproduction frequently generates phenotypic diversity, and the majority of these variant progeny are aneuploid. Aneuploidy is responsible for the observed phenotypic changes, as chromosome loss restoring euploidy results in a wild-type phenotype. Other genetic changes, including diploidization, chromosome length polymorphisms, SNPs, and indels, were also generated. Phenotypic/genotypic changes were not observed following asexual mitotic reproduction. Aneuploidy was also detected in progeny from a-α opposite-sex congenic mating; thus, both homothallic and heterothallic sexual reproduction can generate phenotypic diversity de novo. Our study suggests that the ability to undergo unisexual reproduction may be an evolutionary strategy for eukaryotic microbial pathogens, enabling de novo genotypic and phenotypic plasticity and facilitating rapid adaptation to novel environments.

Prebiological evolution and the metabolic origins of life.

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Pratt, Andrew J

2011-01-01

The chemoton model of cells posits three subsystems: metabolism, compartmentalization, and information. A specific model for the prebiological evolution of a reproducing system with rudimentary versions of these three interdependent subsystems is presented. This is based on the initial emergence and reproduction of autocatalytic networks in hydrothermal microcompartments containing iron sulfide. The driving force for life was catalysis of the dissipation of the intrinsic redox gradient of the planet. The codependence of life on iron and phosphate provides chemical constraints on the ordering of prebiological evolution. The initial protometabolism was based on positive feedback loops associated with in situ carbon fixation in which the initial protometabolites modified the catalytic capacity and mobility of metal-based catalysts, especially iron-sulfur centers. A number of selection mechanisms, including catalytic efficiency and specificity, hydrolytic stability, and selective solubilization, are proposed as key determinants for autocatalytic reproduction exploited in protometabolic evolution. This evolutionary process led from autocatalytic networks within preexisting compartments to discrete, reproducing, mobile vesicular protocells with the capacity to use soluble sugar phosphates and hence the opportunity to develop nucleic acids. Fidelity of information transfer in the reproduction of these increasingly complex autocatalytic networks is a key selection pressure in prebiological evolution that eventually leads to the selection of nucleic acids as a digital information subsystem and hence the emergence of fully functional chemotons capable of Darwinian evolution.

Spatial variation in pollinator communities and reproductive performance of Prosopis juliflora (Fabaceae

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Asif Sajjad

2012-06-01

Full Text Available This study was conducted in an effort to understand the effects of spatial variations in pollinator assemblage due to habitat isolation on the reproductive performance of perennial plant species. Variations in pollinator assemblage structure (abundance, diversity and Shannon-Wiener index were studied at three widely isolated (100 to 200 km apart nature reserves of Southern Punjab, Pakistan, in order to explore its effects on reproductive performance of Prosopis juliflora. Species richness and abundance were highest in Pirowal Sanctuary followed by Chichawatni Sanctuary and Chak Katora forest reserve. The pollination system of P. juliflora was highly generalized with 77 insect visitor species in four orders among all the three sites. However, pollinator assemblage varied significantly in composition among the sites. Out of the four reproductive parameters considered, the number of pods per raceme and germination varied significantly among the three locations. The reproductive performance of P. juliflora in terms of number of pods per raceme and germination improved with abundance of pollinators.

Isolation and Characterization of the Etheostoma tallapoosae (Teleostei: Percidae CENP-A Gene

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Leos G. Kral

2011-10-01

Full Text Available Both centromeric alpha-satellite sequences as well as centromeric protein A (CENP-A are highly variable in eukaryotes. CENP-A, a histone H3 variant, is thought to act as the epigenetic “mark” for assembly of centromeric proteins. While most of the histone fold domain (HFD of the CENP-A is fairly well conserved, a portion of this HFD as well as the N-terminal tail show adaptive variation in both plants and animals. Such variation may establish reproductive barriers that may lead to speciation. The family Percidae contains over 200 species most of which are within the subfamily Etheostomatinae. This subfamily represents a species rich radiation of freshwater fishes in North America and these species exhibit both allopatric and sympatric distributions. In order to study the evolution of CENP-A in percid fish species, we have isolated and characterized the CENP-A gene from Etheostoma tallapoosae by PCR based gene walking. As a result of this study we have demonstrated that the Tallapoosa darter CENP-A gene HFD sequences can be isolated from genomic DNA by nested PCR in a manner that does not lead to the amplification of the highly sequence related histone H3 gene. We also demonstrated that PCR based walking can be subsequently used to isolate the rest of the CENP-A gene and adjacent gene sequences. These adjacent gene sequences provide us with a primer binding sites for PCR isolation of the CENP-A gene from other percid species of fishes. An initial comparison of three percid species shows that the N-terminal tail of the percid CENP-A gene shows adaptive evolution.

POPULATION SYNTHESIS OF YOUNG ISOLATED NEUTRON STARS: THE EFFECT OF FALLBACK DISK ACCRETION AND MAGNETIC FIELD EVOLUTION

International Nuclear Information System (INIS)

Fu, Lei; Li, Xiang-Dong

2013-01-01

The spin evolution of isolated neutron stars (NSs) is dominated by their magnetic fields. The measured braking indices of young NSs show that the spin-down mechanism due to magnetic dipole radiation with constant magnetic fields is inadequate. Assuming that the NS magnetic field is buried by supernova fallback matter and re-emerges after accretion stops, we carry out a Monte Carlo simulation of the evolution of young NSs, and show that most of the pulsars have braking indices ranging from –1 to 3. The results are compatible with the observational data of NSs associated with supernova remnants. They also suggest that the initial spin periods of NSs might occupy a relatively wide range

Human evolution: humanistic selection and looking to the future.

Science.gov (United States)

Krsiak, Miloslav

2006-10-01

Cultural evolution has predominated over biological evolution in modern man (Homo sapiens sapiens). Cultural evolution differs from biological evolution not only by inheritance of acquired characteristics but also, as is proposed in the present essay, by another kind of selection mechanism. Whereas selection in biological evolution is executed according to a criterion of reproductive success (the natural selection), selection in cultural evolution appears to be carried out according to human and humanistic criteria (success or fitness in meeting human needs, interests and humanistic values--"humanistic selection"). Many humanistic needs or values do not seem to be prerequisite for reproductive success, yet some of them (e.g. a need for freedom) seem to be inborn. Innateness, humanistic selection (decisive at a community level) and hierarchy of some human needs, interests and values appear to give cultural evolution a generally upward trend although long periods of stagnation or even regression may occur. Modern humans appear to be still at the early stage of their cultural evolution. A further cultural evolution of man appears to be, in contrast to biological evolution, predictable (with an optimistic outlook) and testable. The problem is that the hopeful result of this test will probably be known only in the fairly remote future provided that this species will not become extinct before that.

Sexual selection affects the evolution of lifespan and ageing in the decorated cricket Gryllodes sigillatus.

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Archer, C R; Zajitschek, F; Sakaluk, S K; Royle, N J; Hunt, J

2012-10-01

Recent work suggests that sexual selection can influence the evolution of ageing and lifespan by shaping the optimal timing and relative costliness of reproductive effort in the sexes. We used inbred lines of the decorated cricket, Gryllodes sigillatus, to estimate the genetic (co)variance between age-dependent reproductive effort, lifespan, and ageing within and between the sexes. Sexual selection theory predicts that males should die sooner and age more rapidly than females. However, a reversal of this pattern may be favored if reproductive effort increases with age in males but not in females. We found that male calling effort increased with age, whereas female fecundity decreased, and that males lived longer and aged more slowly than females. These divergent life-history strategies were underpinned by a positive genetic correlation between early-life reproductive effort and ageing rate in both sexes, although this relationship was stronger in females. Despite these sex differences in life-history schedules, age-dependent reproductive effort, lifespan, and ageing exhibited strong positive intersexual genetic correlations. This should, in theory, constrain the independent evolution of these traits in the sexes and may promote intralocus sexual conflict. Our study highlights the importance of sexual selection to the evolution of sex differences in ageing and lifespan in G. sigillatus. © 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.

Unisexual reproduction in Huntiella moniliformis.

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Wilson, A M; Godlonton, T; van der Nest, M A; Wilken, P M; Wingfield, M J; Wingfield, B D

2015-07-01

Sexual reproduction in fungi is controlled by genes present at the mating type (MAT) locus, which typically harbors transcription factors that influence the expression of many sex-related genes. The MAT locus exists as two alternative idiomorphs in ascomycetous fungi and sexual reproduction is initiated when genes from both idiomorphs are expressed. Thus, the gene content of this locus determines whether a fungus is heterothallic (self-sterile) or homothallic (self-fertile). Recently, a unique sub-class of homothallism has been described in fungi, where individuals possessing a single MAT idiomorph can reproduce sexually in the absence of a partner. Using various mycological, molecular and bioinformatic techniques, we investigated the sexual strategies and characterized the MAT loci in two tree wound-infecting fungi, Huntiella moniliformis and Huntiella omanensis. H. omanensis was shown to exhibit a typically heterothallic sexual reproductive cycle, with isolates possessing either the MAT1-1 or MAT1-2 idiomorph. This was in contrast to the homothallism via unisexual reproduction that was shown in H. moniliformis, where only the MAT1-2-1 gene was present in sexually reproducing cultures. While the evolutionary benefit and mechanisms underpinning a unisexual mating strategy remain unknown, it could have evolved to minimize the costs, while retaining the benefits, of normal sexual reproduction. Copyright © 2015 Elsevier Inc. All rights reserved.

Reproductive biology and its impact on body size: comparative analysis of mammalian, avian and dinosaurian reproduction.

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Werner, Jan; Griebeler, Eva Maria

2011-01-01

Janis and Carrano (1992) suggested that large dinosaurs might have faced a lower risk of extinction under ecological changes than similar-sized mammals because large dinosaurs had a higher potential reproductive output than similar-sized mammals (JC hypothesis). First, we tested the assumption underlying the JC hypothesis. We therefore analysed the potential reproductive output (reflected in clutch/litter size and annual offspring number) of extant terrestrial mammals and birds (as "dinosaur analogs") and of extinct dinosaurs. With the exception of rodents, the differences in the reproductive output of similar-sized birds and mammals proposed by Janis and Carrano (1992) existed even at the level of single orders. Fossil dinosaur clutches were larger than litters of similar-sized mammals, and dinosaur clutch sizes were comparable to those of similar-sized birds. Because the extinction risk of extant species often correlates with a low reproductive output, the latter difference suggests a lower risk of population extinction in dinosaurs than in mammals. Second, we present a very simple, mathematical model that demonstrates the advantage of a high reproductive output underlying the JC hypothesis. It predicts that a species with a high reproductive output that usually faces very high juvenile mortalities will benefit more strongly in terms of population size from reduced juvenile mortalities (e.g., resulting from a stochastic reduction in population size) than a species with a low reproductive output that usually comprises low juvenile mortalities. Based on our results, we suggest that reproductive strategy could have contributed to the evolution of the exceptional gigantism seen in dinosaurs that does not exist in extant terrestrial mammals. Large dinosaurs, e.g., the sauropods, may have easily sustained populations of very large-bodied species over evolutionary time.

Reproductive Biology and Its Impact on Body Size: Comparative Analysis of Mammalian, Avian and Dinosaurian Reproduction

Science.gov (United States)

Werner, Jan; Griebeler, Eva Maria

2011-01-01

Janis and Carrano (1992) suggested that large dinosaurs might have faced a lower risk of extinction under ecological changes than similar-sized mammals because large dinosaurs had a higher potential reproductive output than similar-sized mammals (JC hypothesis). First, we tested the assumption underlying the JC hypothesis. We therefore analysed the potential reproductive output (reflected in clutch/litter size and annual offspring number) of extant terrestrial mammals and birds (as “dinosaur analogs”) and of extinct dinosaurs. With the exception of rodents, the differences in the reproductive output of similar-sized birds and mammals proposed by Janis and Carrano (1992) existed even at the level of single orders. Fossil dinosaur clutches were larger than litters of similar-sized mammals, and dinosaur clutch sizes were comparable to those of similar-sized birds. Because the extinction risk of extant species often correlates with a low reproductive output, the latter difference suggests a lower risk of population extinction in dinosaurs than in mammals. Second, we present a very simple, mathematical model that demonstrates the advantage of a high reproductive output underlying the JC hypothesis. It predicts that a species with a high reproductive output that usually faces very high juvenile mortalities will benefit more strongly in terms of population size from reduced juvenile mortalities (e.g., resulting from a stochastic reduction in population size) than a species with a low reproductive output that usually comprises low juvenile mortalities. Based on our results, we suggest that reproductive strategy could have contributed to the evolution of the exceptional gigantism seen in dinosaurs that does not exist in extant terrestrial mammals. Large dinosaurs, e.g., the sauropods, may have easily sustained populations of very large-bodied species over evolutionary time. PMID:22194835

Reproductive biology and its impact on body size: comparative analysis of mammalian, avian and dinosaurian reproduction.

Directory of Open Access Journals (Sweden)

Jan Werner

Full Text Available Janis and Carrano (1992 suggested that large dinosaurs might have faced a lower risk of extinction under ecological changes than similar-sized mammals because large dinosaurs had a higher potential reproductive output than similar-sized mammals (JC hypothesis. First, we tested the assumption underlying the JC hypothesis. We therefore analysed the potential reproductive output (reflected in clutch/litter size and annual offspring number of extant terrestrial mammals and birds (as "dinosaur analogs" and of extinct dinosaurs. With the exception of rodents, the differences in the reproductive output of similar-sized birds and mammals proposed by Janis and Carrano (1992 existed even at the level of single orders. Fossil dinosaur clutches were larger than litters of similar-sized mammals, and dinosaur clutch sizes were comparable to those of similar-sized birds. Because the extinction risk of extant species often correlates with a low reproductive output, the latter difference suggests a lower risk of population extinction in dinosaurs than in mammals. Second, we present a very simple, mathematical model that demonstrates the advantage of a high reproductive output underlying the JC hypothesis. It predicts that a species with a high reproductive output that usually faces very high juvenile mortalities will benefit more strongly in terms of population size from reduced juvenile mortalities (e.g., resulting from a stochastic reduction in population size than a species with a low reproductive output that usually comprises low juvenile mortalities. Based on our results, we suggest that reproductive strategy could have contributed to the evolution of the exceptional gigantism seen in dinosaurs that does not exist in extant terrestrial mammals. Large dinosaurs, e.g., the sauropods, may have easily sustained populations of very large-bodied species over evolutionary time.

The Pace of Hybrid Incompatibility Evolution in House Mice.

Science.gov (United States)

Wang, Richard J; White, Michael A; Payseur, Bret A

2015-09-01

Hybrids between species are often sterile or inviable. This form of reproductive isolation is thought to evolve via the accumulation of mutations that interact to reduce fitness when combined in hybrids. Mathematical formulations of this "Dobzhansky-Muller model" predict an accelerating buildup of hybrid incompatibilities with divergence time (the "snowball effect"). Although the Dobzhansky-Muller model is widely accepted, the snowball effect has only been tested in two species groups. We evaluated evidence for the snowball effect in the evolution of hybrid male sterility among subspecies of house mice, a recently diverged group that shows partial reproductive isolation. We compared the history of subspecies divergence with patterns of quantitative trait loci (QTL) detected in F2 intercrosses between two pairs of subspecies (Mus musculus domesticus with M. m. musculus and M. m. domesticus with M. m. castaneus). We used a recently developed phylogenetic comparative method to statistically measure the fit of these data to the snowball prediction. To apply this method, QTL were partitioned as either shared or unshared in the two crosses. A heuristic partitioning based on the overlap of QTL confidence intervals produced unambiguous support for the snowball effect. An alternative approach combining data among crosses favored the snowball effect for the autosomes, but a linear accumulation of incompatibilities for the X chromosome. Reasoning that the X chromosome analyses are complicated by low mapping resolution, we conclude that hybrid male sterility loci have snowballed in house mice. Our study illustrates the power of comparative genetic mapping for understanding mechanisms of speciation. Copyright © 2015 by the Genetics Society of America.

A role for sexual conflict in the evolution of reproductive traits in Nasonia wasps?

NARCIS (Netherlands)

Geuverink, Elzemiek; Gerritsma, Sylvia; Pannebakker, Bart A.; Beukeboom, Leo W.

2009-01-01

Sexual conflict theory predicts that female and male reproductive traits coevolve resulting in disruption of reproductive behaviour upon mating of individuals from diverged populations. We used interfertile species of haplodiploid Nasonia wasps to compare re-mating frequency, longevity, oviposition

Love Influences Reproductive Success in Humans

Science.gov (United States)

Sorokowski, Piotr; Sorokowska, Agnieszka; Butovskaya, Marina; Karwowski, Maciej; Groyecka, Agata; Wojciszke, Bogdan; Pawłowski, Bogusław

2017-01-01

As love seems to be universal, researchers have attempted to find its biological basis. However, no studies till date have shown its direct association with reproductive success, which is broadly known to be a good measure of fitness. Here, we show links between love, as defined by the Sternberg Triangular Theory of Love, and reproductive success among the Hadza—traditional hunter-gatherer population. We found that commitment and reproductive success were positively and consistently related in both sexes, with number of children showing negative and positive associations with intimacy and passion, respectively, only among women. Our study may shed new light on the meaning of love in humans' evolutionary past, especially in traditional hunter-gatherer societies in which individuals, not their parents, were responsible for partner choice. We suggest that passion and commitment may be the key factors that increase fitness, and therefore, that selection promoted love in human evolution. However, further studies in this area are recommended. PMID:29209243

Neurogenetics of female reproductive behaviors in Drosophila melanogaster.

Science.gov (United States)

Laturney, Meghan; Billeter, Jean-Christophe

2014-01-01

We follow an adult Drosophila melanogaster female through the major reproductive decisions she makes during her lifetime, including habitat selection, precopulatory mate choice, postcopulatory physiological changes, polyandry, and egg-laying site selection. In the process, we review the molecular and neuronal mechanisms allowing females to integrate signals from both environmental and social sources to produce those behavioral outputs. We pay attention to how an understanding of D. melanogaster female reproductive behaviors contributes to a wider understanding of evolutionary processes such as pre- and postcopulatory sexual selection as well as sexual conflict. Within each section, we attempt to connect the theories that pertain to the evolution of female reproductive behaviors with the molecular and neurobiological data that support these theories. We draw attention to the fact that the evolutionary and mechanistic basis of female reproductive behaviors, even in a species as extensively studied as D. melanogaster, remains poorly understood. Copyright © 2014 Elsevier Inc. All rights reserved.

Hybrid chickadees are deficient in learning and memory.

Science.gov (United States)

McQuillan, Michael A; Roth, Timothy C; Huynh, Alex V; Rice, Amber M

2018-05-01

Identifying the phenotypes underlying postzygotic reproductive isolation is crucial for fully understanding the evolution and maintenance of species. One potential postzygotic isolating barrier that has rarely been examined is learning and memory ability in hybrids. Learning and memory are important fitness-related traits, especially in scatter-hoarding species, where accurate retrieval of hoarded food is vital for winter survival. Here, we test the hypothesis that learning and memory ability can act as a postzygotic isolating barrier by comparing these traits among two scatter-hoarding songbird species, black-capped (Poecile atricapillus) and Carolina chickadees (Poecile carolinensis), and their naturally occurring hybrids. In an outdoor aviary setting, we find that hybrid chickadees perform significantly worse on an associative learning spatial task and are worse at solving a novel problem compared to both parental species. Deficiencies in learning and memory abilities could therefore contribute to postzygotic reproductive isolation between chickadee species. Given the importance of learning and memory for fitness, our results suggest that these traits may play an important, but as yet overlooked, role in postzygotic reproductive isolation. © 2018 The Author(s). Evolution © 2018 The Society for the Study of Evolution.

[Advances in the study of neuroendocrinological regulation of kisspeptin in fish reproduction].

Science.gov (United States)

Zhuo, Qi

2013-10-01

Kisspeptin, a key factor in the neuroendocrinological regulation of animal reproduction, is a peptide product encoded by kiss genes, which act as the natural ligand of GPR54. Over the last decade, multiple functional molecular forms of kisspeptin have been found in vertebrate species. In fish, the major molecular structural form is kisspeptin-10. The kisspeptin/GPR54 system has multiple important functions in reproduction. This review provides an overview of our current knowledge on kisspeptin and its role in regulating fish reproductive, including the distribution and location of kisspeptin neurons in the brain, the molecular polymorphism of fish kisspeptin, functional diversity, the molecular mechanism of fish reproductive regulation, and the molecular evolution of kisspeptin as well as the co-regulation of fish reproduction by kisspeptin and other functional molecules. Perspectives on the future of kisspeptin regulation in fish reproduction are also highlighted.

Selfish strategies and honest signalling: reproductive conflicts in ant queen associations

DEFF Research Database (Denmark)

Holman, Luke; Dreier, Stephanie; d'Ettorre, Patrizia

2010-01-01

Social insects offer unique opportunities to test predictions regarding the evolution of cooperation, life histories and communication. Colony founding by groups of unrelated queens, some of which are later killed, may select for selfish reproductive strategies, honest signalling and punishment....... Here, we use a brood transfer experiment to test whether cofounding queens of the ant Lasius niger 'selfishly' adjust their productivity when sharing the nest with future competitors. We simultaneously analysed queen cuticular hydrocarbon (CHC) profiles to investigate whether queens honestly signal...... correlated with reproductive maturation, and to a lesser extent with productivity; the same hydrocarbons were more abundant on queens that were not killed, suggesting that workers select productive queens using these chemical cues. Our results highlight the role of honest signalling in the evolution...

Behavioural isolation may facilitate homoploid hybrid speciation in cichlid fish

NARCIS (Netherlands)

Selz, O. M.; Thommen, R.; Maan, M. E.; Seehausen, O.

Hybrid speciation is constrained by the homogenizing effects of gene flow from the parental species. In the absence of post-mating isolation due to structural changes in the genome, or temporal or spatial premating isolation, another form of reproductive isolation would be needed for homoploid

Asexual Reproduction Does Not Apparently Increase the Rate of Chromosomal Evolution: Karyotype Stability in Diploid and Triploid Clonal Hybrid Fish (Cobitis, Cypriniformes, Teleostei).

Science.gov (United States)

Majtánová, Zuzana; Choleva, Lukáš; Symonová, Radka; Ráb, Petr; Kotusz, Jan; Pekárik, Ladislav; Janko, Karel

2016-01-01

Interspecific hybridization, polyploidization and transitions from sexuality to asexuality considerably affect organismal genomes. Especially the last mentioned process has been assumed to play a significant role in the initiation of chromosomal rearrangements, causing increased rates of karyotype evolution. We used cytogenetic analysis and molecular dating of cladogenetic events to compare the rate of changes of chromosome morphology and karyotype in asexually and sexually reproducing counterparts in European spined loach fish (Cobitis). We studied metaphases of three sexually reproducing species and their diploid and polyploid hybrid clones of different age of origin. The material includes artificial F1 hybrid strains, representatives of lineage originated in Holocene epoch, and also individuals of an oldest known age to date (roughly 0.37 MYA). Thereafter we applied GISH technique as a marker to differentiate parental chromosomal sets in hybrids. Although the sexual species accumulated remarkable chromosomal rearrangements after their speciation, we observed no differences in chromosome numbers and/or morphology among karyotypes of asexual hybrids. These hybrids possess chromosome sets originating from respective parental species with no cytogenetically detectable recombinations, suggesting their integrity even in a long term. The switch to asexual reproduction thus did not provoke any significant acceleration of the rate of chromosomal evolution in Cobitis. Asexual animals described in other case studies reproduce ameiotically, while Cobitis hybrids described here produce eggs likely through modified meiosis. Therefore, our findings indicate that the effect of asexuality on the rate of chromosomal change may be context-dependent rather than universal and related to particular type of asexual reproduction.

Asexual Reproduction Does Not Apparently Increase the Rate of Chromosomal Evolution: Karyotype Stability in Diploid and Triploid Clonal Hybrid Fish (Cobitis, Cypriniformes, Teleostei.

Directory of Open Access Journals (Sweden)

Zuzana Majtánová

Full Text Available Interspecific hybridization, polyploidization and transitions from sexuality to asexuality considerably affect organismal genomes. Especially the last mentioned process has been assumed to play a significant role in the initiation of chromosomal rearrangements, causing increased rates of karyotype evolution. We used cytogenetic analysis and molecular dating of cladogenetic events to compare the rate of changes of chromosome morphology and karyotype in asexually and sexually reproducing counterparts in European spined loach fish (Cobitis. We studied metaphases of three sexually reproducing species and their diploid and polyploid hybrid clones of different age of origin. The material includes artificial F1 hybrid strains, representatives of lineage originated in Holocene epoch, and also individuals of an oldest known age to date (roughly 0.37 MYA. Thereafter we applied GISH technique as a marker to differentiate parental chromosomal sets in hybrids. Although the sexual species accumulated remarkable chromosomal rearrangements after their speciation, we observed no differences in chromosome numbers and/or morphology among karyotypes of asexual hybrids. These hybrids possess chromosome sets originating from respective parental species with no cytogenetically detectable recombinations, suggesting their integrity even in a long term. The switch to asexual reproduction thus did not provoke any significant acceleration of the rate of chromosomal evolution in Cobitis. Asexual animals described in other case studies reproduce ameiotically, while Cobitis hybrids described here produce eggs likely through modified meiosis. Therefore, our findings indicate that the effect of asexuality on the rate of chromosomal change may be context-dependent rather than universal and related to particular type of asexual reproduction.

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.

United theory of biological evolution: Disaster-forced evolution through Supernova, radioactive ash fall-outs, genome instability, and mass extinctions

Directory of Open Access Journals (Sweden)

Toshikazu Ebisuzaki

2015-01-01

Full Text Available We present the disaster-forced biological evolution model as a general framework that includes Darwinian “phylogenic gradualism”, Eldredge-Gould's “punctuated equilibrium”, mass extinctions, and allopatric, parapatric, and sympatric speciation. It describes how reproductive isolation of organisms is established through global disasters due to supernova encounters and local disasters due to radioactive volcanic ash fall-outs by continental alkaline volcanism. Our new evolution model uniquely highlights three major factors of disaster-forced speciation: enhanced mutation rate by higher natural radiation level, smaller population size, and shrunken habitat size (i.e., isolation among the individual populations. We developed a mathematical model describing speciation of a half-isolated group from a parental group, taking into account the population size (Ne, immigration rate (m, and mutation rate (μ. The model gives a quantitative estimate of the speciation, which is consistent with the observations of speciation speed. For example, the speciation takes at least 105 generations, if mutation rate is less than 10−3 per generation per individual. This result is consistent with the previous studies, in which μ is assumed to be 10−3–10−5. On the other hand, the speciation is much faster (less than 105 generations for the case that μ is as large as 0.1 in parapatric conditions (m ＜ μ. Even a sympatric (m ～ 1 speciation can occur within 103 generations, if mutation rate is very high (μ ～ 1 mutation per individual per generation, and if Ne ＜ 20–30. Such a high mutation rate is possible during global disasters due to supernova encounters and local disasters due to radioactive ash fall-outs. They raise natural radiation level by a factor of 100–1000. Such rapid speciation events can also contribute to macro-evolution during mass extinction events, such as observed during the Cambrian explosion of biodiversity. A

Reproductive niche conservatism in the isolated New Zealand flora over 23 million years.

Science.gov (United States)

Conran, John G; Lee, William G; Lee, Daphne E; Bannister, Jennifer M; Kaulfuss, Uwe

2014-10-01

The temporal stability of plant reproductive features on islands has rarely been tested. Using flowers, fruits/cones and seeds from a well-dated (23 Ma) Miocene Lagerstätte in New Zealand, we show that across 23 families and 30 genera of forest angiosperms and conifers, reproductive features have remained constant for more than 20 Myr. Insect-, wind- and bird-pollinated flowers and wind- and bird-dispersed diaspores all indicate remarkable reproductive niche conservatism, despite widespread environmental and biotic change. In the past 10 Myr, declining temperatures and the absence of low-latitude refugia caused regional extinction of thermophiles, while orogenic processes steepened temperature, precipitation and nutrient gradients, limiting forest niches. Despite these changes, the palaeontological record provides empirical support for evidence from phylogeographical studies of strong niche conservatism within lineages and biomes. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

No effect of partner age and lifespan on female age-specific reproductive performance in blue tits

NARCIS (Netherlands)

Amininasab, Seyed Mehdi; Hammers, Martijn; Vedder, Oscar; Komdeur, Jan; Korsten, Peter

Studies of age-specific reproductive performance are fundamental to our understanding of population dynamics and the evolution of life-history strategies. In species with bi-parental care, reproductive ageing trajectories of either parent may be influenced by their partner's age, but this has rarely

No effect of partner age and lifespan on female age‐specific reproductive performance in blue tits

NARCIS (Netherlands)

Amininasab, Seyed Mehdi; Hammers, Martijn; Vedder, Oscar; Komdeur, Jan; Korsten, Peter

Studies of age-specific reproductive performance are fundamental to our understanding of population dynamics and the evolution of life-history strategies. In species with bi-parental care, reproductive ageing trajectories of either parent may be influenced by their partner's age, but this has rarely

Investigating Climate Change and Reproduction: Experimental Tools from Evolutionary Biology

Directory of Open Access Journals (Sweden)

Oliver Y. Martin

2012-09-01

Full Text Available It is now generally acknowledged that climate change has wide-ranging biological consequences, potentially leading to impacts on biodiversity. Environmental factors can have diverse and often strong effects on reproduction, with obvious ramifications for population fitness. Nevertheless, reproductive traits are often neglected in conservation considerations. Focusing on animals, recent progress in sexual selection and sexual conflict research suggests that reproductive costs may pose an underestimated hurdle during rapid climate change, potentially lowering adaptive potential and increasing extinction risk of certain populations. Nevertheless, regime shifts may have both negative and positive effects on reproduction, so it is important to acquire detailed experimental data. We hence present an overview of the literature reporting short-term reproductive consequences of exposure to different environmental factors. From the enormous diversity of findings, we conclude that climate change research could benefit greatly from more coordinated efforts incorporating evolutionary approaches in order to obtain cross-comparable data on how individual and population reproductive fitness respond in the long term. Therefore, we propose ideas and methods concerning future efforts dealing with reproductive consequences of climate change, in particular by highlighting the advantages of multi-generational experimental evolution experiments.

The gynogenetic reproduction of diploid and triploid hybrid spined loaches (Cobitis: Teleostei), and their ability to establish successful clonal lineages - on the evolution of polyploidy in asexual vertebrates

Czech Academy of Sciences Publication Activity Database

Janko, Karel; Bohlen, Jörg; Lamatsch, D.; Flajšhans, Martin; Epplen, J. T.; Ráb, Petr; Kotlík, Petr; Šlechtová, Věra

2007-01-01

Roč. 131, - (2007), s. 185-194 ISSN 0016-6707 R&D Projects: GA ČR GP206/05/P586 Grant - others:EU Marie Curie Research amd Training Network(EU) MCRTN-CT-2004-512492; German Research Foundation(DE) SFB 567 Institutional research plan: CEZ:AV0Z50450515 Keywords : asexual reproduction * evolution of polyploidy * hybridisation Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.396, year: 2007

Presence and distribution of yeasts in the reproductive tract in healthy female horses.

Science.gov (United States)

Azarvandi, A; Khosravi, A R; Shokri, H; Talebkhan Garoussi, M; Gharahgouzlou, F; Vahedi, G; Sharifzadeh, A

2017-09-01

Yeasts are commensal organisms found in the reproductive and gastrointestinal tracts, and on the skin and other mucosa in mammals. The purpose of this study was to isolate and identify yeast flora in the caudal reproductive tract in healthy female horses. Longitudinal study. A total of 453 samples were collected using double-guarded swabs from the vestibule, clitoral fossa and vagina in 151 horses. All samples were cultured on Sabouraud 4% dextrose agar and incubated at 35°C for 7-10 days. Isolates were identified according to their morphological characteristics and biochemical profiles. Yeast colonies were isolated from 60 (39.7%) of the 151 horses. The isolated yeasts belonged to nine genera, and included Candida spp. (53.2%), Cryptococcus spp. (12.2%), Saccharomyces spp. (10.5%), Geotrichum spp. (8.0%), Rhodotorula spp. (7.1%), Malassezia spp. (3.7%), Trichosporon spp. (2.6%), Kluyveromyces spp. (2.6%) and Sporothrix spp. (0.2%). Candida krusei (43.1%) was the most frequent Candida species isolated. There was a significant difference in prevalence between C. krusei and other Candida species (Pyeast isolates (48.0%) than the vagina (18.3%). The isolation of yeast colonies from multiparous females (76.8%) was significantly higher than from maiden mares (P<0.05). The study was limited by the difficulty of distinguishing between normal flora and potential pathogens. Candida spp., in particular C. krusei, represent important flora resident in the caudal reproductive tract in healthy female horses. This is particularly important in contexts that require the initiation of empirical treatment prior to the completion of culture results. © 2016 EVJ Ltd.

Microbiota Influences Morphology and Reproduction of the Brown Alga Ectocarpus sp.

Science.gov (United States)

Tapia, Javier E; González, Bernardo; Goulitquer, Sophie; Potin, Philippe; Correa, Juan A

2016-01-01

Associated microbiota play crucial roles in health and disease of higher organisms. For macroalgae, some associated bacteria exert beneficial effects on nutrition, morphogenesis and growth. However, current knowledge on macroalgae-microbiota interactions is mostly based on studies on green and red seaweeds. In this study, we report that when cultured under axenic conditions, the filamentous brown algal model Ectocarpus sp. loses its branched morphology and grows with a small ball-like appearance. Nine strains of periphytic bacteria isolated from Ectocarpus sp. unialgal cultures were identified by 16S rRNA sequencing, and assessed for their effect on morphology, reproduction and the metabolites secreted by axenic Ectocarpus sp. Six of these isolates restored morphology and reproduction features of axenic Ectocarpus sp. Bacteria-algae co-culture supernatants, but not the supernatant of the corresponding bacterium growing alone, also recovered morphology and reproduction of the alga. Furthermore, colonization of axenic Ectocarpus sp. with a single bacterial isolate impacted significantly the metabolites released by the alga. These results show that the branched typical morphology and the individuals produced by Ectocarpus sp. are strongly dependent on the presence of bacteria, while the bacterial effect on the algal exometabolome profile reflects the impact of bacteria on the whole physiology of this alga.

On the thermodynamics of multilevel evolution.

Science.gov (United States)

Tessera, Marc; Hoelzer, Guy A

2013-09-01

Biodiversity is hierarchically structured both phylogenetically and functionally. Phylogenetic hierarchy is understood as a product of branching organic evolution as described by Darwin. Ecosystem biologists understand some aspects of functional hierarchy, such as food web architecture, as a product of evolutionary ecology; but functional hierarchy extends to much lower scales of organization than those studied by ecologists. We argue that the more general use of the term "evolution" employed by physicists and applied to non-living systems connects directly to the narrow biological meaning. Physical evolution is best understood as a thermodynamic phenomenon, and this perspective comfortably includes all of biological evolution. We suggest four dynamical factors that build on each other in a hierarchical fashion and set the stage for the Darwinian evolution of biological systems: (1) the entropic erosion of structure; (2) the construction of dissipative systems; (3) the reproduction of growing systems and (4) the historical memory accrued to populations of reproductive agents by the acquisition of hereditary mechanisms. A particular level of evolution can underpin the emergence of higher levels, but evolutionary processes persist at each level in the hierarchy. We also argue that particular evolutionary processes can occur at any level of the hierarchy where they are not obstructed by material constraints. This theoretical framework provides an extensive basis for understanding natural selection as a multilevel process. The extensive literature on thermodynamics in turn provides an important advantage to this perspective on the evolution of higher levels of organization, such as the evolution of altruism that can accompany the emergence of social organization. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

The reproductive biology and the histological and ultrastructural ...

African Journals Online (AJOL)

STORAGESEVER

2010-04-26

Apr 26, 2010 ... characterized by “appearance of isolated follicular epithelial cells around the oocyte and the formation ... Sea. Murua and Motos (2004) studied reproductive biology and histological examination of European hake. (Merluccius merluccius) in the Bay of ... female M. merluccius in the Mediterranean Sea.

Evolution in a Contemporary Human Population: Intersexual Constraints and Costs of Reproduction

Energy Technology Data Exchange (ETDEWEB)

Stearns, Stephen [Yale University

2012-03-14

In this talk I will use an analysis of the population described in the Framingham Heart Study to make three points: (1) Contemporary humans are still evolving, and we can in part predict how they are responding to selection. (2) Selection on males and females differs, and its interaction with intersexual genetic correlations constrains the responses of each sex to selection. In other words, males are constrained by processes occurring in females, and females are constrained by processes occurring in males. (3) There are costs of reproduction in humans that are paid in lifespan, but it is likely that these costs were deferred to a point at which our ancestors would already have died for other reasons. When we detect those costs today, we find evidence that the versions of some genes that make us susceptible to cancer also increase reproductive success early in life. This confirms in humans a central assumption of the evolutionary theory of aging – the existence of genes that mediate a tradeoff between reproduction and survival - that had previously only been confirmed in model organisms like fruit flies and worms.

Influence of adult nutrition on the relationship between body size and reproductive parameters in a parasitoid wasp

NARCIS (Netherlands)

Bezemer, T.M.; Harvey, J.A.; Mills, N.J.

2005-01-01

1. An important constraint upon life-history evolution in parasitoids is the limit imposed by body size on allocation of limited metabolic resources to different fitness-related physiological functions such as reproduction and survival. 2. The influence of adult nutrition on reproductive and

Genes underlying reproductive division of labor in termites, with comparisons to social Hymenoptera

Directory of Open Access Journals (Sweden)

Judith eKorb

2016-04-01

Full Text Available All social insects are characterized by a reproductive division of labor. Within a colony only a few individuals reproduce (queens and in termites, also a king while the large majority (workers and soldiers forgo reproduction, at least temporarily. The evolution of such reproductive altruism can ultimately be explained by inclusive fitness theory. Here, I will review the proximate genetic mechanisms underlying this altruism in termites. As social cockroaches they evolved eusociality independently from the social Hymenoptera, which makes them interesting test cases to look for common underlying mechanisms of eusociality and lineage specific idiosyncrasies. First, I will provide a summary of the genes and their function that have been identified to underlie reproductive division of labor - so called 'queen genes,' - in the drywood termite Cryptotermes secundus, an emerging model to study termite social evolution. Second, I outline how widespread these queen genes are across the termite phylogeny, using also evidence from recent genome analyses. I will provide hypotheses about the evolutionary origin of these queen genes, aiming to link proximate mechanisms with ultimate functions. Finally, I will draw comparisons to social Hymenoptera to indicate potential common underpinnings that warrant further testing.

The mating type locus (MAT and sexual reproduction of Cryptococcus heveanensis: insights into the evolution of sex and sex-determining chromosomal regions in fungi.

Directory of Open Access Journals (Sweden)

Banu Metin

2010-05-01

Full Text Available Mating in basidiomycetous fungi is often controlled by two unlinked, multiallelic loci encoding homeodomain transcription factors or pheromones/pheromone receptors. In contrast to this tetrapolar organization, Cryptococcus neoformans/Cryptococcus gattii have a bipolar mating system, and a single biallelic locus governs sexual reproduction. The C. neoformans MAT locus is unusually large (>100 kb, contains >20 genes, and enhances virulence. Previous comparative genomic studies provided insights into how this unusual MAT locus might have evolved involving gene acquisitions into two unlinked loci and fusion into one contiguous locus, converting an ancestral tetrapolar system to a bipolar one. Here we tested this model by studying Cryptococcus heveanensis, a sister species to the pathogenic Cryptococcus species complex. An extant sexual cycle was discovered; co-incubating fertile isolates results in the teleomorph (Kwoniella heveanensis with dikaryotic hyphae, clamp connections, septate basidia, and basidiospores. To characterize the C. heveanensis MAT locus, a fosmid library was screened with C. neoformans/C. gattii MAT genes. Positive fosmids were sequenced and assembled to generate two large probably unlinked MAT gene clusters: one corresponding to the homeodomain locus and the other to the pheromone/receptor locus. Strikingly, two divergent homeodomain genes (SXI1, SXI2 are present, similar to the bE/bW Ustilago maydis paradigm, suggesting one or the other homeodomain gene was recently lost in C. neoformans/C. gattii. Sequencing MAT genes from other C. heveanensis isolates revealed a multiallelic homeodomain locus and at least a biallelic pheromone/receptor locus, similar to known tetrapolar species. Taken together, these studies reveal an extant C. heveanensis sexual cycle, define the structure of its MAT locus consistent with tetrapolar mating, and support the proposed evolutionary model for the bipolar Cryptococcus MAT locus revealing

Evolution, reproduction and autopoiesis

Directory of Open Access Journals (Sweden)

Francois Durand

2017-11-01

Full Text Available The term autopoiesis was coined to describe the regenerating and self-maintaining chemical systems of cells. The term has subsequently been applied to many different fields, including sociology, systems theory and information systems. This theory postulates that an autopoietic unity (cell, machine is an organised network of processes that exists in a delimited space, which produces components which in turn continuously regenerate and create the network of processes that produced them. The Santiago Theory of Cognition grew from the Theory of Allopoiesis stating that all living systems are cognitive systems, and the process of living is a process of cognition. Cognition is the ability to adapt to a certain environment and cognition emerges because of a continuous bilateral interaction between the system and its environment. The resultant complexity seen in living systems is caused by this interaction between the system and its environment. Autopoiesis and cognition are however opposing concepts because cognition can only exist when the system is open and not closed as autopoiesis suggests. It is also difficult to see how autopoietic systems could originate if they are closed and how the continuous change which we see in evolution can be explained if life consists of autopoietic systems. It is postulated that cells and organisms are in fact open systems relating genetically to ancestors before them and their ever-changing descendants after them and the flow of molecules and energy through an ever-changing ecology.

Race, genetics, and human reproductive strategies.

Science.gov (United States)

Rushton, J P

1996-02-01

The international literature on racial differences is reviewed, novel data are reported, and a distinct pattern is found. People of east Asian ancestry and people of African ancestry average at opposite ends of a continuum, with people of European ancestry averaging intermediately, albeit with much variability within each major race. The racial matrix emerges from measures taken of reproductive behavior, sex hormones, twinning rate, speed of physical maturation, personality, family stability, brain size, intelligence, law abidingness, and social organization. An evolutionary theory of human reproduction is proposed, familiar to biologists as the r-K scale of reproductive strategies. At one end of this scale are r-strategies, which emphasize high reproductive rates; at the other end are K-strategies, which emphasize high levels of parental investment. This scale is generally used to compare the life histories of widely disparate species, but here it is used to describe the immensely smaller variations among human races. It is hypothesized that, again on average, Mongoloid people are more K-selected than Caucasoids, who are more K-selected than Negroids. The r-K scale of reproductive strategies is also mapped on to human evolution. Genetic distances indicate that Africans emerged from the ancestral hominid line about 200,000 years ago, with an African/non-African split about 110,000 years ago, and a Caucasoid/Mongoloid split about 41,000 years ago. Such an ordering fits with and explains how and why the variables cluster.

Life-history tradeoffs and reproductive cycles in Spotted Owls

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Stoelting, Ricka E.; Gutierrez, R.J.; Kendall, William L.; Peery, M. Zachariah

2015-01-01

The study of tradeoffs among life-history traits has long been key to understanding the evolution of life-history strategies. However, more recently, evolutionary ecologists have realized that reproductive costs have the potential to influence population dynamics. Here, we tested for costs of reproduction in the California Spotted Owl (Strix occidentalis occidentalis), and assessed whether costs of reproduction in year t − 1 on reproduction in year t could be responsible for regionally synchronized biennial cycles in reproductive output. Logistic regression analysis and multistate mark–recapture models with state uncertainty revealed that breeding reduced the likelihood of reproducing in the subsequent year by 16% to 38%, but had no influence on subsequent survival. We also found that costs of reproduction in year t − 1 were correlated with climatic conditions in year t, with evidence of higher costs during the dry phase of the El Niño–Southern Oscillation. Using a simulation-based population model, we showed that strong reproductive costs had the potential to create biennial cycles in population-level reproductive output; however, estimated costs of reproduction appeared to be too small to explain patterns observed in Spotted Owls. In the absence of strong reproductive costs, we hypothesize that observed natural cycles in the reproductive output of Spotted Owls are related to as-yet-unmeasured, regionally concordant fluctuations in environmental conditions or prey resources. Despite theoretical evidence for demographic effects, our analyses illustrate that linking tradeoffs to actual changes in population processes will be challenging because of the potential confounding effects of individual and environmental variation.

Haldane's rule and other aspects of reproductive isolation observed in the Anastrepha fraterculus complex (Diptera: Tephritidae

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Selivon Denise

1999-01-01

Full Text Available Some aspects of reproductive isolation between allopatric populations of two closely related species of the Anastrepha fraterculus complex (A. fraterculus sp. 1 and sp. 2 were evaluated in laboratory conditions. Most of the crosses were fertile in each species as well as between sp. 2 females and sp. 1 males. In the reciprocal cross only 41.7% of the matings yielded viable progeny. Egg hatching occurred at similar rates within the two species, but was significantly lower in the crosses between the species. Adult emergence did not differ significantly among crosses. The sex ratio of adult progeny within each species, as well as in the hybrid progeny derived from sp. 1 females crossed to sp. 2 males, did not differ from the expected 1:1 ratio. However, in the crosses between sp. 2 females to sp. 1 males, a significant deviation in the sex ratio in favor of females was observed, according to the Haldane's rule. The results reinforce previous data which indicated that A. fraterculus sp. 1 and A. fraterculus sp. 2 are distinct biological entities.

Lack of Population Structure and Mixed Reproduction Modes in Exserohilum turcicum from South Africa.

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Human, Maria Petronella; Barnes, Irene; Craven, Maryke; Crampton, Bridget Genevieve

2016-11-01

Exserohilum turcicum is the causal agent of northern corn leaf blight, a destructive foliar disease of maize that results in yield losses worldwide. In South Africa, typical yield losses range from 15 to 30%. Previous studies found high haplotypic diversity with evidence for sexual recombination in E. turcicum populations from tropical climates such as Kenya. However, the population genetic structure and method of reproduction of E. turcicum in South Africa is unknown and, therefore, was investigated. Twelve polymorphic microsatellite markers were screened on 258 E. turcicum isolates from maize collected during 2012 and 2013 from three maize fields in South Africa. A multiplex polymerase chain reaction assay amplifying both mating type idiomorphs was applied to investigate the distribution of mating types. No distinct genetic clusters were observed. Shared haplotypes were identified between isolates separated by distances of up to 762 km, which provided evidence of migration. High haplotypic diversity indicated that sexual reproduction is occurring among E. turcicum isolates, although mating type ratios and linkage disequilibrium analyses did not support the hypothesis of random mating. The population genetic structure of E. turcicum in South Africa is likely due to the direct movement and spread of isolates undergoing a mixed reproductive lifecycle.

Activins in reproductive biology and beyond.

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Wijayarathna, R; de Kretser, D M

2016-04-01

Activins are members of the pleiotrophic family of the transforming growth factor-beta (TGF-β) superfamily of cytokines, initially isolated for their capacity to induce the release of FSH from pituitary extracts. Subsequent research has demonstrated that activins are involved in multiple biological functions including the control of inflammation, fibrosis, developmental biology and tumourigenesis. This review summarizes the current knowledge on the roles of activin in reproductive and developmental biology. It also discusses interesting advances in the field of modulating the bioactivity of activins as a therapeutic target, which would undoubtedly be beneficial for patients with reproductive pathology. A comprehensive literature search was carried out using PUBMED and Google Scholar databases to identify studies in the English language which have contributed to the advancement of the field of activin biology, since its initial isolation in 1987 until July 2015. 'Activin', 'testis', 'ovary', 'embryonic development' and 'therapeutic targets' were used as the keywords in combination with other search phrases relevant to the topic of activin biology. Activins, which are dimers of inhibin β subunits, act via a classical TGF-β signalling pathway. The bioactivity of activin is regulated by two endogenous inhibitors, inhibin and follistatin. Activin is a major regulator of testicular and ovarian development. In the ovary, activin A promotes oocyte maturation and regulates granulosa cell steroidogenesis. It is also essential in endometrial repair following menstruation, decidualization and maintaining pregnancy. Dysregulation of the activin-follistatin-inhibin system leads to disorders of female reproduction and pregnancy, including polycystic ovary syndrome, ectopic pregnancy, miscarriage, fetal growth restriction, gestational diabetes, pre-eclampsia and pre-term birth. Moreover, a rise in serum activin A, accompanied by elevated FSH, is characteristic of female

Detection of phospholipase activity of Candida albicans and non albicans isolated from women of reproductive age with vulvovaginal candidiasis in rural area

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S R Fule

2015-01-01

Full Text Available Background: Vulvovaginal candidiasis (VVC is most common accounting for 17 to 39% of symptomatic women. Both Candida albicans and non albicans Candida species are involved in VVC. Amongst various virulence factors proposed for Candida, extracellular phospholipases is one of the virulence factor implicated in its pathogenicity. With this background the present study was carried out to find the prevalence of different Candida species and to detect phospholipase producing strains isolated from symptomatic women with VVC. Materials and Methods: At least two vaginal swabs from 156 women of reproductive age with abnormal vaginal discharge were collected. Direct microscopy and Gram′s stained smear examined for presence of budding yeast and pseudo mycelia followed by isolation and identification of Candida species. Extracellular phospholipase activity was studied by inoculating all isolates on Sabouraud′s dextrose egg yolk agar (SDA medium. Results: Of the 156 women with curdy white discharge alone or in combination with other signs, 59 (37.82% women showed laboratory evidence of VVC. A total of 31 (52.54% women had curdy white discharge followed by 12 (20.33% with other signs and symptoms. C. albicans (62.59% and non albicans Candida (37.28% in a ratio of 1.68:1 were isolated. Of the 37 strains of C. albians 30 (81.08% showed the enzyme activity. Seventeen (56.66% strains showed higher Pz value of < 0.70 (++++. Conclusion: Although there may be typical clinical presentation of Candidiasis. all the patients did not show laboratory evidence of infection. Pregnancy was found to be major risk factor for development of VVC. C. albicans was prevalent species but non albicans species were also frequently isolated. Extracellular phospholipase activity was seen in C. albicans and not in non albicans Candida isolates.

Variable virulence among isolates of Ascosphaera apis: testing the parasite-pathogen hypothesis for the evolution of polyandry in social insects

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Lee, G. M.; McGee, P. A.; Oldroyd, B. P.

2013-03-01

The queens of many eusocial insect species are polyandrous. The evolution of polyandry from ancestral monoandry is intriguing because polyandry undermines the kin-selected benefits of high intracolonial relatedness that are understood to have been central to the evolution of eusociality. An accumulating body of evidence suggests that polyandry evolved from monoandry in part because genetically diverse colonies better resist infection by pathogens. However, a core assumption of the "parasite-pathogen hypothesis", that there is variation in virulence among strains of pathogens, remains largely untested in vivo. Here, we demonstrate variation in virulence among isolates of Ascosphaera apis, the causative organism of chalkbrood disease in its honey bee ( Apis mellifera) host. More importantly, we show a pathogen-host genotypic interaction for resistance and pathogenicity. Our findings therefore support the parasite-parasite hypothesis as a factor in the evolution of polyandry among eusocial insects.

Influences on communication about reproduction : The cultural evolution of low fertility

NARCIS (Netherlands)

Newson, L; Postmes, T.; Lea, S.E G; Webley, P; Richerson, P.J; McElreath, R

The cultural norms of traditional societies encourage behavior that is consistent with maximizing reproductive success but those of modem post-demographic transition societies do not. Newson et al (2005) proposed that this might be because interaction between kin is relatively less frequent in modem

Galaxy evolution in extreme environments: Molecular gas content star formation and AGN in isolated void galaxies

Science.gov (United States)

Das, Mousumi; Iono, Daisuke; Saito, Toshiki; Subramanian, Smitha

Since the early redshift surveys of the large scale structure of our universe, it has become clear that galaxies cluster along walls, sheet and filaments leaving large, empty regions called voids between them. Although voids represent the most under dense parts of our universe, they do contain a sparse but significant population of isolated galaxies that are generally low luminosity, late type disk galaxies. Recent studies show that most void galaxies have ongoing star formation and are in an early stage of evolution. We present radio, optical studies of the molecular gas content and star formation in a sample of void galaxies. Using SDSS data, we find that AGN are rare in these systems and are found only in the Bootes void; their black hole masses and radio properties are similar to bright spirals galaxies. Our studies suggest that close galaxy interactions and gas accretion are the main drivers of galaxy evolution in these systems despite their location in the underdense environment of the voids.

[Male sexual and reproductive rights].

Science.gov (United States)

Diaz, A M

1998-06-01

In late 1997, PROFAMILIA began a study of the role of male sexual and reproductive rights as part of the construction of new masculine identities. The work was approached from the disciplines of law and sociology. Patriarchy, as a system of domination, permeated most cultures, giving men a position of power in relation to women and leading to a series of violent and self-destructive male behaviors. The patriarchal system imposed aggressive, promiscuous, risky, and irresponsible behaviors on men, which created a climate for sexual abuse, unwanted pregnancy, propagation of sexually transmitted diseases, and violence against women. Changes in female roles have created the need for changes in male roles. The most visible sexual and reproductive needs of men were studied through literature reviews and semistructured questionnaires with PROFAMILIA clients. Among the needs identified were a new type of male participation in family and domestic life, a new content for male sexual freedom, greater participation of men in reproductive decisions and in raising their children, and new ways of relating to others and sharing feelings and emotions. The need to avoid behaviors that put health at risk was also identified. A review of the evolution of existing sexual and reproductive rights and of the documents that constitute their ethical and juridical framework led to the conclusion that the construction of new rights specifically for men is not necessary, or juridically possible, in the current historical context.

Hybrid female mate choice as a species isolating mechanism: environment matters.

Science.gov (United States)

Schmidt, E M; Pfennig, K S

2016-04-01

A fundamental goal of biology is to understand how new species arise and are maintained. Female mate choice is potentially critical to the speciation process: mate choice can prevent hybridization and thereby generate reproductive isolation between potentially interbreeding groups. Yet, in systems where hybridization occurs, mate choice by hybrid females might also play a key role in reproductive isolation by affecting hybrid fitness and contributing to patterns of gene flow between species. We evaluated whether hybrid mate choice behaviour could serve as such an isolating mechanism using spadefoot toad hybrids of Spea multiplicata and Spea bombifrons. We assessed the mate preferences of female hybrid spadefoot toads for sterile hybrid males vs. pure-species males in two alternative habitat types in which spadefoots breed: deep or shallow water. We found that, in deep water, hybrid females preferred the calls of sterile hybrid males to those of S. multiplicata males. Thus, maladaptive hybrid mate preferences could serve as an isolating mechanism. However, in shallow water, the preference for hybrid male calls was not expressed. Moreover, hybrid females did not prefer hybrid calls to those of S. bombifrons in either environment. Because hybrid female mate choice was context-dependent, its efficacy as a reproductive isolating mechanism will depend on both the environment in which females choose their mates as well as the relative frequencies of males in a given population. Thus, reproductive isolation between species, as well as habitat specific patterns of gene flow between species, might depend critically on the nature of hybrid mate preferences and the way in which they vary across environments. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology.

Pheromone evolution, reproductive genes, and comparative transcriptomics in mediterranean earthworms (annelida, oligochaeta, hormogastridae).

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Novo, Marta; Riesgo, Ana; Fernández-Guerra, Antoni; Giribet, Gonzalo

2013-07-01

Animals inhabiting cryptic environments are often subjected to morphological stasis due to the lack of obvious agents driving selection, and hence chemical cues may be important drivers of sexual selection and individual recognition. Here, we provide a comparative analysis of de novo-assembled transcriptomes in two Mediterranean earthworm species with the objective to detect pheromone proteins and other reproductive genes that could be involved in cryptic speciation processes, as recently characterized in other earthworm species. cDNA libraries of unspecific tissue of Hormogaster samnitica and three different tissues of H. elisae were sequenced in an Illumina Genome Analyzer II or Hi-Seq. Two pheromones, Attractin and Temptin were detected in all tissue samples and both species. Attractin resulted in a reliable marker for phylogenetic inference. Temptin contained multiple paralogs and was slightly overexpressed in the digestive tissue, suggesting that these pheromones could be released with the casts. Genes involved in sexual determination and fertilization were highly expressed in reproductive tissue. This is thus the first detailed analysis of the molecular machinery of sexual reproduction in earthworms.

Molecular evolution in Panagrolaimus nematodes: origins of parthenogenesis, hermaphroditism and the Antarctic species P. davidi

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LaMunyon Craig W

2009-01-01

Full Text Available Abstract Background As exemplified by the famously successful model organism Caenorhabditis elegans, nematodes offer outstanding animal systems for investigating diverse biological phenomena due to their small genome sizes, short generation times and ease of laboratory maintenance. Nematodes in the genus Panagrolaimus have served in comparative development and anhydrobiosis studies, and the Antarctic species P. davidi offers a powerful paradigm for understanding the biological mechanisms of extreme cold tolerance. Panagrolaimus nematodes are also unique in that examples of gonochoristic, hermaphroditic and parthenogenetic reproductive modes have been reported for members of this genus. The evolutionary origins of these varying reproductive modes and the Antarctic species P. davidi, however, remain enigmatic. Results We collected nuclear ribosomal RNA gene and mitochondrial protein-coding gene sequences from diverse Panagrolaimus species and strains, including newly discovered isolates from Oregon, to investigate phylogenetic relationships in this nematode genus. Nuclear phylogenies showed that the species and strains historically identified as members of Panagrolaimus constitute a paraphyletic group, suggesting that taxonomic revision is required for Panagrolaimus and related nematode lineages. Strain-specific reproductive modes were mapped onto the molecular phylogeny to show a single origin of parthenogenesis from a presumably gonochoristic ancestor. The hermaphroditic strains were all placed outside a major monophyletic clade that contained the majority of other Panagrolaimus nematodes. Phylogenetic analyses of mitochondrial sequences showed that substantial molecular and geographic diversity exists within the clade of parthenogenetic strains. The Antarctic species P. davidi was found to be very closely related to two Panagrolaimus strains from southern California. Phylogenetic and molecular clock analyses suggested that P. davidi and the

J Maynard Smith: From Engineering to Evolution

Indian Academy of Sciences (India)

ary maintenance of sexual reproduction, the evolution of social behaviours in animals, and the ... the application of Game Theory to evolutionary questions and gave us the now ... gant") although he enjoyed learning mathematics there. Indeed ...

Identification of a Novel Recombinant Type 2 Porcine Reproductive and Respiratory Syndrome Virus in China

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Long Zhou

2018-03-01

Full Text Available Since the emergence of NADC30-like porcine reproductive and respiratory syndrome virus (PRRSV in China in 2013, PRRSVs have undergone rapid evolution. In this study, a novel variant of PRRSV strain (designated SCcd17 was successfully isolated from piglets with clinical signs in Sichuan Province in China in 2017, and the complete genomic sequence was determined. The genome of this new isolate was 15,015 nucleotides (nt long, and comparative analysis revealed that SCcd17 exhibited 90.2%, 85.2%, 84.9%, and 84.0% nucleotide similarity to PRRSVs NADC30, JXA1, CH-1a, and VR-2332, respectively. Phylogenetic analysis indicated that the SCcd17 strain was classified into the NADC30-like sub-genotype, in which all the strains contained the unique discontinuous 131-amino acid deletion in nonstructural protein 2 (nsp2 when compared to VR-2332-like viruses. Notably, extensive amino acid substitutions were observed in nsp2 and a unique single amino acid deletion at position 33 of the GP5 is being described for the first time. Strikingly, recombination analysis revealed that SCcd17 was the result of recombination between the NADC30-like, JXA1-like, and VR-2332-like strains at five recombination breakpoints: nsp1α (nt 641, nsp3 (nt 5141, nsp10 (nt 9521, open reading frame 3 (ORF3 (nt 12,581, and ORF4 (nt 13,021. The genomic data of SCcd17 will be helpful for understanding the role of genomic recombination in the evolution of PRRSV.

Diversity and evolution of Lactobacillus casei group isolated from fermented dairy products in Tibet.

Science.gov (United States)

Feng, Jing; Jiang, Yujun; Li, Mingyu; Zhao, Siyu; Zhang, Yanming; Li, Xuesong; Wang, Hui; Lin, Guangen; Wang, Hao; Li, Tiejing; Man, Chaoxin

2018-05-25

Bacteria in Lactobacillus casei group, including Lactobacillus casei (L. casei), Lactobacillus paracasei (L. paracasei), and Lactobacillus rhamnosus (L. rhamnosus) are important lactic acid bacteria in the production of fermented dairy products and are faced with the controversial nomenclatural status due to their close phylogenetic similarity. To probe the evolution and phylogeny of L. casei group, 100 isolates of lactic acid bacteria originated from naturally fermented dairy products in Tibet of China were subjected to multilocus sequence typing (MLST). The MLST scheme, based on analysis of the housekeeping genes fusA, ileS, lepA, leuS, pyrG, recA and recG, revealed that all the isolates belonged to a group containing the L. paracasei reference strains and were clearly different from the strains of L. casei and L. rhamnosus. Although nucleotide diversity (π) was low for the seven genes (ranging from 0.00341 for fusA to 0.01307 for recG), high genetic diversity represented by 83 sequence types (STs) with a discriminatory index of 0.98 was detected. A network-like structure based on split decomposition analysis, and the high values of the relative effect of recombination and mutation in the diversification of the lineages (r/m = 4.76) and the relative frequency of occurrence of recombination and mutation (ρ/θ = 2.62) indicated that intra-species recombination occurred frequently and homologous recombination played a key role in generating genotypic diversity amongst L. paracasei strains in Tibet. The discovery of 51 new STs and the results of STRUCTURE analysis suggested that the L. casei group in Tibet had an individual and particular population structure in comparison to European isolates. Overall, this research might be the first report about genetic diversity and population structure of Lactobacillus populations isolated from naturally fermented dairy products in Tibet based on MLST scheme.

Genome diversity and divergence in Drosophila mauritiana: multiple signatures of faster X evolution.

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Garrigan, Daniel; Kingan, Sarah B; Geneva, Anthony J; Vedanayagam, Jeffrey P; Presgraves, Daven C

2014-09-04

Drosophila mauritiana is an Indian Ocean island endemic species that diverged from its two sister species, Drosophila simulans and Drosophila sechellia, approximately 240,000 years ago. Multiple forms of incomplete reproductive isolation have evolved among these species, including sexual, gametic, ecological, and intrinsic postzygotic barriers, with crosses among all three species conforming to Haldane's rule: F(1) hybrid males are sterile and F(1) hybrid females are fertile. Extensive genetic resources and the fertility of hybrid females have made D. mauritiana, in particular, an important model for speciation genetics. Analyses between D. mauritiana and both of its siblings have shown that the X chromosome makes a disproportionate contribution to hybrid male sterility. But why the X plays a special role in the evolution of hybrid sterility in these, and other, species remains an unsolved problem. To complement functional genetic analyses, we have investigated the population genomics of D. mauritiana, giving special attention to differences between the X and the autosomes. We present a de novo genome assembly of D. mauritiana annotated with RNAseq data and a whole-genome analysis of polymorphism and divergence from ten individuals. Our analyses show that, relative to the autosomes, the X chromosome has reduced nucleotide diversity but elevated nucleotide divergence; an excess of recurrent adaptive evolution at its protein-coding genes; an excess of recent, strong selective sweeps; and a large excess of satellite DNA. Interestingly, one of two centimorgan-scale selective sweeps on the D. mauritiana X chromosome spans a region containing two sex-ratio meiotic drive elements and a high concentration of satellite DNA. Furthermore, genes with roles in reproduction and chromosome biology are enriched among genes that have histories of recurrent adaptive protein evolution. Together, these genome-wide analyses suggest that genetic conflict and frequent positive natural

Protein domain evolution is associated with reproductive diversification and adaptive radiation in the genus Eucalyptus.

Science.gov (United States)

Kersting, Anna R; Mizrachi, Eshchar; Bornberg-Bauer, Erich; Myburg, Alexander A

2015-06-01

Eucalyptus is a pivotal genus within the rosid order Myrtales with distinct geographic history and adaptations. Comparative analysis of protein domain evolution in the newly sequenced Eucalyptus grandis genome and other rosid lineages sheds light on the adaptive mechanisms integral to the success of this genus of woody perennials. We reconstructed the ancestral domain content to elucidate the gain, loss and expansion of protein domains and domain arrangements in Eucalyptus in the context of rosid phylogeny. We used functional gene ontology (GO) annotation of genes to investigate the possible biological and evolutionary consequences of protein domain expansion. We found that protein modulation within the angiosperms occurred primarily on the level of expansion of certain domains and arrangements. Using RNA-Seq data from E. grandis, we showed that domain expansions have contributed to tissue-specific expression of tandemly duplicated genes. Our results indicate that tandem duplication of genes, a key feature of the Eucalyptus genome, has played an important role in the expansion of domains, particularly in proteins related to the specialization of reproduction and biotic and abiotic interactions affecting root and floral biology, and that tissue-specific expression of proteins with expanded domains has facilitated subfunctionalization in domain families. © 2014 University of Pretoria New Phytologist © 2014 New Phytologist Trust.

Rethinking reproductive "tourism" as reproductive "exile".

Science.gov (United States)

Inhorn, Marcia C; Patrizio, Pasquale

2009-09-01

Whereas reproductive "tourism" implies leisure travel, reproductive "exile" bespeaks the numerous difficulties and constraints faced by infertile patients who are "forced" to travel globally for assisted reproduction. Given this reality, it is time to rethink the language of "reproductive tourism," replacing it with more accurate and patient-centered terms.

Individual quality and age but not environmental or social conditions modulate costs of reproduction in a capital breeder

OpenAIRE

Debeffe, Lucie; Poissant, Jocelyn; McLoughlin, Philip D.

2017-01-01

Abstract Costs associated with reproduction are widely known to play a role in the evolution of reproductive tactics with consequences to population and eco?evolutionary dynamics. Evaluating these costs as they pertain to species in the wild remains an important goal of evolutionary ecology. Individual heterogeneity, including differences in individual quality (i.e., among?individual differences in traits associated with survival and reproduction) or state, and variation in environmental and ...

Effects of gamma irradiation of an isolated flower in reproductive stages on seed production of Brassica napus L

International Nuclear Information System (INIS)

Minami, Harufumi; Sakurai, Noboru; Muroyama, Takeo; Hogetsu, Daisuke

1999-01-01

We examined seed production after gamma irradiation of an isolated whole flower (a flower with pedicel) of Brassica napus strain 1 through a flower organ culture and estimated the effects of gamma rays on embryogenesis in sexual reproductive stages. The whole flowers were irradiated with 17, 32, 57 and 87 Gy of gamma rays in unpollinated stage at day of anthesis, in stage shortly after fertilization and early embryo stage. The gamma irradiation of flowers in stage shortly after fertilization showed a drastic effect on the mature seed production. The number of seeds per pod began to decrease at 17 Gy and dropped to 15% of that of unirradiated flowers at 32 Gy. On the other hand, the flowers irradiated in the unpollinated and early embryo stages began to reduce the number of seeds at 57 Gy. The ovary elongation was suppressed with increasing irradiation dose when the flower was irradiated in unpollinated stage and stage shortly after fertilization. (author)

Infanticide and within-clutch competition select for reproductive synchrony in a cooperative bird.

Science.gov (United States)

Riehl, Christina

2016-08-01

Reproduction among members of social animal groups is often highly synchronized, but neither the selective advantages nor the proximate causes of synchrony are fully understood. Here I investigate the evolution of hatching synchrony in the Greater Ani (Crotophaga major), a communally nesting bird in which several unrelated females contribute eggs to a large, shared clutch. Hatching synchrony is variable, ranging from complete synchrony to moderate asynchrony, and is determined by the onset of incubation of the communal clutch. Data from a 10-year field study indicate that individual reproductive success is highest in synchronous groups, and that nestlings that hatch in the middle of the hatching sequence are most likely to survive. Nestling mortality is high in asynchronous clutches because early-hatching nestlings are more likely to be killed by adult group members, whereas late-hatching nestlings are more likely to starve due competition with their older nest-mates. Therefore, the timing of hatching appears to be under stabilizing selection from infanticide and resource competition acting in concert. These results provide empirical support for models predicting that synchrony may evolve as an adaptive counter-strategy to infanticide, and they highlight the importance of competition in shaping the timing of reproduction in social groups. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

Genetic dissection of a key reproductive barrier between nascent species of house mice.

Science.gov (United States)

White, Michael A; Steffy, Brian; Wiltshire, Tim; Payseur, Bret A

2011-09-01

Reproductive isolation between species is often caused by deleterious interactions among loci in hybrids. Finding the genes involved in these incompatibilities provides insight into the mechanisms of speciation. With recently diverged subspecies, house mice provide a powerful system for understanding the genetics of reproductive isolation early in the speciation process. Although previous studies have yielded important clues about the genetics of hybrid male sterility in house mice, they have been restricted to F1 sterility or incompatibilities involving the X chromosome. To provide a more complete characterization of this key reproductive barrier, we conducted an F2 intercross between wild-derived inbred strains from two subspecies of house mice, Mus musculus musculus and Mus musculus domesticus. We identified a suite of autosomal and X-linked QTL that underlie measures of hybrid male sterility, including testis weight, sperm density, and sperm morphology. In many cases, the autosomal loci were unique to a specific sterility trait and exhibited an effect only when homozygous, underscoring the importance of examining reproductive barriers beyond the F1 generation. We also found novel two-locus incompatibilities between the M. m. musculus X chromosome and M. m. domesticus autosomal alleles. Our results reveal a complex genetic architecture for hybrid male sterility and suggest a prominent role for reproductive barriers in advanced generations in maintaining subspecies integrity in house mice.

Genetic Dissection of a Key Reproductive Barrier Between Nascent Species of House Mice

Science.gov (United States)

White, Michael A.; Steffy, Brian; Wiltshire, Tim; Payseur, Bret A.

2011-01-01

Reproductive isolation between species is often caused by deleterious interactions among loci in hybrids. Finding the genes involved in these incompatibilities provides insight into the mechanisms of speciation. With recently diverged subspecies, house mice provide a powerful system for understanding the genetics of reproductive isolation early in the speciation process. Although previous studies have yielded important clues about the genetics of hybrid male sterility in house mice, they have been restricted to F1 sterility or incompatibilities involving the X chromosome. To provide a more complete characterization of this key reproductive barrier, we conducted an F2 intercross between wild-derived inbred strains from two subspecies of house mice, Mus musculus musculus and Mus musculus domesticus. We identified a suite of autosomal and X-linked QTL that underlie measures of hybrid male sterility, including testis weight, sperm density, and sperm morphology. In many cases, the autosomal loci were unique to a specific sterility trait and exhibited an effect only when homozygous, underscoring the importance of examining reproductive barriers beyond the F1 generation. We also found novel two-locus incompatibilities between the M. m. musculus X chromosome and M. m. domesticus autosomal alleles. Our results reveal a complex genetic architecture for hybrid male sterility and suggest a prominent role for reproductive barriers in advanced generations in maintaining subspecies integrity in house mice. PMID:21750261

Herbivore-mediated ecological costs of reproduction shape the life history of an iteroparous plant.

Science.gov (United States)

Miller, Tom E X; Tenhumberg, Brigitte; Louda, Svata M

2008-02-01

Plant reproduction yields immediate fitness benefits but can be costly in terms of survival, growth, and future fecundity. Life-history theory posits that reproductive strategies are shaped by trade-offs between current and future fitness that result from these direct costs of reproduction. Plant reproduction may also incur indirect ecological costs if it increases susceptibility to herbivores. Yet ecological costs of reproduction have received little empirical attention and remain poorly integrated into life-history theory. Here, we provide evidence for herbivore-mediated ecological costs of reproduction, and we develop theory to examine how these costs influence plant life-history strategies. Field experiments with an iteroparous cactus (Opuntia imbricata) indicated that greater reproductive effort (proportion of meristems allocated to reproduction) led to greater attack by a cactus-feeding insect (Narnia pallidicornis) and that damage by this herbivore reduced reproductive success. A dynamic programming model predicted strongly divergent optimal reproductive strategies when ecological costs were included, compared with when these costs were ignored. Meristem allocation by cacti in the field matched the optimal strategy expected under ecological costs of reproduction. The results indicate that plant reproductive allocation can strongly influence the intensity of interactions with herbivores and that associated ecological costs can play an important selective role in the evolution of plant life histories.

The evolution of the Waste Isolation Pilot Plant (WIPP) project's public affairs program

International Nuclear Information System (INIS)

Walter, L.H.

1988-01-01

As a first-of-a-kind facility, the Waste Isolation Pilot Plant (WIPP) presents a unique perspective on the value of designing a public affairs program that grown with and complements a project's evolution from construction to operations. Like the project itself, the public affairs programs progressed through several stages to its present scope. During the construction phase, foundations were laid in the community. Then, in this past year as the project entered a preoperational status, emphasis shifted to broaden the positive image that had been created locally. In this stage, public affairs presented the project's positive elements to the various state agencies, government officials, and federal organizations involved in our country's radioactive waste management program. Most recently, and continuing until receipt of the first shipment of waste in October 1988, an even broader, more aggressive public affairs program is planned

Comparative phylogenetic analysis of male alternative reproductive tactics in ray-finned fishes.

Science.gov (United States)

Mank, Judith E; Avise, John C

2006-06-01

Using comparative phylogenetic analysis, we analyzed the evolution of male alternative reproductive tactics (MARTs) in ray-finned fishes (Actinopterygii). Numerous independent origins for each type of MART (involving sneaker males, female mimics, pirates, and satellite males) indicate that these behaviors have been highly labile across actinopterygiian evolution, consistent with a previous notion that convergent selection in fishes can readily mold the underlying suites of reproductive hormones into similar behaviors. The evolutionary appearance of MARTs was significantly correlated with the presence of sexually selected traits in bourgeois males (P = 0.001) but not with the presence of male parental care. This suggests that MARTs often arise from selection on some males to circumvent bourgeois male investment in mate monopolization, rather than to avoid male brood care per se. We found parsimony evidence for an evolutionary progression of MARTs wherein sneaking is usually the evolutionary precursor to the presumably more complex MARTs of female mimicry and cooperative satellite behavior. Nest piracy appears not to be part of this evolutionary progression, possibly because its late onset in the life cycle of most ray-finned fishes reduces the effects of selection on this reproductive tactic.

The first multi-gene phylogeny of the Macrostomorpha sheds light on the evolution of sexual and asexual reproduction in basal Platyhelminthes.

Science.gov (United States)

Janssen, Toon; Vizoso, Dita B; Schulte, Gregor; Littlewood, D Timothy J; Waeschenbach, Andrea; Schärer, Lukas

2015-11-01

The Macrostomorpha-an early branching and species-rich clade of free-living flatworms-is attracting interest because it contains Macrostomum lignano, a versatile model organism increasingly used in evolutionary, developmental, and molecular biology. We elucidate the macrostomorphan molecular phylogeny inferred from both nuclear (18S and 28S rDNA) and mitochondrial (16S rDNA and COI) marker genes from 40 representatives. Although our phylogeny does not recover the Macrostomorpha as a statistically supported monophyletic grouping, it (i) confirms many taxa previously proposed based on morphological evidence, (ii) permits the first placement of many families and genera, and (iii) reveals a number of unexpected placements. Specifically, Myozona and Bradynectes are outside the three classic families (Macrostomidae, Microstomidae and Dolichomacrostomidae) and the asexually fissioning Myomacrostomum belongs to a new subfamily, the Myozonariinae nov. subfam. (Dolichomacrostomidae), rather than diverging early. While this represents the first evidence for asexuality among the Dolichomacrostomidae, we show that fissioning also occurs in another Myozonariinae, Myozonaria fissipara nov. sp. Together with the placement of the (also fissioning) Microstomidae, namely as the sister taxon of Dolichomacrostomidae, this suggests that fissioning is not basal within the Macrostomorpha, but rather restricted to the new taxon Dolichomicrostomida (Dolichomacrostomidae+Microstomidae). Furthermore, our phylogeny allows new insights into the evolution of the reproductive system, as ancestral state reconstructions reveal convergent evolution of gonads, and male and female genitalia. Finally, the convergent evolution of sperm storage organs in the female genitalia appears to be linked to the widespread occurrence of hypodermic insemination among the Macrostomorpha. Copyright © 2015 Elsevier Inc. All rights reserved.

An experimental test for age-related improvements in reproductive performance in a frog that cares for its young

Science.gov (United States)

Dugas, Matthew B.; Moore, Michael P.; Wamelink, Caitlin N.; Richards-Zawacki, Corinne L.; Martin, Ryan A.

2015-10-01

Reproductive performance often increases with age in long-lived iteroparous organisms, a pattern that can result from within-individual increases in effort and/or competence. In free-living populations, it is typically difficult to distinguish these mechanisms or to isolate particular features of reproduction-influencing outcomes. In captive Oophaga pumilio, a frog in which mothers provide extended offspring provisioning via trophic eggs, we experimentally manipulated the age at which females started breeding and then monitored them across repeated reproductive events. This experiment allowed us to decouple age and experience and isolate maternal care as the proximate source of any differences in performance. Younger first-time mothers produced larger broods than older first-time mothers, but did not rear more offspring to independence. Across repeated reproductive events, maternal age was unassociated with any metric of performance. At later reproductive events, however, mothers produced fewer metamorphs, and a lower proportion of individuals in their broods reached independence. These patterns suggest that performance does not improve with age or breeding experience in this frog, and that eventual declines in performance are driven by reproductive activity, not age per se. Broadly, age-specific patterns of reproductive performance may depend on the proximate mechanism by which parents influence offspring fitness and how sensitive these are to effort and competence.

Comparative analyses of reproductive structures in harvestmen (opiliones reveal multiple transitions from courtship to precopulatory antagonism.

Directory of Open Access Journals (Sweden)

Mercedes M Burns

Full Text Available Explaining the rapid, species-specific diversification of reproductive structures and behaviors is a long-standing goal of evolutionary biology, with recent research tending to attribute reproductive phenotypes to the evolutionary mechanisms of female mate choice or intersexual conflict. Progress in understanding these and other possible mechanisms depends, in part, on reconstructing the direction, frequency and relative timing of phenotypic evolution of male and female structures in species-rich clades. Here we examine evolution of reproductive structures in the leiobunine harvestmen or "daddy long-legs" of eastern North America, a monophyletic group that includes species in which males court females using nuptial gifts and other species that are equipped for apparent precopulatory antagonism (i.e., males with long, hardened penes and females with sclerotized pregenital barriers. We used parsimony- and Bayesian likelihood-based analyses to reconstruct character evolution in categorical reproductive traits and found that losses of ancestral gift-bearing penile sacs are strongly associated with gains of female pregenital barriers. In most cases, both events occur on the same internal branch of the phylogeny. These coevolutionary changes occurred at least four times, resulting in clade-specific designs in the penis and pregenital barrier. The discovery of convergent origins and/or enhancements of apparent precopulatory antagonism among closely related species offers an unusual opportunity to investigate how major changes in reproductive morphology have occurred. We propose new hypotheses that attribute these enhancements to changes in ecology or life history that reduce the duration of breeding seasons, an association that is consistent with female choice, sexual conflict, and/or an alternative evolutionary mechanism.

Explaining LIGO's observations via isolated binary evolution with natal kicks

Science.gov (United States)

Wysocki, Daniel; Gerosa, Davide; O'Shaughnessy, Richard; Belczynski, Krzysztof; Gladysz, Wojciech; Berti, Emanuele; Kesden, Michael; Holz, Daniel E.

2018-02-01

We compare binary evolution models with different assumptions about black-hole natal kicks to the first gravitational-wave observations performed by the LIGO detectors. Our comparisons attempt to reconcile merger rate, masses, spins, and spin-orbit misalignments of all current observations with state-of-the-art formation scenarios of binary black holes formed in isolation. We estimate that black holes (BHs) should receive natal kicks at birth of the order of σ ≃200 (50 ) km /s if tidal processes do (not) realign stellar spins. Our estimate is driven by two simple factors. The natal kick dispersion σ is bounded from above because large kicks disrupt too many binaries (reducing the merger rate below the observed value). Conversely, the natal kick distribution is bounded from below because modest kicks are needed to produce a range of spin-orbit misalignments. A distribution of misalignments increases our models' compatibility with LIGO's observations, if all BHs are likely to have natal spins. Unlike related work which adopts a concrete BH natal spin prescription, we explore a range of possible BH natal spin distributions. Within the context of our models, for all of the choices of σ used here and within the context of one simple fiducial parameterized spin distribution, observations favor low BH natal spin.

A conceptual framework for clutch size evolution in songbirds

Science.gov (United States)

Martin, Thomas E.

2014-01-01

Causes of evolved differences in clutch size among songbird species remain debated. I propose a new conceptual framework that integrates aspects of traditional life history theory, while including novel elements, to explain evolution of clutch size among songbirds. I review evidence that selection by nest predation on length of time that offspring develop in the nest creates a gradient in offspring characteristics at nest-leaving (fledging), including flight mobility, spatial dispersion, and self-feeding rate. I postulate that this gradient has consequences for offspring mortality rates and parental energy expenditure per offspring. These consequences then determine how reproductive effort is partitioned among offspring, while reproductive effort evolves from age-specific mortality effects. Using data from a long-term site in Arizona, as well as from the literature, I provide support for hypothesized relationships. Nestling development period consistently explains fledgling mortality, energy expenditure per offspring, and clutch size while accounting for reproductive effort (i.e., total energy expenditure) to thereby support the framework. Tests in this paper are not definitive, but they document previously unrecognized relationships and address diverse traits (developmental strategies, parental care strategies, energy requirements per offspring, evolution of reproductive effort, clutch size) that justify further investigations of hypotheses proposed here.

Rapid isolation of gene homologs across taxa: Efficient identification and isolation of gene orthologs from non-model organism genomes, a technical report

Directory of Open Access Journals (Sweden)

Heffer Alison

2011-03-01

Full Text Available Abstract Background Tremendous progress has been made in the field of evo-devo through comparisons of related genes from diverse taxa. While the vast number of species in nature precludes a complete analysis of the molecular evolution of even one single gene family, this would not be necessary to understand fundamental mechanisms underlying gene evolution if experiments could be designed to systematically sample representative points along the path of established phylogenies to trace changes in regulatory and coding gene sequence. This isolation of homologous genes from phylogenetically diverse, representative species can be challenging, especially if the gene is under weak selective pressure and evolving rapidly. Results Here we present an approach - Rapid Isolation of Gene Homologs across Taxa (RIGHT - to efficiently isolate specific members of gene families. RIGHT is based upon modification and a combination of degenerate polymerase chain reaction (PCR and gene-specific amplified fragment length polymorphism (AFLP. It allows targeted isolation of specific gene family members from any organism, only requiring genomic DNA. We describe this approach and how we used it to isolate members of several different gene families from diverse arthropods spanning millions of years of evolution. Conclusions RIGHT facilitates systematic isolation of one gene from large gene families. It allows for efficient gene isolation without whole genome sequencing, RNA extraction, or culturing of non-model organisms. RIGHT will be a generally useful method for isolation of orthologs from both distant and closely related species, increasing sample size and facilitating the tracking of molecular evolution of gene families and regulatory networks across the tree of life.

Sexual selection, sexual isolation and pheromones in Drosophila melanogaster strains after long-term maintaining on different diets.

Science.gov (United States)

Trajković, Jelena; Miličić, Dragana; Savić, Tatjana; Pavković-Lučić, Sofija

2017-07-01

Evolution of reproductive isolation may be a consequence of a variety of signals used in courtship and mate preferences. Pheromones play an important role in both sexual selection and sexual isolation. The abundance of pheromones in Drosophila melanogaster may depend on different environmental factors, including diet. The aim of this study was to ascertain to which degree principal pheromones affect sexual selection in D. melanogaster. We used D. melanogaster strains reared for 14 years on four substrates: standard cornmeal substrate and those containing tomato, banana and carrot. We have previously determined that long-term maintaining of these dietary strains resulted in differences in their cuticular hydrocarbons profile (CHs). In this work, we have tested the level of sexual selection and sexual isolation between aforementioned strains. We found that the high levels of cis-vaccenyl acetate, 7-pentacosene and 7,11-nonacosadiene in the strain reared on a substrate containing carrot affected the individual attractiveness and influenced sexual isolation between flies of this strain and flies reared on a substrate containing banana. Based on these results, long-term different diets, may contribute, to sexual behaviour of D. melanogaster via the effects of principal pheromones. Copyright © 2017 Elsevier B.V. All rights reserved.

Evolution of glycaemia during irradiation syndrome; Evolution de la glycemie au cours du syndrome d'irradiation

Energy Technology Data Exchange (ETDEWEB)

Raisonnier, A [Commissariat a l' Energie Atomique, Fontenay aux Roses (France). Centre d' Etudes Nucleaires

1967-03-15

The evolution of glycaemia following irradiation has been followed in the rat and pig. The results concerning a case of human accidental exposure have also been included. The author has tried to see whether the observed variations are reproducible and have a prognostic value. (author) [French] L'evolution de la glycemie a ete suivie, chez le rat et le porc, apres irradiation. Les resultats relatifs a une irradiation accidentelle humaine sont egalement rapportes. L'auteur cherche a definir si les variations observees sont reproductibles et ont une valeur pronostique. (auteur)

The genetic basis of behavioral isolation between Drosophila mauritiana and D. sechellia.

Science.gov (United States)

McNabney, Daniel R

2012-07-01

Understanding how species form is a fundamental question in evolutionary biology. Identifying the genetic bases of barriers that prevent gene flow between species provides insight into how speciation occurs. Here, I analyze a poorly understood reproductive isolating barrier, prezygotic reproductive isolation. I perform a genetic analysis of prezygotic isolation between two closely related species of Drosophila, D. mauritiana and D. sechellia. I first confirm the existence of strong behavioral isolation between D. mauritiana females and D. sechellia males. Next, I examine the genetic basis of behavioral isolation by (1) scanning an existing set of introgression lines for chromosomal regions that have a large effect on isolation; and (2) mapping quantitative trait loci (QTL) that underlie behavioral isolation via backcross analysis. In particular, I map QTL that determine whether a hybrid backcross female and a D. sechellia male will mate. I identify a single significant QTL, on the X chromosome, suggesting that few major-effect loci contribute to behavioral isolation between these species. In further work, I refine the map position of the QTL to a small region of the X chromosome. © 2012 The Author(s).

No evidence for extrinsic post-zygotic isolation in a wild Saccharomyces yeast system.

Science.gov (United States)

Charron, Guillaume; Landry, Christian R

2017-06-01

Although microorganisms account for the largest fraction of Earth's biodiversity, we know little about how their reproductive barriers evolve. Sexual microorganisms such as Saccharomyces yeasts rapidly develop strong intrinsic post-zygotic isolation, but the role of extrinsic isolation in the early speciation process remains to be investigated. We measured the growth of F 1 hybrids between two incipient species of Saccharomyces paradoxus to assess the presence of extrinsic post-zygotic isolation across 32 environments. More than 80% of hybrids showed either partial dominance of the best parent or over-dominance for growth, revealing no fitness defects in F 1 hybrids. Extrinsic reproductive isolation therefore likely plays little role in limiting gene flow between incipient yeast species and is not a requirement for speciation. © 2017 The Author(s).

Morphological evolution of porous nanostructures grown from a single isolated anodic alumina nanochannel

Science.gov (United States)

Chen, Shih-Yung; Chang, Hsuan-Hao; Lai, Ming-Yu; Liu, Chih-Yi; Wang, Yuh-Lin

2011-09-01

Porous anodic aluminum oxide (AAO) membranes have been widely used as templates for growing nanomaterials because of their ordered nanochannel arrays with high aspect ratio and uniform pore diameter. However, the intrinsic growth behavior of an individual AAO nanochannel has never been carefully studied for the lack of a means to fabricate a single isolated anodic alumina nanochannel (SIAAN). In this study, we develop a lithographic method for fabricating a SIAAN, which grows into a porous hemispherical structure with its pores exhibiting fascinating morphological evolution during anodization. We also discover that the mechanical stress affects the growth rate and pore morphology of AAO porous structures. This study helps reveal the growth mechanism of arrayed AAO nanochannels grown on a flat aluminum surface and provides insights to help pave the way to altering the geometry of nanochannels on AAO templates for the fabrication of advanced nanocomposite materials.

Morphological evolution of porous nanostructures grown from a single isolated anodic alumina nanochannel

International Nuclear Information System (INIS)

Chen, Shih-Yung; Wang, Yuh-Lin; Chang, Hsuan-Hao; Lai, Ming-Yu; Liu, Chih-Yi

2011-01-01

Porous anodic aluminum oxide (AAO) membranes have been widely used as templates for growing nanomaterials because of their ordered nanochannel arrays with high aspect ratio and uniform pore diameter. However, the intrinsic growth behavior of an individual AAO nanochannel has never been carefully studied for the lack of a means to fabricate a single isolated anodic alumina nanochannel (SIAAN). In this study, we develop a lithographic method for fabricating a SIAAN, which grows into a porous hemispherical structure with its pores exhibiting fascinating morphological evolution during anodization. We also discover that the mechanical stress affects the growth rate and pore morphology of AAO porous structures. This study helps reveal the growth mechanism of arrayed AAO nanochannels grown on a flat aluminum surface and provides insights to help pave the way to altering the geometry of nanochannels on AAO templates for the fabrication of advanced nanocomposite materials.

Reproduction and pathogenicity of endemic populations of Rotylenchulus reniformis on cotton

Science.gov (United States)

The reniform nematode (Rotylenchulus reniformis) is the predominant parasitic nematode of upland cotton (Gossypium hirsutum) in the southern United States. Little is known about variability in geographic isolates of reniform nematode. In order to evaluate the comparative reproduction and pathogenici...

Social stress and reproductive success in the female Syrian hamster: endocrine and behavioral correlates.

Science.gov (United States)

Chelini, Marie Odile Monier; Palme, Rupert; Otta, Emma

2011-10-24

In many mammal species, reproduction is not shared equally among the members of a social unit. Even though reproductive skew seems unlikely in females of solitary species, this phenomenon could result from environmental factors. Although solitary in the wild, captive Syrian hamsters (Mesocricetus auratus) are generally housed in groups. We investigated whether social stress produces some degree of reproductive skew in this solitary species and whether female reproductive success varies as a function of social rank. To assess the physiological relationship between social stress and fertility, we monitored reproductive hormones and glucocorticoids of solitary and pair-housed females during pregnancy by means of recently established non-invasive methods for measuring hormone metabolites in the feces. The patterns of fecal progesterone, estrogen and glucocorticoid metabolites were similar to those found in blood and reported in the literature for pregnant hamsters. As expected, dominant females had higher breeding success than subordinate females. However the rate of reproductive failure was also very high among the singly housed females of our control group. The number of pups per litter, the average sex-ratio in each group, and the mean weight of pups did not differ significantly among groups. Glucocorticoid concentrations were unaffected by housing and social rank and the few differences between the endocrine profiles of singly- and pair-housed females are not sufficient to explain the observed difference in breeding success. It is likely that social isolation impairs reproduction in the same manner as subordination. Our findings suggest that social isolation of animals accustomed to group living was equally as disturbing as cohabitation with an unknown conspecific. Copyright © 2011 Elsevier Inc. All rights reserved.

Isolation of key retinoid signalling and metabolic modules in invertebrates

Directory of Open Access Journals (Sweden)

Ana André

2014-05-01

Full Text Available Retinoids are a class of molecules related to vitamin A (Retinol that are required for regulation of critical chordate ndocrine-mediated process, such as embryonic development, reproduction, and vision. To maintain such physiological process, chordates have a complex mechanism to regulate the spatial and temporal distribution of retinoids that includes metabolic and signalling modules. Initially, retinoid modules were seen as a chordate novelty. However, emerging biochemical and genomic evidences have challenged this view, clearly pointing to a more basal ancestry than previously thought. However, for the majority of non-chordate invertebrate lineages a clearly characterization of the main enzymatic/molecular players is still missing. Despite limited, the available evidence supports the presence of biologically active retinoid pathways in invertebrates. In order to enhance our insights on retinoid biology, evolution, and its putative disruption by environmental chemicals, the isolation and functional characterization of key retinoid metabolic players in marine invertebrates has been carried out.

A reconstruction of sexual modes throughout animal evolution.

Science.gov (United States)

Sasson, Daniel A; Ryan, Joseph F

2017-12-06

Although most extant animals have separate sexes, simultaneous hermaphrodites can be found in lineages throughout the animal kingdom. However, the sexual modes of key ancestral nodes including the last common ancestor (LCA) of all animals remain unclear. Without these data, it is difficult to infer the reproductive-state transitions that occurred early in animal evolution, and thus a broad understanding of the evolution of animal reproduction remains elusive. In this study, we use a composite phylogeny from four previously published studies, two alternative topologies (ctenophores or sponges as sister to the rest of animals), and multiple phylogenetic approaches to conduct the most extensive analysis to date of the evolution of animal sexual modes. Our analyses clarify the sexual mode of many ancestral animal nodes and allow for sound inferences of modal transitions that have occurred in animal history. Our results also indicate that the transition from separate sexes to hermaphroditism has been more common in animal history than the reverse. These results provide the most complete view of the evolution of animal sexual modes to date and provide a framework for future inquiries into the correlation of these transitions with genes, behaviors, and physiology. These results also suggest that mutations promoting hermaphroditism have historically been more likely to invade gonochoristic populations than vice versa.

Visual communication stimulates reproduction in Nile tilapia, Oreochromis niloticus (L.).

Science.gov (United States)

Castro, A L S; Gonçalves-de-Freitas, E; Volpato, G L; Oliveira, C

2009-04-01

Reproductive fish behavior is affected by male-female interactions that stimulate physiological responses such as hormonal release and gonad development. During male-female interactions, visual and chemical communication can modulate fish reproduction. The aim of the present study was to test the effect of visual and chemical male-female interaction on the gonad development and reproductive behavior of the cichlid fish Nile tilapia, Oreochromis niloticus (L.). Fifty-six pairs were studied after being maintained for 5 days under one of the four conditions (N = 14 for each condition): 1) visual contact (V); 2) chemical contact (Ch); 3) chemical and visual contact (Ch+V); 4) no sensory contact (Iso) - males and females isolated. We compared the reproductive behavior (nesting, courtship and spawning) and gonadosomatic index (GSI) of pairs of fish under all four conditions. Visual communication enhanced the frequency of courtship in males (mean +/- SEM; V: 24.79 +/- 3.30, Ch+V: 20.74 +/- 3.09, Ch: 0.1 +/- 0.07, Iso: 4.68 +/- 1.26 events/30 min; P communication did not affect the reproductive behavior of pairs nor did it enhance the effects of visual contact. Therefore, male-female visual communication is an effective cue, which stimulates reproduction among pairs of Nile tilapia.

[Fitness of sexual reproduction of Toona ciliata var. pubescens natural populations and their sexual reproduction and regeneration].

Science.gov (United States)

Huang, Hong Lan; Zhang, Lu; Jia, Li Ming; Liang, Yue-Long; Cai, Jun Huo

2018-04-01

To examine the reproduction fitness coefficients and individual-level fitness of Toona ciliata var. pubescens, their sexual reproduction and natural regeneration were investigated during 2006-2016, with four natural populations in Jiulianshan National Reserve as test objects. The results showed that there were only 2-10 trees for the natural populations of T. ciliata var. pubescens with a small initial number of fruiting plants (3-9 trees), which were from the initial fruiting plants or their first/second generation. The sexual reproduction of these isolated populations were significantly different, and their seed production capacities tended to decline over time. With the maturing of communities, soil seed banks and seed germinations were extremely poor, and the number of trees that could be growing to mature stage was nearly zero. The optimum maturity age of T. ciliata var. pubescens was about 40 a, and the fitness coefficients (2.0-2.8) rapidly increased in early development stage, but then was sharply reduced (0.3-0.5), and then gradually dropped to almost 0. There were significant differences in the fitness at individual level (0-14 tree·cm -2 ) among different populations, but their values were low (close to zero). Based on the existing reproduction rate, the actual values of sexual reproduction and regeneration fitness were much lower than the predicted ones. Due to the low level of genetic fitness, the sexual reproductive ability of different populations all showed decreasing trends. The natural sexual regeneration ability tended to decline, while the fitness of T. ciliata var. pubescens further decreased. All those factors suggested higher investment risks. Therefore, the systems of sexual reproduction became unbalanced and deteriorating. We proposed that more studies, including breeding mating, pollination, seed setting, and genetic diversity evaluation, are needed. Moreover, we should provide suitable forest environment through cleaning up litter in the

Evolution of genetic systems in filamentous ascomycetes

NARCIS (Netherlands)

Nauta, M.J.

1994-01-01

A great variety of genetic systems exist in filamentous ascomycetes. The transmission of genetic material does not only occur by (sexual or asexual) reproduction, but it can also follow vegetative fusion of different strains. In this thesis the evolution of this variability is studied,

Characterization of three porcine reproductive and respiratory syndrome virus isolates from a single swine farm bearing strong homology to a vaccine strain.

Science.gov (United States)

Jiang, Yi-feng; Xia, Tian-qi; Zhou, Yan-jun; Yu, Ling-xue; Yang, Shen; Huang, Qin-feng; Li, Li-wei; Gao, Fei; Qu, Ze-hui; Tong, Wu; Tong, Guang-zhi

2015-09-30

Three porcine reproductive and respiratory syndrome viruses (PRRSV), NT1, NT2, and NT3, were isolated from three dying piglets from a single pig farm in Jiangsu Province, China. Whole genome sequencing revealed that the three isolates share the highest homology with JXA1-P80, an attenuated vaccine strain developed by serial passage of highly pathogenic PRRSV JXA1 in MARC-145 cells. More than ten amino acids residues in ORF1a, ORF1b, GP4, and GP5 that were thought to be unique to JXA1 attenuated on MARC-145 cells were each found in the corresponding locations of NT1, NT2, and NT3. In virulence assays, piglets infected with NT1, NT2, or NT3 exhibited clinical signs of disease, including high fever, anorexia, and respiratory distress, leading to the death of the majority of the piglets within two weeks. Collectively, these data indicate that NT1, NT2, and NT3 are highly pathogenic PRRSVs and they are likely to be revertants of the vaccine strain JXA1-P80. Copyright © 2015 Elsevier B.V. All rights reserved.

Magic cues versus magic preferences in speciation

NARCIS (Netherlands)

Maan, Martine E.; Seehausen, Ole

Question: How does divergent natural selection lead to divergence in mating traits and the evolution of reproductive isolation? Background: Ecological speciation of non-allopatric taxa usually requires the evolution of an association between selective mating and the traits underlying ecological

Porcine reproductive and respiratory syndrome virus: antigenic and molecular diversity of British isolates and implications for diagnosis.

Science.gov (United States)

Frossard, Jean-Pierre; Fearnley, Catherine; Naidu, Brindha; Errington, Jane; Westcott, David G; Drew, Trevor W

2012-08-17

Porcine reproductive and respiratory syndrome (PRRS) is an endemic disease of pigs, caused by PRRS virus, a member of the Arteriviridae family. First seen in Britain in 1991, the disease continues to be a significant economic and welfare problem for pig producers. To date, only PRRSV genotype 1 has been found in Britain. At the genetic level, a considerable increase has been reported in the diversity of PRRS viruses isolated in Britain between 2003 and 2007, versus the early 1990 s. In this study, the diversity has been shown to extend to the antigenic level too, with potential consequences for diagnostic methods. Antigenic diversity was assessed using a panel of twelve monoclonal antibodies, only one of which reacted with all isolates tested. Nine diverse viruses were compared as potential antigens in immunoperoxidase monolayer assays, where each one produced quite different results for a common panel of sera. As a single virus is used in each diagnostic assay, results must therefore be interpreted cautiously. For a real-time RT-PCR assay, published oligonucleotide primer and probe sequences were evaluated against available genetic sequences of British and European viruses, and were re-designed where considerable mismatches were found. The multiplex assay incorporating these modified primers to detect genotype 1 and 2 PRRS viruses was then validated for use with diagnostic sera and tissues. As the increasing degree of diversity exhibited by British strains is mirrored in other countries, PRRSV will continue to provide an ongoing challenge to diagnosis at a global, as well as national level. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

Chance, choice, and the future of reproduction.

Science.gov (United States)

Miller, W B

1983-11-01

The evolution of reproduction has been characterized by the development of complex biological and behavioral mechanisms that serve to regulate chance events. Human reproduction has been characterized by the increasing importance of individual choice. Some contemporary manifestations of this broad trend are the high incidence of contraceptive and "proceptive" behavior among couples in Western, industrialized nations. The former behavior willingly attempts to prevent conception while the latter actively attempts to induce conception (such as concentrating intercourse around the time of ovulation). Both patterns of behavior indicate that a choice is being made. A 3-year study of 1000 women revealed proceptive behavior as the most important factor predicting occurance of conception among married couples in the United States. The general strategeis people follow while making childbearing decisions: termination, sequencing, and pre-planning form a continuum following the historical trend toward greater reproductive control. In the terminating strategy, a couple makes no decision about child bearing until the number of children they have become enough or too much. In the sequencing strategy, decisions to have children are made 1 child at a time until a satisfactory limit is reached. In the pre-planning strategy, a plan is worked out ahead of time and is subsequently carried out. As new reproductive technology is introduced and as progressive change is made in society's reproductive related values and beliefs, choice will continue to dominate chance as the highly likely trend for the future of reproduction. Surrogate maternity is just 1 example of this trend. However, these new options, which culminate in the theory and practice of "progensis," (still in its infancy), as well as offering a rich opportunity, can also incur psychological burdens on a couple. Thus, as with any kind of freedom, these developments will require care, caution and responsibility.

Evolution of glycaemia during irradiation syndrome; Evolution de la glycemie au cours du syndrome d'irradiation

Energy Technology Data Exchange (ETDEWEB)

Raisonnier, A. [Commissariat a l' Energie Atomique, Fontenay aux Roses (France). Centre d' Etudes Nucleaires

1967-03-15

The evolution of glycaemia following irradiation has been followed in the rat and pig. The results concerning a case of human accidental exposure have also been included. The author has tried to see whether the observed variations are reproducible and have a prognostic value. (author) [French] L'evolution de la glycemie a ete suivie, chez le rat et le porc, apres irradiation. Les resultats relatifs a une irradiation accidentelle humaine sont egalement rapportes. L'auteur cherche a definir si les variations observees sont reproductibles et ont une valeur pronostique. (auteur)

Effects of phytosterols on zebrafish reproduction in multigeneration test

International Nuclear Information System (INIS)

Nakari, Tarja; Erkomaa, Kirsti

2003-01-01

A multigeneration test is used to show disruption of the reproductive system by phytosterols. - Zebrafish from mixed sex populations were exposed continuously across three generations to two phytosterol preparations both containing β-sitosterol. The phytosterols were isolated from wood and soy beans. Blood vitellogenin levels and sex ratio changes were used as intermediate indicators of the reproduction failures. Both sterol preparations caused vitellogenin induction in the exposed fish. The wood sterol changed the sex ratio of the exposed fish. In generation F1, the predominant sex was male, and in generation F2 it was female. The soy sterol in the used test concentration was lethal to the exposed fish in generation F1. This multigeneration test evidenced that phytosterols containing β-sitosterol disrupt the reproduction system of zebrafish by changing the sex ratios and by inducing the vitellogenin production in the exposed fish

Effects of phytosterols on zebrafish reproduction in multigeneration test

Energy Technology Data Exchange (ETDEWEB)

Nakari, Tarja; Erkomaa, Kirsti

2003-05-01

A multigeneration test is used to show disruption of the reproductive system by phytosterols. - Zebrafish from mixed sex populations were exposed continuously across three generations to two phytosterol preparations both containing {beta}-sitosterol. The phytosterols were isolated from wood and soy beans. Blood vitellogenin levels and sex ratio changes were used as intermediate indicators of the reproduction failures. Both sterol preparations caused vitellogenin induction in the exposed fish. The wood sterol changed the sex ratio of the exposed fish. In generation F1, the predominant sex was male, and in generation F2 it was female. The soy sterol in the used test concentration was lethal to the exposed fish in generation F1. This multigeneration test evidenced that phytosterols containing {beta}-sitosterol disrupt the reproduction system of zebrafish by changing the sex ratios and by inducing the vitellogenin production in the exposed fish.

Ancestral state reconstructions require biological evidence to test evolutionary hypotheses: A case study examining the evolution of reproductive mode in squamate reptiles.

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Griffith, Oliver W; Blackburn, Daniel G; Brandley, Matthew C; Van Dyke, James U; Whittington, Camilla M; Thompson, Michael B

2015-09-01

To understand evolutionary transformations it is necessary to identify the character states of extinct ancestors. Ancestral character state reconstruction is inherently difficult because it requires an accurate phylogeny, character state data, and a statistical model of transition rates and is fundamentally constrained by missing data such as extinct taxa. We argue that model based ancestral character state reconstruction should be used to generate hypotheses but should not be considered an analytical endpoint. Using the evolution of viviparity and reversals to oviparity in squamates as a case study, we show how anatomical, physiological, and ecological data can be used to evaluate hypotheses about evolutionary transitions. The evolution of squamate viviparity requires changes to the timing of reproductive events and the successive loss of features responsible for building an eggshell. A reversal to oviparity requires that those lost traits re-evolve. We argue that the re-evolution of oviparity is inherently more difficult than the reverse. We outline how the inviability of intermediate phenotypes might present physiological barriers to reversals from viviparity to oviparity. Finally, we show that ecological data supports an oviparous ancestral state for squamates and multiple transitions to viviparity. In summary, we conclude that the first squamates were oviparous, that frequent transitions to viviparity have occurred, and that reversals to oviparity in viviparous lineages either have not occurred or are exceedingly rare. As this evidence supports conclusions that differ from previous ancestral state reconstructions, our paper highlights the importance of incorporating biological evidence to evaluate model-generated hypotheses. © 2015 Wiley Periodicals, Inc.

Climate processes shape the evolution of populations and species leading to the assembly of modern biotas - examples along a continuum from shallow to deep time

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Jacobs, D. K.

2014-12-01

California experiences droughts, so lets begin with the effects of streamflow variation on population evolution in a coastal lagoon-specialist endangered fish, the tidewater goby. Streamflow controls the closing and opening of lagoons to the sea determining genetic isolation or gene flow. Here evolution is a function of habitat preference for closing lagoons. Other estuarine fishes, with different habitat preferences, differentiate at larger spatial scales in response to longer glacio-eustatic control of estuarine habitat. Species of giraffes in Africa are a puzzle. Why do the ranges of large motile, potentially interbreeding, species occur in contact each other without hybridization? The answer resides in the timing of seasonal precipitation. Although the degree of seaonality of climate does not vary much between species, the timing of precipitation and seasonal "greenup" does. This provides a selective advantage to reproductive isolation, as reproductive timing can be coordinated in each region with seasonal browse availability for lactating females. Convective rainfall in Africa follows the sun and solar intensity is influenced by the precession cycle such that more extensive summer rains fell across the Sahara and South Asia early in the Holocene, this may also contribute to the genetic isolation and speciation of giraffes and others savanna species. But there also appears to be a correlation with rarity (CITES designation) of modern wetland birds, as the dramatic drying of the late Holocene landscape contributes to this conservation concern. Turning back to the West Coast we find the most diverse temperate coastal fauna in the world, yet this diversity evolved and is a relict of diversity accumulation during the apex of upwelling in the late Miocene, driven by the reglaciation of Antarctica. Lastly we can see that the deep-sea evolution is broadly constrained by the transitions from greenhouse to icehouse worlds over the last 90 mya as broad periods of warm

Effects of plant sex on range distributions and allocation to reproduction.

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Johnson, Marc T J; Smith, Stacey D; Rausher, Mark D

2010-05-01

Despite an abundance of theory, few empirical studies have explored the ecological and evolutionary consequences of sex. We used a comparative phylogenetic approach to examine whether transitions between sexual and asexual reproduction are associated with changes in the size and distribution of species' geographical ranges, and their investment in reproduction. Here, we reconstructed the phylogeny of the genus Oenothera sections Oenothera and Calylophus (Onagraceae), which contain 35 sexual and 30 functionally asexual species. From each species, we collected data on the geographical distribution and variation in plant traits related to reproduction. Functionally asexual species occurred at higher latitudes, but did not differ in range size, compared with sexual species. Transitions to asexuality were associated with decreased investment in floral structures, including the length of petals, floral tubes and styles. Decreased anther size and increased seed size within asexual species also suggest altered allocation to male and female fitness. The observed range shifts are consistent with superior colonization of environments by asexual species following glaciation, and the observed changes in reproductive allocation support predictions made by models relating to the evolution of selfing. Our results suggest that the evolutionary consequences of asexual reproduction might be less restrictive than previously thought.

Isolation-by-distance and outbreeding depression are sufficient to drive parapatric speciation in the absence of environmental influences.

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Guy A Hoelzer

Full Text Available A commonly held view in evolutionary biology is that speciation (the emergence of genetically distinct and reproductively incompatible subpopulations is driven by external environmental constraints, such as localized barriers to dispersal or habitat-based variation in selection pressures. We have developed a spatially explicit model of a biological population to study the emergence of spatial and temporal patterns of genetic diversity in the absence of predetermined subpopulation boundaries. We propose a 2-D cellular automata model showing that an initially homogeneous population might spontaneously subdivide into reproductively incompatible species through sheer isolation-by-distance when the viability of offspring decreases as the genomes of parental gametes become increasingly different. This simple implementation of the Dobzhansky-Muller model provides the basis for assessing the process and completion of speciation, which is deemed to occur when there is complete postzygotic isolation between two subpopulations. The model shows an inherent tendency toward spatial self-organization, as has been the case with other spatially explicit models of evolution. A well-mixed version of the model exhibits a relatively stable and unimodal distribution of genetic differences as has been shown with previous models. A much more interesting pattern of temporal waves, however, emerges when the dispersal of individuals is limited to short distances. Each wave represents a subset of comparisons between members of emergent subpopulations diverging from one another, and a subset of these divergences proceeds to the point of speciation. The long-term persistence of diverging subpopulations is the essence of speciation in biological populations, so the rhythmic diversity waves that we have observed suggest an inherent disposition for a population experiencing isolation-by-distance to generate new species.

Formal Definitions of Unbounded Evolution and Innovation Reveal Universal Mechanisms for Open-Ended Evolution in Dynamical Systems.

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Adams, Alyssa; Zenil, Hector; Davies, Paul C W; Walker, Sara Imari

2017-04-20

Open-ended evolution (OEE) is relevant to a variety of biological, artificial and technological systems, but has been challenging to reproduce in silico. Most theoretical efforts focus on key aspects of open-ended evolution as it appears in biology. We recast the problem as a more general one in dynamical systems theory, providing simple criteria for open-ended evolution based on two hallmark features: unbounded evolution and innovation. We define unbounded evolution as patterns that are non-repeating within the expected Poincare recurrence time of an isolated system, and innovation as trajectories not observed in isolated systems. As a case study, we implement novel variants of cellular automata (CA) where the update rules are allowed to vary with time in three alternative ways. Each is capable of generating conditions for open-ended evolution, but vary in their ability to do so. We find that state-dependent dynamics, regarded as a hallmark of life, statistically out-performs other candidate mechanisms, and is the only mechanism to produce open-ended evolution in a scalable manner, essential to the notion of ongoing evolution. This analysis suggests a new framework for unifying mechanisms for generating OEE with features distinctive to life and its artifacts, with broad applicability to biological and artificial systems.

Effects of Clonal Reproduction on Evolutionary Lag and Evolutionary Rescue.

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Orive, Maria E; Barfield, Michael; Fernandez, Carlos; Holt, Robert D

2017-10-01

Evolutionary lag-the difference between mean and optimal phenotype in the current environment-is of keen interest in light of rapid environmental change. Many ecologically important organisms have life histories that include stage structure and both sexual and clonal reproduction, yet how stage structure and clonality interplay to govern a population's rate of evolution and evolutionary lag is unknown. Effects of clonal reproduction on mean phenotype partition into two portions: one that is phenotype dependent, and another that is genotype dependent. This partitioning is governed by the association between the nonadditive genetic plus random environmental component of phenotype of clonal offspring and their parents. While clonality slows phenotypic evolution toward an optimum, it can dramatically increase population survival after a sudden step change in optimal phenotype. Increased adult survival slows phenotypic evolution but facilitates population survival after a step change; this positive effect can, however, be lost given survival-fecundity trade-offs. Simulations indicate that the benefits of increased clonality under environmental change greatly depend on the nature of that change: increasing population persistence under a step change while decreasing population persistence under a continuous linear change requiring de novo variation. The impact of clonality on the probability of persistence for species in a changing world is thus inexorably linked to the temporal texture of the change they experience.

Reproductive ecology of lampreys

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Johnson, Nicholas S.; Buchinger, Tyler J.; Li, Weiming

2014-01-01

Lampreys typically spawn in riffle habitats during the spring. Spawning activity and diel (i.e., during daylight and at night) behavioral patterns are initiated when spring water temperatures increase to levels that coincide with optimal embryologic development. Nests are constructed in gravel substrate using the oral disc to move stones and the tail to fan sediment out of the nest. Spawning habitat used by individual species is generally a function of adult size, where small-bodied species construct nests in shallower water with slower flow and smaller gravel than large-bodied species. The mating system of lampreys is primarily polygynandrous (i.e., where multiple males mate with multiple females). Lamprey species with adult total length less than 30 cm generally spawn communally, where a nest may contain 20 or more individuals of both sexes. Lamprey species with adult sizes greater than 35 cm generally spawn in groups of two to four. Operational sex ratios of lampreys are highly variable across species, populations, and time, but are generally male biased. The act of spawning typically starts with the male attaching with his oral disc to the back of the female’s head; the male and female then entwine and simultaneously release gametes. However, alternative mating behaviors (e.g., release of gametes without paired courtship and sneaker males) have been observed. Future research should determine how multiple modalities of communication among lampreys (including mating pheromones) are integrated to inform species recognition and mate choice. Such research could inform both sea lamprey control strategies and provide insight into possible evolution of reproductive isolation mechanisms between paired lamprey species in sympatry.

Investigation of the antigenic evolution of field isolates using the reverse genetics system of infectious bursal disease virus (IBDV).

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Durairaj, Vijay; Sellers, Holly S; Linnemann, Erich G; Icard, Alan H; Mundt, Egbert

2011-10-01

The antigenic profiles of over 300 infectious bursal disease virus (IBDV) isolates were analyzed using a panel of monoclonal antibodies in a reverse genetics system. In addition, the sequences of a large portion of the neutralizing-antibody-inducing VP2 of IBDV were determined. Phylogenetic analysis of nucleotide and amino acid sequences in combination with the antigenic profiles obtained using the monoclonal antibody panel, revealed a lack of correlation between antigenicity and isolate's placement within the phylogenetic tree. In-depth analysis of amino acid exchanges revealed that changes within a certain region of the VP2 molecule resulted in differences in the antigenicity of the virus. This comprehensive analysis of VP2 sequences indicated a high selective pressure in the field that was likely due to vaccination programs, which increase the rate of evolution of the virus.

Reproductive rights approach to reproductive health in developing countries

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Vijayan K. Pillai

2011-12-01

Full Text Available Research on reproductive health in developing countries focuses mostly on the role of economic development on various components of reproductive health. Cross-sectional and empirical research studies in particular on the effects of non-economic factors such as reproductive rights remain few and far between.This study investigates the influence of two components of an empowerment strategy, gender equality, and reproductive rights on women's reproductive health in developing countries. The empowerment strategy for improving reproductive health is theoretically situated on a number of background factors such as economic and social development.Cross-national socioeconomic and demographic data from a number of international organizations on 142 developing countries are used to test a model of reproductive rights and reproductive health.The findings suggest that both economic and democratic development have significant positive effects on levels of gender equality. The level of social development plays a prominent role in promoting reproductive rights. It is found that reproductive rights channel the influences of social structural factors and gender equality on reproductive health.

Reproductive rights approach to reproductive health in developing countries.

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Pillai, Vijayan K; Gupta, Rashmi

2011-01-01

Research on reproductive health in developing countries focuses mostly on the role of economic development on various components of reproductive health. Cross-sectional and empirical research studies in particular on the effects of non-economic factors such as reproductive rights remain few and far between. This study investigates the influence of two components of an empowerment strategy, gender equality, and reproductive rights on women's reproductive health in developing countries. The empowerment strategy for improving reproductive health is theoretically situated on a number of background factors such as economic and social development. Cross-national socioeconomic and demographic data from a number of international organizations on 142 developing countries are used to test a model of reproductive rights and reproductive health. The findings suggest that both economic and democratic development have significant positive effects on levels of gender equality. The level of social development plays a prominent role in promoting reproductive rights. It is found that reproductive rights channel the influences of social structural factors and gender equality on reproductive health.

Prezygotic barriers to hybridization in marine broadcast spawners: reproductive timing and mating system variation.

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Carla A Monteiro

Full Text Available Sympatric assemblages of congeners with incomplete reproductive barriers offer the opportunity to study the roles that ecological and non-ecological factors play in reproductive isolation. While interspecific asynchrony in gamete release and gametic incompatibility are known prezygotic barriers to hybridization, the role of mating system variation has been emphasized in plants. Reproductive isolation between the sibling brown algal species Fucus spiralis, Fucus guiryi (selfing hermaphrodite and Fucus vesiculosus (dioecious was studied because they form hybrids in parapatry in the rocky intertidal zone, maintain species integrity over a broad geographic range, and have contrasting mating systems. We compared reproductive synchrony (spawning overlap between the three species at several temporal scales (yearly/seasonal, semilunar/tidal, and hourly during single tides. Interspecific patterns of egg release were coincident at seasonal (single peak in spring to early summer to semilunar timescales. Synthesis of available data indicated that spawning is controlled by semidiurnal tidal and daily light-dark cues, and not directly by semilunar cycles. Importantly, interspecific shifts in timing detected at the hourly scale during single tides were consistent with a partial ecological prezygotic hybridization barrier. The species displayed patterns of gamete release consistent with a power law distribution, indicating a high degree of reproductive synchrony, while the hypothesis of weaker selective constraints for synchrony in selfing versus outcrossing species was supported by observed spawning in hermaphrodites over a broader range of tidal phase than in outcrossers. Synchronous gamete release is critical to the success of external fertilization, while high-energy intertidal environments may offer only limited windows of reproductive opportunity. Within these windows, however, subtle variations in reproductive timing have evolved with the potential to

Hormonally active phytochemicals and vertebrate evolution.

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Lambert, Max R; Edwards, Thea M

2017-06-01

Living plants produce a diversity of chemicals that share structural and functional properties with vertebrate hormones. Wildlife species interact with these chemicals either through consumption of plant materials or aquatic exposure. Accumulating evidence shows that exposure to these hormonally active phytochemicals (HAPs) often has consequences for behavior, physiology, and fecundity. These fitness effects suggest there is potential for an evolutionary response by vertebrates to HAPs. Here, we explore the toxicological HAP-vertebrate relationship in an evolutionary framework and discuss the potential for vertebrates to adapt to or even co-opt the effects of plant-derived chemicals that influence fitness. We lay out several hypotheses about HAPs and provide a path forward to test whether plant-derived chemicals influence vertebrate reproduction and evolution. Studies of phytochemicals with direct impacts on vertebrate reproduction provide an obvious and compelling system for studying evolutionary toxicology. Furthermore, an understanding of whether animal populations evolve in response to HAPs could provide insightful context for the study of rapid evolution and how animals cope with chemical agents in the environment.

Reproductive isolation revealed in preliminary crossbreeding experiments using field collected Triatoma dimidiata (Hemiptera: Reduviidae) from three ITS-2 defined groups.

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García, Mauricio; Menes, Marianela; Dorn, Patricia L; Monroy, Carlota; Richards, Bethany; Panzera, Francisco; Bustamante, Dulce María

2013-12-01

Triatoma dimidiata, a Chagas disease vector distributed in Mexico, Central America, Colombia, Venezuela, Peru and Ecuador, has been studied using genetic markers and four groups have been defined by ITS-2 sequences: 1A, 1B, 2 and 3. To gather evidence on the divergence and reproductive isolation among T. dimidiata ITS-2 groups, we carried out 15 crossbreeding experiments with field-collected sylvan and domestic T. dimidiata from Guatemala where three groups are found: 1A, 2 and 3. Reciprocal crosses between individuals from groups 1A and 2, and a cross between group 2 individuals from different habitats, produced an average 129.78±42.29 eggs with hatching success ranging from 31.6 to 90.1%. The offspring of these crosses reached the adult stage, and crosses between F1 insects produced eggs. These results suggest that there are no pre- or post-zygotic reproductive barriers between groups 1A and 2, or within group 2. Crosses between group 3 females and males from groups 1A or 2 produced on average 85.67±30.26 eggs and none of them hatched. These results support the existence of pre-zygotic barriers between T. dimidiata group 3 and groups 1A and 2. The group 3 individuals were collected in sylvatic environments in Yaxha, Peten, Guatemala. Previously, distinct chromosomal characteristics (cytotype 3) were described in individuals from this population. Based on this evidence we suggest that this population is divergent at the species level from other T. dimidiata populations. Copyright © 2013 Elsevier B.V. All rights reserved.

Reproductive isolation revealed in preliminary crossbreeding experiments using field collected Triatoma dimidiata (Hemiptera: Reduviidae) from three ITS–2 defined groups

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García, Mauricio; Menes, Marianela; Dorn, Patricia L.; Monroy, Carlota; Richards, Bethany; Panzera, Francisco; Bustamante, Dulce María

2013-01-01

Triatoma dimidiata, a Chagas disease vector distributed in Mexico, Central America, Colombia, Venezuela, Peru and Ecuador, has been studied using genetic markers and four groups have been defined by ITS–2 sequences: 1A, 1B, 2 and 3. To gather evidence on the divergence and reproductive isolation among T. dimidiata ITS–2 groups, we carried out 15 crossbreeding experiments with field–collected sylvan and domestic T. dimidiata from Guatemala where three groups are found: 1A, 2 and 3. Reciprocal crosses between individuals from groups 1A and 2, and a cross between group 2 individuals from different habitats, produced an average 129.78±42.29 eggs with hatching success ranging from 31.6% to 90.1%. The offspring of these crosses reached the adult stage, and crosses between F1 insects produced eggs. These results suggest that there are no pre– or post– zygotic reproductive barriers between groups 1A and 2, or within group 2. Crosses between group 3 females and males from groups 1A or 2 produced on average 85.67±30.26 eggs and none of them hatched. These results support the existence of pre– zygotic barriers between T. dimidiata group 3 and groups 1A and 2. The group 3 individuals were collected in sylvatic environments in Yaxha, Peten, Guatemala. Previously, distinct chromosomal characteristics (cytotype 3) were described in individuals from this population. Based on this evidence we suggest that this population is divergent at the species level from other T. dimidiata populations. PMID:24041592

Androgenic signaling systems and their role in behavioral evolution.

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Fuxjager, Matthew J; Schuppe, Eric R

2018-06-05

Sex steroids mediate the organization and activation of masculine reproductive phenotypes in diverse vertebrate taxa. However, the effects of sex steroid action in this context vary tremendously, in that steroid action influences reproductive physiology and behavior in markedly different ways (even among closely related species). This leads to the idea that the mechanisms underlying sex steroid action similarly differ across vertebrates in a manner that supports diversification of important sexual traits. Here, we highlight the Evolutionary Potential Hypothesis as a framework for understanding how androgen-dependent reproductive behavior evolves. This idea posits that the cellular mechanisms underlying androgenic action can independently evolve within a given target tissue to adjust the hormone's functional effects. The result is a seemingly endless number of permutations in androgenic signaling pathways that can be mapped onto the incredible diversity of reproductive phenotypes. One reason this hypothesis is important is because it shifts current thinking about the evolution of steroid-dependent traits away from an emphasis on circulating steroid levels and toward a focus on molecular mechanisms of hormone action. To this end, we also provide new empirical data suggesting that certain cellular modulators of androgen action-namely, the co-factors that dynamically adjust transcritpional effects of steroid action either up or down-are also substrates on which evolution can act. We then close the review with a detailed look at a case study in the golden-collared manakin (Manacus vitellinus). Work in this tropical bird shows how androgenic signaling systems are modified in specific parts of the skeletal muscle system to enhance motor performance necessary to produce acrobatic courtship displays. Altogether, this paper seeks to develop a platform to better understand how steroid action influences the evolution of complex animal behavior. Copyright © 2018 Elsevier Ltd

Early-Life Social Isolation Impairs the Gonadotropin-Inhibitory Hormone Neuronal Activity and Serotonergic System in Male Rats.

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Soga, Tomoko; Teo, Chuin Hau; Cham, Kai Lin; Idris, Marshita Mohd; Parhar, Ishwar S

2015-01-01

Social isolation in early life deregulates the serotonergic system of the brain, compromising reproductive function. Gonadotropin-inhibitory hormone (GnIH) neurons in the dorsomedial hypothalamic nucleus are critical to the inhibitory regulation of gonadotropin-releasing hormone neuronal activity in the brain and release of luteinizing hormone by the pituitary gland. Although GnIH responds to stress, the role of GnIH in social isolation-induced deregulation of the serotonin system and reproductive function remains unclear. We investigated the effect of social isolation in early life on the serotonergic-GnIH neuronal system using enhanced green fluorescent protein (EGFP)-tagged GnIH transgenic rats. Socially isolated rats were observed for anxious and depressive behaviors. Using immunohistochemistry, we examined c-Fos protein expression in EGFP-GnIH neurons in 9-week-old adult male rats after 6 weeks post-weaning isolation or group housing. We also inspected serotonergic fiber juxtapositions in EGFP-GnIH neurons in control and socially isolated male rats. Socially isolated rats exhibited anxious and depressive behaviors. The total number of EGFP-GnIH neurons was the same in control and socially isolated rats, but c-Fos expression in GnIH neurons was significantly reduced in socially isolated rats. Serotonin fiber juxtapositions on EGFP-GnIH neurons were also lower in socially isolated rats. In addition, levels of tryptophan hydroxylase mRNA expression in the dorsal raphe nucleus were significantly attenuated in these rats. These results suggest that social isolation in early-life results in lower serotonin levels, which reduce GnIH neuronal activity and may lead to reproductive failure.

Beyond magic traits: Multimodal mating cues in Heliconius butterflies.

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Mérot, Claire; Frérot, Brigitte; Leppik, Ene; Joron, Mathieu

2015-11-01

Species coexistence involves the evolution of reproductive barriers opposing gene flow. Heliconius butterflies display colorful patterns affecting mate choice and survival through warning signaling and mimicry. These patterns are called "magic traits" for speciation because divergent natural selection may promote mimicry shifts in pattern whose role as mating cue facilitates reproductive isolation. By contrast, between comimetic species, natural selection promotes pattern convergence. We addressed whether visual convergence interferes with reproductive isolation by testing for sexual isolation between two closely related species with similar patterns, H. timareta thelxinoe and H. melpomene amaryllis. Experiments with models confirmed visual attraction based on wing phenotype, leading to indiscriminate approach. Nevertheless, mate choice experiments showed assortative mating. Monitoring male behavior toward live females revealed asymmetry in male preference, H. melpomene males courting both species equally while H. timareta males strongly preferred conspecifics. Experiments with hybrid males suggested an important genetic component for such asymmetry. Behavioral observations support a key role for short-distance cues in determining male choice in H. timareta. Scents extracts from wings and genitalia revealed interspecific divergence in chemical signatures, and hybrid female scent composition was significantly associated with courtship intensity by H. timareta males, providing candidate chemical mating cues involved in sexual isolation. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

Isolating mechanisms among five sympatric species of Aneilema,/i> R. Br. (Commelinaceae in Kenya

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R. B. Faden

1983-11-01

Full Text Available The reproductive biology and ecology of five non-hybridizing, sympatric species of Aneilema in Kenya is investigated. The high number of species at the study site is believed to be due to the ecological diversity at this locality. Differences in ecology and seasonal flowering periods appear to be inadequate to reproductively isolate these species. However, differences in daily flowering times, pollinators, floral morphology and opening behaviour, and in chromosome number, alone or in combination (perhaps also coacting with other factors not fully evaluated, are effective isolating mechanisms.

Genomic confirmation of hybridisation and recent inbreeding in a vector-isolated Leishmania population.

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Rogers, Matthew B; Downing, Tim; Smith, Barbara A; Imamura, Hideo; Sanders, Mandy; Svobodova, Milena; Volf, Petr; Berriman, Matthew; Cotton, James A; Smith, Deborah F

2014-01-01

Although asexual reproduction via clonal propagation has been proposed as the principal reproductive mechanism across parasitic protozoa of the Leishmania genus, sexual recombination has long been suspected, based on hybrid marker profiles detected in field isolates from different geographical locations. The recent experimental demonstration of a sexual cycle in Leishmania within sand flies has confirmed the occurrence of hybridisation, but knowledge of the parasite life cycle in the wild still remains limited. Here, we use whole genome sequencing to investigate the frequency of sexual reproduction in Leishmania, by sequencing the genomes of 11 Leishmania infantum isolates from sand flies and 1 patient isolate in a focus of cutaneous leishmaniasis in the Çukurova province of southeast Turkey. This is the first genome-wide examination of a vector-isolated population of Leishmania parasites. A genome-wide pattern of patchy heterozygosity and SNP density was observed both within individual strains and across the whole group. Comparisons with other Leishmania donovani complex genome sequences suggest that these isolates are derived from a single cross of two diverse strains with subsequent recombination within the population. This interpretation is supported by a statistical model of the genomic variability for each strain compared to the L. infantum reference genome strain as well as genome-wide scans for recombination within the population. Further analysis of these heterozygous blocks indicates that the two parents were phylogenetically distinct. Patterns of linkage disequilibrium indicate that this population reproduced primarily clonally following the original hybridisation event, but that some recombination also occurred. This observation allowed us to estimate the relative rates of sexual and asexual reproduction within this population, to our knowledge the first quantitative estimate of these events during the Leishmania life cycle.

A new paradigma on the plant evolution: from a natural evolution to an artificial evolution?

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Bennici, Andrea

2005-01-01

After evidencing the great importance of plants for animals and humans in consequence of the photosynthesis, several considerations on plant evolution are made. One of the peculiar characteristics of the plant is the sessile property, due especially to the cell wall. This factor, principally, strengthened by the photosynthetic process, determined the particular developmental pattern of the plant, which is characterized by the continuous formation of new organs. The plant immobility, although negative for its survival, has been, in great part, overcome by the acquisition of the capacity of adaptation (plasticity) to the environmental stresses and changes, and the establishment of more adapted genotypes. This capacity to react to the external signals induced Trewavas to speak of "plant intelligence". The plant movement incapacity and the evolution of the sexual reproduction system were strongly correlated. In this context, the evolution of the flower in the Angiosperms has been particularly important to allow the male gamete to fertilize the immobile female gamete. Moreover, the formation of fruit and seed greatly improved the dispersal and conservation of the progeny in the environment. With the flower, mechanisms to favour the outcrossing among different individuals appeared, which are essential to increase the genetic variability and, then, the plant evolution itself. Although the Angiosperms seem highly evolved, the plant evolution is not surely finished, because many reported morpho-physiological processes may be still considered susceptible of further improvement. In the last years the relationships among humans, plants and environment are becoming closer and closer. This is due to the use of the DNA recombinant techniques with the aim to modify artificially plant characters. Therefore, the risk of a plant evolution strongly directed towards practical or commercial objectives, or "an artificial evolution", may be hypothesized.

Demographic consequences of greater clonal than sexual reproduction in Dicentra canadensis.

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Lin, Chia-Hua; Miriti, Maria N; Goodell, Karen

2016-06-01

Clonality is a widespread life history trait in flowering plants that may be essential for population persistence, especially in environments where sexual reproduction is unpredictable. Frequent clonal reproduction, however, could hinder sexual reproduction by spatially aggregating ramets that compete with seedlings and reduce inter-genet pollination. Nevertheless, the role of clonality in relation to variable sexual reproduction in population dynamics is often overlooked. We combined population matrix models and pollination experiments to compare the demographic contributions of clonal and sexual reproduction in three Dicentra canadensis populations, one in a well-forested landscape and two in isolated forest remnants. We constructed stage-based transition matrices from 3 years of census data to evaluate annual population growth rates, λ. We used loop analysis to evaluate the relative contribution of different reproductive pathways to λ. Despite strong temporal and spatial variation in seed set, populations generally showed stable growth rates. Although we detected some pollen limitation of seed set, manipulative pollination treatments did not affect population growth rates. Clonal reproduction contributed significantly more than sexual reproduction to population growth in the forest remnants. Only at the well-forested site did sexual reproduction contribute as much as clonal reproduction to population growth. Flowering plants were more likely to transition to a smaller size class with reduced reproductive potential in the following year than similarly sized nonflowering plants, suggesting energy trade-offs between sexual and clonal reproduction at the individual level. Seed production had negligible effects on growth and tuber production of individual plants. Our results demonstrate that clonal reproduction is vital for population persistence in a system where sexual reproduction is unpredictable. The bias toward clonality may be driven by low fitness returns

New genes as drivers of phenotypic evolution

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Chen, Sidi; Krinsky, Benjamin H.; Long, Manyuan

2014-01-01

During the course of evolution, genomes acquire novel genetic elements as sources of functional and phenotypic diversity, including new genes that originated in recent evolution. In the past few years, substantial progress has been made in understanding the evolution and phenotypic effects of new genes. In particular, an emerging picture is that new genes, despite being present in the genomes of only a subset of species, can rapidly evolve indispensable roles in fundamental biological processes, including development, reproduction, brain function and behaviour. The molecular underpinnings of how new genes can develop these roles are starting to be characterized. These recent discoveries yield fresh insights into our broad understanding of biological diversity at refined resolution. PMID:23949544

Speciation and gene flow between snails of opposite chirality.

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Angus Davison

2005-09-01

Full Text Available Left-right asymmetry in snails is intriguing because individuals of opposite chirality are either unable to mate or can only mate with difficulty, so could be reproductively isolated from each other. We have therefore investigated chiral evolution in the Japanese land snail genus Euhadra to understand whether changes in chirality have promoted speciation. In particular, we aimed to understand the effect of the maternal inheritance of chirality on reproductive isolation and gene flow. We found that the mitochondrial DNA phylogeny of Euhadra is consistent with a single, relatively ancient evolution of sinistral species and suggests either recent "single-gene speciation" or gene flow between chiral morphs that are unable to mate. To clarify the conditions under which new chiral morphs might evolve and whether single-gene speciation can occur, we developed a mathematical model that is relevant to any maternal-effect gene. The model shows that reproductive character displacement can promote the evolution of new chiral morphs, tending to counteract the positive frequency-dependent selection that would otherwise drive the more common chiral morph to fixation. This therefore suggests a general mechanism as to how chiral variation arises in snails. In populations that contain both chiral morphs, two different situations are then possible. In the first, gene flow is substantial between morphs even without interchiral mating, because of the maternal inheritance of chirality. In the second, reproductive isolation is possible but unstable, and will also lead to gene flow if intrachiral matings occasionally produce offspring with the opposite chirality. Together, the results imply that speciation by chiral reversal is only meaningful in the context of a complex biogeographical process, and so must usually involve other factors. In order to understand the roles of reproductive character displacement and gene flow in the chiral evolution of Euhadra, it will be

Five Rules for the Evolution of Cooperation

Science.gov (United States)

Nowak, Martin A.

2006-12-01

Cooperation is needed for evolution to construct new levels of organization. Genomes, cells, multicellular organisms, social insects, and human society are all based on cooperation. Cooperation means that selfish replicators forgo some of their reproductive potential to help one another. But natural selection implies competition and therefore opposes cooperation unless a specific mechanism is at work. Here I discuss five mechanisms for the evolution of cooperation: kin selection, direct reciprocity, indirect reciprocity, network reciprocity, and group selection. For each mechanism, a simple rule is derived that specifies whether natural selection can lead to cooperation.

Cultural evolution as a nonstationary stochastic process

DEFF Research Database (Denmark)

Nicholson, Arwen; Sibani, Paolo

2016-01-01

We present an individual based model of cultural evolution, where interacting agents are coded by binary strings standing for strategies for action, blueprints for products or attitudes and beliefs. The model is patterned on an established model of biological evolution, the Tangled Nature Model...... (TNM), where a “tangle” of interactions between agents determines their reproductive success. In addition, our agents also have the ability to copy part of each other's strategy, a feature inspired by the Axelrod model of cultural diversity. Unlike the latter, but similarly to the TNM, the model...

Reversion of a live porcine reproductive and respiratory virus vaccine investigated by parallel mutations

DEFF Research Database (Denmark)

Nielsen, Henriette S.; Oleksiewicz, Martin B; Forsberg, R

2001-01-01

A live attenuated porcine reproductive and respiratory syndrome (PRRS) vaccine virus has been shown to revert to virulence under field conditions. In order to identify genetic virulence determinants, ORF1 from the attenuated vaccine virus and three Danish vaccine-derived field isolates was sequen......A live attenuated porcine reproductive and respiratory syndrome (PRRS) vaccine virus has been shown to revert to virulence under field conditions. In order to identify genetic virulence determinants, ORF1 from the attenuated vaccine virus and three Danish vaccine-derived field isolates...... in the vaccine virus sequence during cell-culture adaptation. Evaluation of the remaining mutations in the ORF1 sequence revealed stronger selective pressure for amino acid conservation during spread in pigs than during vaccine production. Furthermore, it was found that the selective pressure did not change...

Parasite dispersal risk tolerance is mediated by its reproductive value.

Science.gov (United States)

Nolan, Maxcy P; Delaplane, Keith S

2017-10-01

Parasite dispersal theory draws heavily upon epidemiological SIR models in which host status (susceptible (S), infected (I), or recovered (R)) is used to study parasite dispersal evolution. In contrast to these extrinsically host-centric drivers, in this study we focus on an intrinsic driver, the parasite's reproductive value (predicted future offspring) as a regulator of the extent to which the individual will engage in risky dispersal behaviour. As a model system we use the honeybee Apis mellifera and its ectoparasite, the mite Varroa destructor . Mite reproduction happens exclusively inside cells of bee brood, and newly emerged fecund mites may parasitize either a homocolonial brood cell (low risk dispersal) or emigrate to a new bee colony via phoretic attachment to mature forager bees (high risk dispersal). In an empirical bioassay, prepartum mites (high reproductive value) and postpartum mites (low reproductive value) were offered a choice of newly emerged homocolonial worker bees (low risk), homocolonial pollen forager bees (high risk), or heterocolonial pollen foragers (high risk). A preference for newly emerged bees was earlier and more strongly sustained among prepartum mites. This suggests comparatively greater dispersal risk tolerance among postpartum mites with lower reproductive value. A dangerous bid for dispersal may be adaptive if the individual has already successfully reproduced and the rewards for successful dispersal are sufficiently large.

Reproductive rights approach to reproductive health in developing countries

OpenAIRE

Pillai, Vijayan Kumara; Gupta, Rashmi

2011-01-01

Background: Research on reproductive health in developing countries focuses mostly on the role of economic development on various components of reproductive health. Cross-sectional and empirical research studies in particular on the effects of non-economic factors such as reproductive rights remain few and far between. Objective: This study investigates the influence of two components of an empowerment strategy, gender equality, and reproductive rights on women’s reproductive health in develo...

Sex Attractant Pheromones of Virgin Queens of Sympatric Slave-Making Ant Species in the Genus Polyergus, and their Possible Roles in Reproductive Isolation.

Science.gov (United States)

Greenberg, Les; Johnson, Christine A; Trager, James C; McElfresh, J Steven; Rodstein, Joshua; Millar, Jocelyn G

2018-06-01

Species of the ant genus Polyergus are social parasites that steal brood from colonies of their hosts in the closely related genus Formica. Upon emergence as adults in a mixed population, host Formica workers carry out all the normal worker functions within the Polyergus colony, including foraging, feeding, grooming, and rearing brood of the parasitic Polyergus ants. Some unmated Polyergus gynes (queens) run in the raiding columns of their colonies and attract males by releasing a pheromone from their mandibular glands. There are two Polyergus species groups in North America: an eastern P. lucidus group and a western P. breviceps group. One species of each of these groups, P. lucidus Mayr and P. mexicanus Emery, are sympatric in Missouri. In this study, we characterized the sex pheromones of virgin queens of two species of the P. lucidus group (P. lucidus sensu stricto and P. sanwaldi) and one species of the P. breviceps group (P. mexicanus), and compared these with the previously identified sex pheromone of P. topoffi of the P. breviceps group. We then used sex pheromone blends reconstructed from synthesized components of the two groups to test their efficacy at reproductively isolating these species. We found that methyl 6-methylsalicylate is conserved as the major component of the pheromone blends for both Polyergus species groups; however, methyl (R)-3-ethyl-4-methylpentanoate is the species-specific minor component produced by P. lucidus group queens, and (R)-3-ethyl-4-methylpentan-1-ol is the crucial minor component for P. breviceps group queens. The optimal ratio of the major and minor components for P. lucidus group queens was about 100:1 salicylate to ester. In concurrent field trials in Missouri, males of P. lucidus sensu stricto and P. mexicanus (a member of the P. breviceps group) were attracted almost exclusively to their particular blends of sex pheromone components. To our knowledge, this is the first example of a possible sex

A transcriptomics investigation into pine reproductive organ development.

Science.gov (United States)

Niu, Shihui; Yuan, Huwei; Sun, Xinrui; Porth, Ilga; Li, Yue; El-Kassaby, Yousry A; Li, Wei

2016-02-01

The development of reproductive structures in gymnosperms is still poorly studied because of a lack of genomic information and useful genetic tools. The hermaphroditic reproductive structure derived from unisexual gymnosperms is an even less studied aspect of seed plant evolution. To extend our understanding of the molecular mechanism of hermaphroditism and the determination of sexual identity of conifer reproductive structures in general, unisexual and bisexual cones from Pinus tabuliformis were profiled for gene expression using 60K microarrays. Expression patterns of genes during progression of sexual cone development were analysed using RNA-seq. The results showed that, overall, the transcriptomes of male structures in bisexual cones were more similar to those of female cones. However, the expression of several MADS-box genes in the bisexual cones was similar to that of male cones at the more juvenile developmental stage, while despite these expression shifts, male structures of bisexual cones and normal male cones were histologically indistinguishable and cone development was continuous. This study represents a starting point for in-depth analysis of the molecular regulation of cone development and also the origin of hermaphroditism in pine. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

The heterothallic sugarbeet pathogen Cercospora beticola contains exon fragments of both MAT genes that are homogenized by concerted evolution.

Science.gov (United States)

Bolton, Melvin D; de Jonge, Ronnie; Inderbitzin, Patrik; Liu, Zhaohui; Birla, Keshav; Van de Peer, Yves; Subbarao, Krishna V; Thomma, Bart P H J; Secor, Gary A

2014-01-01

Dothideomycetes is one of the most ecologically diverse and economically important classes of fungi. Sexual reproduction in this group is governed by mating type (MAT) genes at the MAT1 locus. Self-sterile (heterothallic) species contain one of two genes at MAT1 (MAT1-1-1 or MAT1-2-1) and only isolates of opposite mating type are sexually compatible. In contrast, self-fertile (homothallic) species contain both MAT genes at MAT1. Knowledge of the reproductive capacities of plant pathogens are of particular interest because recombining populations tend to be more difficult to manage in agricultural settings. In this study, we sequenced MAT1 in the heterothallic Dothideomycete fungus Cercospora beticola to gain insight into the reproductive capabilities of this important plant pathogen. In addition to the expected MAT gene at MAT1, each isolate contained fragments of both MAT1-1-1 and MAT1-2-1 at ostensibly random loci across the genome. When MAT fragments from each locus were manually assembled, they reconstituted MAT1-1-1 and MAT1-2-1 exons with high identity, suggesting a retroposition event occurred in a homothallic ancestor in which both MAT genes were fused. The genome sequences of related taxa revealed that MAT gene fragment pattern of Cercospora zeae-maydis was analogous to C. beticola. In contrast, the genome of more distantly related Mycosphaerella graminicola did not contain MAT fragments. Although fragments occurred in syntenic regions of the C. beticola and C. zeae-maydis genomes, each MAT fragment was more closely related to the intact MAT gene of the same species. Taken together, these data suggest MAT genes fragmented after divergence of M. graminicola from the remaining taxa, and concerted evolution functioned to homogenize MAT fragments and MAT genes in each species. Published by Elsevier Inc.

Hybridization, transgressive segregation and evolution of new ...

Indian Academy of Sciences (India)

Unknown

This paper is dedicated to the memory of our teacher, Prof. N. B. ... of genetic variations wherein favourably interacting gene complexes are determined ... speciation. Hybrid-zone studies can yield information ... tic systems and in speciation, using an artificial hybrid ...... process of the development of reproductive isolation in.

Early-life Social Isolation Impairs the Gonadotropin-Inhibitory Hormone Neuronal Activity and Serotonergic System in Male Rats

Directory of Open Access Journals (Sweden)

Tomoko eSoga

2015-11-01

Full Text Available Social isolation in early life deregulates the serotonergic system of the brain, compromising reproductive function. Gonadotropin-inhibitory hormone (GnIH neurons in the dorsomedial hypothalamic nucleus are critical to the inhibitory regulation of gonadotropin-releasing hormone neuronal activity in the brain and release of luteinising hormone by the pituitary gland. Although GnIH responds to stress, the role of GnIH in social isolation-induced deregulation of the serotonin system and reproductive function remains unclear. We investigated the effect of social isolation in early life on the serotonergic–GnIH neuronal system using enhanced green fluorescent protein (EGFP-tagged GnIH-transgenic rats. Socially isolated rats were observed for anxious and depressive behaviours. Using immunohistochemistry, we examined c-Fos protein expression in EGFP–GnIH neurons in 9-week-old adult male rats after 6 weeks post-weaning isolation or group -housing. We also inspected serotonergic fibre juxtapositions in EGFP–GnIH neurons in control and socially isolated male rats. Socially isolated rats exhibited anxious and depressive behaviours. The total number of EGFP–GnIH neurons was the same in control and socially isolated rats, but c-Fos expression in GnIH neurons was significantly reduced in socially isolated rats. Serotonin fibre juxtapositions on EGFP–GnIH neurons was also lower in socially isolated rats. In addition, levels of tryptophan hydroxylase mRNA expression in the dorsal raphe nucleus were significantly attenuated in these rats. These results suggest that social isolation in early life results in lower serotonin levels, which reduce GnIH neuronal activity and may lead to reproductive failure.

Editorial: The politics of reproduction and parenting cultures - procreation, pregnancy, childbirth and childrearing.

Science.gov (United States)

Latimer, Joanna; Thomas, Gareth M

2017-07-01

'Controlling life was and is to be achieved in part by rationalizing and industrializing reproductive processes. Multiple heterogeneous and contradictory groups have had an interest in achieving such control - from elites seeking to control others to individuals, especially women, trying to get a grip on their own lives through controlling their reproduction; from eugenicists ultimately trying to control evolution to neo-Malthusians trying to control national and population size; from philanthropists and foundation executives trying to shape the future of science and human life in varied directions to reproductive scientists trying to do their research … The biomedicalization of life itself (human, plant, and animal) is the key overarching and usually taken for granted social process here' (Clarke : 273-5). © 2017 Foundation for the Sociology of Health & Illness.

Mechanisms by Which Phenotypic Plasticity Affects Adaptive Divergence and Ecological Speciation.

Science.gov (United States)

Nonaka, Etsuko; Svanbäck, Richard; Thibert-Plante, Xavier; Englund, Göran; Brännström, Åke

2015-11-01

Phenotypic plasticity is the ability of one genotype to produce different phenotypes depending on environmental conditions. Several conceptual models emphasize the role of plasticity in promoting reproductive isolation and, ultimately, speciation in populations that forage on two or more resources. These models predict that plasticity plays a critical role in the early stages of speciation, prior to genetic divergence, by facilitating fast phenotypic divergence. The ability to plastically express alternative phenotypes may, however, interfere with the early phase of the formation of reproductive barriers, especially in the absence of geographic barriers. Here, we quantitatively investigate mechanisms under which plasticity can influence progress toward adaptive genetic diversification and ecological speciation. We use a stochastic, individual-based model of a predator-prey system incorporating sexual reproduction and mate choice in the predator. Our results show that evolving plasticity promotes the evolution of reproductive isolation under diversifying environments when individuals are able to correctly select a more profitable habitat with respect to their phenotypes (i.e., adaptive habitat choice) and to assortatively mate with relatively similar phenotypes. On the other hand, plasticity facilitates the evolution of plastic generalists when individuals have a limited capacity for adaptive habitat choice. We conclude that plasticity can accelerate the evolution of a reproductive barrier toward adaptive diversification and ecological speciation through enhanced phenotypic differentiation between diverging phenotypes.

Behavioral facilitation of reproduction in sexual and unisexual whiptail lizards.

OpenAIRE

Crews, D; Grassman, M; Lindzey, J

1986-01-01

All-female, parthenogenetic species afford a unique test of hypotheses regarding the nature and evolution of sexuality. Mating behavior accomplishes the transfer of gametes and stimulates the coordination of reproductive activity of the male and female. Cnemidophorus uniparens, a parthenogenetic species, is believed to have resulted from the hybridization of two extant gonochoristic species, Cnemidophorus inornatus and Cnemidophorus gularis. C. uniparens regularly and reliably perform behavio...

Genetics of reproductive isolation in the Drosophila simulans clade: complex epistasis underlying hybrid male sterility.

Science.gov (United States)

Cabot, E L; Davis, A W; Johnson, N A; Wu, C I

1994-05-01

We have analyzed the sterility associated with introgressions of the distal one-fourth of the X chromosome from either Drosophila mauritiana or Drosophila sechellia into the genome of Drosophila simulans using a series of visible and DNA markers. Because in Drosophila hybrids, male sterility is usually complete and is often tightly linked with each of several markers used in crosses, a simple genetic basis has generally been assumed. In our low resolution mapping experiment, we were not able to reject the null hypothesis that a single gene, introgressed from either D. mauritiana or D. sechellia, is the cause of male sterility. High resolution mapping, however, reveals a much more complex picture. At least three distinct factors from D. mauritiana, or two from D. sechellia, were identified that need to be jointly present to confer full sterility. Each individual factor by itself is relatively ineffective in causing sterility, or even a partial spermatogenic defect. Moreover, there appear to be more sterility factors on comparable introgressions from D. mauritiana than from D. sechellia. On the basis of these observations, we propose a model which suggests that multilocus weak allele interactions are a very common cause of reproductive incompatibility between closely related species. We also present theoretical argument and empirical evidence against extrapolating the results of within-species analysis to interpret the genetic basis of species differences. The implications of this model on the theories of evolution of species differences and the attempt to understand the mechanisms of hybrid sterility/inviability at the molecular level are discussed.

The complete genome sequence of a south Indian isolate of Rice tungro spherical virus reveals evidence of genetic recombination between distinct isolates.

Science.gov (United States)

Sailaja, B; Anjum, Najreen; Patil, Yogesh K; Agarwal, Surekha; Malathi, P; Krishnaveni, D; Balachandran, S M; Viraktamath, B C; Mangrauthia, Satendra K

2013-12-01

In this study, complete genome of a south Indian isolate of Rice tungro spherical virus (RTSV) from Andhra Pradesh (AP) was sequenced, and the predicted amino acid sequence was analysed. The RTSV RNA genome consists of 12,171 nt without the poly(A) tail, encoding a putative typical polyprotein of 3,470 amino acids. Furthermore, cleavage sites and sequence motifs of the polyprotein were predicted. Multiple alignment with other RTSV isolates showed a nucleotide sequence identity of 95% to east Indian isolates and 90% to Philippines isolates. A phylogenetic tree based on complete genome sequence showed that Indian isolates clustered together, while Vt6 and PhilA isolates of Philippines formed two separate clusters. Twelve recombination events were detected in RNA genome of RTSV using the Recombination Detection Program version 3. Recombination analysis suggested significant role of 5' end and central region of genome in virus evolution. Further, AP and Odisha isolates appeared as important RTSV isolates involved in diversification of this virus in India through recombination phenomenon. The new addition of complete genome of first south Indian isolate provided an opportunity to establish the molecular evolution of RTSV through recombination analysis and phylogenetic relationship.

Thyroid hormone actions on male reproductive system of teleost fish.

Science.gov (United States)

Tovo-Neto, Aldo; da Silva Rodrigues, Maira; Habibi, Hamid R; Nóbrega, Rafael Henrique

2018-04-17

Thyroid hormones (THs) play important roles in the regulation of many biological processes of vertebrates, such as growth, metabolism, morphogenesis and reproduction. An increasing number of studies have been focused on the involvement of THs in the male reproductive system of vertebrates, in particular of fish. Therefore, this mini-review aims to summarize the main findings on THs role in male reproductive system of fish, focusing on sex differentiation, testicular development and spermatogenesis. The existing data in the literature have demonstrated that THs exert their roles at the different levels of the hypothalamic-pituitary-gonadal (HPG) axis. In general a positive correlation has been shown between THs and fish reproductive status; where THs are associated with testicular development, growth and maturation. Recently, the molecular mechanisms underlying the role of THs in spermatogenesis have been unraveled in zebrafish testis. THs promote germ cell proliferation and differentiation by increasing a stimulatory growth factor of spermatogenesis produced by Sertoli cells. In addition, THs enhanced the gonadotropin-induced androgen release in zebrafish testis. Next to their functions in the adult testis, THs are involved in the gonadal sex differentiation through modulating sex-related gene expression, and testicular development via regulation of Sertoli cell proliferation. In conclusion, this mini-review showed that THs modulate the male reproductive system during the different life stages of fish. The physiological and molecular mechanisms showed a link between the thyroid and reproduction, suggesting a possibly co-evolution and interdependence of these two systems. Copyright © 2018 Elsevier Inc. All rights reserved.

Reproduction and biochemical responses in Enchytraeus albidus (Oligochaeta) to zinc or cadmium exposures

Energy Technology Data Exchange (ETDEWEB)

Novais, Sara C., E-mail: sara.novais@ua.pt [CESAM and Department of Biology, University of Aveiro, 3810-193 Aveiro (Portugal); Gomes, Susana I.L. [CESAM and Department of Biology, University of Aveiro, 3810-193 Aveiro (Portugal); Gravato, Carlos [CIIMAR-Centro Interdisciplinar de Investigacao Marinha e Ambiental, Laboratorio de Ecotoxicologia e Ecologia, Universidade do Porto, Rua dos Bragas, 289, 4050-123 Porto (Portugal); Guilhermino, Lucia [CIIMAR-Centro Interdisciplinar de Investigacao Marinha e Ambiental, Laboratorio de Ecotoxicologia e Ecologia, Universidade do Porto, Rua dos Bragas, 289, 4050-123 Porto (Portugal); ICBAS-Instituto de Ciencias Biomedicas Abel Salazar, Departamento de Estudos de Populacoes, Laboratorio de Ecotoxicologia, Universidade do Porto, Porto (Portugal); De Coen, Wim [University of Antwerp, Department of Biology - E.B.T., Groenenborgerlaan 171 - U.7., B-2020 Antwerp (Belgium); Soares, Amadeu M.V.M.; Amorim, Monica J.B. [CESAM and Department of Biology, University of Aveiro, 3810-193 Aveiro (Portugal)

2011-07-15

To better understand chemical modes of action, emphasis has been given to stress responses at lower levels of biological organization. Cholinesterases and antioxidant defenses are among the most used biomarkers due to their crucial role in the neurocholinergic transmission and in cell homeostasis preventing DNA damage, enzymatic inactivation and lipid peroxidation. The main goal of this study was to investigate the effects of zinc and cadmium on survival and reproduction of E. albidus and to assess metals oxidative stress potential and neurotoxic effects at concentrations that affected reproduction. Both metals affected the enchytraeids' survival and reproduction and induced significant changes in the antioxidant defenses as well as increased lipid peroxidation, indicating oxidative damage. This study demonstrates that determining effects at different levels of biological organization can give better information on the physiological responses of enchytraeids in metal contamination events and further unravel the mechanistic processes dealing with metal stress. - Highlights: > Zinc and cadmium influence the survival and reproduction of Enchytraeus albidus. > Oxidative stress and membrane damage occur at reproduction effect concentrations. > Glutathione seems to be important in the antioxidant defense against metals. > Time intervals (2, 4, 8 days) allowed following the evolution of oxidative events. - Zinc and cadmium cause oxidative stress and membrane damage in Enchytraeus albidus at reproduction effect concentrations.

Reproduction and biochemical responses in Enchytraeus albidus (Oligochaeta) to zinc or cadmium exposures

International Nuclear Information System (INIS)

Novais, Sara C.; Gomes, Susana I.L.; Gravato, Carlos; Guilhermino, Lucia; De Coen, Wim; Soares, Amadeu M.V.M.; Amorim, Monica J.B.

2011-01-01

To better understand chemical modes of action, emphasis has been given to stress responses at lower levels of biological organization. Cholinesterases and antioxidant defenses are among the most used biomarkers due to their crucial role in the neurocholinergic transmission and in cell homeostasis preventing DNA damage, enzymatic inactivation and lipid peroxidation. The main goal of this study was to investigate the effects of zinc and cadmium on survival and reproduction of E. albidus and to assess metals oxidative stress potential and neurotoxic effects at concentrations that affected reproduction. Both metals affected the enchytraeids' survival and reproduction and induced significant changes in the antioxidant defenses as well as increased lipid peroxidation, indicating oxidative damage. This study demonstrates that determining effects at different levels of biological organization can give better information on the physiological responses of enchytraeids in metal contamination events and further unravel the mechanistic processes dealing with metal stress. - Highlights: → Zinc and cadmium influence the survival and reproduction of Enchytraeus albidus. → Oxidative stress and membrane damage occur at reproduction effect concentrations. → Glutathione seems to be important in the antioxidant defense against metals. → Time intervals (2, 4, 8 days) allowed following the evolution of oxidative events. - Zinc and cadmium cause oxidative stress and membrane damage in Enchytraeus albidus at reproduction effect concentrations.

Experimental evidence of population differences in reproductive investment conditional on environmental stochasticity

Energy Technology Data Exchange (ETDEWEB)

Gauthey, Zoé [INRA, UMR 1224, Ecologie Comportementale et Biologie des Populations de Poissons, Aquapôle, quartier Ibarron, 64310 Saint-Pée sur Nivelle (France); Univ Pau & Pays Adour, UMR 1224, Ecologie Comportementale et Biologie des Populations de Poissons, UFR Sciences et Techniques de la Côte Basque, Allée du parc Montaury, 64600 Anglet (France); Panserat, Stéphane [INRA, UR 107, Nutrition Metabolism Aquaculture, Aquapôle, 64310 Saint Pée sur Nivelle (France); Elosegi, Arturo [Faculty of Science and Technology, University of the Basque Country UPV/EHU, 48080 Bilbao (Spain); Herman, Alexandre [INRA, UR 107, Nutrition Metabolism Aquaculture, Aquapôle, 64310 Saint Pée sur Nivelle (France); Tentelier, Cédric [INRA, UMR 1224, Ecologie Comportementale et Biologie des Populations de Poissons, Aquapôle, quartier Ibarron, 64310 Saint-Pée sur Nivelle (France); Univ Pau & Pays Adour, UMR 1224, Ecologie Comportementale et Biologie des Populations de Poissons, UFR Sciences et Techniques de la Côte Basque, Allée du parc Montaury, 64600 Anglet (France); and others

2016-01-15

Environmental stochasticity is expected to shape life histories of species, wherein organisms subjected to strong environmental variation should display adaptive response by being able to tune their reproductive investment. For riverine ecosystems, climate models forecast an increase in the frequency and intensity of extreme events such as floods and droughts. The speed and the mechanisms by which organisms may adapt their reproductive investment are therefore of primary importance to understand how species will cope with such radical environmental changes. In the present study, we sampled spawners from two different populations of wild brown trout, originating from two environments with contrasting levels of flow stochasticity. We placed them in sympatry within an experimental channel during reproductive season. In one modality, water flow was maintained constant, whereas in another modality, water flow was highly variable. Reproductive investment of all individuals was monitored using weight and energetic plasma metabolite variation throughout the reproductive season. Only the populations originating from the most variable environment showed a plastic response to experimental manipulation of water flow, the females being able to reduce their weight variation (from 19.2% to 13.1%) and metabolites variations (from 84.2% to 18.6% for triglycerides for instance) under variable flow conditions. These results imply that mechanisms to cope with environmental stochasticity can differ between populations of the same species, where some populations can be plastic whereas other cannot. - Highlights: • We place two populations of brown trout under contrasting water flow for reproduction. • Energetic metabolite variation is used as a cue of reproductive investment. • In constant flow, both populations show the same reproductive investment. • In variable flow, only one of the populations modifies its reproductive investment. • Divergent evolution of reproductive

Experimental evidence of population differences in reproductive investment conditional on environmental stochasticity

International Nuclear Information System (INIS)

Gauthey, Zoé; Panserat, Stéphane; Elosegi, Arturo; Herman, Alexandre; Tentelier, Cédric

2016-01-01

Environmental stochasticity is expected to shape life histories of species, wherein organisms subjected to strong environmental variation should display adaptive response by being able to tune their reproductive investment. For riverine ecosystems, climate models forecast an increase in the frequency and intensity of extreme events such as floods and droughts. The speed and the mechanisms by which organisms may adapt their reproductive investment are therefore of primary importance to understand how species will cope with such radical environmental changes. In the present study, we sampled spawners from two different populations of wild brown trout, originating from two environments with contrasting levels of flow stochasticity. We placed them in sympatry within an experimental channel during reproductive season. In one modality, water flow was maintained constant, whereas in another modality, water flow was highly variable. Reproductive investment of all individuals was monitored using weight and energetic plasma metabolite variation throughout the reproductive season. Only the populations originating from the most variable environment showed a plastic response to experimental manipulation of water flow, the females being able to reduce their weight variation (from 19.2% to 13.1%) and metabolites variations (from 84.2% to 18.6% for triglycerides for instance) under variable flow conditions. These results imply that mechanisms to cope with environmental stochasticity can differ between populations of the same species, where some populations can be plastic whereas other cannot. - Highlights: • We place two populations of brown trout under contrasting water flow for reproduction. • Energetic metabolite variation is used as a cue of reproductive investment. • In constant flow, both populations show the same reproductive investment. • In variable flow, only one of the populations modifies its reproductive investment. • Divergent evolution of reproductive

Evolution and plasticity: Divergence of song discrimination is faster in birds with innate song than in song learners in Neotropical passerine birds.

Science.gov (United States)

Freeman, Benjamin G; Montgomery, Graham A; Schluter, Dolph

2017-09-01

Plasticity is often thought to accelerate trait evolution and speciation. For example, plasticity in birdsong may partially explain why clades of song learners are more diverse than related clades with innate song. This "song learning" hypothesis predicts that (1) differences in song traits evolve faster in song learners, and (2) behavioral discrimination against allopatric song (a proxy for premating reproductive isolation) evolves faster in song learners. We tested these predictions by analyzing acoustic traits and conducting playback experiments in allopatric Central American sister pairs of song learning oscines (N = 42) and nonlearning suboscines (N = 27). We found that nonlearners evolved mean acoustic differences slightly faster than did leaners, and that the mean evolutionary rate of song discrimination was 4.3 times faster in nonlearners than in learners. These unexpected results may be a consequence of significantly greater variability in song traits in song learners (by 54-79%) that requires song-learning oscines to evolve greater absolute differences in song before achieving the same level of behavioral song discrimination as nonlearning suboscines. This points to "a downside of learning" for the evolution of species discrimination, and represents an important example of plasticity reducing the rate of evolution and diversification by increasing variability. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

Does gene flow constrain adaptive divergence or vice versa? A test using ecomorphology and sexual isolation in Timema cristinae walking-sticks.

Science.gov (United States)

Nosil, P; Crespi, B J

2004-01-01

Population differentiation often reflects a balance between divergent natural selection and the opportunity for homogenizing gene flow to erode the effects of selection. However, during ecological speciation, trait divergence results in reproductive isolation and becomes a cause, rather than a consequence, of reductions in gene flow. To assess both the causes and the reproductive consequences of morphological differentiation, we examined morphological divergence and sexual isolation among 17 populations of Timema cristinae walking-sticks. Individuals from populations adapted to using Adenostoma as a host plant tended to exhibit smaller overall body size, wide heads, and short legs relative to individuals using Ceonothus as a host. However, there was also significant variation in morphology among populations within host-plant species. Mean trait values for each single population could be reliably predicted based upon host-plant used and the potential for homogenizing gene flow, inferred from the size of the neighboring population using the alternate host and mitochondrial DNA estimates of gene flow. Morphology did not influence the probability of copulation in between-population mating trials. Thus, morphological divergence is facilitated by reductions in gene flow, but does not cause reductions in gene flow via the evolution of sexual isolation. Combined with rearing data indicating that size and shape have a partial genetic basis, evidence for parallel origins of the host-associated forms, and inferences from functional morphology, these results indicate that morphological divergence in T. cristinae reflects a balance between the effects of host-specific natural selection and gene flow. Our findings illustrate how data on mating preferences can help determine the causal associations between trait divergence and levels of gene flow.

Male Reproductive Toxicology: Environmental Exposures vs Reproductive Competence

Science.gov (United States)

Like the lecture this chapter begins with an overview of male reproductive biology and transitions into male reproductive toxicology. It ends with a brief discussion of the strengths and weaknesses in male reproductive toxicology and epidemiology today. This chapter is highly il...

Female reproductive disorders

DEFF Research Database (Denmark)

Crain, D Andrew; Janssen, Sarah J; Edwards, Thea M

2008-01-01

To evaluate the possible role of endocrine-disrupting compounds (EDCs) on female reproductive disorders emphasizing developmental plasticity and the complexity of endocrine-dependent ontogeny of reproductive organs. Declining conception rates and the high incidence of female reproductive disrupti......To evaluate the possible role of endocrine-disrupting compounds (EDCs) on female reproductive disorders emphasizing developmental plasticity and the complexity of endocrine-dependent ontogeny of reproductive organs. Declining conception rates and the high incidence of female reproductive...... disruptions warrant evaluation of the impact of EDCs on female reproductive health....

A model for estimating the minimum number of offspring to sample in studies of reproductive success.

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Anderson, Joseph H; Ward, Eric J; Carlson, Stephanie M

2011-01-01

Molecular parentage permits studies of selection and evolution in fecund species with cryptic mating systems, such as fish, amphibians, and insects. However, there exists no method for estimating the number of offspring that must be assigned parentage to achieve robust estimates of reproductive success when only a fraction of offspring can be sampled. We constructed a 2-stage model that first estimated the mean (μ) and variance (v) in reproductive success from published studies on salmonid fishes and then sampled offspring from reproductive success distributions simulated from the μ and v estimates. Results provided strong support for modeling salmonid reproductive success via the negative binomial distribution and suggested that few offspring samples are needed to reject the null hypothesis of uniform offspring production. However, the sampled reproductive success distributions deviated significantly (χ(2) goodness-of-fit test p value reproductive success distribution at rates often >0.05 and as high as 0.24, even when hundreds of offspring were assigned parentage. In general, reproductive success patterns were less accurate when offspring were sampled from cohorts with larger numbers of parents and greater variance in reproductive success. Our model can be reparameterized with data from other species and will aid researchers in planning reproductive success studies by providing explicit sampling targets required to accurately assess reproductive success.

Uncertain pollination environment promotes the evolution of a stable mixed reproductive system in the self-incompatible Hypochaeris salzmanniana (Asteraceae).

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Arista, M; Berjano, R; Viruel, J; Ortiz, M Á; Talavera, M; Ortiz, P L

2017-09-01

The transition from outcrossing to selfing is a repeated pattern in angiosperm diversification and according to general theory this transition should occur quickly and mixed reproductive systems should be infrequent. However, a large proportion of flowering plants have mixed reproductive systems, even showing inbreeding depression. Recently, several theoretical studies have shown that mixed mating systems can be stable, but empirical studies supporting these assumptions are still scarce. Hypochaeris salzmanniana, an annual species with populations differing in their self-incompatibility expression, was used as a study case to assess the stability of its mixed reproductive system. Here a descriptive study of the pollination environment was combined with measurements of the stability of the self-incompatibility system, outcrossing rate, reproductive assurance and inbreeding depression in four populations for two consecutive years. The reproductive system of populations exhibited a geographical pattern: the proportion of plants decreased from west to east. Pollinator environment also varied geographically, being less favourable from west to east. The self-incompatibility expression of some populations changed markedly in only one year. After selfing, progeny was mainly self-compatible, while after outcrossing both self-incompatible and self-compatible plants were produced. In general, both reproductive assurance and high inbreeding depression were found in all populations and years. The lowest values of inbreeding depression were found in 2014 in the easternmost populations, which experienced a marked increase in self-compatibility in 2015. The mixed reproductive system of H. salzmanniana seems to be an evolutionarily stable strategy, with selfing conferring reproductive assurance when pollinator attendance is low, but strongly limited by inbreeding depression. The fact that the highest frequencies of self-compatible plants appeared in the environments most

Variations upon a theme: Australian lizards provide insights into the endocrine control of vertebrate reproductive cycles.

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Jones, Susan M

2017-04-01

Australian lizards exhibit a broad array of different reproductive strategies and provide an extraordinary diversity and range of models with which to address fundamental problems in reproductive biology. Studies on lizards have frequently led to new insights into hormonal regulatory pathways or mechanisms of control, but we have detailed knowledge of the reproductive cycle in only a small percentage of known species. This review provides an overview and synthesis of current knowledge of the hormonal control of reproductive cycles in Australian lizards. Agamid lizards have provided useful models with which to test hypotheses about the hormonal regulation of the expression of reproductive behaviors, while research on viviparous skinks is providing insights into the evolution of the endocrine control of gestation. However, in order to better understand the potential risks that environmental factors such as climate change and endocrine disrupting chemicals pose to our fauna, better knowledge is required of the fundamental characteristics of the reproductive cycle in a broader range of lizard species. Copyright © 2015 Elsevier Inc. All rights reserved.

Reversion of a live porcine reproductive and respiratory syndrome virus vaccine investigated by parallel mutations

DEFF Research Database (Denmark)

Nielsen, Henriette S.; Oleksiewicz, M.B.; Forsberg, R.

2001-01-01

A live attenuated porcine reproductive and respiratory syndrome (PRRS) vaccine virus has been shown to revert to virulence under field conditions. In order to identify genetic virulence determinants, ORF1 from the attenuated vaccine virus and three Danish vaccine-derived field isolates was sequen......A live attenuated porcine reproductive and respiratory syndrome (PRRS) vaccine virus has been shown to revert to virulence under field conditions. In order to identify genetic virulence determinants, ORF1 from the attenuated vaccine virus and three Danish vaccine-derived field isolates...... in the vaccine virus sequence during cell-culture adaptation. Evaluation of the remaining mutations in the ORF1 sequence revealed stronger selective pressure for amino acid conservation during spread in pigs than during vaccine production. Furthermore, it was found that the selective pressure did not change...

The impact of parental investment on lifetime reproductive success in Iceland.

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Lynch, Robert F; Lynch, Emily C

2017-01-01

Demonstrating the impact that parents have on the fitness of their children is a crucial step towards understanding how parental investment has affected human evolution. Parents not only transfer genes to their children, they also influence their environments. By analyzing reproductive patterns within and between different categories of close relatives, this study provides insight into the genetic and environmental effects that parents have on the fitness of their offspring. We use data spanning over two centuries from an exceptionally accurate Icelandic genealogy, Íslendingabók, to analyze the relationship between the fertility rates of close relatives. Also, using genetic data, we determine narrow sense heritability estimates ( h 2 ) to further explore the genetic impact on lifetime reproductive success. Finally, we construct four simulations to model the expected contribution of genes and resources on reproductive success. The relationship between the reproduction of all full sibling pairs was significant and positive across all birth decades ( r  = 0.19) while the reproductive relationship between parents and offspring was often negative across many decades and undetectable overall ( r  = 0.00) (Fig. 1 and Table 1). Meanwhile, genetic data among 8,456 pairs of full siblings revealed a narrow sense heritability estimate ( h 2 ) of 0.00 for lifetime reproductive success. A resources model (following the rule that resources are transmitted from parents to children, distributed equally among siblings, and are the only factor affecting reproductive success) revealed a similar trend: a negative relationship between parent and offspring reproduction ( r  =  - 0.35) but a positive relationship among full siblings ( r  = 0.28). The relationship between parent and offspring lifetime reproductive success (LRS) and full sibling LRS was strongly and positively correlated across time ( r  = 0.799, p  investment has had an important impact on fitness. Overall

Generation of an infectious clone of VR-2332, a highly virulent North American type isolate of porcine reproductive and respiratory syndrome virus

DEFF Research Database (Denmark)

Nielsen, H.S.; Liu, G.; Nielsen, Jens

2003-01-01

A full-length cDNA clone of the prototypical North American porcine reproductive and respiratory syndrome virus (PRRSV) isolate VR-2332 was assembled in the plasmid vector pOK(12). To rescue infectious virus, capped RNA was transcribed in vitro from the pOK(12) clone and transfected into BHK-21C...... cells. The supernatant from transfected monolayers were serially passaged on Marc-145 cells and porcine pulmonary alveolar macrophages. Infectious PRRSV was recovered on Marc-145 cells as well as porcine pulmonary macrophages; thus, the cloned virus exhibited the same cell tropism as the parental VR......-2332 strain. However, the cloned virus was clearly distinguishable from the parental VR-2332 strain by an engineered marker, a BstZ171 restriction site. The full-length cDNA clone had 11 nucleotide changes, 2 of which affected coding, compared to the parental VR-2332 strain. Additionally...

Reproductive Rights or Reproductive Justice? Lessons from Argentina.

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Morgan, Lynn

2015-06-11

Argentine sexual and reproductive rights activists insist on using the language and framework of "human rights," even when many reproductive rights activists in the US and elsewhere now prefer the framework of "reproductive justice." Reflecting on conversations with Argentine feminist anthropologists, social scientists, and reproductive rights activists, this paper analyzes why the Argentine movement to legalize abortion relies on the contested concept of human rights. Its conclusion that "women's rights are human rights" is a powerful claim in post-dictatorship politics where abortion is not yet legal and the full scope of women's rights has yet to be included in the government's human rights agenda. Argentine feminist human rights activists have long been attentive to the ways that social class, gender, migration, and racism intersect with reproduction. Because their government respects and responds to a human rights framework, however, they have not felt it necessary--as U.S. feminists have--to invent a new notion of reproductive justice in order to be heard. Given the increasing popularity of reproductive justice in health and human rights, the Argentine case shows that rights-based claims can still be politically useful when a State values the concept of human rights. Copyright 2015 Morgan. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original author and source are credited.

[Infectious burdens of reproduction of female dogs].

Science.gov (United States)

Wendt, K; Stellmacher, H

1996-02-01

The results of gynecological investigations in 142 bitches were evaluated and the complexity of infectious affections is discussed. High proportions of infectious cases were found in cases of limitation of fertility (67.5%), in vaginal discharge in the estrus (60.8%), in cases of mastitis/pseudopregnancy (61.5%) and in mortality of newborn puppies. St. aureus and E. coli were often isolated. There is a high etiological correlation in epidemiology of diseases of the reproductive tract in the single bitch and especially in kennel bitches.

Diverse modes of reproduction in the marine free-living ciliate Glauconema trihymene

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Zufall Rebecca A

2010-04-01

Full Text Available Abstract Background Most free-living ciliates reproduce by equal fission or budding during vegetative growth. In certain ciliates, reproduction occurs inside the cyst wall, viz. reproductive cysts, but more complex reproductive strategies have generally been thought to be confined to parasitic or symbiotic species, e.g. Radiophrya spp. Results In addition to equal fission, asymmetric binary division and reproductive cysts were discovered in the free-living bacterivorous scuticociliate Glauconema trihymene Thompson, 1966. Asymmetric division is an innate physiological state that can be induced by sufficient food, and the higher the food concentration, the longer the asymmetric division persists. During asymmetric division, nuclear and somatic structures divide with transiently arrested cytokinesis and variable positioning of macronuclei. Phylogenetic analysis, based on the small subunit of ribosomal DNA (SSU rDNA sequences, showed that the G. trihymene isolate studied here nests with typical scuticociliates and is paraphyletic to both the symbiotic apostome and astome ciliates, some of which also produce progeny by asymmetric division. Conclusions The asymmetric division in G. trihymene has no precedent among undisturbed free-living ciliates. The coexistence of multiple modes of reproduction may represent a previously undescribed reproductive strategy for ciliates living on food patches in coastal waters. This may also be indicative of similar reproductive strategies among other polyphenic ciliates, which have not been intensively studied. Asymmetric division provides a special opportunity for studying ciliates' phenotypic plasticity and may also illuminate the origins of multicellularity.

Land inheritance establishes sibling competition for marriage and reproduction in rural Ethiopia.

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Gibson, Mhairi A; Gurmu, Eshetu

2011-02-08

Intergenerational transfer of wealth has been proposed as playing a pivotal role in the evolution of human sibling relationships. Sibling rivalry is assumed to be more marked when offspring compete for limited heritable resources, which are crucial for reproductive success (e.g., land and livestock); whereas in the absence of heritable wealth, related siblings may cooperate. To date, comparative studies undertaken to support this evolutionary assumption have been confounded by other socioecological factors, which vary across populations, e.g., food sharing and intergroup conflict. In this article we explore effects of sibling competition and cooperation for agricultural resources, marriage, and reproduction in one contemporary Ethiopian agropastoralist society. Here recent changes in land tenure policy, altering transfers of land from parents to offspring, present a unique framework to test the importance of intergenerational transfers of wealth in driving sibling competition, while controlling for socioeconomic biases. In households where land is inherited, the number of elder brothers reduces a man's agricultural productivity, marriage, and reproductive success, as resources diminish and competition increases with each additional sibling. Where land is not inherited (for males receiving land directly from the government and all females) older siblings do not have a competitive effect and in some instances may be beneficial. This study has wider implications for the evolution of human family sizes. Recent changes in wealth transfers, which have driven sibling competition, may be contributing to an increased desire for smaller family sizes.

Endosymbiont-dependent host reproduction maintains bacterial-fungal mutualism.

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Partida-Martinez, Laila P; Monajembashi, Shamci; Greulich, Karl-Otto; Hertweck, Christian

2007-05-01

Bacterial endosymbionts play essential roles for many organisms, and thus specialized mechanisms have evolved during evolution that guarantee the persistence of the symbiosis during or after host reproduction. The rice seedling blight fungus Rhizopus microsporus represents a unique example of a mutualistic life form in which a fungus harbors endobacteria (Burkholderia sp.) for the production of a phytotoxin. Here we report the unexpected observation that in the absence of endosymbionts, the host is not capable of vegetative reproduction. Formation of sporangia and spores is restored only upon reintroduction of endobacteria. To monitor this process, we succeeded in GFP labeling cultured endosymbionts. We also established a laserbeam transformation technique for the first controlled introduction of bacteria into fungi to observe their migration to the tips of the aseptate hyphae. The persistence of this fungal-bacterial mutualism through symbiont-dependent sporulation is intriguing from an evolutionary point of view and implies that the symbiont produces factors that are essential for the fungal life cycle. Reproduction of the host has become totally dependent on endofungal bacteria, which in return provide a highly potent toxin for defending the habitat and accessing nutrients from decaying plants. This scenario clearly highlights the significance for a controlled maintenance of this fungal-bacterial symbiotic relationship.

A role for a neo-sex chromosome in stickleback speciation

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Kitano, Jun; Ross, Joseph A.; Mori, Seiichi; Kume, Manabu; Jones, Felicity C.; Chan, Yingguang F.; Absher, Devin M.; Grimwood, Jane; Schmutz, Jeremy; Myers, Richard M.; Kingsley, David M.; Peichel, Catherine L.

2009-01-01

Sexual antagonism, or conflict between the sexes, has been proposed as a driving force in both sex chromosome turnover and speciation. Although closely related species often have different sex chromosome systems, it is unknown whether sex chromosome turnover contributes to the evolution of reproductive isolation between species. In this study, we show that a newly evolved sex chromosome harbours genes that contribute to speciation in threespine stickleback fish (Gasterosteus aculeatus). We first identified a neo-sex chromosome system found only in one member of a sympatric species pair in Japan. We then performed genetic linkage mapping of male-specific traits important for reproductive isolation between the Japanese species pair. The neo-X chromosome harbours loci for male courtship display traits that contribute to behavioural isolation, while the ancestral X chromosome contains loci for both behavioural isolation and hybrid male sterility. Our work not only provides strong evidence for a large-X effect on reproductive isolation in a vertebrate system, but also provides direct evidence that a young neo-X chromosome contributes to reproductive isolation between closely related species. Our data suggest that sex chromosome turnover might play a greater role in speciation than previously appreciated. PMID:19783981

Genomic Conflicts that Cause Pollen Mortality and Raise Reproductive Barriers in Arabidopsis thaliana.

Science.gov (United States)

Simon, Matthieu; Durand, Stéphanie; Pluta, Natacha; Gobron, Nicolas; Botran, Lucy; Ricou, Anthony; Camilleri, Christine; Budar, Françoise

2016-07-01

Species differentiation and the underlying genetics of reproductive isolation are central topics in evolutionary biology. Hybrid sterility is one kind of reproductive barrier that can lead to differentiation between species. Here, we analyze the complex genetic basis of the intraspecific hybrid male sterility that occurs in the offspring of two distant natural strains of Arabidopsis thaliana, Shahdara and Mr-0, with Shahdara as the female parent. Using both classical and quantitative genetic approaches as well as cytological observation of pollen viability, we demonstrate that this particular hybrid sterility results from two causes of pollen mortality. First, the Shahdara cytoplasm induces gametophytic cytoplasmic male sterility (CMS) controlled by several nuclear loci. Second, several segregation distorters leading to allele-specific pollen abortion (pollen killers) operate in hybrids with either cytoplasm. The complete sterility of the hybrid with the Shahdara cytoplasm results from the genetic linkage of the two causes of pollen mortality, i.e., CMS nuclear determinants and pollen killers. Furthermore, natural variation at these loci in A. thaliana is associated with different male-sterility phenotypes in intraspecific hybrids. Our results suggest that the genomic conflicts that underlie segregation distorters and CMS can concurrently lead to reproductive barriers between distant strains within a species. This study provides a new framework for identifying molecular mechanisms and the evolutionary history of loci that contribute to reproductive isolation, and possibly to speciation. It also suggests that two types of genomic conflicts, CMS and segregation distorters, may coevolve in natural populations. Copyright © 2016 by the Genetics Society of America.

Branching habit and the allocation of reproductive resources in conifers.

Science.gov (United States)

Leslie, Andrew B

2012-09-01

Correlated relationships between branch thickness, branch density, and twig and leaf size have been used extensively to study the evolution of plant canopy architecture, but fewer studies have explored the impact of these relationships on the allocation of reproductive resources. This study quantifies pollen cone production in conifers, which have similar basic reproductive biology but vary dramatically in branching habit, in order to test how differences in branch diameter influence pollen cone size and the density with which they are deployed in the canopy. Measurements of canopy branch density, the number of cones per branch and cone size were used to estimate the amount of pollen cone tissues produced by 16 species in three major conifer clades. The number of pollen grains produced was also estimated using direct counts from individual pollen cones. The total amount of pollen cone tissues in the conifer canopy varied little among species and clades, although vegetative traits such as branch thickness, branch density and pollen cone size varied over several orders of magnitude. However, branching habit controls the way these tissues are deployed: taxa with small branches produce small pollen cones at a high density, while taxa with large branches produce large cones relatively sparsely. Conifers appear to invest similar amounts of energy in pollen production independent of branching habit. However, similar associations between branch thickness, branch density and pollen cone size are seen across conifers, including members of living and extinct groups not directly studied here. This suggests that reproductive features relating to pollen cone size are in large part a function of the evolution of vegetative morphology and branching habit.

Structural markers of the evolution of whey protein isolate powder during aging and effects on foaming properties.

Science.gov (United States)

Norwood, E-A; Le Floch-Fouéré, C; Briard-Bion, V; Schuck, P; Croguennec, T; Jeantet, R

2016-07-01

The market for dairy powders, including high added-value products (e.g., infant formulas, protein isolates) has increased continuously over the past decade. However, the processing and storage of whey protein isolate (WPI) powders can result in changes in their structural and functional properties. It is therefore of great importance to understand the mechanisms and to identify the structural markers involved in the aging of WPI powders to control their end use properties. This study was performed to determine the effects of different storage conditions on protein lactosylations, protein denaturation in WPI, and in parallel on their foaming and interfacial properties. Six storage conditions involving different temperatures (θ) and water activities (aw) were studied for periods of up to 12mo. The results showed that for θ≤20°C, foaming properties of powders did not significantly differ from nonaged whey protein isolates (reference), regardless of the aw. On the other hand, powders presented significant levels of denaturation/aggregation and protein modification involving first protein lactosylation and then degradation of Maillard reaction products, resulting in a higher browning index compared with the reference, starting from the early stage of storage at 60°C. These changes resulted in a higher foam density and a slightly better foam stability (whisking) at 6mo. At 40°C, powders showed transitional evolution. The findings of this study will make it possible to define maximum storage durations and to recommend optimal storage conditions in accordance with WPI powder end-use properties. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Ovarian stem cells and neo-oogenesis: A breakthrough in reproductive biology research

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S Mooyottu1

2011-04-01

Full Text Available The concept of ovarian stem cells which can replenish the ovarian reserve in postnatal mammalian females is a revolutionary breakthrough in reproductive biology. This idea overturned the central dogma existed in female reproductive physiology. Contradicting the popular belief that oogenesis does not occur in post natal life, researchers proved the existence of putative stem cells in ovary, which can supply functional follicles in post natal ovaries. Even though the idea of neo-oogenesis in postnatal ovaries in normal conditions is controversial, the isolation and manipulation of ovarian stem cells have got tremendous application in medical, veterinary and animal production fields. [Veterinary World 2011; 4(2.000: 89-91

Evolution of morphology, ontogeny and life cycles within the Crustacea Thecostraca

DEFF Research Database (Denmark)

Høeg, Jens Thorvald; Perez-Losada, M; Glenner, H

2009-01-01

metamorphosis and endoparasitism known from the Rhizocephala and strongly indicated for the Facetotecta are the result of convergent evolution. We also discuss reproductive systems, which range from separate sexes, over hermaphrodites combined with a separate male sex (androdioecy), to pure hermaphroditism...

An individual reproduction model sensitive to milk yield and body condition in Holstein dairy cows.

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Brun-Lafleur, L; Cutullic, E; Faverdin, P; Delaby, L; Disenhaus, C

2013-08-01

To simulate the consequences of management in dairy herds, the use of individual-based herd models is very useful and has become common. Reproduction is a key driver of milk production and herd dynamics, whose influence has been magnified by the decrease in reproductive performance over the last decades. Moreover, feeding management influences milk yield (MY) and body reserves, which in turn influence reproductive performance. Therefore, our objective was to build an up-to-date animal reproduction model sensitive to both MY and body condition score (BCS). A dynamic and stochastic individual reproduction model was built mainly from data of a single recent long-term experiment. This model covers the whole reproductive process and is composed of a succession of discrete stochastic events, mainly calving, ovulations, conception and embryonic loss. Each reproductive step is sensitive to MY or BCS levels or changes. The model takes into account recent evolutions of reproductive performance, particularly concerning calving-to-first ovulation interval, cyclicity (normal cycle length, prevalence of prolonged luteal phase), oestrus expression and pregnancy (conception, early and late embryonic loss). A sensitivity analysis of the model to MY and BCS at calving was performed. The simulated performance was compared with observed data from the database used to build the model and from the bibliography to validate the model. Despite comprising a whole series of reproductive steps, the model made it possible to simulate realistic global reproduction outputs. It was able to well simulate the overall reproductive performance observed in farms in terms of both success rate (recalving rate) and reproduction delays (calving interval). This model has the purpose to be integrated in herd simulation models to usefully test the impact of management strategies on herd reproductive performance, and thus on calving patterns and culling rates.

Function and evolution of microRNAs in eusocial Hymenoptera

Directory of Open Access Journals (Sweden)

Eirik eSovik

2015-05-01

Full Text Available The emergence of eusociality (true sociality in several insect lineages represents one of the most successful evolutionary adaptations in the animal kingdom in terms of species richness and global biomass. In contrast to solitary insects, eusocial insects evolved a set of unique behavioral and physiological traits such as reproductive division of labor and cooperative brood care, which likely played a major role in their ecological success. The molecular mechanisms that support the social regulation of behavior in eusocial insects, and their evolution, are mostly unknown. The recent whole-genome sequencing of several eusocial insect species set the stage for deciphering the molecular and genetic bases of eusociality, and the possible evolutionary modifications that led to it. Studies of mRNA expression patterns in the brains of diverse eusocial insect species have indicated that specific social behavioral states of individual workers and queens are often associated with particular tissue-specific transcriptional profiles. Here we discuss recent findings that highlight the role of non-coding microRNAs (miRNAs in modulating traits associated with reproductive and behavioral divisions of labor in eusocial insects. We provide bioinformatic and phylogenetic data, which suggest that some Hymenoptera-specific miRNA may have contributed to the evolution of traits important for the evolution of eusociality in this group.

The ecology and evolutionary endocrinology of reproduction in the human female.

Science.gov (United States)

Vitzthum, Virginia J

2009-01-01

Human reproductive ecology (HRE) is the study of the mechanisms that link variation in reproductive traits with variation in local habitats. Empirical and theoretical contributions from biological anthropology, physiology, and demography have established the foundation necessary for developing a comprehensive understanding, grounded in life history theory (LHT), of temporal, individual, and populational variation in women's reproductive functioning. LHT posits that natural selection leads to the evolution of mechanisms that tend to allocate resources to the competing demands of growth, reproduction, and survival such that fitness is locally maximized. (That is, among alternative allocation patterns exhibited in a population, those having the highest inclusive fitness will become more common over generational time.) Hence, strategic modulation of reproductive effort is potentially adaptive because investment in a new conception may risk one's own survival, future reproductive opportunities, and/or current offspring survival. The hypothalamic-pituitary-ovarian (HPO) axis is the principal neuroendocrine pathway by which the human female modulates reproductive functioning according to the changing conditions in her habitat. Adjustments of reproductive investment in a potential conception are manifested in temporal and individual variation in ovarian cycle length, ovulation, hormone levels, and the probability of conception. Understanding the extent and causes of adaptive and non-adaptive variation in ovarian functioning is fundamental to ascertaining the proximate and remote determinants of human reproductive patterns. In this review I consider what is known and what still needs to be learned of the ecology of women's reproductive biology, beginning with a discussion of the principal explanatory frameworks in HRE and the biometry of ovarian functioning. Turning next to empirical studies, it is evident that marked variation between cycles, women, and populations is the

Genetics of reproduction and regulation of honeybee (Apis mellifera L.) social behavior.

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Page, Robert E; Rueppell, Olav; Amdam, Gro V

2012-01-01

Honeybees form complex societies with a division of labor for reproduction, nutrition, nest construction and maintenance, and defense. How does it evolve? Tasks performed by worker honeybees are distributed in time and space. There is no central control over behavior and there is no central genome on which selection can act and effect adaptive change. For 22 years, we have been addressing these questions by selecting on a single social trait associated with nutrition: the amount of surplus pollen (a source of protein) that is stored in the combs of the nest. Forty-two generations of selection have revealed changes at biological levels extending from the society down to the level of the gene. We show how we constructed this vertical understanding of social evolution using behavioral and anatomical analyses, physiology, genetic mapping, and gene knockdowns. We map out the phenotypic and genetic architectures of food storage and foraging behavior and show how they are linked through broad epistasis and pleiotropy affecting a reproductive regulatory network that influences foraging behavior. This is remarkable because worker honeybees have reduced reproductive organs and are normally sterile; however, the reproductive regulatory network has been co-opted for behavioral division of labor.

The evolution of extreme altruism and inequality in insect societies

OpenAIRE

Ratnieks, Francis L. W.; Helanterä, Heikki

2009-01-01

In eusocial organisms, some individuals specialize in reproduction and others in altruistic helping. The evolution of eusociality is, therefore, also the evolution of remarkable inequality. For example, a colony of honeybees (Apis mellifera) may contain 50 000 females all of whom can lay eggs. But 100 per cent of the females and 99.9 per cent of the males are offspring of the queen. How did such extremes evolve? Phylogenetic analyses show that high relatedness was almost certainly necessary f...

The Evolution of Human Longevity: Toward a Biocultural Theory.

Science.gov (United States)

Mayer, Peter J.

Homo sapiens is the only extant species for which there exists a significant post-reproductive period in the normal lifespan. Explanations for the evolution of this species-specific trait are possible through "non-deterministic" theories of aging positing "wear and tear" or the failure of nature to eliminate imperfection, or…

Promoter isolation and characterization of GhAO-like1, a Gossypium hirsutum gene similar to multicopper oxidases that is highly expressed in reproductive organs.

Science.gov (United States)

Lambret-Frotté, Julia; Artico, Sinara; Muniz Nardeli, Sarah; Fonseca, Fernando; Brilhante Oliveira-Neto, Osmundo; Grossi-de-Sá, Maria Fatima; Alves-Ferreira, Marcio

2016-01-01

Cotton is one of the most economically important cultivated crops. It is the major source of natural fiber for the textile industry and an important target for genetic modification for both biotic stress and herbicide tolerance. Therefore, the characterization of genes and regulatory regions that might be useful for genetic transformation is indispensable. The isolation and characterization of new regulatory regions is of great importance to drive transgene expression in genetically modified crops. One of the major drawbacks in cotton production is pest damage; therefore, the most promising, cost-effective, and sustainable method for pest control is the development of genetically resistant cotton lines. Considering this scenario, our group isolated and characterized the promoter region of a MCO (multicopper oxidase) from Gossypium hirsutum, named GhAO-like1 (ascorbate oxidase-like1). The quantitative expression, together with the in vivo characterization of the promoter region reveals that GhAO-like1 has a flower- and fruit-specific expression pattern. The GUS activity is mainly observed in stamens, as expected considering that the GhAO-like1 regulatory sequence is enriched in cis elements, which have been characterized as a target of reproductive tissue specific transcription factors. Both histological and quantitative analyses in Arabidopsis thaliana have confirmed flower (mainly in stamens) and fruit expression of GhAO-like1. In the present paper, we isolated and characterized both in silico and in vivo the promoter region of the GhAO-like1 gene. The regulatory region of GhAO-like1 might be useful to confer tissue-specific expression in genetically modified plants.

Discovery of methylfarnesoate as the annelid brain hormone reveals an ancient role of sesquiterpenoids in reproduction.

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Schenk, Sven; Krauditsch, Christian; Frühauf, Peter; Gerner, Christopher; Raible, Florian

2016-11-29

Animals require molecular signals to determine when to divert resources from somatic functions to reproduction. This decision is vital in animals that reproduce in an all-or-nothing mode, such as bristle worms: females committed to reproduction spend roughly half their body mass for yolk and egg production; following mass spawning, the parents die. An enigmatic brain hormone activity suppresses reproduction. We now identify this hormone as the sesquiterpenoid methylfarnesoate. Methylfarnesoate suppresses transcript levels of the yolk precursor Vitellogenin both in cell culture and in vivo , directly inhibiting a central energy-costly step of reproductive maturation. We reveal that contrary to common assumptions, sesquiterpenoids are ancient animal hormones present in marine and terrestrial lophotrochozoans. In turn, insecticides targeting this pathway suppress vitellogenesis in cultured worm cells. These findings challenge current views of animal hormone evolution, and indicate that non-target species and marine ecosystems are susceptible to commonly used insect larvicides.

Little evidence for intralocus sexual conflict over the optimal intake of nutrients for life span and reproduction in the black field cricket Teleogryllus commodus.

Science.gov (United States)

Rapkin, James; Archer, C Ruth; Grant, Charles E; Jensen, Kim; House, Clarissa M; Wilson, Alastair J; Hunt, John

2017-09-01

There is often large divergence in the effects of key nutrients on life span (LS) and reproduction in the sexes, yet nutrient intake is regulated in the same way in males and females given dietary choice. This suggests that the sexes are constrained from feeding to their sex-specific nutritional optima for these traits. Here, we examine the potential for intralocus sexual conflict (IASC) over optimal protein and carbohydrate intake for LS and reproduction to constrain the evolution of sex-specific nutrient regulation in the field cricket, Teleogryllus commodus. We show clear sex differences in the effects of protein and carbohydrate intake on LS and reproduction and strong positive genetic correlations between the sexes for the regulated intake of these nutrients. However, the between-sex additive genetic covariance matrix had very little effect on the predicted evolutionary response of nutrient regulation in the sexes. Thus, IASC appears unlikely to act as an evolutionary constraint on sex-specific nutrient regulation in T. commodus. This finding is supported by clear sexual dimorphism in the regulated intake of these nutrients under dietary choice. However, nutrient regulation did not coincide with the nutritional optima for LS or reproduction in either sex, suggesting that IASC is not completely resolved in T. commodus. © 2017 The Author(s). Evolution published by Wiley Periodicals, Inc. on behalf of The Society for the Study of Evolution.

Experimental evolution of sperm competitiveness in a mammal

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Simmons Leigh W

2011-01-01

Full Text Available Abstract Background When females mate with multiple partners, sperm from rival males compete to fertilise the ova. Studies of experimental evolution have proven the selective action of sperm competition on male reproductive traits. However, while reproductive traits may evolve in response to sperm competition, this does not necessarily provide evidence that sperm competitive ability responds to selection. Indeed, a study of Drosophila failed to observe divergence in sperm competitive ability of males in lines selected for enhanced sperm offence and defence. Results Adopting the naturally polygamous house mouse (Mus domesticus as our vertebrate model, we performed an experimental evolution study and observed genetic divergence in sperm quality; males from the polygamous selection lines produced ejaculates with increased sperm numbers and greater sperm motility compared to males from the monogamous lines. Here, after 12 generations of experimental evolution, we conducted competitive matings between males from lineages evolving under sperm competition and males from lineages subject to relaxed selection. We reduced variation in paternity arising from embryo mortality by genotyping embryos in utero at 14 days gestation. Our microsatellite data revealed a significant paternity bias toward males that evolved under the selective regime of sperm competition. Conclusion We provide evidence that the sperm competitiveness phenotype can respond to selection, and show that improved sperm quality translates to greater competitive fertilisation success in house mice.

Rock Sparrow Song Reflects Male Age and Reproductive Success

DEFF Research Database (Denmark)

Nemeth, Erwin; Kempenaers, Bart; Matessi, Giuliano

2012-01-01

The evolution of mating signals is closely linked to sexual selection. Acoustic ornaments are often used as secondary sexual traits that signal the quality of the signaller. Here we show that song performance reflects age and reproductive success in the rock sparrow (Petronia petronia...... nests. Older males could be distinguished from yearlings by singing at lower rate and higher amplitudes. Our findings suggest that song rate may be used as a signal of age and together with song pitch as a signal of reproductive success in this species. Alternatively, younger and less successful males...... success. Males with higher breeding success sang at a lower rate and with a higher maximum frequency. We found also that older males gained more extra-pair young and had a higher overall breeding success, although they also differed almost significantly by having a higher loss of paternity in their own...

Isolation and evolution of labile sulfur allotropes via kinetic encapsulation in interactive porous networks

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Hakuba Kitagawa

2016-07-01

Full Text Available The isolation and characterization of small sulfur allotropes have long remained unachievable because of their extreme lability. This study reports the first direct observation of disulfur (S2 with X-ray crystallography. Sulfur gas was kinetically trapped and frozen into the pores of two Cu-based porous coordination networks containing interactive iodide sites. Stabilization of S2 was achieved either through physisorption or chemisorption on iodide anions. One of the networks displayed shape selectivity for linear molecules only, therefore S2 was trapped and remained stable within the material at room temperature and higher. In the second network, however, the S2 molecules reacted further to produce bent-S3 species as the temperature was increased. Following the thermal evolution of the S2 species in this network using X-ray diffraction and Raman spectroscopy unveiled the generation of a new reaction intermediate never observed before, the cyclo-trisulfur dication (cyclo-S32+. It is envisaged that kinetic guest trapping in interactive crystalline porous networks will be a promising method to investigate transient chemical species.

Statistical aspects of evolution under natural selection, with implications for the advantage of sexual reproduction.

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Crouch, Daniel J M

2017-10-27

The prevalence of sexual reproduction remains mysterious, as it poses clear evolutionary drawbacks compared to reproducing asexually. Several possible explanations exist, with one of the most likely being that finite population size causes linkage disequilibria to randomly generate and impede the progress of natural selection, and that these are eroded by recombination via sexual reproduction. Previous investigations have either analysed this phenomenon in detail for small numbers of loci, or performed population simulations for many loci. Here we present a quantitative genetic model for fitness, based on the Price Equation, in order to examine the theoretical consequences of randomly generated linkage disequilibria when there are many loci. In addition, most previous work has been concerned with the long-term consequences of deleterious linkage disequilibria for population fitness. The expected change in mean fitness between consecutive generations, a measure of short-term evolutionary success, is shown under random environmental influences to be related to the autocovariance in mean fitness between the generations, capturing the effects of stochastic forces such as genetic drift. Interaction between genetic drift and natural selection, due to randomly generated linkage disequilibria, is demonstrated to be one possible source of mean fitness autocovariance. This suggests a possible role for sexual reproduction in reducing the negative effects of genetic drift, thereby improving the short-term efficacy of natural selection. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mathematical models of ecology and evolution

DEFF Research Database (Denmark)

Zhang, Lai

2012-01-01

-history processes: net-assimilation mechanism of 􀀀rule and net-reproduction mechanism of size dependence using a simple model comprising a size-structured consumer Daphina and an unstructured resource alge. It is found that in contrast to the former mechanism, the latter tends to destabilize population...... dynamics but as a trade-o promotes species survival by shortening juvenile delay between birth and the onset of reproduction. Paper II compares the size-spectrum and food-web representations of communities using two traits (body size and habitat location) based unstructured population model of Lotka......) based size-structured population model, that is, interference in foraging, maintenance, survival, and recruitment. Their impacts on the ecology and evolution of size-structured populations and communities are explored. Ecologically, interference aects population demographic properties either negatively...

Female reproductive disorders

DEFF Research Database (Denmark)

Crain, D Andrew; Janssen, Sarah J; Edwards, Thea M

2008-01-01

To evaluate the possible role of endocrine-disrupting compounds (EDCs) on female reproductive disorders emphasizing developmental plasticity and the complexity of endocrine-dependent ontogeny of reproductive organs. Declining conception rates and the high incidence of female reproductive...... disruptions warrant evaluation of the impact of EDCs on female reproductive health....

Evolution of helping and harming in heterogeneous groups.

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Rodrigues, António M M; Gardner, Andy

2013-08-01

Social groups are often composed of individuals who differ in many respects. Theoretical studies on the evolution of helping and harming behaviors have largely focused upon genetic differences between individuals. However, nongenetic variation between group members is widespread in natural populations, and may mediate differences in individuals' social behavior. Here, we develop a framework to study how variation in individual quality mediates the evolution of unconditional and conditional social traits. We investigate the scope for the evolution of social traits that are conditional on the quality of the actor and/or recipients. We find that asymmetries in individual quality can lead to the evolution of plastic traits with different individuals expressing helping and harming traits within the same group. In this context, population viscosity can mediate the evolution of social traits, and local competition can promote both helping and harming behaviors. Furthermore, asymmetries in individual quality can lead to the evolution of competition-like traits between clonal individuals. Overall, we highlight the importance of asymmetries in individual quality, including differences in reproductive value and the ability to engage in successful social interactions, in mediating the evolution of helping and harming behaviors. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

Exploiting rRNA operon copy number to investigate bacterial reproductive strategies.

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Roller, Benjamin R K; Stoddard, Steven F; Schmidt, Thomas M

2016-09-12

The potential for rapid reproduction is a hallmark of microbial life, but microbes in nature must also survive and compete when growth is constrained by resource availability. Successful reproduction requires different strategies when resources are scarce and when they are abundant 1,2 , but a systematic framework for predicting these reproductive strategies in bacteria has not been available. Here, we show that the number of ribosomal RNA operons (rrn) in bacterial genomes predicts two important components of reproduction-growth rate and growth efficiency-which are favoured under contrasting regimes of resource availability 3,4 . We find that the maximum reproductive rate of bacteria doubles with a doubling of rrn copy number, and the efficiency of carbon use is inversely related to maximal growth rate and rrn copy number. We also identify a feasible explanation for these patterns: the rate and yield of protein synthesis mirror the overall pattern in maximum growth rate and growth efficiency. Furthermore, comparative analysis of genomes from 1,167 bacterial species reveals that rrn copy number predicts traits associated with resource availability, including chemotaxis and genome streamlining. Genome-wide patterns of orthologous gene content covary with rrn copy number, suggesting convergent evolution in response to resource availability. Our findings imply that basic cellular processes adapt in contrasting ways to long-term differences in resource availability. They also establish a basis for predicting changes in bacterial community composition in response to resource perturbations using rrn copy number measurements 5 or inferences 6,7 .

Mathematical modelling of decline in follicle pool during female reproductive ageing.

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Thilagam, Alagu

2016-03-01

The factors which govern the subtle links between follicle loss and mammalian female reproductive ageing remain unclear despite extensive studies undertaken to understand the critical physiological and biochemical mechanisms that underly the accelerated decline in follicle numbers in women older than 37 years. It is not certain whether there is a sole control by the ovary or whether other factors which affect ageing also intersect with the ovarian effect. There is convincing experimental evidence for an interplay of several processes that seem to influence the follicle loss-female reproductive ageing links, with specific hormones (follicle-stimulating hormone, anti-Müllerian hormone, dehydroepiandrosterone) noted to play important roles in follicular dynamics and ovarian ageing. In this work, we examine the subtle links between the rate of follicular decline with ageing and the role of hormones via a series of non-autonomous equations. Simulation results based on the time evolution of the number of ovarian follicles and biochemical changes in the ovarian environment influenced by hormone levels is compared with empirical data based on follicle loss-reproductive ageing correlation studies. © Crown copyright 2015.

Effects of exposure to short-term heat stress on male reproductive fitness in a soil arthropod.

NARCIS (Netherlands)

Zizzari, Z.V.; Ellers, J.

2011-01-01

Ambient temperature is a key environmental factor influencing a variety of aspects of the ecology and evolution of ectotherms. Reproductive traits have been suggested to be more sensitive to thermal stress than other life history traits. This study investigated the direct and indirect effects of

Conserved form and function of the germinal epithelium through 500 million years of vertebrate evolution.

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Grier, Harry J; Uribe, Mari Carmen; Lo Nostro, Fabiana L; Mims, Steven D; Parenti, Lynne R

2016-08-01

The germinal epithelium, i.e., the site of germ cell production in males and females, has maintained a constant form and function throughout 500 million years of vertebrate evolution. The distinguishing characteristic of germinal epithelia among all vertebrates, males, and females, is the presence of germ cells among somatic epithelial cells. The somatic epithelial cells, Sertoli cells in males or follicle (granulosa) cells in females, encompass and isolate germ cells. Morphology of all vertebrate germinal epithelia conforms to the standard definition of an epithelium: epithelial cells are interconnected, border a body surface or lumen, are avascular and are supported by a basement membrane. Variation in morphology of gonads, which develop from the germinal epithelium, is correlated with the evolution of reproductive modes. In hagfishes, lampreys, and elasmobranchs, the germinal epithelia of males produce spermatocysts. A major rearrangement of testis morphology diagnoses osteichthyans: the spermatocysts are arranged in tubules or lobules. In protogynous (female to male) sex reversal in teleost fishes, female germinal epithelial cells (prefollicle cells) and oogonia transform into the first male somatic cells (Sertoli cells) and spermatogonia in the developing testis lobules. This common origin of cell types from the germinal epithelium in fishes with protogynous sex reversal supports the homology of Sertoli cells and follicle cells. Spermatogenesis in amphibians develops within spermatocysts in testis lobules. In amniotes vertebrates, the testis is composed of seminiferous tubules wherein spermatogenesis occurs radially. Emerging research indicates that some mammals do not have lifetime determinate fecundity. The fact emerged that germinal epithelia occur in the gonads of all vertebrates examined herein of both sexes and has the same form and function across all vertebrate taxa. Continued study of the form and function of the germinal epithelium in vertebrates

Reproduction Symposium: developmental programming of reproductive and metabolic health.

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Padmanabhan, V; Veiga-Lopez, A

2014-08-01

Inappropriate programming of the reproductive system by developmental exposure to excess steroid hormones is of concern. Sheep are well suited for investigating developmental origin of reproductive and metabolic disorders. The developmental time line of female sheep (approximately 5 mo gestation and approximately 7 mo to puberty) is ideal for conducting sequential studies of the progression of metabolic and/or reproductive disruption from the developmental insult to manifestation of adult consequences. Major benefits of using sheep include knowledge of established critical periods to target adult defects, a rich understanding of reproductive neuroendocrine regulation, availability of noninvasive approaches to monitor follicular dynamics, established surgical approaches to obtain hypophyseal portal blood for measurement of hypothalamic hormones, and the ability to perform studies in natural setting thereby keeping behavioral interactions intact. Of importance is the ability to chronically instrument fetus and mother for determining early endocrine perturbations. Prenatal exposure of the female to excess testosterone (T) leads to an array of adult reproductive disorders that include LH excess, functional hyperandrogenism, neuroendocrine defects, multifollicular ovarian morphology, and corpus luteum dysfunction culminating in early reproductive failure. At the neuroendocrine level, all 3 feedback systems are compromised. At the pituitary level, gonadotrope (LH secretion) sensitivity to GnRH is increased. Multifollicular ovarian morphology stems from persistence of follicles as well as enhanced follicular recruitment. These defects culminate in progressive loss of cyclicity and reduced fecundity. Prenatal T excess also leads to fetal growth retardation, an early marker of adult reproductive and metabolic diseases, insulin resistance, hypertension, and behavioral deficits. Collectively, the reproductive and metabolic deficits of prenatal T-treated sheep provide proof of

Brucellosis seroprevalence in Bali cattle with reproductive failure in South Sulawesi and Brucella abortus biovar 1 genotypes in the Eastern Indonesian archipelago.

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Muflihanah, Hanah; Hatta, Mochammad; Rood, Ente; Scheelbeek, Pauline; Abdoel, Theresia H; Smits, Henk L

2013-11-26

Brucellosis is a major cause of infertility and reproductive failure in livestock. While cattle in the Eastern Indonesian archipelago suffers from reproductive problems information on bovine brucellosis in the region is fragmentary. The control of brucellosis requires a major and prolonged effort and confirmation of the infection by isolation with detailed knowledge of the spread of the infection is essential when planning a control program. Serological investigation of Brucella infection in beef cattle tended under extensive farming conditions revealed a high seroprevalence (19.3%; 95% CI, 17-22) in the compliment fixation tests. The results of a rapid and simple field test correlated well with the Rose Bengal test (kappa, 0.917) and indicated an acceptable sensitivity (87.5%) and specificity (98.1%) compared with the complement fixation test. Reproductive failure was reported for 39.0% of the cows with a loss of calves due to abortion or early death amounting to 19.3%. Past reproductive failure did not, however, correlate with seropositivity in the complement fixation test (RP = 1.21; P = 0.847). B. abortus biovar 1 was freshly isolated from the hygromas of two cows and together with thirty banked isolates collected since 1990 from different parts of Sulawesi and Timor eight related genotypes could be distinguished with one genotype being identical to that of an isolate (BfR91) from Switzerland. The Indonesian genotypes formed together with BfR91 and one African and one North American isolate a distinct branch on the B. abortus biovar 1 dendogram. Bovine brucellosis appears to be widespread in the Eastern Indonesian archipelago and calls for urgent intervention. The fresh isolation of the pathogen together with the observed high seroprevalence demonstrates the presence and frequent exposure of cattle in the area to the pathogen. The application of a rapid and simple field test for brucellosis could be very useful for the quick screening of cattle at the pen side.

Comparison of aerobic conjunctival bacterial flora in pregnant, reproductive-aged and postmenopausal women

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Melike Balikoglu-Yilmaz

2012-12-01

Full Text Available AIM: To evaluate the effect of hormonal status on aerobic conjunctival flora in women.METHODS: One hundred fifty-eight women [reproductive-aged (n=55, pregnant (n=51, and postmenopausal (n=52] who admitted to outpatient clinic of Obstetrics and Gynecology Department of Denizli State Hospital were enrolled. Age, body-mass index (BMI, obstetric history, cigarette smoking, drug usage, presence of systemic disease, and intraocular pressure (IOP were recorded for each patient. The samples were taken from the lower fornix with two culture swabs and directly incubated in culture containing 5% sheep blood, eosin-methylene blue and chocolate agar. The other swab specimen was Gram stained. All growths and microscopic results were analyzed.RESULTS: The coagulase-negative Staphylococcus was the predominant organism isolated in the conjunctival samples in both three groups. The aerobic microorganism growth rate for all isolated aerobic organisms revealed no significant change in the three groups (P >0.05. The conjunctival culture positivity rates were similar in the three groups (49% in reproductive-aged, 57% in pregnant and 58% in postmenopausal women (P >0.05. Age, IOP, BMI, gravidity, parity, cigarette smoking, drug usage, and presence of systemic diseases did not have an effect on culture positivity in three groups.CONCLUSION: Results of this study showed that conjunctival aerobic flora and bacterial colonization did not differ between reproductive-aged, pregnant and postmenopausal women.

Effect of chronic treatment with a cyclooxygenase inhibitor on reproductive parameters in male rat

International Nuclear Information System (INIS)

Saeed, S.A.; Anwar, N.; Khan, K.M.; Sarfraz, N.

2009-01-01

Indomethacin is a member of non-steroidal anti-inflammatory drugs (NSAIDs) commonly used for treatment of gout, arthritis, and other inflammatory conditions. It has been shown to inhibit ovarian prostaglandins synthesis in mammals, birds, fish and reptiles. However, the effects of its chronic administration on male reproductive functions remain largely unknown. Using rat as a model, we studied the effect of chronic treatment with indomethacin on the male reproductive system. Methods: Testosterone was measured in the serum, testicular tissue, and testicular interstitial fluid by radioimmunoassay. Moreover, we also studied the direct effect of indomethacin in vitro on luteinizing hormone stimulated testosterone secretion from the Leydig cells isolated from various treatment groups. Results: Indomethacin treatment for 50 days caused a significant but reversible decrease in prostate weight, epididymal sperm reserves and sperm motility score compared with control rats (p<0.05). In vitro stimulation of Leydig cells isolated from treated rat's testes with luteinizing hormone (250 mu IU) produced significantly reduced testosterone compared with cells from control groups (p<0.05). Furthermore, stimulatory effect of luteinizing hormone on the control Leydig cells was significantly reduced when these cells were challenged with luteinizing hormone in the presence of indomethacin, (p<0.05). Testosterone concentration in the testicular tissue and testicular interstitial fluid reduced after indomethacin treatment (p<0.05). Conclusion: Due to its significant inhibition of key reproductive hormones, indomethacin effectively inhibits reproductive functions if used on a long-term basis. In his study, we have identified potential risks in the long-term use of cyclooxygenase inhibitors. (author)

Evolution of male and female genitalia following release from sexual selection.

Science.gov (United States)

Cayetano, Luis; Maklakov, Alexei A; Brooks, Robert C; Bonduriansky, Russell

2011-08-01

Despite the key functions of the genitalia in sexual interactions and fertilization, the role of sexual selection and conflict in shaping genital traits remains poorly understood. Seed beetle (Callosobruchus maculatus) males possess spines on the intromittent organ, and females possess a thickened reproductive tract wall that also bears spines. We investigated the role of sexual selection and conflict by imposing monogamous mating on eight replicate populations of this naturally polygamous insect, while maintaining eight other populations under polygamy. To establish whether responses to mating system manipulation were robust to ecological context, we simultaneously manipulated life-history selection (early/late reproduction). Over 18-21 generations, male genital spines evolved relatively reduced length in large males (i.e., shallower static allometry) in monogamous populations. Two nonintromittent male genital appendages also evolved in response to the interaction of mating system and ecology. In contrast, no detectable evolution occurred in female genitalia, consistent with the expectation of a delayed response in defensive traits. Our results support a sexually antagonistic role for the male genital spines, and demonstrate the evolution of static allometry in response to variation in sexual selection opportunity. We argue that further advances in the study of genital coevolution will require a much more detailed understanding of the functions of male and female genital traits. © 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.

Reproductive system abnormalities in Schistosoma mansoni adult worms isolated from Nectomys squamipes (Muridae: Sigmodontinae: brightfield and confocal laser scanning microscopy analysis

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Neves Renata Heisler

2003-01-01

Full Text Available Schistosoma mansoni adult worms with genital anomalies isolated from Nectomys squamipes (Muridae: Sigmodontinae were studied by confocal laser scanning microscopy under the reflected mode. One male without testicular lobes (testicular agenesia/anorchism and two females, one with an atrophied ovary and another with 17 uterine eggs, were identified. The absence of testicular lobes occurred in a worm presenting otherwise normal male adult characteristics: tegument, tubercles and a gynaecophoric canal with spines. In both female specimens the digestive tube showed a vacuolated appearance, and the specimen with supernumerary uterine eggs exhibited a developing miracidium and an egg with a formed shell. The area of the ventral sucker was similar in both specimens however the tegument thickness, ovary and vitelline glands of the specimen with the atrophied ovary were smaller than those of the one with supernumerary eggs. These reported anomalies in the reproductive system call attention to the need to improve our understanding of genetic regulation and the possible role of environmental influences upon trematode development.

Convergent and divergent patterns of morphological differentiation provide more evidence for reproductive character displacement in a wood cricket Gryllus fultoni (Orthoptera: Gryllidae

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Choe Jae

2009-02-01

Full Text Available Abstract Background In ecological character displacement, traits involved in reproductive isolation may not evolve in arbitrary directions when changes in these traits are by-products of adaptation to an ecological niche. In reproductive character displacement, however, selection acts directly on reproductive characters to enhance the degree of reproductive isolation between sympatric populations. Thus, the direction of change in reproductive characters may be arbitrary in relation to changes in other morphological characters. We characterized both tegminal characters and characters indicative of body size in sympatric and allopatric populations of Gryllus fultoni, a species displaying character displacement in its calling song characters in areas of sympatry with G. vernalis populations, to infer the nature and direction of selection acting on reproductive and morphological characters in sympatry. Results Except for mirror area, the number of teeth in a file, and ovipositor length of G. fultoni, all male and female morphological characters in G. fultoni and G. vernalis exhibited a uniform tendency to decrease in size with increasing latitude. There was no significant variation in female morphological characters between sympatric and allopatric G. fultoni populations. However, males of sympatric and allopatric G. fultoni populations significantly differed in head width, hind femur length, and mirror area even after controlling for clinal factors. Head width and hind femur length of G. fultoni were more similar to those of G. vernalis in sympatric populations than in allopatric populations, resulting in morphological convergence of G. fultoni and G. vernalis in sympatry. However, the mirror area of G. fultoni displayed the divergent pattern in relation to the sympatric G. vernalis populations. Conclusion Divergence-enhancing selection may be acting on mirror area as well as calling song characters, whereas local adaptation or clinal effects may

The Genetic Architecture Underlying the Evolution of a Rare Piscivorous Life History Form in Brown Trout after Secondary Contact and Strong Introgression

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Arne Jacobs

2018-05-01

Full Text Available Identifying the genetic basis underlying phenotypic divergence and reproductive isolation is a longstanding problem in evolutionary biology. Genetic signals of adaptation and reproductive isolation are often confounded by a wide range of factors, such as variation in demographic history or genomic features. Brown trout (Salmo trutta in the Loch Maree catchment, Scotland, exhibit reproductively isolated divergent life history morphs, including a rare piscivorous (ferox life history form displaying larger body size, greater longevity and delayed maturation compared to sympatric benthivorous brown trout. Using a dataset of 16,066 SNPs, we analyzed the evolutionary history and genetic architecture underlying this divergence. We found that ferox trout and benthivorous brown trout most likely evolved after recent secondary contact of two distinct glacial lineages, and identified 33 genomic outlier windows across the genome, of which several have most likely formed through selection. We further identified twelve candidate genes and biological pathways related to growth, development and immune response potentially underpinning the observed phenotypic differences. The identification of clear genomic signals divergent between life history phenotypes and potentially linked to reproductive isolation, through size assortative mating, as well as the identification of the underlying demographic history, highlights the power of genomic studies of young species pairs for understanding the factors shaping genetic differentiation.

Reproductive Isolation in Hybrid Mice Due to Spermatogenesis Defects at Three Meiotic Stages

OpenAIRE

Oka, Ayako; Mita, Akihiko; Takada, Yuki; Koseki, Haruhiko; Shiroishi, Toshihiko

2010-01-01

Early in the process of speciation, reproductive failures occur in hybrid animals between genetically diverged populations. The sterile hybrid animals are often males in mammals and they exhibit spermatogenic disruptions, resulting in decreased number and/or malformation of mature sperms. Despite the generality of this phenomenon, comparative study of phenotypes in hybrid males from various crosses has not been done, and therefore the comprehensive genetic basis of the disruption is still elu...

Short-term genome evolution of Listeria monocytogenes in a non-controlled environment

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Ivy Reid A

2008-11-01

Full Text Available Abstract Background While increasing data on bacterial evolution in controlled environments are available, our understanding of bacterial genome evolution in natural environments is limited. We thus performed full genome analyses on four Listeria monocytogenes, including human and food isolates from both a 1988 case of sporadic listeriosis and a 2000 listeriosis outbreak, which had been linked to contaminated food from a single processing facility. All four isolates had been shown to have identical subtypes, suggesting that a specific L. monocytogenes strain persisted in this processing plant over at least 12 years. While a genome sequence for the 1988 food isolate has been reported, we sequenced the genomes of the 1988 human isolate as well as a human and a food isolate from the 2000 outbreak to allow for comparative genome analyses. Results The two L. monocytogenes isolates from 1988 and the two isolates from 2000 had highly similar genome backbone sequences with very few single nucleotide (nt polymorphisms (1 – 8 SNPs/isolate; confirmed by re-sequencing. While no genome rearrangements were identified in the backbone genome of the four isolates, a 42 kb prophage inserted in the chromosomal comK gene showed evidence for major genome rearrangements. The human-food isolate pair from each 1988 and 2000 had identical prophage sequence; however, there were significant differences in the prophage sequences between the 1988 and 2000 isolates. Diversification of this prophage appears to have been caused by multiple homologous recombination events or possibly prophage replacement. In addition, only the 2000 human isolate contained a plasmid, suggesting plasmid loss or acquisition events. Surprisingly, besides the polymorphisms found in the comK prophage, a single SNP in the tRNA Thr-4 prophage represents the only SNP that differentiates the 1988 isolates from the 2000 isolates. Conclusion Our data support the hypothesis that the 2000 human listeriosis

Evolution of senescence in nature: physiological evolution in populations of garter snake with divergent life histories.

Science.gov (United States)

Robert, Kylie A; Bronikowski, Anne M

2010-02-01

Evolutionary theories of aging are linked to life-history theory in that age-specific schedules of reproduction and survival determine the trajectory of age-specific mutation/selection balances across the life span and thus the rate of senescence. This is predicted to manifest at the organismal level in the evolution of energy allocation strategies of investing in somatic maintenance and robust stress responses in less hazardous environments in exchange for energy spent on growth and reproduction. Here we report experiments from long-studied populations of western terrestrial garter snakes (Thamnophis elegans) that reside in low and high extrinsic mortality environments, with evolved long and short life spans, respectively. Laboratory common-environment colonies of these two ecotypes were tested for a suite of physiological traits after control and stressed gestations. In offspring derived from control and corticosterone-treated dams, we measured resting metabolism; mitochondrial oxygen consumption, ATP and free radical production rates; and erythrocyte DNA damage and repair ability. We evaluated whether these aging biomarkers mirrored the evolution of life span and whether they were sensitive to stress. Neonates from the long-lived ecotype (1) were smaller, (2) consumed equal amounts of oxygen when corrected for body mass, (3) had DNA that damaged more readily but repaired more efficiently, and (4) had more efficient mitochondria and more efficient cellular antioxidant defenses than short-lived snakes. Many ecotype differences were enhanced in offspring derived from stress-treated dams, which supports the conclusion that nongenetic maternal effects may further impact the cellular stress defenses of offspring. Our findings reveal that physiological evolution underpins reptilian life histories and sheds light on the connectedness between stress response and aging pathways in wild-dwelling organisms.

Semen quality, reproductive hormones and fertility of men operated for hypospadias

DEFF Research Database (Denmark)

Asklund, C; Jensen, Tina Kold; Main, K M

2010-01-01

The testicular function of men previously operated for hypospadias has been sparsely investigated. Therefore, we investigated semen quality and reproductive hormones of 92 men with isolated hypospadias (IH) and 20 with hypospadias and additional genital disorders (HAGD) and compared with similar...... results from young men from the general Danish population. All participants lived the Copenhagen area of Denmark. Additionally, fertility information on 1083 men registered as operated for hypospadias was retrieved from national registries. The semen quality of men with IH did not differ from controls...... was 29.4% (p semen quality, whereas it was reduced for men with HAGD. However, reproductive hormone levels indicated a subtle impairment of testicular function also in men with IH. An observed lower number of fathers among men with hypospadias...

Multilocus genetics to reconstruct aeromonad evolution

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Roger Frédéric

2012-04-01

Full Text Available Abstract Background Aeromonas spp. are versatile bacteria that exhibit a wide variety of lifestyles. In an attempt to improve the understanding of human aeromonosis, we investigated whether clinical isolates displayed specific characteristics in terms of genetic diversity, population structure and mode of evolution among Aeromonas spp. A collection of 195 Aeromonas isolates from human, animal and environmental sources was therefore genotyped using multilocus sequence analysis (MLSA based on the dnaK, gltA, gyrB, radA, rpoB, tsf and zipA genes. Results The MLSA showed a high level of genetic diversity among the population, and multilocus-based phylogenetic analysis (MLPA revealed 3 major clades: the A. veronii, A. hydrophila and A. caviae clades, among the eleven clades detected. Lower genetic diversity was observed within the A. caviae clade as well as among clinical isolates compared to environmental isolates. Clonal complexes, each of which included a limited number of strains, mainly corresponded to host-associated subsclusters of strains, i.e., a fish-associated subset within A. salmonicida and 11 human-associated subsets, 9 of which included only disease-associated strains. The population structure was shown to be clonal, with modes of evolution that involved mutations in general and recombination events locally. Recombination was detected in 5 genes in the MLSA scheme and concerned approximately 50% of the STs. Therefore, these recombination events could explain the observed phylogenetic incongruities and low robustness. However, the MLPA globally confirmed the current systematics of the genus Aeromonas. Conclusions Evolution in the genus Aeromonas has resulted in exceptionally high genetic diversity. Emerging from this diversity, subsets of strains appeared to be host adapted and/or “disease specialized” while the A. caviae clade displayed an atypical tempo of evolution among aeromonads. Considering that A. salmonicida has been

Screening and identification of lactic acid bacteria isolated from ...

African Journals Online (AJOL)

The lactic acid bacteria (LAB) isolated from sorghum (Sorghum bicolor. L.) silage were identified during different periods of evolution of sorghum silage in west Algeria. Morphological, physiological, biochemical and technological techniques were used to characterize lactic acid bacteria isolates. A total number of 27 ...

Sex Ratio Bias Leads to the Evolution of Sex Role Reversal in Honey Locust Beetles.

Science.gov (United States)

Fritzsche, Karoline; Booksmythe, Isobel; Arnqvist, Göran

2016-09-26

The reversal of conventional sex roles was enigmatic to Darwin, who suggested that it may evolve when sex ratios are female biased [1]. Here we present direct evidence confirming Darwin's hypothesis. We investigated mating system evolution in a sex-role-reversed beetle (Megabruchidius dorsalis) using experimental evolution under manipulated sex ratios and food regimes. In female-biased populations, where reproductive competition among females was intensified, females evolved to be more attractive and the sex roles became more reversed. Interestingly, female-specific mating behavior evolved more rapidly than male-specific mating behavior. We show that sexual selection due to reproductive competition can be strong in females and can target much the same traits as in males of species with conventional mating systems. Our study highlights two central points: the role of ecology in directing sexual selection and the role that females play in mating system evolution. Copyright © 2016 Elsevier Ltd. All rights reserved.

Combined action of radiation and immobilization stress on reproductive system male rats station

International Nuclear Information System (INIS)

Vereshchako, G.G.; Chueshova, N.V.; Gorokh, G.A.; Naumov, A.D.

2015-01-01

It was studied the effect of irradiation (0.5 Gy), immobilization stress (3 hours/day for 7 days), and their combined effect on the reproductive system of male rats. The action of these factors, individually or together caused a significant imbalance quantitative composition of the spermatogenic cells in the testis tissue, marked decrease the viability of epididymal spermatozoa, and increased DNA fragmentation in them, which may result in reduced fertility of animals. Under these influences reproductive disorders save for a long time. In some cases, the effects of the combined action of irradiation and immobilization stress is significantly higher than the isolated action of each of them. (authors)

Uniparental Inheritance Promotes Adaptive Evolution in Cytoplasmic Genomes.

Science.gov (United States)

Christie, Joshua R; Beekman, Madeleine

2017-03-01

Eukaryotes carry numerous asexual cytoplasmic genomes (mitochondria and plastids). Lacking recombination, asexual genomes should theoretically suffer from impaired adaptive evolution. Yet, empirical evidence indicates that cytoplasmic genomes experience higher levels of adaptive evolution than predicted by theory. In this study, we use a computational model to show that the unique biology of cytoplasmic genomes-specifically their organization into host cells and their uniparental (maternal) inheritance-enable them to undergo effective adaptive evolution. Uniparental inheritance of cytoplasmic genomes decreases competition between different beneficial substitutions (clonal interference), promoting the accumulation of beneficial substitutions. Uniparental inheritance also facilitates selection against deleterious cytoplasmic substitutions, slowing Muller's ratchet. In addition, uniparental inheritance generally reduces genetic hitchhiking of deleterious substitutions during selective sweeps. Overall, uniparental inheritance promotes adaptive evolution by increasing the level of beneficial substitutions relative to deleterious substitutions. When we assume that cytoplasmic genome inheritance is biparental, decreasing the number of genomes transmitted during gametogenesis (bottleneck) aids adaptive evolution. Nevertheless, adaptive evolution is always more efficient when inheritance is uniparental. Our findings explain empirical observations that cytoplasmic genomes-despite their asexual mode of reproduction-can readily undergo adaptive evolution. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Armed reproductives: Evolution of the frontal gland in imagoes of Termitidae

Czech Academy of Sciences Publication Activity Database

Kutalová, Kateřina; Bourguignon, T.; Sillam-Dusses, D.; Hanus, Robert; Roisin, Y.; Šobotník, Jan

2013-01-01

Roč. 42, č. 4 (2013), s. 339-348 ISSN 1467-8039 R&D Projects: GA ČR GAP506/10/1570 Institutional support: RVO:61388963 Keywords : alate * defence * Isoptera * morphological evolution Subject RIV: CC - Organic Chemistry Impact factor: 1.826, year: 2013

Sexual conflict and the evolution of asexuality at low population densities.

Science.gov (United States)

Gerber, Nina; Kokko, Hanna

2016-10-26

Theories for the evolution of sex rarely include facultatively sexual reproduction. Sexual harassment by males is an underappreciated factor: it should at first sight increase the relative advantage of asexual reproduction by increasing the cost of sex. However, if the same females can perform either sexual or asexual life cycles, then females trying to reproduce asexually may not escape harassment. If resisting male harassment is costly, it might be beneficial for a female to accept a mating and undertake a sexual life cycle rather than 'insist' on an asexual one. We investigate the effects of sexual harassment on the maintenance of sex under different population densities. Our model shows that resisting matings pays off at low population densities, which leads to the complete extinction of males, and thus to the evolution of completely asexual populations. Facultative sex persists in a narrow range of slightly higher densities. At high densities, selection favours giving up resisting male mating attempts and thus sexual reproduction takes over. These interactions between the outcomes of sexual conflict and population density suggest an explanation for the rarity of facultative sex and also patterns of geographical parthenogenesis, where marginal environments with potentially low densities are associated with asexuality. © 2016 The Author(s).

Permeability of natural rock salt from the Waste Isolation Pilot Plant (WIPP) during damage evolution and healing

International Nuclear Information System (INIS)

Pfeifle, T.W.; Hurtado, L.D.

1998-06-01

The US Department of Energy has developed the Waste Isolation Pilot Plant (WIPP) in the bedded salt of southeastern New Mexico to demonstrate the safe disposal of radioactive transuranic wastes. Four vertical shafts provide access to the underground workings located at a depth of about 660 meters. These shafts connect the underground facility to the surface and potentially provide communication between lithologic units, so they will be sealed to limit both the release of hazardous waste from and fluid flow into the repository. The seal design must consider the potential for fluid flow through a disturbed rock zone (DRZ) that develops in the salt near the shafts. The DRZ, which forms initially during excavation and then evolves with time, is expected to have higher permeability than the native salt. The closure of the shaft openings (i.e., through salt creep) will compress the seals, thereby inducing a compressive back-stress on the DRZ. This back-stress is expected to arrest the evolution of the DRZ, and with time will promote healing of damage. This paper presents laboratory data from tertiary creep and hydrostatic compression tests designed to characterize damage evolution and healing in WIPP salt. Healing is quantified in terms of permanent reduction in permeability, and the data are used to estimate healing times based on considerations of first-order kinetics

Quantum evolution across singularities

International Nuclear Information System (INIS)

Craps, Ben; Evnin, Oleg

2008-01-01

Attempts to consider evolution across space-time singularities often lead to quantum systems with time-dependent Hamiltonians developing an isolated singularity as a function of time. Examples include matrix theory in certain singular time-dependent backgounds and free quantum fields on the two-dimensional compactified Milne universe. Due to the presence of the singularities in the time dependence, the conventional quantum-mechanical evolution is not well-defined for such systems. We propose a natural way, mathematically analogous to renormalization in conventional quantum field theory, to construct unitary quantum evolution across the singularity. We carry out this procedure explicitly for free fields on the compactified Milne universe and compare our results with the matching conditions considered in earlier work (which were based on the covering Minkowski space)

Selection and geographic isolation influence hummingbird speciation: genetic, acoustic and morphological divergence in the wedge-tailed sabrewing (Campylopterus curvipennis

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Ornelas Juan

2011-02-01

Full Text Available Abstract Background Mesoamerica is one of the most threatened biodiversity hotspots in the world, yet we are far from understanding the geologic history and the processes driving population divergence and speciation for most endemic taxa. In species with highly differentiated populations selective and/or neutral factors can induce rapid changes to traits involved in mate choice, promoting reproductive isolation between allopatric populations that can eventually lead to speciation. We present the results of genetic differentiation, and explore drift and selection effects in promoting acoustic and morphological divergence among populations of Campylopterus curvipennis, a lekking hummingbird with an extraordinary vocal variability across Mesoamerica. Results Analyses of two mitochondrial genes and ten microsatellite loci genotyped for 160 individuals revealed the presence of three lineages with no contemporary gene flow: C. c. curvipennis, C. c. excellens, and C. c. pampa disjunctly distributed in the Sierra Madre Oriental, the Tuxtlas region and the Yucatan Peninsula, respectively. Sequence mtDNA and microsatellite data were congruent with two diversification events: an old vicariance event at the Isthmus of Tehuantepec (c. 1.4 Ma, and a more recent Pleistocene split, isolating populations in the Tuxtlas region. Hummingbirds of the excellens group were larger, and those of the pampa group had shorter bills, and lineages that have been isolated the longest shared fewer syllables and differed in spectral and temporal traits of a shared syllable. Coalescent simulations showed that fixation of song types has occurred faster than expected under neutrality but the null hypothesis that morphological divergence resulted from drift was not rejected. Conclusions Our phylogeographic analyses uncovered the presence of three Mesoamerican wedge-tailed sabrewing lineages, which diverged at different time scales. These results highlight the importance of the

Whole genome sequence analysis of the first Australian OXA-48-producing outbreak-associated Klebsiella pneumoniae isolates: the resistome and in vivo evolution.

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Björn A Espedido

Full Text Available Whole genome sequencing was used to characterize the resistome of intensive care unit (ICU outbreak-associated carbapenem-resistant K. pneumoniae isolates. Importantly, and of particular concern, the carbapenem-hydrolyzing β-lactamase gene bla(OXA-48 and the extended-spectrum β-lactamase gene bla(CTX-M-14, were identified on a single broad host-range conjugative plasmid. This represents the first report of bla(OXA-48 in Australia and highlights the importance of resistance gene surveillance, as such plasmids can silently spread amongst enterobacterial populations and have the potential to drastically limit treatment options. Furthermore, the in vivo evolution of these isolates was also examined after 18 months of intra-abdominal carriage in a patient that transited through the ICU during the outbreak period. Reflecting the clonality of K. pneumoniae, only 11 single nucleotide polymorphisms (SNPs were accumulated during this time-period and many of these were associated with genes involved in tolerance/resistance to antibiotics, metals or organic solvents, and transcriptional regulation. Collectively, these SNPs are likely to be associated with changes in virulence (at least to some extent that have refined the in vivo colonization capacity of the original outbreak isolate.

Whole Genome Sequence Analysis of the First Australian OXA-48-Producing Outbreak-Associated Klebsiella pneumoniae Isolates: The Resistome and In Vivo Evolution

Science.gov (United States)

Espedido, Björn A.; Steen, Jason A.; Ziochos, Helen; Grimmond, Sean M.; Cooper, Matthew A.; Gosbell, Iain B.; van Hal, Sebastiaan J.; Jensen, Slade O.

2013-01-01

Whole genome sequencing was used to characterize the resistome of intensive care unit (ICU) outbreak-associated carbapenem-resistant K. pneumoniae isolates. Importantly, and of particular concern, the carbapenem-hydrolyzing β-lactamase gene bla OXA-48 and the extended-spectrum β-lactamase gene bla CTX-M-14, were identified on a single broad host-range conjugative plasmid. This represents the first report of bla OXA-48 in Australia and highlights the importance of resistance gene surveillance, as such plasmids can silently spread amongst enterobacterial populations and have the potential to drastically limit treatment options. Furthermore, the in vivo evolution of these isolates was also examined after 18 months of intra-abdominal carriage in a patient that transited through the ICU during the outbreak period. Reflecting the clonality of K. pneumoniae, only 11 single nucleotide polymorphisms (SNPs) were accumulated during this time-period and many of these were associated with genes involved in tolerance/resistance to antibiotics, metals or organic solvents, and transcriptional regulation. Collectively, these SNPs are likely to be associated with changes in virulence (at least to some extent) that have refined the in vivo colonization capacity of the original outbreak isolate. PMID:23555831

[Study protocol on the effect of the economic crisis on mortality and reproductive health and health inequalities in Spain].

Science.gov (United States)

Pérez, Glòria; Gotsens, Mercè; Palència, Laia; Marí-Dell'Olmo, Marc; Domínguez-Berjón, M Felicitas; Rodríguez-Sanz, Maica; Puig, Vanessa; Bartoll, Xavier; Gandarillas, Ana; Martín, Unai; Bacigalupe, Amaia; Díez, Elia; Ruiz, Miguel; Esnaola, Santiago; Calvo, Montserrat; Sánchez, Pablo; Luque Fernández, Miguel Ángel; Borrell, Carme

The aim is to present the protocol of the two sub-studies on the effect of the economic crisis on mortality and reproductive health and health inequalities in Spain. Substudy 1: describe the evolution of mortality and reproductive health between 1990 and 2013 through a longitudinal ecological study in the Autonomous Communities. This study will identify changes caused by the economic crisis in trends or reproductive health and mortality indicators using panel data (17 Autonomous Communities per study year) and adjusting Poisson models with random effects variance. Substudy 2: analyse inequalities by socioeconomic deprivation in mortality and reproductive health in several areas of Spain. An ecological study analysing trends in the pre-crisis (1999-2003 and 2004-2008) and crisis (2009-2013) periods will be performed. Random effects models Besag York and Mollié will be adjusted to estimate mortality indicators softened in reproductive health and census tracts. Copyright © 2016 SESPAS. Publicado por Elsevier España, S.L.U. All rights reserved.

Fitness prospects: effects of age, sex and recruitment age on reproductive value in a long-lived seabird.

Science.gov (United States)

Zhang, He; Rebke, Maren; Becker, Peter H; Bouwhuis, Sandra

2015-01-01

Reproductive value is an integrated measure of survival and reproduction fundamental to understanding life-history evolution and population dynamics, but little is known about intraspecific variation in reproductive value and factors explaining such variation, if any. By applying generalized additive mixed models to longitudinal individual-based data of the common tern Sterna hirundo, we estimated age-specific annual survival probability, breeding probability and reproductive performance, based on which we calculated age-specific reproductive values. We investigated effects of sex and recruitment age (RA) on each trait. We found age effects on all traits, with survival and breeding probability declining with age, while reproductive performance first improved with age before levelling off. We only found a very small, marginally significant, sex effect on survival probability, but evidence for decreasing age-specific breeding probability and reproductive performance with RA. As a result, males had slightly lower age-specific reproductive values than females, while birds of both sexes that recruited at the earliest ages of 2 and 3 years (i.e. 54% of the tern population) had somewhat higher fitness prospects than birds recruiting at later ages. While the RA effects on breeding probability and reproductive performance were statistically significant, these effects were not large enough to translate to significant effects on reproductive value. Age-specific reproductive values provided evidence for senescence, which came with fitness costs in a range of 17-21% for the sex-RA groups. Our study suggests that intraspecific variation in reproductive value may exist, but that, in the common tern, the differences are small. © 2014 The Authors. Journal of Animal Ecology © 2014 British Ecological Society.

When to care for, abandon, or eat your offspring: the evolution of parental care and filial cannibalism.

Science.gov (United States)

Klug, Hope; Bonsall, Michael B

2007-12-01

Parental care and filial cannibalism (the consumption of one's own offspring) co-occur in many animals. While parental care typically increases offspring survival, filial cannibalism involves the killing of one's young. Using an evolutionary ecology approach, we evaluate the importance of a range of factors on the evolution of parental care and filial cannibalism. Parental care, no care/total abandonment, and filial cannibalism evolved and often coexisted over a range of parameter space. While no single benefit was essential for the evolution of filial cannibalism, benefits associated with adult or offspring survival and/or reproduction facilitated the evolution of cannibalism. Our model highlights the plausibility of a range of alternative hypotheses. Specifically, the evolution of filial cannibalism was enhanced if (1) parents could selectively cannibalize lower-quality offspring, (2) filial cannibalism increased egg maturation rate, (3) energetic benefits of eggs existed, or (4) cannibalism increased a parent's reproductive rate (e.g., through mate attractiveness). Density-dependent egg survivorship alone did not favor the evolution of cannibalism. However, when egg survival was density dependent, filial cannibalism invaded more often when the density dependence was relatively more intense. Our results suggest that population-level resource competition potentially plays an important role in the evolution of both parental care and filial cannibalism.

Visual communication stimulates reproduction in Nile tilapia, Oreochromis niloticus (L.

Directory of Open Access Journals (Sweden)

A.L.S. Castro

2009-04-01

Full Text Available Reproductive fish behavior is affected by male-female interactions that stimulate physiological responses such as hormonal release and gonad development. During male-female interactions, visual and chemical communication can modulate fish reproduction. The aim of the present study was to test the effect of visual and chemical male-female interaction on the gonad development and reproductive behavior of the cichlid fish Nile tilapia, Oreochromis niloticus (L.. Fifty-six pairs were studied after being maintained for 5 days under one of the four conditions (N = 14 for each condition: 1 visual contact (V; 2 chemical contact (Ch; 3 chemical and visual contact (Ch+V; 4 no sensory contact (Iso - males and females isolated. We compared the reproductive behavior (nesting, courtship and spawning and gonadosomatic index (GSI of pairs of fish under all four conditions. Visual communication enhanced the frequency of courtship in males (mean ± SEM; V: 24.79 ± 3.30, Ch+V: 20.74 ± 3.09, Ch: 0.1 ± 0.07, Iso: 4.68 ± 1.26 events/30 min; P < 0.05, two-way ANOVA with LSD post hoc test, induced spawning in females (3 spawning in V and also 3 in Ch+V condition, and increased GSI in males (mean ± SEM; V: 1.39 ± 0.08, Ch+V: 1.21 ± 0.08, Ch: 1.04 ± 0.07, Iso: 0.82 ± 0.07%; P < 0.05, two-way ANOVA with LSD post hoc test. Chemical communication did not affect the reproductive behavior of pairs nor did it enhance the effects of visual contact. Therefore, male-female visual communication is an effective cue, which stimulates reproduction among pairs of Nile tilapia.

Parasites contribute to ecologically dependent postmating isolation in the adaptive radiation of three-spined stickleback.

Science.gov (United States)

El Nagar, Aliya; MacColl, Andrew D C

2016-08-17

Spatial variation in parasitic infections is common, and has the potential to drive population divergence and the reproductive isolation of hosts. However, despite support from theory and model laboratory systems, little strong evidence has been forthcoming from the wild. Here, we show that parasites are likely to cause reproductive isolation in the adaptive radiation of three-spined stickleback. Adjacent wild populations on the Scottish island of North Uist differ greatly and consistently in the occurrence of different parasites that have substantial effects on fitness. Laboratory-reared fish are more resistant to experimental infection by parasite species from their own population. Furthermore, hybrid backcrosses between the host populations are more resistant to parasites from the parental population to which they are more closely related. These patterns provide strong evidence that parasites can cause ecological speciation, by contributing to selection against migrants and ecologically dependent postmating isolation. © 2016 The Author(s).

Reproductive patterns among Danish women with oral clefts

DEFF Research Database (Denmark)

Yttri, Janne Elin; Christensen, Kaare; Knudsen, Lisbeth

2011-01-01

Abstract Objective: The aim of the study was to compare the reproduction pattern among Danish women born with isolated oral clefts with the Danish background population. Design and setting: A nationwide population based historic cohort-study based on three registers: The Danish Facial Cleft...... Register, The Danish Civil Registration System and the Fertility of Women and Couples Dataset. Participants: Through linkages of the registers, number of children and the exact age at childbirth of all Danish women born with an oral cleft during 1950 through 1988 (N=1,931) were obtained. These data were...

Reproductive toxicity: Male and female reproductive systems as targets for chemical injury

Energy Technology Data Exchange (ETDEWEB)

Mattison, D.R.; Plowchalk, D.R.; Meadows, M.J.; Al-Juburi, A.Z.; Gandy, J.; Malek, A. (Univ. of Arkansas for Medical Sciences, Little Rock (USA))

1990-03-01

On the basis of current knowledge of reproductive biology and toxicology, it is apparent that chemicals affecting reproduction may elicit their effects at a number of sites in both the male and the female reproductive system. This multiplicity of targets is attributable to the dynamic nature of the reproductive system, in which the hypothalamic-pituitary-gonadal axis is controlled by precise positive and negative feedback mechanisms among its components. Interference by a xenobiotic at any level in either the male or the female reproductive system may ultimately impair hypothalamic or pituitary function. Normal gonadal processes such as spermatogenesis or oogenesis, ejaculation or ovulation, hormone production by Leydig or granulosa cells, and the structure or function of the accessory reproductive structures (e.g., epididymis, fallopian tube) also appear vulnerable to xenobiotics. The reproductive system is a complex one that requires local and circulating hormones for control. This brief review illustrates a system for characterizing the mechanism of action of reproductive toxicants, as well as for defining the sites available for disruption of reproduction. Unfortunately, at present, data addressing the actual vulnerability of reproduction are sorely lacking. However, when experiments have been conducted and combined with epidemiologic data or clinical observation, it has been possible to demonstrate impairment of reproductive processes by xenobiotics. The role of environmental exposure to xenobiotics in the increase in infertility that has been observed remains to be defined. 87 references.

Evolution in action : host race formation in Galerucella nymphaeae

NARCIS (Netherlands)

Pappers, Stephanie Maria

2001-01-01

A host race is a population which is partially reproductively isolated as a direct consequence of adaptation to a certain host. For host race formation to occur five conditions should be met. First of all, the populations should occur in sympatry, which means that they co-occur within the normal

Male Reproductive System

Science.gov (United States)

... With the Male Reproductive System Print en español Sistema reproductor masculino Reproduction All living things reproduce. Reproduction — ... of Use Notice of Nondiscrimination Visit the Nemours Web site. Note: All information on KidsHealth® is for ...

A Socratic Method for Surveying Students' Readiness to Study Evolution

Science.gov (United States)

Stansfield, William D.

2013-01-01

Before beginning a series of presentations on evolution, it would be prudent to survey the general level of students' understanding of prerequisite basic concepts of reproduction, heredity, ontology, and phenotypic diversity so that teachers can avoid devoting time to well-known subjects of general knowledge and can spend more time on subjects…

Chemical Evolution and the Evolutionary Definition of Life.

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Higgs, Paul G

2017-06-01

Darwinian evolution requires a mechanism for generation of diversity in a population, and selective differences between individuals that influence reproduction. In biology, diversity is generated by mutations and selective differences arise because of the encoded functions of the sequences (e.g., ribozymes or proteins). Here, I draw attention to a process that I will call chemical evolution, in which the diversity is generated by random chemical synthesis instead of (or in addition to) mutation, and selection acts on physicochemical properties, such as hydrolysis, photolysis, solubility, or surface binding. Chemical evolution applies to short oligonucleotides that can be generated by random polymerization, as well as by template-directed replication, and which may be too short to encode a specific function. Chemical evolution is an important stage on the pathway to life, between the stage of "just chemistry" and the stage of full biological evolution. A mathematical model is presented here that illustrates the differences between these three stages. Chemical evolution leads to much larger differences in molecular concentrations than can be achieved by selection without replication. However, chemical evolution is not open-ended, unlike biological evolution. The ability to undergo Darwinian evolution is often considered to be a defining feature of life. Here, I argue that chemical evolution, although Darwinian, does not quite constitute life, and that a good place to put the conceptual boundary between non-life and life is between chemical and biological evolution.

Lessons from reproductive immunology for other fields of immunology and clinical approaches.

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Markert, Udo R; Fitzgerald, Justine S; Seyfarth, Lydia; Heinzelmann, Joana; Varosi, Frauke; Voigt, Sandra; Schleussner, Ekkehard; Seewald, Hans-Joachim

2005-01-01

Reproduction is indispensable to evolution and, thus, life. Nonetheless, it overcomes common rules known to established life. Immunology of reproduction, and especially the tolerance of two genetically distinct organisms and their fruitful symbiosis, is one of the most imposing paradox of life. Mechanisms, which are physiologically used for induction of said tolerance, are frequently abused by pathogens or tumors intending to escape the host's immune response. Understanding the regulation of immune responses in pregnancy and the invasion of allogeneic fetus-derived trophoblast cells into the decidua may lead to new therapeutic concepts. In transplantation, knowledge concerning local physiological immunotolerance may be useful for the development of new therapies, which do not require a general immune suppression of the patient. In immunological disorders, such as autoimmune diseases or allergies, immune deviations occur which are either prevented during pregnancy or have parallels to pregnancy. Vice versa, lessons from other fields of immunology may also offer new notions for the comprehension of reproductive immunology and may lead to new therapies for the treatment of pregnancy-related problems.

Invasive plants and enemy release: Evolution of trait means and trait correlations in Ulex europaeus

OpenAIRE

Hornoy , Benjamin; Tarayre , Michèle; Hervé , Maxime; Gigord , Luc; Atlan , Anne

2011-01-01

International audience; Several hypotheses that attempt to explain invasive processes are based on the fact that plants have been introduced without their natural enemies. Among them, the EICA (Evolution of Increased Competitive Ability) hypothesis is the most influential. It states that, due to enemy release, exotic plants evolve a shift in resource allocation from defence to reproduction or growth. In the native range of the invasive species Ulex europaeus, traits involved in reproduction a...

Positive selection neighboring functionally essential sites and disease-implicated regions of mammalian reproductive proteins.

LENUS (Irish Health Repository)

Morgan, Claire C

2010-01-01

ABSTRACT: BACKGROUND: Reproductive proteins are central to the continuation of all mammalian species. The evolution of these proteins has been greatly influenced by environmental pressures induced by pathogens, rival sperm, sexual selection and sexual conflict. Positive selection has been demonstrated in many of these proteins with particular focus on primate lineages. However, the mammalia are a diverse group in terms of mating habits, population sizes and germ line generation times. We have examined the selective pressures at work on a number of novel reproductive proteins across a wide variety of mammalia. RESULTS: We show that selective pressures on reproductive proteins are highly varied. Of the 10 genes analyzed in detail, all contain signatures of positive selection either across specific sites or in specific lineages or a combination of both. Our analysis of SP56 and Col1a1 are entirely novel and the results show positively selected sites present in each gene. Our findings for the Col1a1 gene are suggestive of a link between positive selection and severe disease type. We find evidence in our dataset to suggest that interacting proteins are evolving in symphony: most likely to maintain interacting functionality. CONCLUSION: Our in silico analyses show positively selected sites are occurring near catalytically important regions suggesting selective pressure to maximize efficient fertilization. In those cases where a mechanism of protein function is not fully understood, the sites presented here represent ideal candidates for mutational study. This work has highlighted the widespread rate heterogeneity in mutational rates across the mammalia and specifically has shown that the evolution of reproductive proteins is highly varied depending on the species and interacting partners. We have shown that positive selection and disease are closely linked in the Col1a1 gene.

Asymmetric dominance and asymmetric mate choice oppose premating isolation after allopatric divergence.

Science.gov (United States)

Sefc, Kristina M; Hermann, Caroline M; Steinwender, Bernd; Brindl, Hanna; Zimmermann, Holger; Mattersdorfer, Karin; Postl, Lisbeth; Makasa, Lawrence; Sturmbauer, Christian; Koblmüller, Stephan

2015-04-01

Assortative mating promotes reproductive isolation and allows allopatric speciation processes to continue in secondary contact. As mating patterns are determined by mate preferences and intrasexual competition, we investigated male-male competition and behavioral isolation in simulated secondary contact among allopatric populations. Three allopatric color morphs of the cichlid fish Tropheus were tested against each other. Dyadic male-male contests revealed dominance of red males over bluish and yellow-blotch males. Reproductive isolation in the presence of male-male competition was assessed from genetic parentage in experimental ponds and was highly asymmetric among pairs of color morphs. Red females mated only with red males, whereas the other females performed variable degrees of heteromorphic mating. Discrepancies between mating patterns in ponds and female preferences in a competition-free, two-way choice paradigm suggested that the dominance of red males interfered with positive assortative mating of females of the subordinate morphs and provoked asymmetric hybridization. Between the nonred morphs, a significant excess of negative assortative mating by yellow-blotch females with bluish males did not coincide with asymmetric dominance among males. Hence, both negative assortative mating preferences and interference of male-male competition with positive assortative preferences forestall premating isolation, the latter especially in environments unsupportive of competition-driven spatial segregation.

Has Human Evolution Stopped?

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Alan R. Templeton

2010-07-01

Full Text Available It has been argued that human evolution has stopped because humans now adapt to their environment via cultural evolution and not biological evolution. However, all organisms adapt to their environment, and humans are no exception. Culture defines much of the human environment, so cultural evolution has actually led to adaptive evolution in humans. Examples are given to illustrate the rapid pace of adaptive evolution in response to cultural innovations. These adaptive responses have important implications for infectious diseases, Mendelian genetic diseases, and systemic diseases in current human populations. Moreover, evolution proceeds by mechanisms other than natural selection. The recent growth in human population size has greatly increased the reservoir of mutational variants in the human gene pool, thereby enhancing the potential for human evolution. The increase in human population size coupled with our increased capacity to move across the globe has induced a rapid and ongoing evolutionary shift in how genetic variation is distributed within and among local human populations. In particular, genetic differences between human populations are rapidly diminishing and individual heterozygosity is increasing, with beneficial health effects. Finally, even when cultural evolution eliminates selection on a trait, the trait can still evolve due to natural selection on other traits. Our traits are not isolated, independent units, but rather are integrated into a functional whole, so selection on one trait can cause evolution to occur on another trait, sometimes with mildly maladaptive consequences.

Condition-dependent chemosignals in reproductive behavior of lizards.

Science.gov (United States)

Martín, José; López, Pilar

2015-02-01

This article is part of a Special Issue "Chemosignals and Reproduction". Many lizards have diverse glands that produce chemosignals used in intraspecific communication and that can have reproductive consequences. For example, information in chemosignals of male lizards can be used in intrasexual competition to identify and assess the fighting potential or dominance status of rival males either indirectly through territorial scent-marks or during agonistic encounters. Moreover, females of several lizard species "prefer" to establish or spend more time on areas scent-marked by males with compounds signaling a better health or body condition or a higher genetic compatibility, which can have consequences for their mating success and inter-sexual selection processes. We review here recent studies that suggest that the information content of chemosignals of lizards may be reliable because several physiological and endocrine processes would regulate the proportions of chemical compounds available for gland secretions. Because chemosignals are produced by the organism or come from the diet, they should reflect physiological changes, such as different hormonal levels (e.g. testosterone or corticosterone) or different health states (e.g. parasitic infections, immune response), and reflect the quality of the diet of an individual. More importantly, some compounds that may function as chemosignals also have other important functions in the organism (e.g. as antioxidants or regulating the immune system), so there could be trade-offs between allocating these compounds to attending physiological needs or to produce costly sexual "chemical ornaments". All these factors may contribute to maintain chemosignals as condition-dependent sexual signals, which can inform conspecifics on the characteristics and state of the sender and allow making behavioral decisions with reproductive consequences. To understand the evolution of chemical secretions of lizards as sexual signals and their

2014-2017. How medically assisted reproduction changed in Italy. A short comparative synthesis with European countries.

Science.gov (United States)

Malvasi, A; Signore, F; Napoletano, S; Bruti, V; Sestili, C; Di Luca, N M

2017-01-01

More than ten years after law n. 40 of February 19, 2004 became effective, regulation on medically assisted reproduction has dramatically changed outlook. The authors report on the steps that led to these changes through Courts' rulings, the Supreme Court's verdicts and the European Court of Human Rights' decisions, as well as ministerial regulations and guidelines concerning medically assisted reproduction. The aforementioned jurisprudential evolution was set to reach a new balance between the embryo's right to its own dignity and the woman's right to health and freedom of self-determination in reproduction. No court ruling denies that embryos have also to be safeguarded. In fact, there are still numerous prohibitions, including using embryos for experimental purposes. Judges aim primarily at avoiding that embryos' rights overcome the right to parenthood. The authors review the legislation of the various European countries: some have adopted a legislation to regulate medically assisted reproduction, while others have developed in this field some recommendations or guidelines. This is why they call for enactment of a European law governing the implementation/operational methods of medically assisted reproduction in order to avoid the scourge of procreative tourism to countries that have a more permissive law.

Evolution of sociality by natural selection on variances in reproductive fitness: evidence from a social bee.

Science.gov (United States)

Stevens, Mark I; Hogendoorn, Katja; Schwarz, Michael P

2007-08-29

The Central Limit Theorem (CLT) is a statistical principle that states that as the number of repeated samples from any population increase, the variance among sample means will decrease and means will become more normally distributed. It has been conjectured that the CLT has the potential to provide benefits for group living in some animals via greater predictability in food acquisition, if the number of foraging bouts increases with group size. The potential existence of benefits for group living derived from a purely statistical principle is highly intriguing and it has implications for the origins of sociality. Here we show that in a social allodapine bee the relationship between cumulative food acquisition (measured as total brood weight) and colony size accords with the CLT. We show that deviations from expected food income decrease with group size, and that brood weights become more normally distributed both over time and with increasing colony size, as predicted by the CLT. Larger colonies are better able to match egg production to expected food intake, and better able to avoid costs associated with producing more brood than can be reared while reducing the risk of under-exploiting the food resources that may be available. These benefits to group living derive from a purely statistical principle, rather than from ecological, ergonomic or genetic factors, and could apply to a wide variety of species. This in turn suggests that the CLT may provide benefits at the early evolutionary stages of sociality and that evolution of group size could result from selection on variances in reproductive fitness. In addition, they may help explain why sociality has evolved in some groups and not others.

The origin and evolution of the sexes: Novel insights from a distant eukaryotic linage.

Science.gov (United States)

Mignerot, Laure; Coelho, Susana M

2016-01-01

Sexual reproduction is an extraordinarily widespread phenomenon that assures the production of new genetic combinations in nearly all eukaryotic lineages. Although the core features of sexual reproduction (meiosis and syngamy) are highly conserved, the control mechanisms that determine whether an individual is male or female are remarkably labile across eukaryotes. In genetically controlled sexual systems, gender is determined by sex chromosomes, which have emerged independently and repeatedly during evolution. Sex chromosomes have been studied in only a handful of classical model organism, and empirical knowledge on the origin and evolution of the sexes is still surprisingly incomplete. With the advent of new generation sequencing, the taxonomic breadth of model systems has been rapidly expanding, bringing new ideas and fresh views on this fundamental aspect of biology. This mini-review provides a quick state of the art of how the remarkable richness of the sexual characteristics of the brown algae is helping to increase our knowledge about the evolution of sex determination. Copyright © 2016 Académie des sciences. Published by Elsevier SAS. All rights reserved.

Female Drosophila melanogaster gene expression and mate choice: the X chromosome harbours candidate genes underlying sexual isolation.

Directory of Open Access Journals (Sweden)

Richard I Bailey

2011-02-01

Full Text Available The evolution of female choice mechanisms favouring males of their own kind is considered a crucial step during the early stages of speciation. However, although the genomics of mate choice may influence both the likelihood and speed of speciation, the identity and location of genes underlying assortative mating remain largely unknown.We used mate choice experiments and gene expression analysis of female Drosophila melanogaster to examine three key components influencing speciation. We show that the 1,498 genes in Zimbabwean female D. melanogaster whose expression levels differ when mating with more (Zimbabwean versus less (Cosmopolitan strain preferred males include many with high expression in the central nervous system and ovaries, are disproportionately X-linked and form a number of clusters with low recombination distance. Significant involvement of the brain and ovaries is consistent with the action of a combination of pre- and postcopulatory female choice mechanisms, while sex linkage and clustering of genes lead to high potential evolutionary rate and sheltering against the homogenizing effects of gene exchange between populations.Taken together our results imply favourable genomic conditions for the evolution of reproductive isolation through mate choice in Zimbabwean D. melanogaster and suggest that mate choice may, in general, act as an even more important engine of speciation than previously realized.

Magneto–Thermal Evolution of Neutron Stars with Emphasis to ...

Indian Academy of Sciences (India)

The magnetic and thermal evolution of neutron stars is a very complex process with many non-linear interactions. For a decent understanding of neutron star physics, these evolutions cannot be considered isolated. A brief overview is presented, which describes the main magneto–thermal interactions that determine the fate ...

Bovine herpes virus-1 (BoHV-1 detection in dairy cattle with reproductive problems in Sudan

Directory of Open Access Journals (Sweden)

Amira Mohamed Elhassan

2015-06-01

Full Text Available The present work aimed to observe the infection pattern of Bovine herpes virus-1 (BoHV-1 in dairy cattle with reproductive problems in Sudan. A total of 140 samples comprising of vaginal swab (n=97, placenta (n=15, whole blood (n=19, uterine fluid (n=1, and serum (n=8 were collected from 16 dairy herds showing particularly high rate of abortion and infertility in Khartoum State. The samples were used for virus isolation, and were tested by Enzyme-Linked Immunosorbent Assay (ELISA and polymerase chain reaction (PCR. No virus could be isolated from the samples inoculated for isolation in cell culture. Out of 80 specimens tested by ELISA, 7 (8.75% were found to be positive, and one sample was doubtful. Using PCR, 11 (10.7% out of 103 samples were found to be positive. When comparing between two methods for DNA extraction, the DNA extracted by commercial kit was found to be better in quality as compared to the DNA extracted using phenol/chloroform/isoamyl-alcohol method. The study confirmed the presence of BoHV-1 in cattle farms with reproductive problems in Sudan.

Divergent genetic evolution of hemagglutinin in influenza A H1N1 and A H1N2 subtypes isolated in the south-France since the winter of 2001-2002.

Science.gov (United States)

Al Faress, Shaker; Cartet, Gaëlle; Ferraris, Olivier; Norder, Helene; Valette, Martine; Lina, Bruno

2005-07-01

Influenza A viruses are divided into subtypes based on their hemagglutinin (H1 to H15) and neuraminidase (N1 to N9) glycoproteins. Of these, three A subtypes H1N1, H3N2 and H1N2 circulate in the human population. Influenza A viruses display a high antigenic variability called "antigenic drift" which allows the virus to escape antibody neutralization. Evaluate the mutations apparition that might predict a divergent antigenic evolution of hemagglutinin in influenza A H1N1 and A H1N2 viruses. During the three winters of 2001-2002 to 2003-2004, 58 A H1N1 and 23 A H1N2 subtypes have been isolated from patients with influenza-like illness in the south of France. The HA1 region was analyzed by RT-PCR and subsequently sequenced to compare the HA1 genetic evolution of influenza A H1N1 and A H1N2 subtypes. Our results showed that 28 amino acid substitutions have accumulated in the HA1 region since the circulation of A/New Caledonia/20/99-like viruses in France. Of these, fifteen were located in four antigenic sites (B, C, D and E). Six of them were observed only in the A H1N2 isolates, six only in the A H1N1 isolates and three in both subtypes. Furthermore, nine of twenty two A H1N2 isolates from the winter of 2002-2003 shared a T90A amino acid change which has not been observed in any A H1N1 isolate; resulting in the introduction of a new glycosylation site close to the antigenic site E. This might mask some antigenic E determinants and therefore, modify the A H1N2 antigenicity. The divergent genetic evolution of hemagglutinin may ultimately lead to a significant different antigenicity between A H1N1 and A H1N2 subtypes that would require the introduction of a new subtype in the vaccine batches.

[Transgenerational evolution of age of the main stages of reproductive life in Guadeloupe].

Science.gov (United States)

Kadhel, P; Deloumeaux, J; Janky, E

2013-04-01

The aim of this study was to assess changes in the ages at which the main stages of reproductive life, including first sexual intercourse in particular, occur in Guadeloupe (French West Indies). We conducted a transverse study of three generations of men and women over the age of 20 years. We recorded age at first intercourse and at first child for all subjects, plus age at menarche, at first pregnancy and at menopause for the women. We collected information for 803 women and 169 men. For women, median age at menarche and at first intercourse had decreased significantly, reaching 12 and 17 years, respectively. The risk of first intercourse occurring before the median age was linked to the earliness of menarche. Age at first pregnancy, at menopause for women and at first intercourse for men remained roughly stable. A non-significant trend towards increasing age at the birth of the first child was observed in both sexes. Age indicators for the main stages of reproductive life in Guadeloupe follow the trends reported in most Western countries, including mainland France. However, most of the ages recorded for particular stages are below those in mainland France. The link between age at menarche and sexual precocity may justify targeted awareness programs. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Safety and protective efficacy of porcine reproductive and respiratory syndrome recombinant virus vaccines in young pigs.

NARCIS (Netherlands)

Verheije, M.H.; Kroese, M.V.; Linden, van der I.F.A.; Boer-Luijtze, de E.A.; Rijn, van P.A.; Pol, J.M.A.; Meulenberg, J.J.M.; Steverink, P.J.G.M.

2003-01-01

Three porcine reproductive and respiratory syndrome virus (PRRSV) recombinants, generated by mutagenesis of an infectious cDNA clone of the Lelystad virus (LV) isolate, were tested for their safety and protective efficacy as potential PRRSV vaccines in pigs. Recombinant vABV688 contains two amino

Discovery of HeLa Cell Contamination in HES Cells: Call for Cell Line Authentication in Reproductive Biology Research.

Science.gov (United States)

Kniss, Douglas A; Summerfield, Taryn L

2014-08-01

Continuous cell lines are used frequently in reproductive biology research to study problems in early pregnancy events and parturition. It has been recognized for 50 years that many mammalian cell lines contain inter- or intraspecies contaminations with other cells. However, most investigators do not routinely test their culture systems for cross-contamination. The most frequent contributor to cross-contamination of cell lines is the HeLa cell isolated from an aggressive cervical adenocarcinoma. We report on the discovery of HeLa cell contamination of the human endometrial epithelial cell line HES isolated in our laboratory. Short tandem repeat analysis of 9 unique genetic loci demonstrated molecular identity between HES and HeLa cells. In addition, we verified that WISH cells, isolated originally from human amnion epithelium, were also contaminated with HeLa cells. Inasmuch as our laboratory did not culture HeLa cells at the time of HES cell derivations, the source of contamination was the WISH cell line. These data highlight the need for continued diligence in authenticating cell lines used in reproductive biology research. © The Author(s) 2014.

Reproductive decisions in the lives of West Bank Palestinian women: Dimensions and contradictions.

Science.gov (United States)

Pell, Stephanie

2017-02-01

Palestinian women have one of the highest fertility rates in the world, averaging 4.38 births per woman. However, Palestinian fertility patterns are distinct from those of other developing nations, in that high fertility rates coexist alongside high levels of education and low levels of infant mortality - both of which have been established elsewhere as predictors of low total fertility rates. This study explores the dimensions and context of the contradictions between fertility predictors and rates, isolating main factors that shape Palestinian reproductive behaviour. Furthermore, while this study addresses factors that influence the high fertility in the Palestinian Territories, it also addresses factors that contribute to the steady decline of this trend. In-depth interviews were conducted with Palestinian women in urban refugee communities and key informant interviews with experts on Palestinian reproductive health. The findings indicate that five factors shape women's reproductive behaviour: (1) the fear of losing one's children in the ongoing conflict; (2) socio-economic factors including poverty and density of space; (3) the marital relationship; (4) religious values; and (5) generational differences. These results highlight the influence of socio-political conditions on reproductive behaviour and the significance of women's agency in manoeuvring their fertility outcomes.

Reproductive Disorders in Snakes.

Science.gov (United States)

Di Girolamo, Nicola; Selleri, Paolo

2017-05-01

Reproduction of snakes is one of the challenging aspects of herpetology medicine. Due to the complexity of reproduction, several disorders may present before, during, or after this process. This article describes the physical examination, and radiographic, ultrasonographic, and endoscopic findings associated with reproductive disorders in snakes. Surgical techniques used to resolve reproductive disorders in snakes are described. Finally, common reproductive disorders in snakes are individually discussed. Copyright © 2017 Elsevier Inc. All rights reserved.

Evolution of polyploidy and the diversification of plant-pollinator interactions.

Science.gov (United States)

Thompson, John N; Merg, Kurt F

2008-08-01

One of the major mechanisms of plant diversification has been the evolution of polyploid populations that differ from their diploid progenitors in morphology, physiology, and environmental tolerances. Recent studies have indicated that polyploidy may also have major effects on ecological interactions with herbivores and pollinators. We evaluated pollination of sympatric diploid and tetraploid plants of the rhizomatous herb Heuchera grossulariifolia (Saxifragaceae) along the Selway and Salmon Rivers of northern Idaho, USA, during four consecutive years. Previous molecular and ecological analyses had indicated that the tetraploid populations along these two river systems are independently derived and differ from each other in multiple traits. In each region, we evaluated floral visitation rate by all insect visitors, pollination efficacy of all major visitors, and relative contribution of all major pollinators to seed set. In both regions, diploid and tetraploid plants attracted different suites of floral visitors. Most pollination was attributable to several bee species and the moth Greya politella. Lasioglossum bees preferentially visited diploid plants at Lower Salmon but not at Upper Selway, queen Bombus centralis preferentially visited tetraploids at both sites, and worker B. centralis differed between sites in their cytotype preference. Hence, diploid and autotetraploid H. grossulariifolia plants act essentially as separate ecological species and may experience partial reproductive isolation through differential visitation and pollination by their major floral visitors. Overall the results, together with recent results from other studies, suggest that the repeated evolution of polyploidy in plants may contribute importantly to the structure and diversification of ecological interactions in terrestrial communities.

Stochastic spin evolution of neutron stars

OpenAIRE

Popov, S. B.; Prokhorov, M. E.; Khoperskov, A. V.; Lipunov, V. M.

2001-01-01

In this paper we present calculations of period distribution for old accreting isolated neutron stars (INSs). At the age about a few billions years low velocity INSs come to the stage of accretion. At that stage their period evolution is governed by magnetic breaking and accreted angular momentum. Due to turbulence of the interstellar medium (ISM) accreted momentum can both accelerate and decelerate rotation of an INS and spin evolution has chaotic character. Calculations show that for consta...

Ice barriers promote supercooling and prevent frost injury in reproductive buds, flowers and fruits of alpine dwarf shrubs throughout the summer.

Science.gov (United States)

Kuprian, Edith; Briceño, Verónica F; Wagner, Johanna; Neuner, Gilbert

2014-10-01

Over-wintering reproductive buds of many woody plants survive frost by supercooling. The bud tissues are isolated from acropetally advancing ice by the presence of ice barriers that restrict ice growth. Plants living in alpine environments also face the risk of ice formation in summer months. Little knowledge exists, how reproductive structures of woody alpine plants are protected from frost injury during episodic summer frosts. In order to address this question, frost resistance of three common dwarf shrubs, Calluna vulgaris , Empetrum hermaphroditum and Loiseleuria procumbens was measured and ice formation and propagation were monitored in twigs bearing reproductive shoots during various stages of reproductive development (bud, anthesis, and fruit) throughout the alpine summer. Results indicated that, in the investigated species, ice barriers were present at all reproductive stages, isolating the reproductive shoots from ice advancing from the subtending vegetative shoot. Additionally, in the reproductive stems ice nucleating agents that are active at warm, sub-zero temperatures, were absent. The ice barriers were 100% effective, with the exception of L. procumbens , where in 13% of the total observations, the ice barrier failed. The ice barriers were localized at the base of the pedicel, at the anatomical junction of the vegetative and reproductive shoot. There, structural aspects of the tissue impede or prevent ice from advancing from the frozen stem into the pedicel of the reproductive shoot. Under the experimental conditions used in this study, ice nucleation initially occurred in the stem of the vegetative shoot at species-specific mean temperatures in the range of -4.7 to -5.8 °C. Reproductive shoots, however, remained supercooled and ice free down to a range of -7.2 to -18.2 °C or even below -22 °C, the lowest temperature applied in the study. This level of supercooling is sufficient to prevent freezing of reproductive structures at the lowest air

Hybrid incompatibilities in the parasitic wasp genus Nasonia : Negative effects of hemizygosity and the identification of transmission ratio distortion loci

NARCIS (Netherlands)

Koevoets, T.; Niehuis, O.; van de Zande, L.; Beukeboom, L. W.

The occurrence of hybrid incompatibilities forms an important stage during the evolution of reproductive isolation. In early stages of speciation, males and females often respond differently to hybridization. Haldane's rule states that the heterogametic sex suffers more from hybridization than the

Induced defences alter the strength and direction of natural selection on reproductive traits in common milkweed.

Science.gov (United States)

Thompson, K A; Cory, K A; Johnson, M T J

2017-06-01

Evolutionary biologists have long sought to understand the ecological processes that generate plant reproductive diversity. Recent evidence indicates that constitutive antiherbivore defences can alter natural selection on reproductive traits, but it is unclear whether induced defences will have the same effect and whether reduced foliar damage in defended plants is the cause of this pattern. In a factorial field experiment using common milkweed, Asclepias syriaca L., we induced plant defences using jasmonic acid (JA) and imposed foliar damage using scissors. We found that JA-induced plants experienced selection for more inflorescences that were smaller in size (fewer flowers), whereas control plants only experienced a trend towards selection for larger inflorescences (more flowers); all effects were independent of foliar damage. Our results demonstrate that induced defences can alter both the strength and direction of selection on reproductive traits, and suggest that antiherbivore defences may promote the evolution of plant reproductive diversity. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

THE ANALYSIS OF REPRODUCTION INDICES IN THE TRANSYLVANIAN HALF-HEAVY HORSE BREED IN BECLEAN STUD FARM

Directory of Open Access Journals (Sweden)

IOANA CAMELIA LUDU

2007-10-01

Full Text Available The values of the main reproduction indices for the Transylvanian half-heavy horsematerial from Beclean stud farm are presented and analysed in this paper. Theanalysis is based on the data obtained from the evidence of the reproduction activityof 126 mother mares, data recorded in the period between 2000 and 2006. The mostsignificant indices have been rated, as the number of cycles/gestation, the number ofmatings/gestation, service-period (SP, gestation period (GP and the periodbetween bringing forth. The studied indices have been determined based on thenumber of bringing forth, on genealogical lines and on the entire population andaccording to the male stud used for mating. The connection between the puerperalperiod and the main reproduction indices has also been estimated. The averagevalues of the analysed reproduction indices show a normal evolution of thereproduction function for the Transylvanian half-heavy mother mares, a value that can behighlighted by creating some absolute accordance between the biological requests of thisbreed and the technological conditions which are provided for them.

Sex chromosome-linked species recognition and evolution of reproductive isolation in flycatchers

NARCIS (Netherlands)

Saether, Stein A.; Saetre, Glenn-Peter; Borge, Thomas; Wiley, Chris; Svedin, Nina; Andersson, Gunilla; Veen, Thor; Haavie, Jon; Servedio, Maria R.; Bures, Stanislav; Kral, Miroslav; Hjernquist, Marten B.; Gustafsson, Lars; Traeff, Johan; Qvarnstroem, Anna

2007-01-01

Interbreeding between species (hybridization) typically produces unfit offspring. Reduced hybridization should therefore be favored by natural selection. However, this is difficult to accomplish because hybridization also sets the stage for genetic recombination to dissociate species-specific traits

Evolution of egoism on semi-directed and undirected Barabási-Albert networks

Science.gov (United States)

Lima, F. W. S.

2015-05-01

Through Monte Carlo simulations, we study the evolution of the four strategies: Ethnocentric, altruistic, egoistic and cosmopolitan in one community of individuals. Interactions and reproduction among computational agents are simulated on undirected and semi-directed Barabási-Albert (BA) networks. We study the Hammond-Axelrod (HA) model on undirected and semi-directed BA networks for the asexual reproduction case. With a small modification in the traditional HA model, our simulations showed that egoism wins, differently from other results found in the literature where ethnocentric strategy is common. Here, mechanisms such as reciprocity are absent.

Did Lizards Follow Unique Pathways in Sex Chromosome Evolution?

Science.gov (United States)

Gleeson, Dianne; Georges, Arthur

2018-01-01

Reptiles show remarkable diversity in modes of reproduction and sex determination, including high variation in the morphology of sex chromosomes, ranging from homomorphic to highly heteromorphic. Additionally, the co-existence of genotypic sex determination (GSD) and temperature-dependent sex determination (TSD) within and among sister clades makes this group an attractive model to study and understand the evolution of sex chromosomes. This is particularly so with Lizards (Order Squamata) which, among reptiles, show extraordinary morphological diversity. They also show no particular pattern of sex chromosome degeneration of the kind observed in mammals, birds and or even in snakes. We therefore speculate that sex determination sensu sex chromosome evolution is labile and rapid and largely follows independent trajectories within lizards. Here, we review the current knowledge on the evolution of sex chromosomes in lizards and discuss how sex chromosome evolution within that group differs from other amniote taxa, facilitating unique evolutionary pathways. PMID:29751579

Did Lizards Follow Unique Pathways in Sex Chromosome Evolution?

Directory of Open Access Journals (Sweden)

Shayer Mahmood Ibney Alam

2018-05-01

Full Text Available Reptiles show remarkable diversity in modes of reproduction and sex determination, including high variation in the morphology of sex chromosomes, ranging from homomorphic to highly heteromorphic. Additionally, the co-existence of genotypic sex determination (GSD and temperature-dependent sex determination (TSD within and among sister clades makes this group an attractive model to study and understand the evolution of sex chromosomes. This is particularly so with Lizards (Order Squamata which, among reptiles, show extraordinary morphological diversity. They also show no particular pattern of sex chromosome degeneration of the kind observed in mammals, birds and or even in snakes. We therefore speculate that sex determination sensu sex chromosome evolution is labile and rapid and largely follows independent trajectories within lizards. Here, we review the current knowledge on the evolution of sex chromosomes in lizards and discuss how sex chromosome evolution within that group differs from other amniote taxa, facilitating unique evolutionary pathways.

Identification of three new isolates of Tomato spotted wilt virus from different hosts in China: molecular diversity, phylogenetic and recombination analyses.

Science.gov (United States)

Zhang, Zhenjia; Wang, Deya; Yu, Chengming; Wang, Zenghui; Dong, Jiahong; Shi, Kerong; Yuan, Xuefeng

2016-01-14

Destructive diseases caused by Tomato spotted wilt virus (TSWV) have been reported associated with many important plants worldwide. Recently, TSWV was reported to infect different hosts in China. It is of value to clone TSWV isolates from different hosts and examine diversity and evolution among different TSWV isolates in China as well as worldwide. RT-PCR was used to clone the full-length genome (L, M and S segments) of three new isolates of TSWV that infected different hosts (tobacco, red pepper and green pepper) in China. Identity of nucleotide and amino acid sequences among TSWV isolates were analyzed by DNAMAN. MEGA 5.0 was used to construct phylogenetic trees. RDP4 was used to detect recombination events during evolution of these isolates. Whole-genome sequences of three new TSWV isolates in China were determined. Together with other available isolates, 29 RNA L, 62 RNA M and 66 RNA S of TSWV isolates were analyzed for molecular diversity, phylogenetic and recombination events. This analysis revealed that the entire TSWV genome, especially the M and S RNAs, had major variations in genomic size that mainly involve the A-U rich intergenic region (IGR). Phylogenetic analyses on TSWV isolates worldwide revealed evidence for frequent reassortments in the evolution of tripartite negative-sense RNA genome. Significant numbers of recombination events with apparent 5' regional preference were detected among TSWV isolates worldwide. Moreover, TSWV isolates with similar recombination events usually had closer relationships in phylogenetic trees. All five Chinese TSWV isolates including three TSWV isolates of this study and previously reported two isolates can be divided into two groups with different origins based on molecular diversity and phylogenetic analysis. During their evolution, both reassortment and recombination played roles. These results suggest that recombination could be an important mechanism in the evolution of multipartite RNA viruses, even negative

Host and food searching in a parasitic wasp Venturia canescens: a trade-off between current and future reproduction?

NARCIS (Netherlands)

Desouhant, E.; Driessen, G.J.J.; Amat, I.; Bernstein, C.

2005-01-01

Whether to invest in current or future reproduction is an important trade-off in life history evolution. For insect parasitoids, this trade-off is determined, among other factors, by the decision whether to search for hosts (immediate gain of fitness) or food (delayed fitness gains). Although host

Different rates of defense evolution and niche preferences in clonal and nonclonal milkweeds (Asclepias spp.).

Science.gov (United States)

Pellissier, Loïc; Litsios, Glenn; Fishbein, Mark; Salamin, Nicolas; Agrawal, Anurag A; Rasmann, Sergio

2016-02-01

Given the dual role of many plant traits to tolerate both herbivore attack and abiotic stress, the climatic niche of a species should be integrated into the study of plant defense strategies. Here we investigate the impact of plant reproductive strategy and components of species' climatic niche on the rate of chemical defense evolution in the milkweeds using a common garden experiment of 49 species. We found that across Asclepias species, clonal reproduction repeatedly evolved in lower temperature conditions, in species generally producing low concentrations of a toxic defense (cardenolides). Additionally, we found that rates of cardenolide evolution were lower for clonal than for nonclonal species. We thus conclude that because the clonal strategy is based on survival, long generation times, and is associated with tolerance of herbivory, it may be an alternative to toxicity in colder ecosystems. Taken together, these results indicate that the rate of chemical defense evolution is influenced by the intersection of life-history strategy and climatic niches into which plants radiate. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Optimization of yeast (Saccharomyces cerevisiae) RNA isolation ...

African Journals Online (AJOL)

Yomi

2012-01-16

Jan 16, 2012 ... isolation method for real-time quantitative PCR and microarray ... disease genes to experimental evolution and systems biology (Landry et al., .... scanning, and preliminary analyses with GeneChip Operating. Software 1.4 ...

The koala (Phascolarctos cinereus): a case study in the development of reproductive technology in a marsupial.

Science.gov (United States)

Johnston, Stephen D; Holt, William V

2014-01-01

The successful development and application of an assisted breeding program in any animal relies primarily on a thorough understanding of the fundamental reproductive biology (anatomy, physiology and behaviour) of the species in question. Surely, the ultimate goal and greatest hallmark of such a program is the efficacious establishment of a series of reliable techniques that facilitate the reproductive and genetic management of fragmented populations, both in captivity and in the wild. Such an achievement is all the more challenging when the reproductive biology of that species is essentially rudimentary and without adequate reproductive models to compare to. Using the koala (Phascolarctos cinereus) as a case study, this chapter provides some personal insights into the evolution of a concept that began as a small undergraduate student project but that subsequently evolved into the first-ever successful artificial insemination of a marsupial. Apart from this historical perspective, we also provide a brief review of the current reproductive biology of the koala, discuss technical elements of current assisted breeding technology of this species, its potential application to the wombat, and the future role it might play in helping to conserve wild koala populations. There is little doubt that the unique reproductive biology and tractability of the koala has in this case been a benefit rather than a hindrance to the success of artificial breeding in this species.

Spin-dependent quasiparticle tunneling in junction superconductor-isolator-ferromagnetic

International Nuclear Information System (INIS)

Shlapak, Yu.V.; Shaternik, V.E.; Rudenko, E.M.

2001-01-01

The influence of Andreev reflection of quasiparticles in transparent tunnel junctions of superconductor-isolator-ferromagnetic on electric-current transport is studied within the framework of the Blonder-Tinkham-Klapwijk (BTK) model. It's obtained that current and signal-to-noise ratio can be increased for the memory cell by using in it the double-barrier tunnel junction ferromagnetic-isolator-superconductor-isolator-ferromagnetic instead off the usual tunnel junction ferromagnetic-isolator-ferromagnetic. The evolution of non-linear (tunnel-type) current-voltage characteristics with increasing of the junction transparency is described. (orig.)

Sexual reproduction of Acropora reef corals at Moorea, French Polynesia

Science.gov (United States)

Carroll, A.; Harrison, P.; Adjeroud, M.

2006-03-01

Little information is available on reproductive processes among corals in isolated central Pacific reef regions, including French Polynesia. This study examined the timing and mode of sexual reproduction for Acropora reef corals at Moorea. Spawning was observed and/or inferred in 110 Acropora colonies, representing 12 species, following full moon periods in September through November 2002. Gamete release was observed and inferred in four species of Acropora between 9 and 13 nights after the full moon (nAFM) in September 2002. Twelve Acropora spp. spawned gametes between 5 and 10 nAFM in October 2002, with six species spawning 7 nAFM and four species spawning 9 nAFM. In November 2002, spawning of egg and sperm bundles was observed and inferred in 27 colonies of Acropora austera, 6 nAFM. These are the first detailed records of spawning by Acropora corals in French Polynesia.

Comparisons of host mitochondrial, nuclear and endosymbiont bacterial genes reveal cryptic fig wasp species and the effects of Wolbachia on host mtDNA evolution and diversity

Directory of Open Access Journals (Sweden)

Feng Gui

2011-04-01

Full Text Available Abstract Background Figs and fig-pollinating wasp species usually display a highly specific one-to-one association. However, more and more studies have revealed that the "one-to-one" rule has been broken. Co-pollinators have been reported, but we do not yet know how they evolve. They may evolve from insect speciation induced or facilitated by Wolbachia which can manipulate host reproduction and induce reproductive isolation. In addition, Wolbachia can affect host mitochondrial DNA evolution, because of the linkage between Wolbachia and associated mitochondrial haplotypes, and thus confound host phylogeny based on mtDNA. Previous research has shown that fig wasps have the highest incidence of Wolbachia infection in all insect taxa, and Wolbachia may have great influence on fig wasp biology. Therefore, we look forward to understanding the influence of Wolbachia on mitochondrial DNA evolution and speciation in fig wasps. Results We surveyed 76 pollinator wasp specimens from nine Ficus microcarpa trees each growing at a different location in Hainan and Fujian Provinces, China. We found that all wasps were morphologically identified as Eupristina verticillata, but diverged into three clades with 4.22-5.28% mtDNA divergence and 2.29-20.72% nuclear gene divergence. We also found very strong concordance between E. verticillata clades and Wolbachia infection status, and the predicted effects of Wolbachia on both mtDNA diversity and evolution by decreasing mitochondrial haplotypes. Conclusions Our study reveals that the pollinating wasp E. verticillata on F. microcarpa has diverged into three cryptic species, and Wolbachia may have a role in this divergence. The results also indicate that Wolbachia strains infecting E. verticillata have likely resulted in selective sweeps on host mitochondrial DNA.

Demographic mechanisms of inbreeding adjustment through extra-pair reproduction.

Science.gov (United States)

Reid, Jane M; Duthie, A Bradley; Wolak, Matthew E; Arcese, Peter

2015-07-01

populations might allow females to adjust mean f of offspring through random extra-pair reproduction without necessarily requiring explicit kin discrimination, implying that adjustment of offspring f might be an inevitable consequence of extra-pair reproduction. New theoretical and empirical studies are required to explore the general magnitude of such effects and quantify the degree to which they could facilitate or constrain long-term evolution of extra-pair reproduction. © 2015 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.

Evolution of the placenta and associated reproductive characters in bats

DEFF Research Database (Denmark)

Carter, Anthony M; Mess, Andrea

2008-01-01

Recent advances in molecular phylogenetics indicate that the order Chiroptera is monophyletic and that one of four lineages of microbats (Rhinolophoidea) shares a common origin with megabats. Against this background we undertook a comprehensive analysis of placental evolution in bats. We defined...... that characterize higher-level clades within Chiroptera, i.e. the megabats and the four lineages of microbats. The character condition occurring in the last common ancestor of Chiroptera was unequivocal for 21 of the 25 characters included in the analysis. The data did not offer support for a megabat...

The impact of parental investment on lifetime reproductive success in Iceland

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Robert F. Lynch

2017-01-01

Full Text Available Background Demonstrating the impact that parents have on the fitness of their children is a crucial step towards understanding how parental investment has affected human evolution. Parents not only transfer genes to their children, they also influence their environments. By analyzing reproductive patterns within and between different categories of close relatives, this study provides insight into the genetic and environmental effects that parents have on the fitness of their offspring. Methods We use data spanning over two centuries from an exceptionally accurate Icelandic genealogy, Íslendingabók, to analyze the relationship between the fertility rates of close relatives. Also, using genetic data, we determine narrow sense heritability estimates (h2 to further explore the genetic impact on lifetime reproductive success. Finally, we construct four simulations to model the expected contribution of genes and resources on reproductive success. Results The relationship between the reproduction of all full sibling pairs was significant and positive across all birth decades (r = 0.19 while the reproductive relationship between parents and offspring was often negative across many decades and undetectable overall (r = 0.00 (Fig. 1 and Table 1. Meanwhile, genetic data among 8,456 pairs of full siblings revealed a narrow sense heritability estimate (h2 of 0.00 for lifetime reproductive success. A resources model (following the rule that resources are transmitted from parents to children, distributed equally among siblings, and are the only factor affecting reproductive success revealed a similar trend: a negative relationship between parent and offspring reproduction (r =  − 0.35 but a positive relationship among full siblings (r = 0.28. The relationship between parent and offspring lifetime reproductive success (LRS and full sibling LRS was strongly and positively correlated across time (r = 0.799, p < 0.001. Similarly, the LRS among

Evolution of sociality by natural selection on variances in reproductive fitness: evidence from a social bee

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Stevens Mark I

2007-08-01

Full Text Available Abstract Background The Central Limit Theorem (CLT is a statistical principle that states that as the number of repeated samples from any population increase, the variance among sample means will decrease and means will become more normally distributed. It has been conjectured that the CLT has the potential to provide benefits for group living in some animals via greater predictability in food acquisition, if the number of foraging bouts increases with group size. The potential existence of benefits for group living derived from a purely statistical principle is highly intriguing and it has implications for the origins of sociality. Results Here we show that in a social allodapine bee the relationship between cumulative food acquisition (measured as total brood weight and colony size accords with the CLT. We show that deviations from expected food income decrease with group size, and that brood weights become more normally distributed both over time and with increasing colony size, as predicted by the CLT. Larger colonies are better able to match egg production to expected food intake, and better able to avoid costs associated with producing more brood than can be reared while reducing the risk of under-exploiting the food resources that may be available. Conclusion These benefits to group living derive from a purely statistical principle, rather than from ecological, ergonomic or genetic factors, and could apply to a wide variety of species. This in turn suggests that the CLT may provide benefits at the early evolutionary stages of sociality and that evolution of group size could result from selection on variances in reproductive fitness. In addition, they may help explain why sociality has evolved in some groups and not others.

Beam quality management by periodic reproduction of wavefront aberrations in end-pumped Nd:YVO4 laser amplifiers.

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Liu, Bin; Liu, Chong; Shen, Lifeng; Wang, Chunhua; Ye, Zhibin; Liu, Dong; Xiang, Zhen

2016-04-18

A method for beam quality management is presented in a master oscillator power amplifier (MOPA) using Nd:YVO4 as the gain medium by extra-cavity periodic reproduction of wavefront aberrations. The wavefront aberration evolution of the intra-cavity beams is investigated for both symmetrical and asymmetrical resonators. The wavefront aberration reproduction process is successfully realized outside the cavity in four-stage amplifiers. In the MOPA with a symmetrical oscillator, the laser power increases linearly and the beam quality hardly changes. In the MOPA with an asymmetrical oscillator, the beam quality is deteriorated after the odd-stage amplifier and is improved after the even-stage amplifier. The wavefront aberration reproduction during the extra-cavity beam propagation in the amplifiers is equivalent to that during the intra-cavity propagation. This solution helps to achieve the effective beam quality management in laser amplifier chains.

Individual quality and age but not environmental or social conditions modulate costs of reproduction in a capital breeder.

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Debeffe, Lucie; Poissant, Jocelyn; McLoughlin, Philip D

2017-08-01

Costs associated with reproduction are widely known to play a role in the evolution of reproductive tactics with consequences to population and eco-evolutionary dynamics. Evaluating these costs as they pertain to species in the wild remains an important goal of evolutionary ecology. Individual heterogeneity, including differences in individual quality (i.e., among-individual differences in traits associated with survival and reproduction) or state, and variation in environmental and social conditions can modulate the costs of reproduction; however, few studies have considered effects of these factors simultaneously. Taking advantage of a detailed, long-term dataset for a population of feral horses (Sable Island, Nova Scotia, Canada), we address the question of how intrinsic (quality, age), environmental (winter severity, location), and social conditions (group size, composition, sex ratio, density) influence the costs of reproduction on subsequent reproduction. Individual quality was measured using a multivariate analysis on a combination of four static and dynamic traits expected to depict heterogeneity in individual performance. Female quality and age interacted with reproductive status of the previous year to determine current reproductive effort, while no effect of social or environmental covariates was found. High-quality females showed higher probabilities of giving birth and weaning their foal regardless of their reproductive status the previous year, while those of lower quality showed lower probabilities of producing foals in successive years. Middle-aged (prime) females had the highest probability of giving birth when they had not reproduced the year before, but no such relationship with age was found among females that had reproduced the previous year, indicating that prime-aged females bear higher costs of reproduction. We show that individual quality and age were key factors modulating the costs of reproduction in a capital breeder but that

The VIP/VPACR system in the reproductive cycle of male lizard Podarcis sicula.

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Agnese, Marisa; Rosati, Luigi; Prisco, Marina; Coraggio, Francesca; Valiante, Salvatore; Scudiero, Rosaria; Laforgia, Vincenza; Andreuccetti, Piero

2014-09-01

Starting from the knowledge that in the reproductive period the Vasoactive Intestinal Peptide (VIP) is widely distributed in Podarcis sicula testis, we studied VIP expression and the localization of the neuropeptide and its receptors in the testis of the Italian wall lizard P. sicula in the other phases of its reproductive cycle (summer stasis, autumnal resumption, winter stasis, spring resumption). By Real Time-PCR, we demonstrated that testicular VIP mRNA levels change during the reproductive cycle, showing a cyclic trend with two peaks, one in the mid-autumnal resumption and the other in the reproductive period. By in situ hybridization and immunohistochemistry, we demonstrated that both VIP mRNA and protein were widely distributed in the testis in almost all the phases of the cycle, except in the early autumnal resumption. As regards the receptors, the VPAC1R was localized mainly in Leydig cells, while the VPAC2R showed the same distribution of VIP. Our results demonstrate that, differently from mammals, where VIP is present only in nerve fibres innerving the testis, an endotesticular synthesis takes place in the lizard and the VIP synthesis changes throughout the reproductive cycle. Moreover, the VIP/VPAC receptor system distribution observed in germ and somatic cells in various phases of the cycle, and particularly in the autumnal resumption and the reproductive period, strongly suggests its involvement in both spermatogenesis and steroidogenesis. Finally, the wider distribution of VIP in lizards with respect to mammals leads us to hypothesize that during the evolution the synthesis sites have been transferred from the testis to other districts, such as the brain. Copyright © 2014 Elsevier Inc. All rights reserved.

Evolution of tag-based cooperation with emotion on complex networks

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Lima, F. W. S.

2018-04-01

We study the evolution of the four strategies: Ethnocentric, altruistic, egoistic and cosmopolitan in one community of individuals through Monte Carlo simulations. Interactions and reproduction among computational agents are simulated on undirected Barabási-Albert (UBA) networks and Erdös-Rènyi random graphs (ER).We study the Hammond-Axelrod model on both UBA networks and ER random graphs for the asexual reproduction case. We use a modified version of the traditional Hammond-Axelrod model and we also allow the agents’ decisions about one of the strategies to take into account the emotion among their equals. Our simulations showed that egoism and altruism win, differently from other results found in the literature where ethnocentric strategy is common.

Male sexual ornament size is positively associated with reproductive morphology and enhanced fertility in the stalk-eyed fly Teleopsis dalmanni

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Chapman Tracey

2008-08-01

Full Text Available Abstract Background Exaggerated male ornaments and displays often evolve in species where males only provide females with ejaculates during reproduction. Although "good genes" arguments are typically invoked to explain this phenomenon, a simpler alternative is possible if variation in male reproductive quality (e.g. sperm number, ejaculate content, mating rate is an important determinant of female reproductive success. The "phenotype-linked fertility hypothesis" states that female preference for male ornaments or displays has been selected to ensure higher levels of fertility and has driven the evolution of exaggerated male traits. Females of the stalk-eyed fly Teleopsis dalmanni must mate frequently to maintain high levels of fertility and prefer to mate with males exhibiting large eyespan, a condition-dependent sexual ornament. If eyespan indicates male reproductive quality, females could directly increase their reproductive success by mating with males with large eyespan. Here we investigate whether male eyespan indicates accessory gland and testis length, and then ask whether mating with large eyespan males affects female fertility. Results Male eyespan was a better predictor of two key male reproductive traits – accessory gland and testis length – than was body size alone. This positive relationship held true over three levels of increasing environmental stress during the maturation of the adult accessory glands and testes. Furthermore, females housed with a large eyespan male exhibited higher levels of fertility than those with small eyespan males. Conclusion Male eyespan in stalk-eyed flies is subject to strong directional mate preference and is a reliable indicator of male reproductive quality – both because males with larger eyespan have bigger accessory glands and testes, and also as they confer higher fertility on females. Fertility enhancement may have arisen because males with larger eyespan mated more often and/or because

Familial differences in the effects of mercury on reproduction in zebra finches

International Nuclear Information System (INIS)

Varian-Ramos, Claire W.; Swaddle, John P.; Cristol, Daniel A.

2013-01-01

Ecotoxicologists often implicitly assume that populations are homogenous entities in which all individuals have similar responses to a contaminant. However, genetically variable responses occur within populations. This variation can be visualized using dose–response curves of genetically related groups, similar to the way that evolutionary biologists construct reaction norms. We assessed the variation in reproductive success of full-sibling families of captive zebra finches (Taeniopygia guttata) experimentally exposed to methylmercury. We found significant variation among families in the effects of methylmercury on several reproductive parameters. This variation suggests that there may be strong responses to selection for resistant genotypes in contaminated areas. This has important implications for the evolution of tolerance as well as risk assessment and wildlife conservation efforts on sites with legacy contamination. -- Highlights: •Dose-response curves can visualize genetic differences in response to pollutants. •Families of zebra finch respond differently to mercury contamination. •Differences in reproductive success can lead to selection for resistant genotypes. •Resistance to contamination has implications for risk assessment and conservation. -- Genetic variation in response to contaminants can lead to adaptation on long-term contaminated sites, with implications for risk assessment and conservation of impacted populations

Pollination and reproduction of a self-incompatible forest herb in hedgerow corridors and forest patches.

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Schmucki, Reto; de Blois, Sylvie

2009-07-01

Habitat-corridors are assumed to counteract the negative impacts of habitat loss and fragmentation, but their efficiency in doing so depends on the maintenance of ecological processes in corridor conditions. For plants dispersing in linear habitats, one of these critical processes is the maintenance of adequate pollen transfer to insure seed production within the corridor. This study focuses on a common, self-incompatible forest herb, Trillium grandiflorum, to assess plant-pollinator interactions and the influence of spatial processes on plant reproduction in hedgerow corridors compared to forests. First, using pollen supplementation experiments over 2 years, we quantified the extent of pollen limitation in both habitats, testing the prediction of greater limitation in small hedgerow populations than in forests. While pollen limitation of fruit and seed set was common, its magnitude did not differ between habitats. Variations among sites, however, suggested an influence of landscape context on pollination services. Second, we examined the effect of isolation on plant reproduction by monitoring fruit and seed production, as well as pollinator activity and assemblage, in small flower arrays transplanted in hedgerows at increasing distances from forest and from each other. We detected no difference in the proportion of flowers setting fruit or in pollinator activity with isolation, but we observed some differences in pollinator assemblages. Seed set, on the other hand, declined significantly with increasing isolation in the second year of the study, but not in the first year, suggesting altered pollen transfer with distance. Overall, plants in hedgerow corridors and forests benefited from similar pollination services. In this system, plant-pollinator interactions and reproduction seem to be influenced more by variations in resource distribution over years and landscapes than by local habitat conditions.

Genetic characterization of low-pathogenic avian influenza viruses isolated on the Izumi plain in Japan: possible association of dynamic movements of wild birds with AIV evolution.

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Nakagawa, Hiroko; Okuya, Kosuke; Kawabata, Toshiko; Matsuu, Aya; Takase, Kozo; Kuwahara, Masakazu; Toda, Shigehisa; Ozawa, Makoto

2018-04-01

The Izumi plain in Kagoshima Prefecture, Japan, is an overwintering site of endangered cranes (hooded cranes and white-naped cranes) and of many other migratory birds (including wild ducks) that are considered carriers of avian influenza viruses (AIVs). To assess the risks of a highly pathogenic avian influenza outbreak in the crane populations, we tested various environmental samples for AIVs in this area. In the 2014-2015 winter season, we isolated one AIV of the H6N2 subtype from the cranes' roost water and two AIVs of the H11N9 subtype from a crane fecal sample and a cloacal swab of a dead spot-billed duck. Genetic analysis of these AIV isolates indicated that our H6N2 isolate is genetically close to AIVs isolated from wild birds in Southeast Asian countries, except that the PB1 and NS genes belong to the North American virus lineage. All genes of the two H11N9 isolates are related to AIVs belonging to the Eurasian virus lineage. Notably, in our phylogenetic trees, H11 HA and N9 NA genes showing high sequence similarity to the corresponding genes of isolates from wild birds in South Africa and Spain, respectively, did not cluster in the major groups with recent wild-bird isolates from East Asia. These results suggest that AIVs with viral gene segments derived from various locations and bird species have been brought to the Izumi plain. These findings imply a possible association of dynamic movements of wild birds with AIV evolution.

Reproductive endocrinology of wild, long-lived raptors.

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Blas, Julio; López, Lidia; Tanferna, Alessandro; Sergio, Fabrizio; Hiraldo, Fernando

2010-08-01

The last decades have witnessed a surge of studies analyzing the role of sex hormones on the behavior and ecology of wild bird populations, allowing a more integrated view of the evolution of avian physiology and life histories. Despite a marked progress, field studies show a considerable bias towards research on specific phylogenetic groups, neglecting a significant fraction of the class Aves. Here we analysed changes in the circulating levels of sex steroids in relation to reproductive behaviour in wild black kites (Milvus migrans), a long-lived and socially monogamous Accipitridae raptor. Males and females displayed a single seasonal peak of circulating testosterone (males) and estradiol (females) during pre-laying and laying. Absolute male testosterone levels were low even at the seasonal maximum and remained below detection limits in females. The latter results supports the idea that avian species establishing long-term pair bonds require lower amounts of circulating androgens for reproduction. Circulating progesterone showed a single seasonal peak in females and males, but their timing (during Incubation and Post-brooding respectively) did not overlap. The fact that females black kites perform the majority of incubation and males provide the majority of care to fledglings suggests that progesterone is involved in the expression of parental behaviors. Copyright 2010 Elsevier Inc. All rights reserved.

Evidence of Egg Diversity in Squamate Evolution from Cretaceous Anguimorph Embryos.

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Vincent Fernandez

Full Text Available Lizards are remarkable amongst amniotes, for they display a unique mosaic of reproduction modes ranging from egg-laying to live-bearing. Within this patchwork, geckoes are believed to represent the only group to ever have produced fully calcified rigid-shelled eggs, contrasting with the ubiquitous parchment shelled-eggs observed in other lineages. However, this hypothesis relies only on observations of modern taxa and fossilised gecko-like eggshells which have never been found in association with any embryonic or parental remains. We report here the first attested fossil eggs of lizards from the Early Cretaceous of Thailand, combining hard eggshells with exquisitely preserved embryos of anguimoph (e.g. Komodo dragons, mosasaurs. These fossils shed light on an apparently rare reproduction strategy of squamates, demonstrate that the evolution of rigid-shelled eggs are not an exclusive specialization of geckoes, and suggest a high plasticity in the reproductive organs mineralizing eggshells.

Characterization of Italian isolates of Inonotus rickii

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Tiziana ANNESI

2011-01-01

Full Text Available Thirty-seven isolates of Inonotus rickii, a pathogenic fungus causing white rot and cankers, were collected from diseased boxelder trees lining boulevards in Rome and from other hosts in Rome and Sicily. During the survey, it was observed that this fungus occasionally produced basidiomes, but more frequently it had anamorphic structures that released a brown powdery mass of chlamydospores, presumably acting as asexual propagules. All isolates were characterized using random amplified microsatellite analysis and somatic incompatibility tests in order to investigate the diversity of genotypes within and between the different disease centers surveyed in Italy. The results suggest that both sexual and asexual reproduction play an important role in the spread of this disease, with important epidemiological implications. .

Genetic drift evolution under vaccination pressure among H5N1 Egyptian isolates

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Afifi Manal A

2011-06-01

Full Text Available Background The highly pathogenic H5N1 is a major avian pathogen that intensively affects the poultry industry in Egypt even in spite of the adoption of vaccination strategy. Antigenic drift is among the strategies the influenza virus uses to escape the immune system that might develop due to the pressure of extensive vaccination. H5N1 mutates in an intensified manner and is considered a potential candidate for the possible next pandemic with all the catastrophic consequences such an eventuality will entail. Methods H5N1 was isolated from the pooled organ samples of four different affected flocks in specific pathogen free embryonated chicken eggs (SPF-ECE. A reverse transcriptase polymerase chain reaction (RT-PCR was performed to the haemagglutingin and neuraminidase. Sequencing of the full length haemagglutingin was performed. Sequence analyses of the isolated strains were performed and compared to all available H5N1 from Egyptian human and avian strains in the flu database. Changes in the different amino acid that may be related to virus virulence, receptor affinity and epitope configuration were assigned and matched with all available Egyptian strains in the flu database. Results One out of the four strains was found to be related to the B2 Egyptian lineage, 2 were related to A1 lineage and the 4th was related to A2 lineage. Comparing data obtained from the current study by other available Egyptian H5N1 sequences remarkably demonstrates that amino acid changes in the immune escape variants are remarkably restricted to a limited number of locations on the HA molecule during antigenic drift. Molecular diversity in the HA gene, in relevance to different epitopes, were not found to follow a regular trend, suggesting abrupt cumulative sequence mutations. However a number of amino acids were found to be subjected to high mutation pressure. Conclusion The current data provides a comprehensive view of HA gene evolution among H5N1 subtype viruses in

Can IVF influence human evolution?

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Hanevik, Hans Ivar; Hessen, Dag O; Sunde, Arne; Breivik, Jarle

2016-07-01

IVF, a procedure in which pharmacological and technological manipulation is used to promote pregnancy, offers help to infertile couples by circumventing selection at the most fundamental level. Fertility is clearly one of the key fitness-promoting drivers in all forms of sexually reproducing life, and fertilization and pregnancy are fundamental evolutionary processes that involve a range of pre- and post-zygotic screening mechanisms. Here, we discuss the various selection and screening factors involved in fertilization and pregnancy and assess IVF practices in light of these factors. We then focus on the possible consequences of these differences in selection pressures, mainly at the individual but also at the population level, to evaluate whether changes in the reproducing genotype can affect human evolution. The aim of the article is not to argue for or against IVF, but to address aspects of assisted reproduction in an evolutionary context. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Normal Female Reproductive Anatomy

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... historical Searches are case-insensitive Reproductive System, Female, Anatomy Add to My Pictures View /Download : Small: 720x756 ... Large: 3000x3150 View Download Title: Reproductive System, Female, Anatomy Description: Anatomy of the female reproductive system; drawing ...

Reproductive strategies in snakes.

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Shine, Richard

2003-05-22

Snakes of both sexes display remarkable flexibility and diversity in their reproductive tactics. Many features of reproduction in female snakes (such as reproductive mode and frequency, seasonality and multiple mating) allow flexible maternal control. For example, females can manipulate not only the genotypes of their offspring (through mate choice or enhanced sperm competition) but also the phenotypes of their offspring (through allocation 'decisions', behavioural and physiological thermoregulation, and nest-site selection). Reliance on stored energy ('capital') to fuel breeding results in low frequencies of female reproduction and, in extreme cases, semelparity. A sophisticated vomeronasal system not only allows male snakes to locate reproductive females by following scent trails, but also facilitates pheromonally mediated mate choice by males. Male-male rivalry takes diverse forms, including female mimicry and mate guarding; combat bouts impose strong selection for large body size in males of some species. Intraspecific (geographical) variation and phenotypic plasticity in a wide array of reproductive traits (offspring size and number; reproductive frequency; incidence of multiple mating; male tactics such as mate guarding and combat; mate choice criteria) provide exceptional opportunities for future studies.

Avian reproductive physiology

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Gee, G.F.; Gibbons, Edward F.; Durrant, Barbara S.; Demarest, Jack

1995-01-01

Knowledge of the many physiological factors associated with egg production , fertility, incubation, and brooding in nondomestic birds is limited. Science knows even less about reproduction in most of the 238 endangered or threatened birds. This discussion uses studies of nondomestic and, when necessary, domestic birds to describe physiological control of reproduction. Studies of the few nondomestic avian species show large variation in physiological control of reproduction. Aviculturists, in order to successfully propagate an endangered bird, must understand the bird's reproductive peculiarities. First, investigators can do studies with carefully chosen surrogate species, but eventually they need to confirm the results in the target endangered bird. Studies of reproduction in nondomestic birds increased in the last decade. Still, scientists need to do more comparative studies to understand the mechanisms that control reproduction in birds. New technologies are making it possible to study reproductive physiology of nondomestic species in less limiting ways. These technologies include telemetry to collect information without inducing stress on captives (Howey et al., 1987; Klugman, 1987), new tests for most of the humoral factors associated with reproduction, and the skill to collect small samples and manipulate birds without disrupting the physiological mechanisms (Bercovitz et al., 1985). Managers are using knowledge from these studies to improve propagation in zoological parks, private and public propagation facilities, and research institutions. Researchers need to study the control of ovulation, egg formation, and oviposition in the species of nondomestic birds that lay very few eggs in a season, hold eggs in the oviduct for longer intervals, or differ in other ways from the more thoroughly studied domestic birds. Other techniques that would enhance propagation for nondomestlc birds include tissue culture of cloned embryonic cells, cryopreservation of embryos

Reduced costs of reproduction in females mediate a shift from a male-biased to a female-biased lifespan in humans

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Bolund, Elisabeth; Lummaa, Virpi; Smith, Ken R.; Hanson, Heidi A.; Maklakov, Alexei A.

2016-01-01

The causes underlying sex differences in lifespan are strongly debated. While females commonly outlive males in humans, this is generally less pronounced in societies before the demographic transition to low mortality and fertility rates. Life-history theory suggests that reduced reproduction should benefit female lifespan when females pay higher costs of reproduction than males. Using unique longitudinal demographic records on 140,600 reproducing individuals from the Utah Population Database, we demonstrate a shift from male-biased to female-biased adult lifespans in individuals born before versus during the demographic transition. Only women paid a cost of reproduction in terms of shortened post-reproductive lifespan at high parities. Therefore, as fertility decreased over time, female lifespan increased, while male lifespan remained largely stable, supporting the theory that differential costs of reproduction in the two sexes result in the shifting patterns of sex differences in lifespan across human populations. Further, our results have important implications for demographic forecasts in human populations and advance our understanding of lifespan evolution. PMID:27087670

Studies on diversity and evolution of Iridaceae species in southern Brazil

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Tatiana T. Souza-Chies

2012-01-01

Full Text Available Plants of the family Iridaceae are well represented in the grassland vegetation of southern Brazil, occurring in the Pampa and Atlantic Forest biomes. Nevertheless, little is known about the taxonomy and evolution of Iridaceae species in southern Brazil. The main goal of this review is to compile published information about South American Iridaceae, and to discuss the evolution and genetic diversity of the family presenting our own research data in the light of the published literature. The main focus is on the genera Calydorea, Cypella, Herbertia, and Sisyrinchium. Aspects of reproductive system and of pollinator attraction are also discussed.

Singular features of fertilization and their impact on the male reproductive system in eutherian mammals.

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Bedford, J Michael

2014-02-01

Therian (marsupial and eutherian) mammals have evolved a suite of novel reproductive features - seen variously in their gametes, the steps of fertilization and the male reproductive tract - whose adaptive significance remains unclear. Present evidence for the better-understood eutherian mammals suggests that the 'prime mover' in their evolution has been the character of the egg coat, with other such features being adaptations to the consequences of this. Its elastic thickness allows the zona pellucida to stretch to a variable degree and yet remain around the blastocyst during much or all of its expansion before implantation, but its character represents an unusual challenge for spermatozoa. Novel aspects of the acrosome related to this challenge enable it to maintain a relatively prolonged binding after the onset of the acrosome reaction, and the structure, shape and behaviour of the sperm head point to physical thrust as a major element of zona penetration - with the unique configuration of gamete fusion as a sequela of this strategy. In the male, such adaptations are reflected in sperm head formation in the testis and in sperm maturation in the epididymis involving at least the sperm head's structure, plasmalemma and acrosome. This complexity allied to a slow epididymal sperm transport, a relatively modest sperm production and the brief life span of mature spermatozoa kept above the cauda epididymidis could account for the evolution of the sperm storage function - a development seemingly linked, in turn, to the need for sperm capacitation and scrotal evolution.

Phylogenomics of Colombian Helicobacter pylori isolates.

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Gutiérrez-Escobar, Andrés Julián; Trujillo, Esperanza; Acevedo, Orlando; Bravo, María Mercedes

2017-01-01

During the Spanish colonisation of South America, African slaves and Europeans arrived in the continent with their corresponding load of pathogens, including Helicobacter pylori . Colombian strains have been clustered with the hpEurope population and with the hspWestAfrica subpopulation in multilocus sequence typing (MLST) studies. However, ancestry studies have revealed the presence of population components specific to H. pylori in Colombia. The aim of this study was to perform a thorough phylogenomic analysis to describe the evolution of the Colombian urban H. pylori isolates. A total of 115 genomes of H. pylori were sequenced with Illumina technology from H. pylori isolates obtained in Colombia in a region of high risk for gastric cancer. The genomes were assembled, annotated and underwent phylogenomic analysis with 36 reference strains. Additionally, population differentiation analyses were performed for two bacterial genes. The phylogenetic tree revealed clustering of the Colombian strains with hspWestAfrica and hpEurope, along with three clades formed exclusively by Colombian strains, suggesting the presence of independent evolutionary lines for Colombia. Additionally, the nucleotide diversity of horB and vacA genes from Colombian isolates was lower than in the reference strains and showed a significant genetic differentiation supporting the hypothesis of independent clades with recent evolution. The presence of specific lineages suggest the existence of an hspColombia subtype that emerged from a small and relatively isolated ancestral population that accompanied crossbreeding of human population in Colombia.

Redirecting reproductive immunology research toward pregnancy as a period of temporary immune tolerance.

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Gleicher, Norbert; Kushnir, Vitaly A; Barad, David H

2017-04-01

Referring to two recent publications, we here propose that clinical reproductive immunology has for decades stagnated because reproductive medicine, including assisted reproduction (AR), has failed to accept embryo implantation as an immune system-driven process, dependent on establishment of maternal tolerance toward the implanting fetal semi-allograft (and complete allograft in cases of oocyte donation). Pregnancy represents a biologically unique period of temporary (to the period of gestation restricted) tolerance, otherwise only known in association with parasitic infections. Rather than investigating the immune pathways necessary to induce this rather unique state of tolerance toward the rapidly growing parasitic antigen load of the fetus, the field, instead, concentrated on irrelevant secondary immune phenomena (i.e., "immunological noise"). It, therefore, does not surprise that interesting recent research, offering new potential insights into maternal tolerance during pregnancy, was mostly published outside of the field of reproductive medicine. This research offers evidence for existence of inducible maternal tolerance pathways with the ability of improving maternal fecundity and, potentially, reducing such late pregnancy complications as premature labor and preeclampsia/eclampsia due to premature abatement of maternal tolerance. Increasing evidence also suggests that tolerance-inducing immune pathways are similar in successful pregnancy, successful organ transplantation and, likely also in the tolerance of "self" (i.e., prevention of autoimmunity). Identifying and isolating these pathways, therefore, may greatly benefit all three of these clinical areas, and research in reproductive immunology should be accordingly redirected.

Reproduction, physiology and biochemistry

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This chapter summarizes fundamental knowledge and recent discoveries about the reproduction, physiology and biochemistry of plant-parasitic nematodes. Various types of reproduction are reviewed, including sexual reproduction and mitotic and meiotic parthenogenesis. Although much is known about the p...

Fish reproduction

National Research Council Canada - National Science Library

Rocha, Maria João; Arukwe, Augustine; Kapoor, B. G

2008-01-01

... of reproductive systems is essential for such studies. Fishes comprise over 28,000 species, with a remarkable variability in morphology, physiology and environmental adaptation. Knowledge on fish reproduction is scattered across numerous sources that shows a dynamic research field. The Editors believe it to be an opportune moment for a...

The Far-Infrared Properties of the Most Isolated Galaxies

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Lisenfeld, U.; Verdes-Montenegro, L.; Sulentic, J.; Leon, S.; Espada, D.; Bergond, G.; García, E.; Sabater, J.; Santander-Vela, J. D.; Verley, S.

2007-05-01

A long-standing question in galaxy evolution involves the role of nature (self-regulation) vs. nurture (environment) on the observed properties (and evolution) of galaxies. A collaboration centreed at the Instituto de Astrofisica de Andalucia (Granada, Spain) is trying to address this question by producing a observational database for a sample of 1050 isolated galaxies from the catalogue of Karachentseva (1973) with the overarching goal being the generation of a "zero-point" sample against which effects of environment on galaxies can be assessed. The AMIGA (Analysis of the Interstellar Medium of Isolated Galaxies) database (see www.iaa.es/AMIGA.html) will include optical, IR and radio line and continuum measures. The galaxies in the sample represent the most isolated galaxies in the local universe. In the present contribution, we will present the project, as well as the results of an analysis of the far-infrared (FIR) and molecular gas properties of this sample.

Nest predation and reproductive traits in small passerines: a comparative approach

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Yanes, Miguel; Suárez, Francisco

Nest predation can be a decisive factor in the evolution of bird reproduction strategies. This paper compares several reproductive traits in small passerines on the Iberian Peninsula (n=31) with the probability of daily nest survival from predation. We consider the phylogenetic relationships between species by means of an analysis according to three models of evolutionary change: Brownian, punctuational and GRAFEN'S arbitrary. In this comparative evolutionary scenario, clutch size, egg volume and incubation period appear not to change in relation to nest predation, while the nestling phase duration is a positively-related parameter to daily nest survival from predation. These results are consistent for all models of evolutionary change. Thus, from the perspective of nest predation, the nestling period is the most important evolutionary parameter in small passerines. A hypothetical influence of nest predation on passerine clutch and egg size should only be regarded as an indirect factor, linked to the relationship between these parameters and the duration of the nestling period.

Biological species is the only possible form of existence for higher organisms: the evolutionary meaning of sexual reproduction

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Shcherbakov Victor P

2010-03-01

Full Text Available Abstract Consistent holistic view of sexual species as the highest form of biological existence is presented. The Weismann's idea that sex and recombination provide the variation for the natural selection to act upon is dominated in most discussions of the biological meaning of the sexual reproduction. Here, the idea is substantiated that the main advantage of sex is the opposite: the ability to counteract not only extinction but further evolution as well. Living systems live long owing to their ability to reproduce themselves with a high fidelity. Simple organisms (like bacteria reach the continued existence due to the high fidelity of individual genome replication. In organisms with a large genome and complex development, the achievable fidelity of DNA replication is not enough for the precise reproduction of the genome. Such species must be capable of surviving and must remain unchanged in spite of the continuous changes of their genes. This problem has no solution in the frame of asexual ("homeogenomic" lineages. They would rapidly degrade and become extinct or blurred out in the course of the reckless evolution. The core outcome of the transition to sexual reproduction was the creation of multiorganismic entity - biological species. Individual organisms forfeited their ability to reproduce autonomously. It implies that individual organisms forfeited their ability to substantive evolution. They evolve as a part of the biological species. In case of obligatory sexuality, there is no such a thing as synchronic multi-level selection. Natural selection cannot select anything that is not a unit of reproduction. Hierarchy in biology implies the functional predestination of the parts for the sake of the whole. A crucial feature of the sexual reproduction is the formation of genomes of individual organisms by random picking them over from the continuously shuffled gene pool instead of the direct replication of the ancestor's genome. A clear anti

Variation, differential reproduction and oscillation: the evolution of nucleic acid hybridization.

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Suárez-Díaz, Edna

2013-01-01

This paper builds upon Hans-Jörg Rheinberger ideas on the oscillation and intercalation of epistemic things and technical objects in experimental systems, to give a fine-grained analysis of what here is called the problems of "adaptation" between our material and cognitive tools and the phenomena of the material world. To do so, it relies on the case-study of the evolution of nucleic acid hybridization and the stabilization of satellite DNA.

Inheritance patterns of secondary symbionts during sexual reproduction of pea aphid biotypes.

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Peccoud, Jean; Bonhomme, Joël; Mahéo, Frédérique; de la Huerta, Manon; Cosson, Olivier; Simon, Jean-Christophe

2014-06-01

Herbivorous insects frequently harbor bacterial symbionts that affect their ecology and evolution. Aphids host the obligatory endosymbiont Buchnera, which is required for reproduction, together with facultative symbionts whose frequencies vary across aphid populations. These maternally transmitted secondary symbionts have been particularly studied in the pea aphid, Acyrthosiphon pisum, which harbors at least 8 distinct bacterial species (not counting Buchnera) having environmentally dependent effects on host fitness. In particular, these symbiont species are associated with pea aphid populations feeding on specific plants. Although they are maternally inherited, these bacteria are occasionally transferred across insect lineages. One mechanism of such nonmaternal transfer is paternal transmission to the progeny during sexual reproduction. To date, transmission of secondary symbionts during sexual reproduction of aphids has been investigated in only a handful of aphid lineages and 3 symbiont species. To better characterize this process, we investigated inheritance patterns of 7 symbiont species during sexual reproduction of pea aphids through a crossing experiment involving 49 clones belonging to 9 host-specialized biotypes, and 117 crosses. Symbiont species in the progeny were detected with diagnostic qualitative PCR at the fundatrix stage hatching from eggs and in later parthenogenetic generations. We found no confirmed case of paternal transmission of symbionts to the progeny, and we observed that maternal transmission of a particular symbiont species (Serratia symbiotica) was quite inefficient. We discuss these observations in respect to the ecology of the pea aphid. © 2013 Institute of Zoology, Chinese Academy of Sciences.

The evolution of tensor polarization

International Nuclear Information System (INIS)

Huang, H.; Lee, S.Y.; Ratner, L.

1993-01-01

By using the equation of motion for the vector polarization, the spin transfer matrix for spin tensor polarization, the spin transfer matrix for spin tensor polarization is derived. The evolution equation for the tensor polarization is studied in the presence of an isolate spin resonance and in the presence of a spin rotor, or snake

The role of adiponectin in reproduction: from polycystic ovary syndrome to assisted reproduction.

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Michalakis, Konstantinos G; Segars, James H

2010-11-01

To summarize the effects of the adipokine adiponectin on the reproductive endocrine system, from the hypothalamic-pituitary axis to the gonads and target tissues of the reproductive system. A Medline computer search was performed to identify relevant articles. Research institution. None. Adiponectin is a hormone secreted by adipose tissue that acts to reduce insulin resistance and atherogenic damage, but it also exerts actions in other tissues. Adiponectin mediates its actions in the periphery mainly via two receptors, AdipoR1 and AdipoR2. Adiponectin receptors are present in many reproductive tissues, including the central nervous system, ovaries, oviduct, endometrium, and testes. Adiponectin influences gonadotropin release, normal pregnancy, and assisted reproduction outcomes. Adiponectin, a beneficial adipokine, represents a major link between obesity and reproduction. Higher levels of adiponectin are associated with improved menstrual function and better outcomes in assisted reproductive cycles. Published by Elsevier Inc.

Isolation and open reading frame 5 gene analysis of porcine ...

African Journals Online (AJOL)

ARL

2012-11-08

Nov 8, 2012 ... viral RNA of fourth generation, reverse transcriptase (RT)-PCR based on open reading frame 5 (ORF5) ... fourth generation. TCID50 of isolate measured by Reed-Muench method was 10-3.6/0.1 ml. Genetic evolution of ORF5 indicated that the two isolated strains were in a .... generation of the virus culture.

Social context and reproductive potential affect worker reproductive decisions in a eusocial insect.

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Boris Yagound

Full Text Available Context-dependent decision-making conditions individual plasticity and is an integrant part of alternative reproductive strategies. In eusocial Hymenoptera (ants, bees and wasps, the discovery of worker reproductive parasitism recently challenged the view of workers as a homogeneous collective entity and stressed the need to consider them as autonomous units capable of elaborate choices which influence their fitness returns. The reproductive decisions of individual workers thus need to be investigated and taken into account to understand the regulation of reproduction in insect societies. However, we know virtually nothing about the proximate mechanisms at the basis of worker reproductive decisions. Here, we test the hypothesis that the capacity of workers to reproduce in foreign colonies lies in their ability to react differently according to the colonial context and whether this reaction is influenced by a particular internal state. Using the bumble bee Bombus terrestris, we show that workers exhibit an extremely high reproductive plasticity which is conditioned by the social context they experience. Fertile workers reintroduced into their mother colony reverted to sterility, as expected. On the contrary, a high level of ovary activity persisted in fertile workers introduced into a foreign nest, and this despite more frequent direct contacts with the queen and the brood than control workers. Foreign workers' reproductive decisions were not affected by the resident queen, their level of fertility being similar whether or not the queen was removed from the host colony. Workers' physiological state at the time of introduction is also of crucial importance, since infertile workers failed to develop a reproductive phenotype in a foreign nest. Therefore, both internal and environmental factors appear to condition individual reproductive strategies in this species, suggesting that more complex decision-making mechanisms are involved in the regulation

Cross-species correlation between queen mating numbers and worker ovary sizes suggests kin conflict may influence ovary size evolution in honeybees

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Rueppell, Olav; Phaincharoen, Mananya; Kuster, Ryan; Tingek, Salim

2011-09-01

During social evolution, the ovary size of reproductively specialized honey bee queens has dramatically increased while their workers have evolved much smaller ovaries. However, worker division of labor and reproductive competition under queenless conditions are influenced by worker ovary size. Little comparative information on ovary size exists in the different honey bee species. Here, we report ovariole numbers of freshly dissected workers from six Apis species from two locations in Southeast Asia. The average number of worker ovarioles differs significantly among species. It is strongly correlated with the average mating number of queens, irrespective of body size. Apis dorsata, in particular, is characterized by numerous matings and very large worker ovaries. The relation between queen mating number and ovary size across the six species suggests that individual selection via reproductive competition plays a role in worker ovary size evolution. This indicates that genetic diversity, generated by multiple mating, may bear a fitness cost at the colony level.