WorldWideScience

Sample records for survival sexual selection

  1. Stabilizing survival selection on presenescent expression of a sexual ornament followed by a terminal decline.

    Science.gov (United States)

    Simons, M J P; Briga, M; Verhulst, S

    2016-07-01

    Senescence is a decrease in functional capacity, increasing mortality rate with age. Sexual signals indicate functional capacity, because costs of ornamentation ensure signal honesty, and are therefore expected to senesce, tracking physiological deterioration and mortality. For sexual traits, mixed associations with age and positive associations with life expectancy have been reported. However, whether these associations are caused by selective disappearance and/or within-individual senescence of sexual signals, respectively, is not known. We previously reported that zebra finches with redder bills had greater life expectancy, based on a single bill colour measurement per individual. We here extend this analysis using longitudinal data and show that this finding is attributable to terminal declines in bill redness in the year before death, with no detectable change in presenescent redness. Additionally, there was a quadratic relationship between presenescent bill colouration and survival: individuals with intermediate bill redness have maximum survival prospects. This may reflect that redder individuals overinvest in colouration and/or associated physiological changes, while below-average bill redness probably reflects poorer phenotypic quality. Together, this pattern suggests that bill colouration is defended against physiological deterioration, because of mate attraction benefits, or that physiological deterioration is not a gradual process, but accelerates sharply prior to death. We discuss these possibilities in the context of the reliability theory of ageing and sexual selection. © 2016 The Authors. Journal of Evolutionary Biology published by John Wiley & Sons Ltd on behalf of European Society for Evolutionary Biology.

  2. Sexual selection in Fungi

    NARCIS (Netherlands)

    Nieuwenhuis, B.P.S.

    2012-01-01

    Sexual selection is an important factor that drives evolution, in which fitness is increased, not by increasing survival or viability, but by acquiring more or better mates. Sexual selection favours traits that increase the ability of an individual to obtain more matings than other individuals that

  3. Sexual selection is a form of social selection.

    Science.gov (United States)

    Lyon, Bruce E; Montgomerie, Robert

    2012-08-19

    Social selection influences the evolution of weapons, ornaments and behaviour in both males and females. Thus, social interactions in both sexual and non-sexual contexts can have a powerful influence on the evolution of traits that would otherwise appear to be detrimental to survival. Although clearly outlined by West-Eberhard in the early 1980s, the idea that social selection is a comprehensive framework for the study of ornaments and weapons has largely been ignored. In West-Eberhard's view, sexual selection is a form of social selection-a concept supported by several lines of evidence. Darwin's distinction between natural and sexual selection has been useful, but recent confusion about the limits of sexual selection suggests that some traits are not easily categorized as naturally or sexually selected. Because social selection theory has much to offer the current debates about both sexual selection and reproductive competition in females, it is sometimes viewed, narrowly, to be most useful when considering female roles. However, social selection theory encompasses much more than female reproductive competition. Our goal here was to provide that broader perspective.

  4. Sexual selection in complex environments.

    Science.gov (United States)

    Miller, Christine W; Svensson, Erik I

    2014-01-01

    Sexual selection has resulted in some of the most captivating features of insects, including flashy colors, bizarre structures, and complex pheromones. These features evolve in dynamic environments, where conditions can change rapidly over space and time. However, only recently has ecological complexity been embraced by theory and practice in sexual selection. We review replicated selection studies as well as studies on variation in the agents of selection to delineate gaps in current knowledge and clarify exciting new directions for research. Existing work suggests that fluctuations in sexual selection may be extremely common, though work on the ecological factors influencing these fluctuations is scarce. We suggest that deeper ecological perspectives on sexual selection may alter some of the fundamental assumptions of sexual selection theory and rapidly lead to new discoveries.

  5. Sexual selection: Another Darwinian process.

    Science.gov (United States)

    Gayon, Jean

    2010-02-01

    Why was sexual selection so important to Darwin? And why was it de-emphasized by almost all of Darwin's followers until the second half of the 20th century? These two questions shed light on the complexity of the scientific tradition named "Darwinism". Darwin's interest in sexual selection was almost as old as his discovery of the principle of natural selection. From the beginning, sexual selection was just another "natural means of selection", although different from standard "natural selection" in its mechanism. But it took Darwin 30 years to fully develop his theory, from the early notebooks to the 1871 book The Descent of Man, and Selection in Relation to Sex. Although there is a remarkable continuity in his basic ideas about sexual selection, he emphasized increasingly the idea that sexual selection could oppose the action of natural selection and be non adaptive. In time, he also gave more weight to mate choice (especially female choice), giving explicit arguments in favor of psychological notions such as "choice" and "aesthetic sense". But he also argued that there was no strict demarcation line between natural and sexual selection, a major difficulty of the theory from the beginning. Female choice was the main reason why Alfred Russel Wallace, the co-discoverer of the principle of natural selection, engaged in a major controversy with Darwin about sexual selection. Wallace was suspicious about sexual selection in general, trying to minimize it by all sorts of arguments. And he denied entirely the existence of female choice, because he thought that it was both unnecessary and an anthropomorphic notion. This had something to do with his spiritualist convictions, but also with his conception of natural selection as a sufficient principle for the evolutionary explanation of all biological phenomena (except for the origin of mind). This is why Wallace proposed to redefine Darwinism in a way that excluded Darwin's principle of sexual selection. The main result of

  6. Sexual selection in marine plankton

    DEFF Research Database (Denmark)

    Sichlau, Mie Hylstofte

    Copepods are among the most abundant metazoans on the planet and play an important role in the marine food web. Many aspects of their ecology have consequently been studied, including details of their reproductive biology and mating behaviour. Sexual selection, the part of evolution which selects...

  7. Sexual selection and mating systems

    Science.gov (United States)

    Shuster, Stephen M.

    2009-01-01

    Sexual selection is among the most powerful of all evolutionary forces. It occurs when individuals within one sex secure mates and produce offspring at the expense of other individuals within the same sex. Darwin was first to recognize the power of sexual selection to change male and female phenotypes, and, in noting that sexual selection is nonubiquitous, Darwin was also first to recognize the importance of mating system—the “special circumstances” in which reproduction occurs within species. Analyses of mating systems since Darwin have emphasized either the genetic relationships between male and female mating elements, usually among plants, or the numbers of mates males and females may obtain, usually among animals. Combining these schemes yields a quantitative methodology that emphasizes measurement of the sex difference in the variance in relative fitness, as well as phenotypic and genetic correlations underlying reproductive traits that may arise among breeding pairs. Such information predicts the degree and direction of sexual dimorphism within species, it allows the classification of mating systems using existing genetic and life history data, and with information on the spatial and temporal distributions of fertilizations, it may also predict floral morphology in plants. Because this empirical framework identifies selective forces and genetic architectures responsible for observed male-female differences, it compliments discoveries of nucleotide sequence variation and the expression of quantitative traits. Moreover, because this methodology emphasizes the process of evolutionary change, it is easier to test and interpret than frameworks emphasizing parental investment in offspring and its presumed evolutionary outcomes. PMID:19528645

  8. The social selection alternative to sexual selection.

    Science.gov (United States)

    Roughgarden, Joan

    2012-08-19

    Social selection offers an alternative to sexual selection by reversing its logic. Social selection starts with offspring production and works back to mating, and starts with behavioural dynamics and works up to gene pool dynamics. In social selection, courtship can potentially be deduced as a negotiation, leading to an optimal allocation of tasks during offspring rearing. Ornaments facilitate this negotiation and also comprise 'admission tickets' to cliques. Mating pairs may form 'teams' based on the reciprocal sharing of pleasure. The parent-offspring relation can be managed by the parent considered as the owner of a 'family firm' whose product is offspring. The cooperation in reproductive social behaviour evolves as a mutual direct benefit through individual selection rather than as some form of altruism requiring kin or multi-level selection.

  9. Sexual selection and animal personality.

    Science.gov (United States)

    Schuett, Wiebke; Tregenza, Tom; Dall, Sasha R X

    2010-05-01

    Consistent individual behavioural tendencies, termed "personalities", have been identified in a wide range of animals. Functional explanations for personality have been proposed, but as yet, very little consideration has been given to a possible role for sexual selection in maintaining differences in personality and its stability within individuals. We provide an overview of the available literature on the role of personality traits in intrasexual competition and mate choice in both human and non-human animals and integrate this into a framework for considering how sexual selection can generate and maintain personality. For this, we consider the evolution and maintenance of both main aspects of animal personality: inter-individual variation and intra-individual consistency.

  10. The relationship between sexual selection and sexual conflict.

    Science.gov (United States)

    Kokko, Hanna; Jennions, Michael D

    2014-07-18

    Evolutionary conflicts of interest arise whenever genetically different individuals interact and their routes to fitness maximization differ. Sexual selection favors traits that increase an individual's competitiveness to acquire mates and fertilizations. Sexual conflict occurs if an individual of sex A's relative fitness would increase if it had a "tool" that could alter what an individual of sex B does (including the parental genes transferred), at a cost to B's fitness. This definition clarifies several issues: Conflict is very common and, although it extends outside traits under sexual selection, sexual selection is a ready source of sexual conflict. Sexual conflict and sexual selection should not be presented as alternative explanations for trait evolution. Conflict is closely linked to the concept of a lag load, which is context-dependent and sex-specific. This makes it possible to ask if one sex can "win." We expect higher population fitness if females win. Copyright © 2014 Cold Spring Harbor Laboratory Press; all rights reserved.

  11. Darwin's forgotten idea: the social essence of sexual selection.

    Science.gov (United States)

    West-Eberhard, Mary Jane

    2014-10-01

    Darwinian sexual selection can now be seen in the broader context of social selection, or social competition for resources (under sexual selection, mates or fertilization success). The social-interaction aspects of sexually selected traits give them special evolutionary properties of interest for neurobiological studies of stimulus-response systems because they can account for highly complex systems with little information content other than stimulatory effectiveness per se. But these special properties have a long history of being forgotten when other factors dominate the analysis of male-female interactions, such as the mistaken belief that differential responsiveness to signals produced by competing rivals ("female choice") requires an esthetic sense; that species recognition explains all species-specific sexual signals; and, more recently, that successful signals must reflect good survival genes; or that male-female conflict involves female resistance rather than stimulus evaluation. A "conflict paradox" results when male-female conflict is seen as driven by natural selection, whose costs should often move the hypothesized "sexually antagonistic co-evolution" of sensory-response systems toward the powerful domain of sexually synergistic co-evolution under sexual selection. Special properties of sexual selection apply to other forms of social competition as well, showing the wisdom of Darwin's setting it apart from natural selection as an explanation of many otherwise puzzling and extreme traits. Copyright © 2014. Published by Elsevier Ltd.

  12. Sexual selection and natural selection in bird speciation

    OpenAIRE

    Price, T.

    1998-01-01

    The role of sexual selection in speciation is investigated, addressing two main issues. First, how do sexually selected traits become species recognition traits? Theory and empirical evidence suggest that female preferences often do not evolve as a correlated response to evolution of male traits. This implies that, contrary to runaway (Fisherian) models of sexual selection, premating isolation will not arise as an automatic side effect of divergence between populations in sexually selected tr...

  13. Sexual networks: measuring sexual selection in structured, polyandrous populations.

    Science.gov (United States)

    McDonald, Grant C; James, Richard; Krause, Jens; Pizzari, Tommaso

    2013-03-05

    Sexual selection is traditionally measured at the population level, assuming that populations lack structure. However, increasing evidence undermines this approach, indicating that intrasexual competition in natural populations often displays complex patterns of spatial and temporal structure. This complexity is due in part to the degree and mechanisms of polyandry within a population, which can influence the intensity and scale of both pre- and post-copulatory sexual competition. Attempts to measure selection at the local and global scale have been made through multi-level selection approaches. However, definitions of local scale are often based on physical proximity, providing a rather coarse measure of local competition, particularly in polyandrous populations where the local scale of pre- and post-copulatory competition may differ drastically from each other. These limitations can be solved by social network analysis, which allows us to define a unique sexual environment for each member of a population: 'local scale' competition, therefore, becomes an emergent property of a sexual network. Here, we first propose a novel quantitative approach to measure pre- and post-copulatory sexual selection, which integrates multi-level selection with information on local scale competition derived as an emergent property of networks of sexual interactions. We then use simple simulations to illustrate the ways in which polyandry can impact estimates of sexual selection. We show that for intermediate levels of polyandry, the proposed network-based approach provides substantially more accurate measures of sexual selection than the more traditional population-level approach. We argue that the increasing availability of fine-grained behavioural datasets provides exciting new opportunities to develop network approaches to study sexual selection in complex societies.

  14. Darwinian balancing selection: predation counters sexual selection in a wild insect.

    Science.gov (United States)

    Ercit, Kyla; Gwynne, Darryl T

    2015-02-01

    The potential viability costs of sexually selected traits are central to hypotheses about the evolution of exaggerated traits. Estimates of these costs in nature can come from selection analyses using multiple components of fitness during the same time frame. For a population of tree crickets (Oecanthus nigricornis: Gryllidae), we analyzed viability and sexual selection on male traits by comparing Oecanthus prey of a solitary wasp to those that survived, and comparing mating individuals to solitary males. We measured forewing width (sexually size dimorphic and used for singing), head width, pronotum length, and size of hind jumping legs as potential targets of selection. Supporting the hypothesis that sexually selected traits have viability costs, we found that significant directional sexual selection for wider heads was opposed by significant viability selection for narrower heads. Nonlinear selection revealed that individuals with wide heads and small legs were most attractive, but individuals with narrow heads, large legs, and intermediate pronotum length were most likely to survive. Successful mating may put males at greater risk of predation, especially if copulation per se is risky. Such balancing selection in tree crickets may have constrained the evolution of sexual dimorphism in head size-a condition seen in other gryllids and orthopterans. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

  15. Sexual dimorphism in glioma glycolysis underlies sex differences in survival

    Science.gov (United States)

    Ippolito, Joseph E.; Yim, Aldrin Kay-Yuen; Chinnaiyan, Prakash; Rubin, Joshua B.

    2017-01-01

    The molecular bases for sex differences in cancer remain undefined and how to incorporate them into risk stratification remains undetermined. Given sex differences in metabolism and the inverse correlation between fluorodeoxyglucose (FDG) uptake and survival, we hypothesized that glycolytic phenotyping would improve glioma subtyping. Using retrospectively acquired lower-grade glioma (LGG) transcriptome data from The Cancer Genome Atlas (TCGA), we discovered male-specific decreased survival resulting from glycolytic gene overexpression. Patients within this high-glycolytic group showed significant differences in the presence of key genomic alterations (i.e., 1p/19q codeletion, CIC, EGFR, NF1, PTEN, FUBP1, and IDH mutations) compared with the low-glycolytic group. Although glycolytic stratification defined poor prognostic males independent of grade, histology, TP53, and ATRX mutation status, we unexpectedly found that females with high-glycolytic gene expression and wild-type IDH survived longer than all other wild-type patients. Validation with an independent metabolomics dataset from grade 2 gliomas determined that glycolytic metabolites selectively stratified males and also uncovered a potential sexual dimorphism in pyruvate metabolism. These findings identify a potential synergy between patient sex, tumor metabolism, and genomic alterations in determining outcome for glioma patients. PMID:28768910

  16. Intralocus sexual conflict diminishes the benefits of sexual selection.

    Directory of Open Access Journals (Sweden)

    Alison Pischedda

    2006-11-01

    Full Text Available Evolution based on the benefits of acquiring "good genes" in sexual selection is only plausible with the reliable transmission of genetic quality from one generation to the next. Accumulating evidence suggests that sexually antagonistic (SA genes with opposite effects on Darwinian fitness when expressed in the two different sexes may be common in animals and plants. These SA genes should weaken the potential indirect genetic benefits of sexual selection by reducing the fitness of opposite-sex progeny from high-fitness parents. Here we use hemiclonal analysis in the fruit fly, Drosophila melanogaster, to directly measure the inheritance of fitness across generations, over the entire genome. We show that any potential genetic benefits of sexual selection in this system are not merely weakened, but completely reversed over one generation because high-fitness males produce low-fitness daughters and high-fitness mothers produce low-fitness sons. Moreover, male fitness was not inherited by sons, consistent with both theory and recent evidence connecting this form of SA variation with the X chromosome. This inheritance pattern may help to explain how genetic variation for fitness is sustained despite strong sexual selection, and why the ZW sex chromosome system found in birds and butterflies appears to foster the evolution of extreme secondary sexual characters in males.

  17. Environmental heterogeneity generates fluctuating selection on a secondary sexual trait.

    Science.gov (United States)

    Robinson, Matthew R; Pilkington, Jill G; Clutton-Brock, Tim H; Pemberton, Josephine M; Kruuk, Loeske E B

    2008-05-20

    In any population in which resources are limiting, the allocation of resources toward increased reproductive success may generate costs to survival [1-8]. The relationship between a sexually selected trait and fitness will therefore represent a balance between its relative associations with fecundity versus viability [3, 6, 7]. Because the risk of mortality in a population is likely to be heavily determined by ecological conditions, survival costs may vary as a function of the prevailing environment [7]. As a result, for populations experiencing heterogeneous ecological conditions, there may not be a single optimal level of allocation toward reproduction versus survival [9]. Here, we show that early viability and fecundity selection act in opposing directions on a secondary sexual trait and that their relative magnitude depends upon ecological conditions, generating fluctuating selection. In a wild population of Soay sheep (Ovis aries), phenotypic and genetic associations between male horn growth and lifetime reproductive success were positive under good environmental conditions (because of increased breeding success) and negative under poor environmental conditions (because of reduced survival). In an unpredictable environment, high allocation to early horn growth is a gamble that will only pay off if ensuing conditions are favorable. Such fluctuating selection may play an important role in preventing the erosion of genetic variance in secondary sexual traits.

  18. Surviving testicular cancer: : sexuality & other existential issues

    NARCIS (Netherlands)

    Pool, Grietje

    2003-01-01

    The thesis deals with the psychological aspects of ‘sexuality after testicular cancer’, where my collegue, the physician dr. Van Basten formerly predominantly described the physical-biological aspects of this subject. Testicular cancer is a type of male genital cancer, usually diagnosed between

  19. Mate choice, sexual selection, and endocrine-disrupting chemicals.

    Science.gov (United States)

    Gore, Andrea C; Holley, Amanda M; Crews, David

    2017-09-11

    Humans have disproportionately affected the habitat and survival of species through environmental contamination. Important among these anthropogenic influences is the proliferation of organic chemicals, some of which perturb hormone systems, the latter referred to as endocrine-disrupting chemicals (EDCs). EDCs are widespread in the environment and affect all levels of reproduction, including development of reproductive organs, hormone release and regulation through the life cycle, the development of secondary sexual characteristics, and the maturation and maintenance of adult physiology and behavior. However, what is not well-known is how the confluence of EDC actions on the manifestation of morphological and behavioral sexual traits influences mate choice, a process that requires the reciprocal evaluation of and/or acceptance of a sexual partner. Moreover, the outcomes of EDC-induced perturbations are likely to influence sexual selection; yet this has rarely been directly tested. Here, we provide background on the development and manifestation of sexual traits, reproductive competence, and the neurobiology of sexual behavior, and evidence for their perturbation by EDCs. Selection acts on individuals, with the consequences manifest in populations, and we discuss the implications for EDC contamination of these processes, and the future of species. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. The costs of risky male behaviour: sex differences in seasonal survival in a small sexually monomorphic primate

    OpenAIRE

    Kraus, Cornelia; Eberle, Manfred; Kappeler, Peter M

    2008-01-01

    Male excess mortality is widespread among mammals and frequently interpreted as a cost of sexually selected traits that enhance male reproductive success. Sex differences in the propensity to engage in risky behaviours are often invoked to explain the sex gap in survival. Here, we aim to isolate and quantify the survival consequences of two potentially risky male behavioural strategies in a small sexually monomorphic primate, the grey mouse lemur Microcebus murinus: (i) most females hibernate...

  1. Assessing the alignment of sexual and natural selection using radiomutagenized seed beetles.

    Science.gov (United States)

    Power, D J; Holman, L

    2015-05-01

    A major unsolved question in evolutionary biology concerns the relationship between natural and sexual selection. Sexual selection might augment natural selection, for example if mutations that harm female fecundity also reduce male mating success. Conversely, sexual selection might favour traits that impair naturally selected fitness components. We induced detrimental mutations in Callosobruchus maculatus beetles using X-ray irradiation and then experimentally measured the effect of precopulatory sexual selection on offspring number and survival rate. Sexual selection treatment had a negative effect on egg-to-adult survivorship, although the number of progeny reaching adulthood was unaffected, perhaps because eggs and juveniles that failed to develop lessened competition on the survivors. We hypothesize that the negative effect of sexual selection arose because sexually competitive males transmitted a smaller nuptial gift or carried alleles that conferred reduced survival. Although we found no evidence that sexual selection on males can purge alleles that are detrimental to naturally selected fitness components, such benefits might exist in other environmental or genetic contexts. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology.

  2. Natural and sexual selection in a monogamous historical human population.

    Science.gov (United States)

    Courtiol, Alexandre; Pettay, Jenni E; Jokela, Markus; Rotkirch, Anna; Lummaa, Virpi

    2012-05-22

    Whether and how human populations exposed to the agricultural revolution are still affected by Darwinian selection remains controversial among social scientists, biologists, and the general public. Although methods of studying selection in natural populations are well established, our understanding of selection in humans has been limited by the availability of suitable datasets. Here, we present a study comparing the maximum strengths of natural and sexual selection in humans that includes the effects of sex and wealth on different episodes of selection. Our dataset was compiled from church records of preindustrial Finnish populations characterized by socially imposed monogamy, and it contains a complete distribution of survival, mating, and reproductive success for 5,923 individuals born 1760-1849. Individual differences in early survival and fertility (natural selection) were responsible for most variation in fitness, even among wealthier individuals. Variance in mating success explained most of the higher variance in reproductive success in males compared with females, but mating success also influenced reproductive success in females, allowing for sexual selection to operate in both sexes. The detected opportunity for selection is in line with measurements for other species but higher than most previous reports for human samples. This disparity results from biological, demographic, economic, and social differences across populations as well as from failures by most previous studies to account for variation in fitness introduced by nonreproductive individuals. Our results emphasize that the demographic, cultural, and technological changes of the last 10,000 y did not preclude the potential for natural and sexual selection in our species.

  3. Model selection criterion in survival analysis

    Science.gov (United States)

    Karabey, Uǧur; Tutkun, Nihal Ata

    2017-07-01

    Survival analysis deals with time until occurrence of an event of interest such as death, recurrence of an illness, the failure of an equipment or divorce. There are various survival models with semi-parametric or parametric approaches used in medical, natural or social sciences. The decision on the most appropriate model for the data is an important point of the analysis. In literature Akaike information criteria or Bayesian information criteria are used to select among nested models. In this study,the behavior of these information criterion is discussed for a real data set.

  4. A guide to sexual selection theory

    NARCIS (Netherlands)

    Kuijper, Bram; Pen, Ido; Weissing, Franz J.

    2012-01-01

    Mathematical models have played an important role in the development of sexual selection theory. These models come in different flavors and they differ in their assumptions, often in a subtle way. Similar questions can be addressed by modeling frameworks from population genetics, quantitative

  5. Sexual selection studies: A NESCent catalyst meeting

    NARCIS (Netherlands)

    Roughgarden, J.; Adkins-Regan, E.; Akcay, E.; Hinde, C.A.; Hoquet, T.; O'Connor, C.; Prokop, Z.M.; Prum, R.O.; Shafir, S.; Snow, S.S.; Taylor, D.; Cleve, Van J.; Weisberg, M.

    2015-01-01

    A catalyst meeting on sexual selection studies was held in July 2013 at the facilities of the National Evolutionary Synthesis Center (NESCent) in Durham, NC. This article by a subcommittee of the participants foregrounds some of the topics discussed at the meeting. Topics mentioned here include the

  6. Natural and sexual selection against hybrid flycatchers

    NARCIS (Netherlands)

    Svedin, Nina; Wiley, Chris; Veen, Thor; Gustafsson, Lars; Qvarnstrom, Anna

    2008-01-01

    While sexual selection is generally assumed to quickly cause or strengthen prezygotic barriers between sister species, its role in causing postzygotic isolation, through the unattractiveness of intermediate hybrids, is less often examined. Combining 24 years of pedigree data and recently developed

  7. Sexual and natural selection both influence male genital evolution.

    Science.gov (United States)

    House, Clarissa M; Lewis, Zenobia; Hodgson, Dave J; Wedell, Nina; Sharma, Manmohan D; Hunt, John; Hosken, David J

    2013-01-01

    Rapid and divergent evolution of male genital morphology is a conspicuous and general pattern across internally fertilizing animals. Rapid genital evolution is thought to be the result of sexual selection, and the role of natural selection in genital evolution remains controversial. However, natural and sexual selection are believed to act antagonistically on male genital form. We conducted an experimental evolution study to investigate the combined effects of natural and sexual selection on the genital-arch lobes of male Drosophila simulans. Replicate populations were forced to evolve under lifetime monogamy (relaxed sexual selection) or lifetime polyandry (elevated sexual selection) and two temperature regimes, 25°C (relaxed natural selection) or 27°C (elevated natural selection) in a fully factorial design. We found that natural and sexual selection plus their interaction caused genital evolution. Natural selection caused some aspects of genital form to evolve away from their sexually selected shape, whereas natural and sexual selection operated in the same direction for other shape components. Additionally, sexual and natural selection tended to favour larger genitals. Thus we find that the underlying selection driving genital evolution is complex, does not only involve sexual selection, and that natural selection and sexual selection do not always act antagonistically.

  8. The locus of sexual selection: moving sexual selection studies into the post-genomics era.

    Science.gov (United States)

    Wilkinson, G S; Breden, F; Mank, J E; Ritchie, M G; Higginson, A D; Radwan, J; Jaquiery, J; Salzburger, W; Arriero, E; Barribeau, S M; Phillips, P C; Renn, S C P; Rowe, L

    2015-04-01

    Sexual selection drives fundamental evolutionary processes such as trait elaboration and speciation. Despite this importance, there are surprisingly few examples of genes unequivocally responsible for variation in sexually selected phenotypes. This lack of information inhibits our ability to predict phenotypic change due to universal behaviours, such as fighting over mates and mate choice. Here, we discuss reasons for this apparent gap and provide recommendations for how it can be overcome by adopting contemporary genomic methods, exploiting underutilized taxa that may be ideal for detecting the effects of sexual selection and adopting appropriate experimental paradigms. Identifying genes that determine variation in sexually selected traits has the potential to improve theoretical models and reveal whether the genetic changes underlying phenotypic novelty utilize common or unique molecular mechanisms. Such a genomic approach to sexual selection will help answer questions in the evolution of sexually selected phenotypes that were first asked by Darwin and can furthermore serve as a model for the application of genomics in all areas of evolutionary biology. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology.

  9. Adaptations to sexual selection and sexual conflict: insights from experimental evolution and artificial selection.

    Science.gov (United States)

    Edward, Dominic A; Fricke, Claudia; Chapman, Tracey

    2010-08-27

    Artificial selection and experimental evolution document natural selection under controlled conditions. Collectively, these techniques are continuing to provide fresh and important insights into the genetic basis of evolutionary change, and are now being employed to investigate mating behaviour. Here, we focus on how selection techniques can reveal the genetic basis of post-mating adaptations to sexual selection and sexual conflict. Alteration of the operational sex ratio of adult Drosophila over just a few tens of generations can lead to altered ejaculate allocation patterns and the evolution of resistance in females to the costly effects of elevated mating rates. We provide new data to show how male responses to the presence of rivals can evolve. For several traits, the way in which males responded to rivals was opposite in lines selected for male-biased, as opposed to female-biased, adult sex ratio. This shows that the manipulation of the relative intensity of intra- and inter-sexual selection can lead to replicable and repeatable effects on mating systems, and reveals the potential for significant contemporary evolutionary change. Such studies, with important safeguards, have potential utility for understanding sexual selection and sexual conflict across many taxa. We discuss how artificial selection studies combined with genomics will continue to deepen our knowledge of the evolutionary principles first laid down by Darwin 150 years ago.

  10. Experimental evidence that sexual conflict influences the opportunity, form and intensity of sexual selection.

    Science.gov (United States)

    Hall, Matthew D; Bussière, Luc F; Hunt, John; Brooks, Robert

    2008-09-01

    Sexual interactions are often rife with conflict. Conflict between members of the same sex over opportunities to mate has long been understood to effect evolution via sexual selection. Although conflict between males and females is now understood to be widespread, such conflict is seldom considered in the same light as a general agent of sexual selection. Any interaction between males or females that generates variation in fitness, whether due to conflict, competition or mate choice, can potentially influence sexual selection acting on a range of male traits. Here we seek to address a lack of direct experimental evidence for how sexual conflict influences sexual selection more broadly. We manipulate a major source of sexual conflict in the black field cricket, Teleogryllus commodus, and quantify the resulting changes in the nature of sexual selection using formal selection analysis to statistically compare multivariate fitness surfaces. In T. commodus, sexual conflict occurs over the attachment time of an external spermatophore. By experimentally manipulating the ability of males and females to influence spermatophore attachment, we found that sexual conflict significantly influences the opportunity, form, and intensity of sexual selection on male courtship call and body size. When males were able to harass females, the opportunity for selection was smaller, the form of selection changed, and sexual selection was weaker. We discuss the broader evolutionary implications of these findings, including the contributions of sexual conflict to fluctuating sexual selection and the maintenance of additive genetic variation.

  11. Sexual Selection and Humor in Courtship

    Directory of Open Access Journals (Sweden)

    Jeffrey A. Hall

    2015-08-01

    Full Text Available This investigation examines a sexual selection-based argument regarding humor’s role in courtship (i.e., humor production signals intelligence/creativity. Lens model (n =100 analyses suggest that humor production on Facebook profiles were self-reported and perceived to be associated with extroversion, not intelligence. Study 2 (n = 289 found that extroversion was associated humor production, but high school and college grade point average and American College Test (ACT scores were not. In Study 3, pairs of opposite-sex strangers (n = 102 interacted for 10–12 min. Males’ humor production and females’ responsive laughter were both associated with females’ dating interest. Both partners’ dating interest was associated with simultaneous laughter. Without support for the sexual selection argument, three alternative explanations of humor’s role in courtship are discussed.

  12. Sexual selection targets cetacean pelvic bones

    Science.gov (United States)

    Dines, J. P.; Otárola-Castillo, E.; Ralph, P.; Alas, J.; Daley, T.; Smith, A. D.; Dean, M. D.

    2014-01-01

    Male genitalia evolve rapidly, probably as a result of sexual selection. Whether this pattern extends to the internal infrastructure that influences genital movements remains unknown. Cetaceans (whales and dolphins) offer a unique opportunity to test this hypothesis: since evolving from land-dwelling ancestors, they lost external hind limbs and evolved a highly reduced pelvis which seems to serve no other function except to anchor muscles that maneuver the penis. Here we create a novel morphometric pipeline to analyze the size and shape evolution of pelvic bones from 130 individuals (29 species) in the context of inferred mating system. We present two main findings: 1) males from species with relatively intense sexual selection (inferred by relative testes size) have evolved relatively large penises and pelvic bones compared to their body size, and 2) pelvic bone shape diverges more quickly in species pairs that have diverged in inferred mating system. Neither pattern was observed in the anterior-most pair of vertebral ribs, which served as a negative control. This study provides evidence that sexual selection can affect internal anatomy that controls male genitalia. These important functions may explain why cetacean pelvic bones have not been lost through evolutionary time. PMID:25186496

  13. Sexual selection targets cetacean pelvic bones.

    Science.gov (United States)

    Dines, James P; Otárola-Castillo, Erik; Ralph, Peter; Alas, Jesse; Daley, Timothy; Smith, Andrew D; Dean, Matthew D

    2014-11-01

    Male genitalia evolve rapidly, probably as a result of sexual selection. Whether this pattern extends to the internal infrastructure that influences genital movements remains unknown. Cetaceans (whales and dolphins) offer a unique opportunity to test this hypothesis: since evolving from land-dwelling ancestors, they lost external hind limbs and evolved a highly reduced pelvis that seems to serve no other function except to anchor muscles that maneuver the penis. Here, we create a novel morphometric pipeline to analyze the size and shape evolution of pelvic bones from 130 individuals (29 species) in the context of inferred mating system. We present two main findings: (1) males from species with relatively intense sexual selection (inferred by relative testes size) tend to evolve larger penises and pelvic bones compared to their body length, and (2) pelvic bone shape has diverged more in species pairs that have diverged in inferred mating system. Neither pattern was observed in the anterior-most pair of vertebral ribs, which served as a negative control. This study provides evidence that sexual selection can affect internal anatomy that controls male genitalia. These important functions may explain why cetacean pelvic bones have not been lost through evolutionary time. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

  14. Early constraints in sexual dimorphism: survival benefits of feminized phenotypes.

    Science.gov (United States)

    López-Rull, I; Vergara, P; Martínez-Padilla, J; Fargallo, J A

    2016-02-01

    Sexual dimorphism (SD) has evolved in response to selection pressures that differ between sexes. Since such pressures change across an individual's life, SD may vary within age classes. Yet, little is known about how selection on early phenotypes may drive the final SD observed in adults. In many dimorphic species, juveniles resemble adult females rather than adult males, meaning that out of the selective pressures established by sexual selection feminized phenotypes may be adaptive. If true, fitness benefits of early female-like phenotypes may constrain the expression of male phenotypes in adulthood. Using the common kestrel Falco tinnunculus as a study model, we evaluated the fitness advantages of expressing more feminized phenotypes at youth. Although more similar to adult females than to adult males, common kestrel fledglings are still sexually dimorphic in size and coloration. Integrating morphological and chromatic variables, we analysed the phenotypic divergence between sexes as a measure of how much each individual looks like the sex to which it belongs (phenotypic sexual resemblance, PSR). We then tested the fitness benefits associated with PSR by means of the probability of recruitment in the population. We found a significant interaction between PSR and sex, showing that in both sexes more feminized phenotypes recruited more into the population than less feminized phenotypes. Moreover, males showed lower PSR than females and a higher proportion of incorrect sex classifications. These findings suggest that the mechanisms in males devoted to resembling female phenotypes in youth, due to a trend to increase fitness through more feminized phenotypes, may provide a mechanism to constrain the SD in adulthood. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology.

  15. Signal trait sexual dimorphism and mutual sexual selection in Drosophila serrata.

    Science.gov (United States)

    Chenoweth, Stephen F; Blows, Mark W

    2003-10-01

    The evolution of sexual dimorphism may occur when natural and sexual selection result in different optimum trait values for males and females. Perhaps the most prominent examples of sexual dimorphism occur in sexually selected traits, for which males usually display exaggerated trait levels, while females may show reduced expression of the trait. In some species, females also exhibit secondary sexual traits that may either be a consequence of a correlated response to sexual selection on males or direct sexual selection for female secondary sexual traits. In this experiment, we simultaneously measure the intersex genetic correlations and the relative strength of sexual selection on males and females for a set of cuticular hydrocarbons in Drosophila serrata. There was significant directional sexual selection on both male and female cuticular hydrocarbons: the strength of sexual selection did not differ among the sexes but males and females preferred different cuticular hydrocarbons. In contrast with many previous studies of sexual dimorphism, intersex genetic correlations were low. The evolution of sexual dimorphism in D. serrata appears to have been achieved by sex-limited expression of traits controlled by genes on the X chromosome and is likely to be in its final stages.

  16. Sexual and Natural Selection Both Influence Male Genital Evolution

    OpenAIRE

    House, Clarissa M.; Zenobia Lewis; Hodgson, Dave J.; Nina Wedell; Sharma, Manmohan D.; John Hunt; Hosken, David J.

    2013-01-01

    Rapid and divergent evolution of male genital morphology is a conspicuous and general pattern across internally fertilizing animals. Rapid genital evolution is thought to be the result of sexual selection, and the role of natural selection in genital evolution remains controversial. However, natural and sexual selection are believed to act antagonistically on male genital form. We conducted an experimental evolution study to investigate the combined effects of natural and sexual selection on ...

  17. Cardiac transplantation. Selection, immunosuppression, and survival.

    Science.gov (United States)

    Stevenson, L W; Laks, H; Terasaki, P I; Kahan, B D; Drinkwater, D C

    1988-01-01

    Cardiac transplantation has evolved from an experiment to an accepted therapy for severe heart failure. Increasing competition for donor organs mandates a greater emphasis on selection and timing for transplantation and paradoxically forces more reliance on aggressive medical therapy for all patients after evaluation. The growth of recipient and donor pools may enhance the opportunity for assessing histocompatibility, for which distinguishing between autoantibodies and human leukocyte antigen-determined reactivity is important, and some general nonresponders may be detected. Therapy with cyclosporine has improved the outcome after transplantation, but further refinement is needed, perhaps with pharmacologic synergy, to minimize nephrotoxicity and maximize specific immunosuppression. Survival is more than 80% at 1 year, after which the incidence of acute rejection and infection declines and accelerated atherosclerosis becomes prominent. Although resuming employment is not always possible, the overall quality of life is excellent after cardiac transplantation. Images PMID:3074557

  18. Sex differences, sexual selection, and ageing: an experimental evolution approach.

    Science.gov (United States)

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

    2009-10-01

    Life-history (LH) theory predicts that selection will optimize the trade-off between reproduction and somatic maintenance. Reproductive ageing and finite life span are direct consequences of such optimization. Sexual selection and conflict profoundly affect the reproductive strategies of the sexes and thus can play an important role in the evolution of life span and ageing. In theory, sexual selection can favor the evolution of either faster or slower ageing, but the evidence is equivocal. We used a novel selection experiment to investigate the potential of sexual selection to influence the adaptive evolution of age-specific LH traits. We selected replicate populations of the seed beetle Callosobruchus maculatus for age at reproduction ("Young" and "Old") either with or without sexual selection. We found that LH selection resulted in the evolution of age-specific reproduction and mortality but these changes were largely unaffected by sexual selection. Sexual selection depressed net reproductive performance and failed to promote adaptation. Nonetheless, the evolution of several traits differed between males and females. These data challenge the importance of current sexual selection in promoting rapid adaptation to environmental change but support the hypothesis that sex differences in LH-a historical signature of sexual selection-are key in shaping trait responses to novel selection.

  19. Sexual selection and immune function in Drosophila melanogaster.

    Science.gov (United States)

    McKean, Kurt A; Nunney, Leonard

    2008-02-01

    The evolution of immune function depends not only on variation in genes contributing directly to the immune response, but also on genetic variation in other traits indirectly affecting immunocompetence. In particular, sexual selection is predicted to trade-off with immunocompetence because the extra investment of resources needed to increase sexual competitiveness reduces investment in immune function. Additional possible immunological consequences of intensifying sexual selection include an exaggeration of immunological sexual dimorphism, and the reduction of condition-dependent immunological costs due to selection of 'good genes' (the immunocompetence handicap hypothesis, ICHH). We tested for these evolutionary possibilities by increasing sexual selection in laboratory populations of Drosophila melanogaster for 58 generations by reestablishing a male-biased sex ratio at the start of each generation. Sexually selected flies were larger, took longer to develop, and the males were more sexually competitive than males from control (equal sex ratio) lines. We found support for the trade-off hypothesis: sexually selected males were found to have reduced immune function compared to control males. However, we found no evidence that sexual selection promoted immunological sexual dimorphism because females showed a similar reduction in immune function. We found no evidence of evolutionary changes in the condition-dependent expression of immunocompetence contrary to the expectations of the ICHH. Lastly, we compared males from the unselected base population that were either successful (IS) or unsuccessful (IU) in a competitive mating experiment. IS males showed reduced immune function relative to IU males, suggesting that patterns of phenotypic correlation largely mirror patterns of genetic correlation revealed by the selection experiment. Our results suggest increased disease susceptibility could be an important cost limiting increases in sexual competitiveness in

  20. A comparative analysis of sexual harassment policies at selected ...

    African Journals Online (AJOL)

    This article investigates sexual harassment issues by means of an in depth literature review and by analyzing and comparing the sexual harassment policies of selected universities in South Africa. Various alternatives that categorize sexual harassment are proposed in order to form a clear perspective on the different ...

  1. Survival, growth and sexual maturation in Atlantic salmon exposed to infectious pancreatic necrosis

    DEFF Research Database (Denmark)

    Lillehammer, Marie; Ødegård, Jørgen; Madsen, Per

    2013-01-01

    tested on data consisting of 10 972 fish that died and 3959 survivors with recorded growth data. The most complex models (4 and 5) were multivariate normal-binary mixture models including growth, sexual maturity and field survival traits. Growth rate and liability of sexual maturation were treated as two...... (0.39 +/- 0.07 and 0.36 +/- 0.08) and sexual maturation (0.33 +/- 0.05), and high for field survival (0.47 +/- 0.03 and 0.48 +/- 0.03). Growth in healthy animals, runt status and survival showed consistent favourable genetic associations. Sexual maturation showed an unfavourable non...

  2. Sexually antagonistic selection in human male homosexuality.

    Directory of Open Access Journals (Sweden)

    Andrea Camperio Ciani

    Full Text Available Several lines of evidence indicate the existence of genetic factors influencing male homosexuality and bisexuality. In spite of its relatively low frequency, the stable permanence in all human populations of this apparently detrimental trait constitutes a puzzling 'Darwinian paradox'. Furthermore, several studies have pointed out relevant asymmetries in the distribution of both male homosexuality and of female fecundity in the parental lines of homosexual vs. heterosexual males. A number of hypotheses have attempted to give an evolutionary explanation for the long-standing persistence of this trait, and for its asymmetric distribution in family lines; however a satisfactory understanding of the population genetics of male homosexuality is lacking at present. We perform a systematic mathematical analysis of the propagation and equilibrium of the putative genetic factors for male homosexuality in the population, based on the selection equation for one or two diallelic loci and Bayesian statistics for pedigree investigation. We show that only the two-locus genetic model with at least one locus on the X chromosome, and in which gene expression is sexually antagonistic (increasing female fitness but decreasing male fitness, accounts for all known empirical data. Our results help clarify the basic evolutionary dynamics of male homosexuality, establishing this as a clearly ascertained sexually antagonistic human trait.

  3. Sexually Antagonistic Selection in Human Male Homosexuality

    Science.gov (United States)

    Camperio Ciani, Andrea; Cermelli, Paolo; Zanzotto, Giovanni

    2008-01-01

    Several lines of evidence indicate the existence of genetic factors influencing male homosexuality and bisexuality. In spite of its relatively low frequency, the stable permanence in all human populations of this apparently detrimental trait constitutes a puzzling ‘Darwinian paradox’. Furthermore, several studies have pointed out relevant asymmetries in the distribution of both male homosexuality and of female fecundity in the parental lines of homosexual vs. heterosexual males. A number of hypotheses have attempted to give an evolutionary explanation for the long-standing persistence of this trait, and for its asymmetric distribution in family lines; however a satisfactory understanding of the population genetics of male homosexuality is lacking at present. We perform a systematic mathematical analysis of the propagation and equilibrium of the putative genetic factors for male homosexuality in the population, based on the selection equation for one or two diallelic loci and Bayesian statistics for pedigree investigation. We show that only the two-locus genetic model with at least one locus on the X chromosome, and in which gene expression is sexually antagonistic (increasing female fitness but decreasing male fitness), accounts for all known empirical data. Our results help clarify the basic evolutionary dynamics of male homosexuality, establishing this as a clearly ascertained sexually antagonistic human trait. PMID:18560521

  4. Sexual selection counteracts extinction of small populations of the bulb mites.

    Science.gov (United States)

    Jarzebowska, Magdalena; Radwan, Jacek

    2010-05-01

    Genetic drift in small populations can increase frequency of deleterious recessives and consequently lead to inbreeding depression and population extinction. On the other hand, as homozygosity at deleterious recessives increases, they should be purged from populations more effectively by selection. Sexual selection has been postulated to strengthen selection against deleterious mutations, and should thus decrease extinction rate and intensify purging of inbreeding depression. We tested these predictions in the bulb mite Rhizoglyphus robini. We created 100 replicate lines of small populations (five males and five females) and in half of them experimentally removed sexual selection by enforcing monogamy. The lines were propagated for eight generations and then assayed for purging of inbreeding depression. We found that proportion of lines which went extinct was lower with sexual selection than without. We also found evidence for purging of inbreeding depression in the lines with sexual selection, but not in lines without sexual selection. Our results suggest that purging of inbreeding depression was more effective against mutations with relatively large deleterious effects. Thus, although our data clearly indicate a positive impact of sexual selection on short-term survival of bottlenecked populations, long-term consequences are less clear as they may be negatively impacted by accumulation of deleterious mutations of small effect.

  5. Sexual selection determines parental care patterns in cichlid fishes.

    Science.gov (United States)

    Gonzalez-Voyer, Alejandro; Fitzpatrick, John L; Kolm, Niclas

    2008-08-01

    Despite a massive research effort, our understanding of why, in most vertebrates, males compete for mates and females care for offspring remains incomplete. Two alternative hypotheses have been proposed to explain the direction of causality between parental care and sexual selection. Traditionally, sexual selection has been explained as a consequence of relative parental investment, where the sex investing less will compete for the sex investing more. However, a more recent model suggests that parental care patterns result from sexual selection acting on one sex favoring mating competition and lower parental investment. Using species-level comparative analyses on Tanganyikan cichlid fishes we tested these alternative hypotheses employing a proxy of sexual selection based on mating system, sexual dichromatism, and dimorphism data. First, while controlling for female reproductive investment, we found that species with intense sexual selection were associated with female-only care whereas species with moderate sexual selection were associated with biparental care. Second, using contingency analyses, we found that, contrary to the traditional view, evolutionary changes in parental care type are dependent on the intensity of sexual selection. Hence, our results support the hypothesis that sexual selection determines parental care patterns in Tanganyikan cichlid fishes.

  6. Sexual dimorphism and directional sexual selection on aposematic signals in a poison frog

    NARCIS (Netherlands)

    Maan, Martine E.; Cummings, Molly E.

    2009-01-01

    It is commonly assumed that natural selection imposed by predators is the prevailing force driving the evolution of aposematic traits. Here, we demonstrate that aposematic signals are shaped by sexual selection as well. We evaluated sexual selection for coloration brightness in populations of the

  7. Canine evolution in sabretoothed carnivores: natural selection or sexual selection?

    Directory of Open Access Journals (Sweden)

    Marcela Randau

    Full Text Available The remarkable elongated upper canines of extinct sabretoothed carnivorous mammals have been the subject of considerable speculation on their adaptive function, but the absence of living analogues prevents any direct inference about their evolution. We analysed scaling relationships of the upper canines of 20 sabretoothed feliform carnivores (Nimravidae, Barbourofelidae, Machairodontinae, representing both dirk-toothed and scimitar-toothed sabretooth ecomorphs, and 33 non-sabretoothed felids in relation to body size in order to characterize and identify the evolutionary processes driving their development, using the scaling relationships of carnassial teeth in both groups as a control. Carnassials display isometric allometry in both sabretooths and non-sabretooths, supporting their close relationship with meat-slicing, whereas the upper canines of both groups display positive allometry with body size. Whereas there is no statistical difference in allometry of upper canine height between dirk-toothed and scimitar-toothed sabretooth ecomorphs, the significantly stronger positive allometry of upper canine height shown by sabretooths as a whole compared to non-sabretooths reveals that different processes drove canine evolution in these groups. Although sabretoothed canines must still have been effective for prey capture and processing by hypercarnivorous predators, canine morphology in these extinct carnivores was likely to have been driven to a greater extent by sexual selection than in non-sabretooths. Scaling relationships therefore indicate the probable importance of sexual selection in the evolution of the hypertrophied sabretooth anterior dentition.

  8. Sexual selection gradients change over time in a simultaneous hermaphrodite

    NARCIS (Netherlands)

    Hoffer, Jeroen Na; Mariën, Janine; Ellers, Jacintha; Koene, Joris M

    2017-01-01

    Sexual selection is generally predicted to act more strongly on males than on females. The Darwin-Bateman paradigm predicts that this should also hold for hermaphrodites. However, measuring this strength of selection is less straightforward when both sexual functions are performed throughout the

  9. Reducing mutation load through sexual selection on males.

    Science.gov (United States)

    McGuigan, Katrina; Petfield, Donna; Blows, Mark W

    2011-10-01

    Mutation load is a key parameter in evolutionary theories, but relatively little empirical information exists on the mutation load of populations, or the elimination of this load through selection. We manipulated the opportunity for sexual selection within a mutation accumulation divergence experiment to determine how sexual selection on males affected the accumulation of mutations contributing to sexual and nonsexual fitness. Sexual selection prevented the accumulation of mutations affecting male mating success, the target trait, as well as reducing mutation load on productivity, a nonsexual fitness component. Mutational correlations between mating success and productivity (estimated in the absence of sexual selection) were positive. Sexual selection significantly reduced these fitness component correlations. Male mating success significantly diverged between sexual selection treatments, consistent with the fixation of genetic differences. However, the rank of the treatments was not consistent across assays, indicating that the mutational effects on mating success were conditional on biotic and abiotic context. Our experiment suggests that greater insight into the genetic targets of natural and sexual selection can be gained by focusing on mutational rather than standing genetic variation, and on the behavior of trait variances rather than means. © 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.

  10. SEXUAL SELECTION AND THE EVOLUTION OF SEXUAL SIZE DIMORPHISM IN THE WATER STRIDER, AQUARIUS REMIGIS.

    Science.gov (United States)

    Fairbairn, Daphne J; Preziosi, Richard F

    1996-08-01

    Sexual size dimorphism (SSD) is often attributed to sexual selection, particularly when males are the larger sex. However, sexual selection favoring large males is common even in taxa where females are the larger sex, and is therefore not a sufficient explanation of patterns of SSD. As part of a more extensive study of the evolution of SSD in water striders (Heteroptera, Gerridae), we examine patterns of sexual selection and SSD in 12 populations of Aquarius remigis. We calculate univariate and multivariate selection gradients from samples of mating and single males, for two sexually dimorphic traits (total length and profemoral width) and two sexually monomorphic traits (mesofemoral length and wing form). The multivariate analyses reveal strong selection favoring larger males, in spite of the female-biased SSD for this trait, and weaker selection favoring aptery and reduced mesofemoral length. Selection is weakest on the most dimorphic trait, profemoral width, and is stabilizing rather than directional. The pattern of sexual selection on morphological traits is therefore not concordant with the pattern of SSD. The univariate selection gradients reveal little net selection (direct + indirect) on any of the traits, and suggest that evolution away from the plesiomorphic pattern of SSD is constrained by antagonistic patterns of selection acting on this suite of positively correlated morphological traits. We hypothesize that SSD in A. remigis is not in equilibrium, a hypothesis that is consistent with both theoretical models of the evolution of SSD and our previous studies of allometry for SSD. A negative interpopulation correlation between the intensity of sexual selection and the operational sex ratio supports the hypothesis that, as in several other water strider species, sexual selection in A. remigis occurs through generalized female reluctance rather than active female choice. The implications of this for patterns of sexual selection are discussed. © 1996 The

  11. Sexual selection, germline mutation rate and sperm competition

    Directory of Open Access Journals (Sweden)

    Møller AP

    2003-04-01

    Full Text Available Abstract Background An important component of sexual selection arises because females obtain viability benefits for their offspring from their mate choice. Females choosing extra-pair fertilization generally favor males with exaggerated secondary sexual characters, and extra-pair paternity increases the variance in male reproductive success. Furthermore, females are assumed to benefit from 'good genes' from extra-pair sires. How additive genetic variance in such viability genes is maintained despite strong directional selection remains an evolutionary enigma. We propose that sexual selection is associated with elevated mutation rates, changing the balance between mutation and selection, thereby increasing variance in fitness and hence the benefits to be obtained from good genes sexual selection. Two hypotheses may account for such elevated mutation: (1 Increased sperm production associated with sperm competition may increase mutation rate. (2 Mutator alleles increase mutation rates that are revealed by the expression of condition-dependent secondary sexual characters used by choosy females during their mate choice. M Petrie has independently developed the idea that mutator alleles may account for the maintenance of genetic variation in viability despite strong directional selection. Results A comparative study of birds revealed a positive correlation between mutation rate at minisatellite loci and extra-pair paternity, but not between mutation rate and relative testes mass which is a measure of relative sperm production. Minisatellite mutation rates were not related to longevity, suggesting a meiotic rather than a mitotic origin of mutations. Conclusion We found evidence of increased mutation rate in species with more intense sexual selection. Increased mutation was not associated with increased sperm production, and we suggest that species with intense sexual selection may maintain elevated mutation rates because sexual selection continuously

  12. The measurement of sexual selection on females and males

    Directory of Open Access Journals (Sweden)

    Karoline FRITZSCHE, Isobel BOOKSMYTHE

    2013-08-01

    Full Text Available As in any field of research, the study of sexual selection is subject to ongoing debate over definitions and interpretations of the fundamental concepts involved. These arguments generally promote progress, as they highlight areas where current explanations are incomplete. Here we briefly review two ongoing discussions in the sexual selection literature. First, the definition of sexual selection has received renewed interest in light of increasing research effort into when and how it operates in females. Second, how best to measure sexual selection is an ongoing subject of debate; in practice, recognition that the appropriate measures depend on the focus of the specific study, and that multiple measures should be employed wherever possible, seems to provide the most informative approach. The wide scope of recent empirical work in these and related areas, with the application of new techniques and approaches, reflects that the field of sexual selection is being constantly expanded and enriched [Current Zoology 59 (4: 558–563, 2013].

  13. Multivariate sexual selection in a rapidly evolving speciation phenotype.

    Science.gov (United States)

    Oh, Kevin P; Shaw, Kerry L

    2013-06-22

    Estimating the fitness surface of rapidly evolving secondary sexual traits can elucidate the origins of sexual isolation and thus speciation. Evidence suggests that sexual selection is highly complex in nature, often acting on multivariate sexual characters that sometimes include non-heritable components of variation, thus presenting a challenge for predicting patterns of sexual trait evolution. Laupala crickets have undergone an explosive species radiation marked by divergence in male courtship song and associated female preferences, yet patterns of sexual selection that might explain this diversification remain unknown. We used female phonotaxis trials to estimate the fitness surface for acoustic characters within one population of Laupala cerasina, a species with marked geographical variation in male song and female preferences. Results suggested significant directional sexual selection on three major song traits, while canonical rotation of the matrix of nonlinear selection coefficients (γ) revealed the presence of significant convex (stabilizing) sexual selection along combinations of characters. Analysis of song variation within and among males indicated significantly higher repeatability along the canonical axis of greatest stabilizing selection than along the axis of greatest linear selection. These results are largely consistent with patterns of song divergence that characterize speciation and suggest that different song characters have the potential to indicate distinct information to females during courtship.

  14. Parental investment, sexual selection and sex ratios.

    Science.gov (United States)

    Kokko, Hanna; Jennions, Michael D

    2008-07-01

    Conventional sex roles imply caring females and competitive males. The evolution of sex role divergence is widely attributed to anisogamy initiating a self-reinforcing process. The initial asymmetry in pre-mating parental investment (eggs vs. sperm) is assumed to promote even greater divergence in post-mating parental investment (parental care). But do we really understand the process? Trivers [Sexual Selection and the Descent of Man 1871-1971 (1972), Aldine Press, Chicago] introduced two arguments with a female and male perspective on whether to care for offspring that try to link pre-mating and post-mating investment. Here we review their merits and subsequent theoretical developments. The first argument is that females are more committed than males to providing care because they stand to lose a greater initial investment. This, however, commits the 'Concorde Fallacy' as optimal decisions should depend on future pay-offs not past costs. Although the argument can be rephrased in terms of residual reproductive value when past investment affects future pay-offs, it remains weak. The factors likely to change future pay-offs seem to work against females providing more care than males. The second argument takes the reasonable premise that anisogamy produces a male-biased operational sex ratio (OSR) leading to males competing for mates. Male care is then predicted to be less likely to evolve as it consumes resources that could otherwise be used to increase competitiveness. However, given each offspring has precisely two genetic parents (the Fisher condition), a biased OSR generates frequency-dependent selection, analogous to Fisherian sex ratio selection, that favours increased parental investment by whichever sex faces more intense competition. Sex role divergence is therefore still an evolutionary conundrum. Here we review some possible solutions. Factors that promote conventional sex roles are sexual selection on males (but non-random variance in male mating success

  15. Understanding the link between sexual selection, sexual conflict and aging using crickets as a model.

    Science.gov (United States)

    Archer, C Ruth; Hunt, John

    2015-11-01

    Aging evolved because the strength of natural selection declines over the lifetime of most organisms. Weak natural selection late in life allows the accumulation of deleterious mutations and may favor alleles that have positive effects on fitness early in life, but costly pleiotropic effects expressed later on. While this decline in natural selection is central to longstanding evolutionary explanations for aging, a role for sexual selection and sexual conflict in the evolution of lifespan and aging has only been identified recently. Testing how sexual selection and sexual conflict affect lifespan and aging is challenging as it requires quantifying male age-dependent reproductive success. This is difficult in the invertebrate model organisms traditionally used in aging research. Research using crickets (Orthoptera: Gryllidae), where reproductive investment can be easily measured in both sexes, has offered exciting and novel insights into how sexual selection and sexual conflict affect the evolution of aging, both in the laboratory and in the wild. Here we discuss how sexual selection and sexual conflict can be integrated alongside evolutionary and mechanistic theories of aging using crickets as a model. We then highlight the potential for research using crickets to further advance our understanding of lifespan and aging. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Sexual selection and the evolution of secondary sexual traits: sex comb evolution in Drosophila.

    Science.gov (United States)

    Snook, Rhonda R; Gidaszewski, Nelly A; Chapman, Tracey; Simmons, Leigh W

    2013-04-01

    Sexual selection can drive rapid evolutionary change in reproductive behaviour, morphology and physiology. This often leads to the evolution of sexual dimorphism, and continued exaggerated expression of dimorphic sexual characteristics, although a variety of other alternative selection scenarios exist. Here, we examined the evolutionary significance of a rapidly evolving, sexually dimorphic trait, sex comb tooth number, in two Drosophila species. The presence of the sex comb in both D. melanogaster and D. pseudoobscura is known to be positively related to mating success, although little is yet known about the sexually selected benefits of sex comb structure. In this study, we used experimental evolution to test the idea that enhancing or eliminating sexual selection would lead to variation in sex comb tooth number. However, the results showed no effect of either enforced monogamy or elevated promiscuity on this trait. We discuss several hypotheses to explain the lack of divergence, focussing on sexually antagonistic coevolution, stabilizing selection via species recognition and nonlinear selection. We discuss how these are important, but relatively ignored, alternatives in understanding the evolution of rapidly evolving sexually dimorphic traits. © 2013 The Authors. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology.

  17. Sexual selection enables long-term coexistence despite ecological equivalence.

    Science.gov (United States)

    M'Gonigle, Leithen K; Mazzucco, Rupert; Otto, Sarah P; Dieckmann, Ulf

    2012-04-26

    Empirical data indicate that sexual preferences are critical for maintaining species boundaries, yet theoretical work has suggested that, on their own, they can have only a minimal role in maintaining biodiversity. This is because long-term coexistence within overlapping ranges is thought to be unlikely in the absence of ecological differentiation. Here we challenge this widely held view by generalizing a standard model of sexual selection to include two ubiquitous features of populations with sexual selection: spatial variation in local carrying capacity, and mate-search costs in females. We show that, when these two features are combined, sexual preferences can single-handedly maintain coexistence, even when spatial variation in local carrying capacity is so slight that it might go unnoticed empirically. This theoretical study demonstrates that sexual selection alone can promote the long-term coexistence of ecologically equivalent species with overlapping ranges, and it thus provides a novel explanation for the maintenance of species diversity.

  18. Sexual selection's impacts on ecological specialization: an experimental test.

    Science.gov (United States)

    Pfennig, Karin S; Pfennig, David W; Porter, Cody; Martin, Ryan A

    2015-05-22

    In many species, individuals specialize on different resources, thereby reducing competition. Such ecological specialization can promote the evolution of alternative ecomorphs-distinct phenotypes adapted for particular resources. Elucidating whether and how this process is influenced by sexual selection is crucial for understanding how ecological specialization promotes the evolution of novel traits and, potentially, speciation between ecomorphs. We evaluated the population-level effects of sexual selection (as mediated by mate choice) on ecological specialization in spadefoot toad tadpoles that express alternative ecomorphs. We manipulated whether sexual selection was present or reversed by mating females to their preferred versus non-preferred males, respectively. We then exposed their tadpoles to resource competition in experimental mesocosms. The resulting distribution of ecomorphs was similar between treatments, but sexual selection generated poorer trait integration in, and lower fitness of, the more specialized carnivore morph. Moreover, disruptive and directional natural selection were weaker in the sexual selection present treatment. Nevertheless, this effect on disruptive selection was smaller than previously documented effects of ecological opportunity and competitor density. Thus, sexual selection can inhibit adaptation to resource competition and thereby hinder ecological specialization, particularly when females obtain fitness benefits from mate choice that offset the cost of producing competitively inferior offspring. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  19. Walking the Woods: The Lived Experience of Sexual Assault Survival for Women in College

    Science.gov (United States)

    Monahan-Kreishman, Mollie M.

    2012-01-01

    This phenomenological study explores the lived experience of sexual assault survival for women in college. Through a grounding in the philosophy of hermeneutic phenomenology (Gadamer, 1960/2000; Heidegger, 1927/1962, 1968, 1928/1998, 1971/2001, 1950/2002), this work uncovers the lives of six sexual assault survivors who lived through rape during…

  20. Methods of Investigation of Sexual Crimes (Selected Issues)

    OpenAIRE

    Pixová, Monika

    2016-01-01

    Cizojazyčné resumé The diploma thesis deals with the methods of investigation of sexual crimes. Because the topic is too broad I've decided to focus only on selected issues of methods of investigation of child sexual abuse. Investigation of child sexual abuse is very specific in comparison to other sexual crimes. During the investigation the child victim must be handled very sensitively in order to avoid secondary victimization. The purpose of this thesis is to describe the specifics of inves...

  1. Sexual selection and conflict as engines of ecological diversification.

    Science.gov (United States)

    Bonduriansky, Russell

    2011-12-01

    Ecological diversification presents an enduring puzzle: how do novel ecological strategies evolve in organisms that are already adapted to their ecological niche? Most attempts to answer this question posit a primary role for genetic drift, which could carry populations through or around fitness "valleys" representing maladaptive intermediate phenotypes between alternative niches. Sexual selection and conflict are thought to play an ancillary role by initiating reproductive isolation and thereby facilitating divergence in ecological traits through genetic drift or local adaptation. Here, I synthesize theory and evidence suggesting that sexual selection and conflict could play a more central role in the evolution and diversification of ecological strategies through the co-optation of sexual traits for viability-related functions. This hypothesis rests on three main premises, all of which are supported by theory and consistent with the available evidence. First, sexual selection and conflict often act at cross-purposes to viability selection, thereby displacing populations from the local viability optimum. Second, sexual traits can serve as preadaptations for novel viability-related functions. Third, ancestrally sex-limited sexual traits can be transferred between sexes. Consequently, by allowing populations to explore a broad phenotypic space around the current viability optimum, sexual selection and conflict could act as powerful drivers of ecological adaptation and diversification.

  2. Sexual selection on brain size in shorebirds (Charadriiformes).

    Science.gov (United States)

    García-Peña, G E; Sol, D; Iwaniuk, A N; Székely, T

    2013-04-01

    Natural selection is considered a major force shaping brain size evolution in vertebrates, whereas the influence of sexual selection remains controversial. On one hand, sexual selection could promote brain enlargement by enhancing cognitive skills needed to compete for mates. On the other hand, sexual selection could favour brain size reduction due to trade-offs between investing in brain tissue and in sexually selected traits. These opposed predictions are mirrored in contradictory relationships between sexual selection proxies and brain size relative to body size. Here, we report a phylogenetic comparative analysis that highlights potential flaws in interpreting relative brain size-mating system associations as effects of sexual selection on brain size in shorebirds (Charadriiformes), a taxonomic group with an outstanding diversity in breeding systems. Considering many ecological effects, relative brain size was not significantly correlated with testis size. In polyandrous species, however, relative brain sizes of males and females were smaller than in monogamous species, and females had smaller brain size than males. Although these findings are consistent with sexual selection reducing brain size, they could also be due to females deserting parental care, which is a common feature of polyandrous species. Furthermore, our analyses suggested that body size evolved faster than brain size, and thus the evolution of body size may be confounding the effect of the mating system on relative brain size. The brain size-mating system association in shorebirds is thus not only due to sexual selection on brain size but rather, to body size evolution and other multiple simultaneous effects. © 2013 The Authors. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology.

  3. The diversification of mate preferences by natural and sexual selection.

    Science.gov (United States)

    Rundle, H D; Chenoweth, S F; Blows, M W

    2009-08-01

    The evolution of sexual display traits or preferences for them in response to divergent natural selection will alter sexual selection within populations, yet the role of sexual selection in ecological speciation has received little empirical attention. We evolved 12 populations of Drosophila serrata in a two-way factorial design to investigate the roles of natural and sexual selection in the evolution of female mate preferences for male cuticular hydrocarbons (CHCs). Mate preferences weakened in populations evolving under natural selection alone, implying a cost in the absence of their expression. Comparison of the vectors of linear sexual selection revealed that the populations diverged in the combination of male CHCs that females found most attractive, although this was not significant using a mixed modelling approach. Changes in preference direction tended to evolve when natural and sexual selection were unconstrained, suggesting that both processes may be the key to initial stages of ecological speciation. Determining the generality of this result will require data from various species across a range of novel environments.

  4. Prevalence of selected sexually transmitted infection (sti) and ...

    African Journals Online (AJOL)

    Prevalence of selected sexually transmitted infection (sti) and associated factors among symptomatic patients attending Gondar Town hospitals and health cCenters. Rozina Ambachew Geremew, Beyene Moges Agizie, Abate Assefa Bashaw, Mengistu Endris Seid, Addisu Gize Yeshanew ...

  5. Human skin-color sexual dimorphism: a test of the sexual selection hypothesis.

    Science.gov (United States)

    Madrigal, Lorena; Kelly, William

    2007-03-01

    Applied to skin color, the sexual selection hypothesis proposes that male preference for light-skinned females explains the presence of light skin in areas of low solar radiation. According to this proposal, in areas of high solar radiation, natural selection for dark skin overrides the universal preference of males for light females. But in areas in which natural selection ceases to act, sexual selection becomes more important, and causes human populations to become light-skinned, and females to be lighter than males. The sexual selection hypothesis proposes that human sexual dimorphism of skin color should be positively correlated with distance from the equator. We tested the prediction that sexual dimorphism should increase with increasing latitude, using adult-only data sets derived from measurements with standard reflectance spectrophotometric devices. Our analysis failed to support the prediction of a positive correlation between increasing distance from the equator and increased sexual dimorphism. We found no evidence in support of the sexual selection hypothesis. (c) 2006 Wiley-Liss, Inc.

  6. Tales of two snails: sexual selection and sexual conflict in Lymnaea stagnalis and Helix aspersa.

    NARCIS (Netherlands)

    Koene, J.M.

    2006-01-01

    Sexual selection and sexual conflict have been shown to play key roles in the evolution of species with separate sexes. Experimental evidence is accumulating that this is also true for simultaneous hermaphrodites. For example, many species of land snails forcefully stab their mating partners with

  7. Sexual selection determines parental care patterns in cichlid fishes

    OpenAIRE

    Gonzalez-Voyer, Alejandro; Fitzpatrick, John L.; Kolm, Niclas

    2008-01-01

    Despite a massive research effort, our understanding of why, in most vertebrates, males compete for mates and females care for offspring remains incomplete. Two alternative hypotheses have been proposed to explain the direction of causality between parental care and sexual selection. Traditionally, sexual selection has been explained as a consequence of relative parental investment, where the sex investing less will compete for the sex investing more. However, a more recent model suggests tha...

  8. Sexual selection predicts brain structure in dragon lizards.

    Science.gov (United States)

    Hoops, D; Ullmann, J F P; Janke, A L; Vidal-Garcia, M; Stait-Gardner, T; Dwihapsari, Y; Merkling, T; Price, W S; Endler, J A; Whiting, M J; Keogh, J S

    2017-02-01

    Phenotypic traits such as ornaments and armaments are generally shaped by sexual selection, which often favours larger and more elaborate males compared to females. But can sexual selection also influence the brain? Previous studies in vertebrates report contradictory results with no consistent pattern between variation in brain structure and the strength of sexual selection. We hypothesize that sexual selection will act in a consistent way on two vertebrate brain regions that directly regulate sexual behaviour: the medial preoptic nucleus (MPON) and the ventromedial hypothalamic nucleus (VMN). The MPON regulates male reproductive behaviour whereas the VMN regulates female reproductive behaviour and is also involved in male aggression. To test our hypothesis, we used high-resolution magnetic resonance imaging combined with traditional histology of brains in 14 dragon lizard species of the genus Ctenophorus that vary in the strength of precopulatory sexual selection. Males belonging to species that experience greater sexual selection had a larger MPON and a smaller VMN. Conversely, females did not show any patterns of variation in these brain regions. As the volumes of both these regions also correlated with brain volume (BV) in our models, we tested whether they show the same pattern of evolution in response to changes in BV and found that the do. Therefore, we show that the primary brain nuclei underlying reproductive behaviour in vertebrates can evolve in a mosaic fashion, differently between males and females, likely in response to sexual selection, and that these same regions are simultaneously evolving in concert in relation to overall brain size. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

  9. Antagonistic natural and sexual selection on wing shape in a scrambling damselfly.

    Science.gov (United States)

    Outomuro, David; Söderquist, Linus; Nilsson-Örtman, Viktor; Cortázar-Chinarro, María; Lundgren, Cecilia; Johansson, Frank

    2016-07-01

    Wings are a key trait underlying the evolutionary success of birds, bats, and insects. For over a century, researchers have studied the form and function of wings to understand the determinants of flight performance. However, to understand the evolution of flight, we must comprehend not only how morphology affects performance, but also how morphology and performance affect fitness. Natural and sexual selection can either reinforce or oppose each other, but their role in flight evolution remains poorly understood. Here, we show that wing shape is under antagonistic selection with regard to sexual and natural selection in a scrambling damselfly. In a field setting, natural selection (survival) favored individuals with long and slender forewings and short and broad hindwings. In contrast, sexual selection (mating success) favored individuals with short and broad forewings and narrow-based hindwings. Both types of selection favored individuals of intermediate size. These results suggest that individuals face a trade-off between flight energetics and maneuverability and demonstrate how natural and sexual selection can operate in similar directions for some wing traits, that is, wing size, but antagonistically for others, that is, wing shape. Furthermore, they highlight the need to study flight evolution within the context of species' mating systems and mating behaviors. © 2016 The Author(s).

  10. Sexual selection and natural selection in bird speciation

    National Research Council Canada - National Science Library

    Trevor Price

    1998-01-01

    .... I evaluate premating isolating mechanisms in one group, the birds. In this group premating isolation is often a consequence of sexual imprinting, whereby young birds learn features of their parents and use these features in mate choice...

  11. Survival sex work and increased HIV risk among sexual minority street-involved youth.

    Science.gov (United States)

    Marshall, Brandon D L; Shannon, Kate; Kerr, Thomas; Zhang, Ruth; Wood, Evan

    2010-04-01

    Exchanging sex for money, drugs, or other commodities for survival is associated with an array of HIV risks. We sought to determine if street-involved drug-using sexual minority youth are at greater risk for survival sex work and are more likely to engage in risk behaviors with clients. We examined factors associated with survival sex work among participants enrolled in the At Risk Youth Study using logistic regression. Self-reported risk behaviors with clients were also examined. Of 558 participants eligible for this analysis, 75 (13.4%) identified as a sexual minority and 63 (11.3%) reported survival sex work in the past 6 months. Sexual minority males (adjusted odds ratio = 16.1, P exchange sex are urgently required.

  12. Sexual selection and the opportunity cost of free mate choice.

    Science.gov (United States)

    Apostolou, Menelaos

    2016-06-01

    The model of sexual selection under parental choice has been proposed to account for the control that parents exercise over their children's mating decisions. The present paper attempts to formalize and advance this model with the purpose of providing a better understanding of how parental choice mandates the course of sexual selection. In particular, in the proposed formulation, free mate choice involves an opportunity cost which motivates parents to place their children's mate choices under their control. When they succeed in doing so, they become a significant sexual selection force, as traits that appeal to parents in an in-law are selected and increase in frequency in the population. The degree of parental control over mating, and thus the strength of sexual selection under parental choice, is positively predicted by the size of the opportunity cost of free mate choice. The primary factors that affect the level of opportunity cost vary between society types, affecting the strength of parental choice as a sexual selection force.

  13. Sexual selection drives speciation in an Amazonian frog

    Science.gov (United States)

    Boul, K.E.; Funk, W.C.; Darst, C.R.; Cannatella, D.C.; Ryan, M.J.

    2007-01-01

    One proposed mechanism of speciation is divergent sexual selection, whereby divergence in female preferences and male signals results in behavioural isolation. Despite the appeal of this hypothesis, evidence for it remains inconclusive. Here, we present several lines of evidence that sexual selection is driving behavioural isolation and speciation among populations of an Amazonian frog (Physalaemus petersi). First, sexual selection has promoted divergence in male mating calls and female preferences for calls between neighbouring populations, resulting in strong behavioural isolation. Second, phylogenetic analysis indicates that populations have become fixed for alternative call types several times throughout the species' range, and coalescent analysis rejects genetic drift as a cause for this pattern, suggesting that this divergence is due to selection. Finally, gene flow estimated with microsatellite loci is an average of 30 times lower between populations with different call types than between populations separated by a similar geographical distance with the same call type, demonstrating genetic divergence and incipient speciation. Taken together, these data provide strong evidence that sexual selection is driving behavioural isolation and speciation, supporting sexual selection as a cause for speciation in the wild. ?? 2006 The Royal Society.

  14. Sexual selection modulates genetic conflicts and patterns of genomic imprinting.

    Science.gov (United States)

    Faria, Gonçalo S; Varela, Susana A M; Gardner, Andy

    2017-03-01

    Recent years have seen a surge of interest in linking the theories of kin selection and sexual selection. In particular, there is a growing appreciation that kin selection, arising through demographic factors such as sex-biased dispersal, may modulate sexual conflicts, including in the context of male-female arms races characterized by coevolutionary cycles. However, evolutionary conflicts of interest need not only occur between individuals, but may also occur within individuals, and sex-specific demography is known to foment such intragenomic conflict in relation to social behavior. Whether and how this logic holds in the context of sexual conflict-and, in particular, in relation to coevolutionary cycles-remains obscure. We develop a kin-selection model to investigate the interests of different genes involved in sexual and intragenomic conflict, and we show that consideration of these conflicting interests yields novel predictions concerning parent-of-origin specific patterns of gene expression and the detrimental effects of different classes of mutation and epimutation at loci underpinning sexually selected phenotypes. © 2016 The Author(s). Evolution published by Wiley Periodicals, Inc. on behalf of The Society for the Study of Evolution.

  15. Sexual selection affects local extinction and turnover in bird communities

    Science.gov (United States)

    Doherty, P.F.; Sorci, G.; Royle, J. Andrew; Hines, J.E.; Nichols, J.D.; Boulinier, T.

    2003-01-01

    Predicting extinction risks has become a central goal for conservation and evolutionary biologists interested in population and community dynamics. Several factors have been put forward to explain risks of extinction, including ecological and life history characteristics of individuals. For instance, factors that affect the balance between natality and mortality can have profound effects on population persistence. Sexual selection has been identified as one such factor. Populations under strong sexual selection experience a number of costs ranging from increased predation and parasitism to enhanced sensitivity to environmental and demographic stochasticity. These findings have led to the prediction that local extinction rates should be higher for species/populations with intense sexual selection. We tested this prediction by analyzing the dynamics of natural bird communities at a continental scale over a period of 21 years (1975-1996), using relevant statistical tools. In agreement with the theoretical prediction, we found that sexual selection increased risks of local extinction (dichromatic birds had on average a 23% higher local extinction rate than monochromatic species). However, despite higher local extinction probabilities, the number of dichromatic species did not decrease over the period considered in this study. This pattern was caused by higher local turnover rates of dichromatic species, resulting in relatively stable communities for both groups of species. Our results suggest that these communities function as metacommunities, with frequent local extinctions followed by colonization. Anthropogenic factors impeding dispersal might therefore have a significant impact on the global persistence of sexually selected species.

  16. Sexual selection on wing interference patterns in Drosophila melanogaster.

    Science.gov (United States)

    Katayama, Natsu; Abbott, Jessica K; Kjærandsen, Jostein; Takahashi, Yuma; Svensson, Erik I

    2014-10-21

    Animals with color vision use color information in intra- and interspecific communication, which in turn may drive the evolution of conspicuous colored body traits via natural and sexual selection. A recent study found that the transparent wings of small flies and wasps in lower-reflectance light environments display vivid and stable structural color patterns, called "wing interference patterns" (WIPs). Such WIPs were hypothesized to function in sexual selection among small insects with wing displays, but this has not been experimentally verified. Here, to our knowledge we present the first experimental evidence that WIPs in males of Drosophila melanogaster are targets of mate choice from females, and that two different color traits--saturation and hue--experience directional and stabilizing sexual selection, respectively. Using isogenic lines from the D. melanogaster Genetic Reference Panel, we compare attractiveness of different male WIPs against black and white visual backgrounds. We show that males with more vivid wings are more attractive to females than are males with dull wings. Wings with a large magenta area (i.e., intermediate trait values) were also preferred over those with a large blue or yellow area. These experimental results add a visual element to the Drosophila mating array, integrating sexual selection with elements of genetics and evo-devo, potentially applicable to a wide array of small insects with hyaline wings. Our results further underscore that the mode of sexual selection on such visual signals can differ profoundly between different color components, in this case hue and saturation.

  17. Positive allometry and the prehistory of sexual selection.

    Science.gov (United States)

    Tomkins, Joseph L; LeBas, Natasha R; Witton, Mark P; Martill, David M; Humphries, Stuart

    2010-08-01

    The function of the exaggerated structures that adorn many fossil vertebrates remains largely unresolved. One recurrent hypothesis is that these elaborated traits had a role in thermoregulation. This orthodoxy persists despite the observation that traits exaggerated to the point of impracticality in extant organisms are almost invariably sexually selected. We use allometric scaling to investigate the role of sexual selection and thermoregulation in the evolution of exaggerated traits of the crested pterosaur Pteranodon longiceps and the sail-backed eupelycosaurs Dimetrodon and Edaphosaurus. The extraordinarily steep positive allometry of the head crest of Pteranodon rules out all of the current hypotheses for this trait's main function other than sexual signaling. We also find interspecific patterns of allometry and sexual dimorphism in the sails of Dimetrodon and patterns of elaboration in Edaphosaurus consistent with a sexually selected function. Furthermore, small ancestral, sail-backed pelycosaurs would have been too small to need adaptations to thermoregulation. Our results question the popular view that the elaborated structures of these fossil species evolved as thermoregulatory organs and provide evidence in support of the hypothesis that Pteranodon crests and eupelycosaur sails are among the earliest and most extreme examples of elaborate sexual signals in the evolution of terrestrial vertebrates.

  18. Sexual selection and genetic colour polymorphisms in animals.

    Science.gov (United States)

    Wellenreuther, Maren; Svensson, Erik I; Hansson, Bengt

    2014-11-01

    Genetic colour polymorphisms are widespread across animals and often subjected to complex selection regimes. Traditionally, colour morphs were used as simple visual markers to measure allele frequency changes in nature, selection, population divergence and speciation. With advances in sequencing technology and analysis methods, several model systems are emerging where the molecular targets of selection are being described. Here, we discuss recent studies on the genetics of sexually selected colour polymorphisms, aiming at (i) reviewing the evidence of sexual selection on colour polymorphisms, (ii) highlighting the genetic architecture, molecular and developmental basis underlying phenotypic colour diversification and (iii) discuss how the maintenance of such polymorphisms might be facilitated or constrained by these. Studies of the genetic architecture of colour polymorphism point towards the importance of tight clustering of colour loci with other trait loci, such as in the case of inversions and supergene structures. Other interesting findings include linkage between colour loci and mate preferences or sex determination, and the role of introgression and regulatory variation in fuelling polymorphisms. We highlight that more studies are needed that explicitly integrate fitness consequences of sexual selection on colour with the underlying molecular targets of colour to gain insights into the evolutionary consequences of sexual selection on polymorphism maintenance. © 2014 John Wiley & Sons Ltd.

  19. Sexual selection in Nauphoeta cinerea: inherited mating preference?

    Science.gov (United States)

    Moore, A J

    1989-09-01

    In the cockroach, Nauphoeta cinerea, female preferences with respect to sexual selection can be easily examined. Mating is nonrandom due to female preferences based on olfactory differences among males. This mate choice results in a mating advantage for socially dominant males. In this paper, results of experiments designed to explore the relationship between female choice in daughters and the preferred male character are described. Using females with male parents of known status and an olfactometer to determine preferences, it is shown that the type of male preferred depends on the status of the female's father. Because social experiences of females were experimentally controlled, these preliminary results suggest that (1) variation in female preferences may have a genetic basis and (2) because of assortative mating, mate choice may be genetically linked to the preferred male character, as predicted by mathematical models of the sexual selection process. N. cinerea appears to be an ideal species for testing predictions and assumptions of models of sexual selection.

  20. Sexual selection favours male parental care, when females can choose.

    Science.gov (United States)

    Alonzo, Suzanne H

    2012-05-07

    Explaining the evolution of male care has proved difficult. Recent theory predicts that female promiscuity and sexual selection on males inherently disfavour male care. In sharp contrast to these expectations, male-only care is often found in species with high extra-pair paternity and striking variation in mating success, where current theory predicts female-only care. Using a model that examines the coevolution of male care, female care and female choice; I show that inter-sexual selection can drive the evolution of male care when females are able to bias mating or paternity towards parental males. Surprisingly, female choice for parental males allows male care to evolve despite low relatedness between the male and the offspring in his care. These results imply that predicting how sexual selection affects parental care evolution will require further understanding of why females, in many species, either do not prefer or cannot favour males that provide care.

  1. Darwin and sexual selection: One hundred years of misunderstanding.

    Science.gov (United States)

    Veuille, Michel

    2010-02-01

    Darwin's book on the Descent of Man and Selection in Relation to Sex (1871) is often viewed as the continuation of The Origin of Species published 12 years earlier (1859), both because of the implicit parallelism between natural selection and sexual selection, and because Darwin himself presents the book as developing a subject (man) which he intentionally omitted in the Origin. But the Descent can also be viewed as the continuation of his book on Variation published three years earlier (1868). Firstly because Darwin's hypothesis of pangenesis links the selection process to the origin of variation through use and disuse, an idea underlying his speculations on the origin of moral sense in humans. Second because like the action of the horticulturist on his domestic crops, sexual selection exerted by one sex on the other sex can develop fancy traits that are not easily accounted for by their utility to the selected organism itself, such as artistic taste, pride, courage, and the morphological differences between human populations. These traits are difficult to reconcile with pangenesis. They add up to other contradictions of the book possibly resulting from Darwin's erroneous inference about the mechanism of inheritance, like those on the determination of sex-ratio, or the confusion between individual adaptation and the advantage to the species. These inconsistencies inaugurate a weakening of the Darwinian message, which will last 50 years after his death. They contributed to the neglect of sexual selection for a century. Darwin however maintained a logical distinction between evolutionary mechanisms and hereditary mechanisms, and an epistemological distinction between evolutionary theory and Pangenesis hypothesis. In the modern context of Mendelian genetics, Darwin's sexual selection retrospectively appears as luminous an idea in its pure principle as natural selection, even though the mechanisms governing the evolution of sexual choice in animals remain largely

  2. Ecological divergence and sexual selection drive sexual size dimorphism in New World pitvipers (Serpentes: Viperidae).

    Science.gov (United States)

    Hendry, C R; Guiher, T J; Pyron, R A

    2014-04-01

    Hypotheses for the origin and maintenance of sexual size dimorphism (SSD) fall into three primary categories: (i) sexual selection on male size, (ii) fecundity selection on female size and (iii) ecological selection for gender-specific niche divergence. We investigate the impact of these forces on SSD evolution in New World pitvipers (Crotalinae). We constructed a phylogeny from up to eight genes (seven mitochondrial, one nuclear) for 104 species of NW crotalines. We gathered morphological and ecological data for 82 species for comparative analyses. There is a strong signal of sexual selection on male size driving SSD, but less evidence for fecundity selection on female size across lineages. No support was found for allometric scaling of SSD (Rensch's rule), nor for directional selection for increasing male size (the Fairbairn-Preziosi hypothesis) in NW crotalines. Interestingly, arboreal lineages experience higher rates of SSD evolution and a pronounced shift to female-biased dimorphism. This suggests that fecundity selection on arboreal females exaggerates ecologically mediated dimorphism, whereas sexual selection drives male size in terrestrial lineages. We find that increasing SSD in both directions (male- and female-biased) decreases speciation rates. In NW crotalines, it appears that increasing magnitudes of ecologically mediated SSD reduce rates of speciation, as divergence accumulates within species among sexes, reducing adaptive divergence between populations leading to speciation. © 2014 The Authors. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

  3. Sexually antagonistic selection on genetic variation underlying both male and female same-sex sexual behavior.

    Science.gov (United States)

    Berger, David; You, Tao; Minano, Maravillas R; Grieshop, Karl; Lind, Martin I; Arnqvist, Göran; Maklakov, Alexei A

    2016-05-13

    Intralocus sexual conflict, arising from selection for different alleles at the same locus in males and females, imposes a constraint on sex-specific adaptation. Intralocus sexual conflict can be alleviated by the evolution of sex-limited genetic architectures and phenotypic expression, but pleiotropic constraints may hinder this process. Here, we explored putative intralocus sexual conflict and genetic (co)variance in a poorly understood behavior with near male-limited expression. Same-sex sexual behaviors (SSBs) generally do not conform to classic evolutionary models of adaptation but are common in male animals and have been hypothesized to result from perception errors and selection for high male mating rates. However, perspectives incorporating sex-specific selection on genes shared by males and females to explain the expression and evolution of SSBs have largely been neglected. We performed two parallel sex-limited artificial selection experiments on SSB in male and female seed beetles, followed by sex-specific assays of locomotor activity and male sex recognition (two traits hypothesized to be functionally related to SSB) and adult reproductive success (allowing us to assess fitness consequences of genetic variance in SSB and its correlated components). Our experiments reveal both shared and sex-limited genetic variance for SSB. Strikingly, genetically correlated responses in locomotor activity and male sex-recognition were associated with sexually antagonistic fitness effects, but these effects differed qualitatively between male and female selection lines, implicating intralocus sexual conflict at both male- and female-specific genetic components underlying SSB. Our study provides experimental support for the hypothesis that widespread pleiotropy generates pervasive intralocus sexual conflict governing the expression of SSBs, suggesting that SSB in one sex can occur due to the expression of genes that carry benefits in the other sex.

  4. Do feather-degrading bacteria affect sexually selected plumage color?

    Science.gov (United States)

    Shawkey, Matthew D.; Pillai, Shreekumar R.; Hill, Geoffrey E.

    2009-01-01

    Models of parasite-mediated sexual selection propose that males with more elaborate sexual traits will have fewer parasites. These models have generally been tested using metazoan or protozoan parasites of the blood, gut, or integument. Fewer studies have examined sexual ornaments in relation to bacterial infections. While most surface bacteria are harmless or beneficial, feather-degrading bacteria may have detrimental effects. In this study, we examined the relationships between overall bacterial load, feather-degrading bacterial load, and sexually selected carotenoid-based plumage color in a wild population of house finches ( Carpodacus mexicanus). We found that males with the redder plumage preferred by females had similar overall bacterial loads, but lower feather-degrading bacterial loads, than males with less red plumage. These data suggest that plumage color can signal abundance of feather-degrading bacteria to potential mates. It remains unclear whether feather-degrading bacteria directly or indirectly affect plumage color, but the observed correlations suggest that feather-degrading bacteria may play some role in sexual selection.

  5. Selection for alternative male reproductive tactics alters intralocus sexual conflict.

    Science.gov (United States)

    Plesnar Bielak, Agata; Skrzynecka, Anna M; Miler, Krzysztof; Radwan, Jacek

    2014-07-01

    Intralocus sexual conflict (IASC) arises when fitness optima for a shared trait differ between the sexes; such conflict may help maintain genetic variation within populations. Sex-limited expression of sexually antagonistic traits may help resolve the conflict, but the extent of this resolution remains a subject of debate. In species with alternative male reproductive tactics, unresolved conflict should manifest more in a more sexually dimorphic male phenotype. We tested this prediction in the bulb mite (Rhizoglyphus robini), a species in which aggressive fighters coexist with benign scramblers. To do this, we established replicated lines in which we increased the proportion of each of the alternative male morphs using artificial selection. After approximately 40 generations, the proportion of fighters and scramblers stabilized at >0.9 in fighter- and scrambler-selected lines, respectively. We then measured several female fitness components. As predicted by IASC theory, female fecundity and longevity were lower in lines selected for fighters and higher in lines selected for scramblers. This finding indicates that sexually selected phenotypes are associated with an ontogenetic conflict that is not easily resolved. Furthermore, we suggest that IASC may be an important mechanism contributing to the maintenance of genetic variation in the expression of alternative reproductive tactics. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

  6. Sexual selection halts the relaxation of protamine 2 among rodents.

    Directory of Open Access Journals (Sweden)

    Lena Lüke

    Full Text Available Sexual selection has been proposed as the driving force promoting the rapid evolutionary changes observed in some reproductive genes including protamines. We test this hypothesis in a group of rodents which show marked differences in the intensity of sexual selection. Levels of sperm competition were not associated with the evolutionary rates of protamine 1 but, contrary to expectations, were negatively related to the evolutionary rate of cleaved- and mature-protamine 2. Since both domains were found to be under relaxation, our findings reveal an unforeseen role of sexual selection: to halt the degree of degeneration that proteins within families may experience due to functional redundancy. The degree of relaxation of protamine 2 in this group of rodents is such that in some species it has become dysfunctional and it is not expressed in mature spermatozoa. In contrast, protamine 1 is functionally conserved but shows directed positive selection on specific sites which are functionally relevant such as DNA-anchoring domains and phosphorylation sites. We conclude that in rodents protamine 2 is under relaxation and that sexual selection removes deleterious mutations among species with high levels of sperm competition to maintain the protein functional and the spermatozoa competitive.

  7. The androgen receptor and prostate cancer: a role for sexual selection and sexual conflict?

    Science.gov (United States)

    Summers, Kyle; Crespi, Bernard

    2008-01-01

    We propose and evaluate the hypothesis that the CAG repeat region of the androgen receptor represents a locus of antagonistic pleiotropy in the context of sexual selection and sexual conflict. Short repeats are associated with increased transactivation of the androgen receptor at the molecular level, and increased fertility at the phenotypic level. However, short repeats are also associated with increased risk of prostate cancer, and with more aggressive forms of the disease. The somatic evolution of cancer cell lineages also shows a repeated pattern of shortening of the CAG repeat in association with cancer progression, apparently as a result of positive selection among cell lineages. We further postulate that other genes associated with prostate cancer are likely to mediate antagonistic pleiotropy in the context of sexual selection and sexual conflict. A key prediction of this hypothesis is that the genes mediating antagonistic pleiotropy will show historical evidence of positive selection, particularly in the context of sexual conflict. Previous research on the molecular evolution of specific genes associated with prostate cancer supports this prediction, and we suggest further critical tests of the role for genomic conflicts and tradeoffs in the evolution of cancer risk.

  8. Novel host plant leads to the loss of sexual dimorphism in a sexually selected male weapon.

    Science.gov (United States)

    Allen, Pablo E; Miller, Christine W

    2017-08-16

    In this time of massive global change, species are now frequently interacting with novel players. Greater insight into the impact of these novel interactions on traits linked to fitness is essential, because effects on these traits can hinder population existence or promote rapid adaptation. Sexually selected weapons and ornaments frequently influence fitness and often have heightened condition-dependence in response to nutrition. Condition-dependence in response to different ecological conditions, a form of developmental plasticity, may be responsible for much of the intraspecific variation in sexually selected ornaments and weapons in wild populations. Here we examined the consequences of developing on a novel plant for the expression of size and shape in the leaf-footed cactus bug Narnia femorata (Hemiptera: Coreidae). The males of this species possess enlarged, sexually dimorphic femurs on their hind legs. These legs are used as weapons in male-male contests. Females are typically larger in overall body size. Our study revealed that developing upon a novel host can lead to pronounced phenotypically plastic change in sexually dimorphic traits. Male hind femurs were greatly impacted by the novel diet to the extent that the sexual dimorphism in hind femurs was lost. Further, dimorphism in body size increased, as males became tiny adults while females better maintained their body size. These patterns underscore the complex effects that novel species interactions may have on sexual phenotypes. © 2017 The Author(s).

  9. Sympatric speciation by sexual selection : A critical reevaluation

    NARCIS (Netherlands)

    van Doorn, G.S.; Dieckmann, U.; Weissing, F.J.

    Several empirical studies put forward sexual selection as an important driving force of sympatric speciation. This idea agrees with recent models suggesting that speciation may proceed by means of divergent Fisherian runaway processes within a single population. Notwithstanding this, the models so

  10. Sympatric speciation and extinction driven by environment dependent sexual selection

    NARCIS (Netherlands)

    Van Doorn, G.S.; Noest, A.J.; Hogeweg, P.

    1998-01-01

    A theoretical model is studied to investigate the possibility of sympatric speciation driven by sexual selection and ecological diversification. In particular, we focus on the rock-dwelling haplochromine cichlid species in Lake Victoria. The high speciation rate in these cichlids has been explained

  11. Sexuality Education Programs for Parents: Bibliography of Selected Resources.

    Science.gov (United States)

    Planned Parenthood Federation of America, Inc., New York, NY. Education Dept.

    This bibliography of selected resources was compiled to provide valuable information for persons involved in planning parent programs in sexuality education. Names and addresses of three sources for additional information and resources are also provided. Citations in the bibliography are organized under Books and Related Materials (38 references)…

  12. "Allohormones" : a class of bioactive substances favoured by sexual selection

    NARCIS (Netherlands)

    Koene, J M; ter Maat, A

    During close bodily contact, many species transfer substances that influence the behaviour or physiology of conspecifics. Such transfer is especially common during courtship and copulation. When this is the case the involved bioactive substances are favoured by sexual selection because their effects

  13. Humans as a model species for sexual selection research

    Science.gov (United States)

    Miller, Carrie M.; Crouse, Kristin N.

    2017-01-01

    Ever since Darwin, questions about humans have driven sexual selection research. While studies of other organisms are often justified as useful for improving understanding of humans, humans themselves can be useful models. Although humans present some drawbacks as model organisms (complicated societies, slow reproduction and strong ethical constraints on experimental options), humans nonetheless offer many advantages (being abundant, accessible and having detailed historical records for some populations). As an additional challenge, humans exhibit a rather puzzling combination of traits. Some traits (pair-bonding, biparental care and modest sexual dimorphism in body size) suggest selection for monogamous mating, while other traits (including sexual dimorphism in body composition and appearance) suggest selection for polygyny. Such puzzles have motivated research on other species, resulting in a rich set of comparative data that provides insights into humans and other species. Recent studies of visual trait dimorphism suggest that human appearance reflects adaptation for multi-level societies, rather than high levels of polygyny. In addition to biological traits, human cultural traits have undergone rapid evolution. Changes in subsistence strategies profoundly affect opportunities for sexual selection. The enormous variability of human behaviour and ecology provides abundant opportunities to test key hypotheses, and poses challenging puzzles for future research. PMID:29118131

  14. On the Origin of Species by Natural and Sexual Selection

    OpenAIRE

    Doorn, Sander van; Edelaar, Pim; Weissing, Franz J.

    2009-01-01

    Ecological speciation is considered an adaptive response to selection for local adaptation. However, besides suitable ecological conditions, the process requires assortative mating to protect the nascent species from homogenization by gene flow. By means of a simple model, we demonstrate that disruptive ecological selection favors the evolution of sexual preferences for ornaments that signal local adaptation. Such preferences induce assortative mating with respect to ecological characters and...

  15. Male Mating Success: Preference or Prowess? Investigating Sexual Selection in the Laboratory Using "Drosophila melanogaster"

    Science.gov (United States)

    Coleman, Seth; Jensen, Jeffrey

    2007-01-01

    Sexual selection is the primary force affecting the evolution of the elaborate sexual displays common in animals, yet sexual selection experiments are largely absent from introductory biology laboratories. Here we describe the rationale, methodology, and results of several experiments using "Drosophila melanogaster" to demonstrate sexual selection…

  16. Divergent sexual selection via male competition: ecology is key.

    Science.gov (United States)

    Lackey, A C R; Boughman, J W

    2013-08-01

    Sexual selection and ecological differences are important drivers of speciation. Much research has focused on female choice, yet the role of male competition in ecological speciation has been understudied. Here, we test how mating habitats impact sexual selection and speciation through male competition. Using limnetic and benthic species of threespine stickleback fish, we find that different mating habitats select differently on male traits through male competition. In mixed habitat with both vegetated and open areas, selection favours two trait combinations of male body size and nuptial colour: large with little colour and small with lots of colour. This matches what we see in reproductively isolated stickleback species, suggesting male competition could promote trait divergence and reproductive isolation. In contrast, when only open habitat exists, selection favours one trait combination, large with lots of colour, which would hinder trait divergence and reproductive isolation. Other behavioural mechanisms in male competition that might promote divergence, such as avoiding aggression with heterospecifics, are insufficient to maintain separate species. This work highlights the importance of mating habitats in male competition for both sexual selection and speciation. © 2013 The Authors. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology.

  17. Contributions of natural and sexual selection to the evolution of premating reproductive isolation: a research agenda.

    Science.gov (United States)

    Safran, Rebecca J; Scordato, Elizabeth S C; Symes, Laurel B; Rodríguez, Rafael L; Mendelson, Tamra C

    2013-11-01

    Speciation by divergent natural selection is well supported. However, the role of sexual selection in speciation is less well understood due to disagreement about whether sexual selection is a mechanism of evolution separate from natural selection, as well as confusion about various models and tests of sexual selection. Here, we outline how sexual selection and natural selection are different mechanisms of evolutionary change, and suggest that this distinction is critical when analyzing the role of sexual selection in speciation. Furthermore, we clarify models of sexual selection with respect to their interaction with ecology and natural selection. In doing so, we outline a research agenda for testing hypotheses about the relative significance of divergent sexual and natural selection in the evolution of reproductive isolation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. A STOCHASTIC SIMULATION STUDY ON SPECIATION BY SEXUAL SELECTION.

    Science.gov (United States)

    Wu, Chung-I

    1985-01-01

    A two-locus multi-allele sexual isolation model incorporating mutation and genetic drift which was first proposed by Nei et al. (1983) is studied here. One locus controls the male mating character, and the other controls female receptivity. All females are assumed to have equal mating success. Therefore, the frequencies of female receptivity alleles are changed by mutation, drift, and hitchhiking with male character alleles. Without hitchhiking, development of sexual isolation between allopatric populations proceeds faster in smaller populations, as expected. The hitchhiking effect, by triggering the mutual reinforcement of mating behavior of both sexes (or the runaway process, Fisher [1958]), speeds up the evolution of sexual isolation significantly. For populations with 2Nv ≤ 0.2 (N = population size, ν = mutation rate), the rates of divergence all approach the maximum possible rate. Sympatric sexual isolation develops quite frequently if two favorable conditions are met: 1) There is no selection on female phenotype (except in some limited cases), and 2) The population size is large enough to carry several female receptivity alleles. Because of stochastic factors, these alleles may lead to the formation of two discrete groups of females, each group receptive to males of different mating characters. The formation of sympatric sexually-isolated groups is also aided significantly, at the incipient stage, by the runaway process. © 1985 The Society for the Study of Evolution.

  19. The evolution of female ornaments and weaponry: social selection, sexual selection and ecological competition.

    Science.gov (United States)

    Tobias, Joseph A; Montgomerie, Robert; Lyon, Bruce E

    2012-08-19

    Ornaments, weapons and aggressive behaviours may evolve in female animals by mate choice and intrasexual competition for mating opportunities-the standard forms of sexual selection in males. However, a growing body of evidence suggests that selection tends to operate in different ways in males and females, with female traits more often mediating competition for ecological resources, rather than mate acquisition. Two main solutions have been proposed to accommodate this disparity. One is to expand the concept of sexual selection to include all mechanisms related to fecundity; another is to adopt an alternative conceptual framework-the theory of social selection-in which sexual selection is one component of a more general form of selection resulting from all social interactions. In this study, we summarize the history of the debate about female ornaments and weapons, and discuss potential resolutions. We review the components of fitness driving ornamentation in a wide range of systems, and show that selection often falls outside the limits of traditional sexual selection theory, particularly in females. We conclude that the evolution of these traits in both sexes is best understood within the unifying framework of social selection.

  20. The counterintuitive role of sexual selection in species maintenance and speciation

    OpenAIRE

    Servedio, Maria R.; Bürger, Reinhard

    2014-01-01

    Sexual selection is generally considered to be an important force in the maintenance of species differentiation. Using population genetic models, we show that when isolated in its purest form of Fisherian sexual selection, sexual selection inhibits rather than assists species maintenance and speciation when isolated populations begin to exchange migrants. The stronger this type of sexual selection becomes, the more it erases any effects of local adaptation that drive trait divergence. Further...

  1. The evolution of the sexually selected sword in xiphophorus does not compromise aerobic locomotor performance

    OpenAIRE

    Oufiero, CE; Meredith, RW; Jugo, KN; Tran, P.; Chappell, MA; Springer, MS; Reznick, DN; Garland, T.

    2014-01-01

    Sexual selection can increase morphological diversity within and among species. Little is known regarding how interspecific variation produced through sexual selection affects other functional systems. Here, we examine how morphological diversity resulting from sexual selection impacts aerobic locomotor performance. Using Xiphophorus (swordtail fish) and their close relatives (N = 19 species), we examined whether the evolution of a longer sexually selected sword affects critical swimming spee...

  2. Pheromones-based sexual selection in a rapidly changing world.

    Science.gov (United States)

    Henneken, Jessica; Jones, Therésa M

    2017-12-01

    Insects utilise chemical cues for a range of different purposes and the complexity and degree of specificity of these signals is arguably unparalleled in the animal kingdom. Chemical signals are particularly important for insect reproduction and the selective pressures driving their evolution and maintenance have been the subject of previous reviews. However, the world in which chemical cues evolved and are maintained is changing at an unprecedented rate. How (or indeed whether) chemical signals used in sexual selection will respond is largely unknown. Here, we explore how recent increases in urbanisation and associated anthropogenic impacts may affect how chemical signals are produced and perceived. We focus on four anthropomorphic influences which have the potential to interact with pheromone-mediated sexual selection processes; climatic temperature shifts, exposure to chemical pollutants, the presence of artificial light at night and nutrient availability. Our aim is to provide a broad overview of key areas where the rapidly changing environment of the future might specifically affect pheromones utilised in sexual selection. Copyright © 2017. Published by Elsevier Inc.

  3. Sexual selection is influenced by both developmental and adult environments.

    Science.gov (United States)

    Gillespie, Stephanie R; Scarlett Tudor, M; Moore, Allen J; Miller, Christine W

    2014-12-01

    Sexual selection is often assumed to be strong and consistent, yet increasing research shows it can fluctuate over space and time. Few experimental studies have examined changes in sexual selection in response to natural environmental variation. Here, we use a difference in resource quality to test for the influence of past environmental conditions and current environmental conditions on male and female mate choice and resulting selection gradients for leaf-footed cactus bugs, Narnia femorata. We raised juveniles on natural high- and low-quality diets, cactus pads with and without ripe cactus fruits. New adults were again assigned a cactus pad with or without fruit, paired with a potential mate, and observed for mating behaviors. We found developmental and adult encounter environments affected mating decisions and the resulting patterns of sexual selection for both males and females. Males were not choosy in the low-quality encounter environment, cactus without fruit, but they avoided mating with small females in the high-quality encounter environment. Females were choosy in both encounter environments, avoiding mating with small males. However, they were the choosiest when they were in the low-quality encounter environment. Female mate choice was also context dependent by male developmental environment. Females were more likely to mate with males that had developed on cactus with fruit when they were currently in the cactus with fruit environment. This pattern disappeared when females were in the cactus without fruit environment. Altogether, these results experimentally demonstrate context-dependent mate choice by both males and females. Furthermore, we demonstrate that simple, seasonal changes in resources can lead to fluctuations in sexual selection. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

  4. Stabilizing sexual selection for female ornaments in a dance fly.

    Science.gov (United States)

    Wheeler, J; Gwynne, D T; Bussière, L F

    2012-07-01

    Ornamental traits function by improving attractiveness and are generally presumed to experience directional selection for mating success. However, given the greater investment of females in offspring than males, female-specific ornaments can in theory signal fecundity yet be constrained by fecundity costs. Theoretical work predicts that such constraints can lead to stabilizing selection via male choice for intermediately ornamented females. Female dance flies Rhamphomyia longicauda (Diptera: Empididae) display two female-specific ornaments in mating swarms - inflatable abdominal sacs and pinnate tibial scales. We investigated the intensity and form of sexual selection on female traits including ornaments and found no evidence for directional sexual selection. Instead, we found marginally nonsignificant quadratic selection for all three measures of ornament expression. Canonical analysis confirmed that the strongest vectors of nonlinear selection were associated with ornamental traits, although the significance of the quadratic coefficients associated with these vectors depended on the statistical approach. Direct Mitchell-Olds and Shaw tests for the location of the maximum fitted fitness value for both raw morphological traits and canonical axes revealed only one marginally nonsignificant result for the multivariate axis loading most heavily on pinnate leg scales. Together, these results provide the first tentative support for stabilizing selection on female-specific ornaments. © 2012 The Authors. Journal of Evolutionary Biology © 2012 European Society For Evolutionary Biology.

  5. Sexual selection, redundancy and survival of the most beautiful

    Indian Academy of Sciences (India)

    Unknown

    Computer models show that there is a dynamic interaction between the mean number of new ... of deleterious mutations cannot be based on assessment of performance. Instead it is based on a simple symmetrical .... Computer programmes written in Pascal are used to investi- gate random, monogamous and polygamous ...

  6. PERSPECTIVE: CHASE-AWAY SEXUAL SELECTION: ANTAGONISTIC SEDUCTION VERSUS RESISTANCE.

    Science.gov (United States)

    Holland, Brett; Rice, William R

    1998-02-01

    A model of sexual selection that leads to the evolution of exaggerated male display characters that is based on antagonistic coevolution between the sexes is described. The model is motivated by three lines of research: intersexual conflict with respect to mating, sensory exploitation, and the evolution of female resistance, as opposed to preference, for male display traits. The model generates unique predictions that permit its operation to be distinguished from other established models of sexual selection. One striking prediction is that females will frequently win the coevolutionary arms race with males, leaving them encumbered with costly ornaments that have little value except that their absence understimulates females. Examples from the literature suggest that the model may have broad application in nature. The chase-away model is a special case of the more general phenomenon of Interlocus Contest Evolution (ICE). © 1998 The Society for the Study of Evolution.

  7. Using theories of sexual selection and sexual conflict to improve our understanding of plant ecology and evolution

    Science.gov (United States)

    Lankinen, Åsa; Karlsson Green, Kristina

    2015-01-01

    Today it is accepted that the theories of sexual selection and sexual conflict are general and can be applied to both animals and plants. However, potentially due to a controversial history, plant studies investigating sexual selection and sexual conflict are relatively rare. Moreover, these theories and concepts are seldom implemented in research fields investigating related aspects of plant ecology and evolution. Even though these theories are complex, and can be difficult to study, we suggest that several fields in plant biology would benefit from incorporating and testing the impact of selection pressures generated by sexual selection and sexual conflict. Here we give examples of three fields where we believe such incorporation would be particularly fruitful, including (i) mechanisms of pollen–pistil interactions, (ii) mating-system evolution in hermaphrodites and (iii) plant immune responses to pests and pathogens. PMID:25613227

  8. Using theories of sexual selection and sexual conflict to improve our understanding of plant ecology and evolution.

    Science.gov (United States)

    Lankinen, Åsa; Karlsson Green, Kristina

    2015-01-22

    Today it is accepted that the theories of sexual selection and sexual conflict are general and can be applied to both animals and plants. However, potentially due to a controversial history, plant studies investigating sexual selection and sexual conflict are relatively rare. Moreover, these theories and concepts are seldom implemented in research fields investigating related aspects of plant ecology and evolution. Even though these theories are complex, and can be difficult to study, we suggest that several fields in plant biology would benefit from incorporating and testing the impact of selection pressures generated by sexual selection and sexual conflict. Here we give examples of three fields where we believe such incorporation would be particularly fruitful, including (i) mechanisms of pollen-pistil interactions, (ii) mating-system evolution in hermaphrodites and (iii) plant immune responses to pests and pathogens. Published by Oxford University Press on behalf of the Annals of Botany Company.

  9. Sexual selection's impacts on ecological specialization: an experimental test

    OpenAIRE

    Pfennig, Karin S.; Pfennig, David W; Porter, Cody; Martin, Ryan A.

    2015-01-01

    In many species, individuals specialize on different resources, thereby reducing competition. Such ecological specialization can promote the evolution of alternative ecomorphs—distinct phenotypes adapted for particular resources. Elucidating whether and how this process is influenced by sexual selection is crucial for understanding how ecological specialization promotes the evolution of novel traits and, potentially, speciation between ecomorphs. We evaluated the population-level effects of s...

  10. Evolution of divergent female mating preference in response to experimental sexual selection.

    Science.gov (United States)

    Debelle, Allan; Ritchie, Michael G; Snook, Rhonda R

    2014-09-01

    Sexual selection is predicted to drive the coevolution of mating signals and preferences (mating traits) within populations, and could play a role in speciation if sexual isolation arises due to mating trait divergence between populations. However, few studies have demonstrated that differences in mating traits between populations result from sexual selection alone. Experimental evolution is a promising approach to directly examine the action of sexual selection on mating trait divergence among populations. We manipulated the opportunity for sexual selection (low vs. high) in populations of Drosophila pseudoobscura. Previous studies on these experimental populations have shown that sexual selection manipulation resulted in the divergence between sexual selection treatments of several courtship song parameters, including interpulse interval (IPI) which markedly influences male mating success. Here, we measure female preference for IPI using a playback design to test for preference divergence between the sexual selection treatments after 130 generations of experimental sexual selection. The results suggest that female preference has coevolved with male signal, in opposite directions between the sexual selection treatments, providing direct evidence of the ability of sexual selection to drive the divergent coevolution of mating traits between populations. We discuss the implications in the context sexual selection and speciation. © 2014 The Authors. Evolution published by Wiley Periodicals, Inc. on behalf of The Society for the Study of Evolution.

  11. Human Homosexuality: A Paradigmatic Arena for Sexually Antagonistic Selection?

    Science.gov (United States)

    Ciani, Andrea Camperio; Battaglia, Umberto; Zanzotto, Giovanni

    2015-01-01

    Sexual conflict likely plays a crucial role in the origin and maintenance of homosexuality in our species. Although environmental factors are known to affect human homosexual (HS) preference, sibling concordances and population patterns related to HS indicate that genetic components are also influencing this trait in humans. We argue that multilocus, partially X-linked genetic factors undergoing sexually antagonistic selection that promote maternal female fecundity at the cost of occasional male offspring homosexuality are the best candidates capable of explaining the frequency, familial clustering, and pedigree asymmetries observed in HS male proband families. This establishes male HS as a paradigmatic example of sexual conflict in human biology. HS in females, on the other hand, is currently a more elusive phenomenon from both the empirical and theoretical standpoints because of its fluidity and marked environmental influence. Genetic and epigenetic mechanisms, the latter involving sexually antagonistic components, have been hypothesized for the propagation and maintenance of female HS in the population. However, further data are needed to truly clarify the evolutionary dynamics of this trait. PMID:25635045

  12. Human homosexuality: a paradigmatic arena for sexually antagonistic selection?

    Science.gov (United States)

    Camperio Ciani, Andrea; Battaglia, Umberto; Zanzotto, Giovanni

    2015-01-29

    Sexual conflict likely plays a crucial role in the origin and maintenance of homosexuality in our species. Although environmental factors are known to affect human homosexual (HS) preference, sibling concordances and population patterns related to HS indicate that genetic components are also influencing this trait in humans. We argue that multilocus, partially X-linked genetic factors undergoing sexually antagonistic selection that promote maternal female fecundity at the cost of occasional male offspring homosexuality are the best candidates capable of explaining the frequency, familial clustering, and pedigree asymmetries observed in HS male proband families. This establishes male HS as a paradigmatic example of sexual conflict in human biology. HS in females, on the other hand, is currently a more elusive phenomenon from both the empirical and theoretical standpoints because of its fluidity and marked environmental influence. Genetic and epigenetic mechanisms, the latter involving sexually antagonistic components, have been hypothesized for the propagation and maintenance of female HS in the population. However, further data are needed to truly clarify the evolutionary dynamics of this trait. Copyright © 2015 Cold Spring Harbor Laboratory Press; all rights reserved.

  13. Probiotic bacteria: selective enumeration and survival in dairy foods.

    Science.gov (United States)

    Shah, N P

    2000-04-01

    A number of health benefits have been claimed for probiotic bacteria such as Lactobacillus acidophilus, Bifidobacterium spp., and Lactobacillus casei. Because of the potential health benefits, these organisms are increasingly incorporated into dairy foods. However, studies have shown low viability of probiotics in market preparations. In order to assess viability of probiotic bacteria, it is important to have a working method for selective enumeration of these probiotic bacteria. Viability of probiotic bacteria is important in order to provide health benefits. Viability of probiotic bacteria can be improved by appropriate selection of acid and bile resistant strains, use of oxygen impermeable containers, two-step fermentation, micro-encapsulation, stress adaptation, incorporation of micronutrients such as peptides and amino acids and by sonication of yogurt bacteria. This review will cover selective enumeration and survival of probiotic bacteria in dairy foods.

  14. Multivariate phenotypic selection on a complex sexual signal.

    Science.gov (United States)

    Tanner, Jessie C; Ward, Jessica L; Shaw, Ruth G; Bee, Mark A

    2017-07-01

    Animal signals are complex, comprising multiple components that receivers may use to inform their decisions. Components may carry information of differing value to receivers, and selection on one component could modulate or reverse selection on another, necessitating a multivariate approach to estimating selection gradients. However, surprisingly few empirical studies have estimated the strength of phenotypic selection on complex signals with appropriate design and adequate power to detect nonlinear selection. We used phonotaxis assays to measure sexual selection on the advertisement signal of Cope's gray tree frog, Hyla chrysoscelis. Female preferences were assessed for five signal components using single- and two-stimulus behavioral assays. Linear, quadratic, and correlational selection gradients were estimated from the single-stimulus data. Significant directional selection is acting on call duration, call rate, pulse rate, and relative amplitude; stabilizing selection is acting on call duration and call rate. Under the two-stimulus paradigm, conclusions were qualitatively different, revealing nonlinear selection on all components except call duration. For individual subjects, the outcomes of single- and two-stimulus trials were frequently discordant, suggesting that the choice of testing paradigm may affect conclusions drawn from experiments. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

  15. Persistent sexual dysfunction after discontinuation of selective serotonin reuptake inhibitors.

    Science.gov (United States)

    Csoka, Antonei B; Csoka, A; Bahrick, Audrey; Mehtonen, Olli-Pekka

    2008-01-01

    Sexual dysfunctions such as low libido, anorgasmia, genital anesthesia, and erectile dysfunction are very common in patients taking selective serotonin reuptake inhibitors (SSRIs). It has been assumed that these side effects always resolve after discontinuing treatment, but recently, four cases were presented in which sexual function did not return to baseline. Here, we describe three more cases. Case #1: A 29-year-old with apparently permanent erectile dysfunction after taking fluoxetine 20 mg once daily for a 4-month period in 1996. Case #2: A 44-year-old male with persistent loss of libido, genital anesthesia, ejaculatory anhedonia, and erectile dysfunction after taking 20-mg once daily citalopram for 18 months. Case #3: A 28-year-old male with persistent loss of libido, genital anesthesia, and ejaculatory anhedonia since taking several different SSRIs over a 2-year period from 2003-2005. No psychological issues related to sexuality were found in any of the three cases, and all common causes of sexual dysfunction such as decreased testosterone, increased prolactin or diabetes were ruled out. Erectile capacity is temporarily restored for Case #1 with injectable alprostadil, and for Case #2 with oral sildenafil, but their other symptoms remain. Case #3 has had some reversal of symptoms with extended-release methylphenidate, although it is not yet known if these prosexual effects will persist when the drug is discontinued. SSRIs can cause long-term effects on all aspects of the sexual response cycle that may persist after they are discontinued. Mechanistic hypotheses including persistent endocrine and epigenetic gene expression alterations were briefly discussed.

  16. Homage to Bateman: sex roles predict sex differences in sexual selection.

    Science.gov (United States)

    Fritzsche, Karoline; Arnqvis, Göran

    2013-07-01

    Classic sex role theory predicts that sexual selection should be stronger in males in taxa showing conventional sex roles and stronger in females in role reversed mating systems. To test this very central prediction and to assess the utility of different measures of sexual selection, we estimated sexual selection in both sexes in four seed beetle species with divergent sex roles using a novel experimental design. We found that sexual selection was sizeable in females and the strength of sexual selection was similar in females and males in role-reversed species. Sexual selection was overall significantly stronger in males than in females and residual selection formed a substantial component of net selection in both sexes. Furthermore, sexual selection in females was stronger in role-reversed species compared to species with conventional sex roles. Variance-based measures of sexual selection (the Bateman gradient and selection opportunities) were better predictors of sexual dimorphism in reproductive behavior and morphology across species compared to trait-based measures (selection differentials). Our results highlight the importance of using assays that incorporate components of fitness manifested after mating. We suggest that the Bateman gradient is generally the most informative measure of the strength of sexual selection in comparisons across sexes and/or species. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

  17. Biometric evidence that sexual selection has shaped the hominin face.

    Directory of Open Access Journals (Sweden)

    Eleanor M Weston

    Full Text Available We consider sex differences in human facial morphology in the context of developmental change. We show that at puberty, the height of the upper face, between the lip and the brow, develops differently in males and females, and that these differences are not explicable in terms of sex differences in body size. We find the same dimorphism in the faces of human ancestors. We propose that the relative shortening in men and lengthening in women of the anterior upper face at puberty is the mechanistic consequence of extreme maxillary rotation during ontogeny. A link between this developmental model and sexual dimorphism is made for the first time, and provides a new set of morphological criteria to sex human crania. This finding has important implications for the role of sexual selection in the evolution of anthropoid faces and for theories of human facial attractiveness.

  18. One tool, many uses: precopulatory sexual selection on genital morphology in Aquarius remigis.

    Science.gov (United States)

    Bertin, A; Fairbairn, D J

    2005-07-01

    While congruent evidence indicates that sexual selection is the most likely selective force explaining the rapid divergence of male genital morphology in insects, the mechanisms involved in this process remain unclear. In particular, little attention has been paid to precopulatory sexual selection. We examine sexual selection for mating success on male genital components in six populations of Aquarius remigis, a water strider characterized by unique genital morphology. Multivariate selection analysis confirms previous findings that precopulatory sexual selection favours longer external genitalia, and provides new evidence that this selection acts independently on external genital components. In contrast, the size of the major internal genital sclerite is not correlated with mating success. Thus, precopulatory sexual selection acts strongly on the size of the external genitalia, but not on the intromittent organ itself. These results highlight the multiple functions of genital organs and the importance of both precopulatory and post-copulatory sexual selection in shaping the remarkable diversity of male genitalia in insects.

  19. Did sexual selection shape human music? Testing predictions from the sexual selection hypothesis of music evolution using a large genetically informative sample of over 10,000 twins

    NARCIS (Netherlands)

    Mosing, M.A.; Verweij, K.J.H.; Madison, G.; Pedersen, N.L.; Zietsch, B.P.; Ullén, F.

    2015-01-01

    Although music is a universal feature of human culture, little is known about its origins and functions. A prominent theory of music evolution is the sexual selection hypothesis, which proposes that music evolved as a signal of genetic quality to potential mates. The sexual selection hypothesis

  20. The Evolution of Genome Structure by Natural and Sexual Selection.

    Science.gov (United States)

    Kirkpatrick, Mark

    2017-01-01

    Progress on understanding how genome structure evolves is accelerating with the arrival of new genomic, comparative, and theoretical approaches. This article reviews progress in understanding how chromosome inversions and sex chromosomes evolve, and how their evolution affects species' ecology. Analyses of clines in inversion frequencies in flies and mosquitoes imply strong local adaptation, and roles for both over- and under dominant selection. Those results are consistent with the hypothesis that inversions become established when they capture locally adapted alleles. Inversions can carry alleles that are beneficial to closely related species, causing them to introgress following hybridization. Models show that this "adaptive cassette" scenario can trigger large range expansions, as recently happened in malaria mosquitoes. Sex chromosomes are the most rapidly evolving genome regions of some taxa. Sexually antagonistic selection may be the key force driving transitions of sex determination between different pairs of chromosomes and between XY and ZW systems. Fusions between sex-chromosomes and autosomes most often involve the Y chromosome, a pattern that can be explained if fusions are mildly deleterious and fix by drift. Sexually antagonistic selection is one of several hypotheses to explain the recent discovery that the sex determination system has strong effects on the adult sex ratios of tetrapods. The emerging view of how genome structure evolves invokes a much richer constellation of forces than was envisioned during the Golden Age of research on Drosophila karyotypes. © The American Genetic Association 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  1. Gender differences in the sexual behaviour of selected adolescents ...

    African Journals Online (AJOL)

    Using the Falaye Adolescent' Sexual Behaviour Inventory (FASBI), adolescents' sexual behaviour was assessed using the proximate determinants of attitude towards pubertal changes and reproductive biology, adolescent source of sex information, adolescent sexual activities (intercourse and contraception) and attitude ...

  2. Lesbians in alcohol recovery surviving childhood sexual abuse and parental substance misuse.

    Science.gov (United States)

    Hall, J M

    1999-05-01

    Narratives of lives disrupted by abuse are essential data sources for understanding women's survival and healing in contexts of childhood sexual abuse. In this qualitative, feminist study of lesbians recovering from alcohol problems who have histories of childhood sexual abuse, a multiethnic sample of 20 women narrated their life stories in a series of three in-depth interviews. The purpose of this paper is to focus on parental substance misuse as it affected these women when they were growing up. Conditions and consequences of surviving childhood sexual abuse and parental substance misuse are analysed using narrative strategies and described using excerpts from the women's narratives. Loss was the overarching core theme that integrated participants' storied descriptions of parental substance misuse. They incurred severe losses in the absence of basic necessities for safe and healthy passages through childhood. In their abusive homes, they were not allowed innocence, and protected from violence, nor nurtured, guided, and loved. As many said, they lost their very childhoods.

  3. Unbiased split variable selection for random survival forests using maximally selected rank statistics.

    Science.gov (United States)

    Wright, Marvin N; Dankowski, Theresa; Ziegler, Andreas

    2017-04-15

    The most popular approach for analyzing survival data is the Cox regression model. The Cox model may, however, be misspecified, and its proportionality assumption may not always be fulfilled. An alternative approach for survival prediction is random forests for survival outcomes. The standard split criterion for random survival forests is the log-rank test statistic, which favors splitting variables with many possible split points. Conditional inference forests avoid this split variable selection bias. However, linear rank statistics are utilized by default in conditional inference forests to select the optimal splitting variable, which cannot detect non-linear effects in the independent variables. An alternative is to use maximally selected rank statistics for the split point selection. As in conditional inference forests, splitting variables are compared on the p-value scale. However, instead of the conditional Monte-Carlo approach used in conditional inference forests, p-value approximations are employed. We describe several p-value approximations and the implementation of the proposed random forest approach. A simulation study demonstrates that unbiased split variable selection is possible. However, there is a trade-off between unbiased split variable selection and runtime. In benchmark studies of prediction performance on simulated and real datasets, the new method performs better than random survival forests if informative dichotomous variables are combined with uninformative variables with more categories and better than conditional inference forests if non-linear covariate effects are included. In a runtime comparison, the method proves to be computationally faster than both alternatives, if a simple p-value approximation is used. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  4. Selecting habitat to survive: the impact of road density on survival in a large carnivore.

    Directory of Open Access Journals (Sweden)

    Mathieu Basille

    Full Text Available Habitat selection studies generally assume that animals select habitat and food resources at multiple scales to maximise their fitness. However, animals sometimes prefer habitats of apparently low quality, especially when considering the costs associated with spatially heterogeneous human disturbance. We used spatial variation in human disturbance, and its consequences on lynx survival, a direct fitness component, to test the Hierarchical Habitat Selection hypothesis from a population of Eurasian lynx Lynx lynx in southern Norway. Data from 46 lynx monitored with telemetry indicated that a high proportion of forest strongly reduced the risk of mortality from legal hunting at the home range scale, while increasing road density strongly increased such risk at the finer scale within the home range. We found hierarchical effects of the impact of human disturbance, with a higher road density at a large scale reinforcing its negative impact at a fine scale. Conversely, we demonstrated that lynx shifted their habitat selection to avoid areas with the highest road densities within their home ranges, thus supporting a compensatory mechanism at fine scale enabling lynx to mitigate the impact of large-scale disturbance. Human impact, positively associated with high road accessibility, was thus a stronger driver of lynx space use at a finer scale, with home range characteristics nevertheless constraining habitat selection. Our study demonstrates the truly hierarchical nature of habitat selection, which aims at maximising fitness by selecting against limiting factors at multiple spatial scales, and indicates that scale-specific heterogeneity of the environment is driving individual spatial behaviour, by means of trade-offs across spatial scales.

  5. Selecting habitat to survive: the impact of road density on survival in a large carnivore.

    Science.gov (United States)

    Basille, Mathieu; Van Moorter, Bram; Herfindal, Ivar; Martin, Jodie; Linnell, John D C; Odden, John; Andersen, Reidar; Gaillard, Jean-Michel

    2013-01-01

    Habitat selection studies generally assume that animals select habitat and food resources at multiple scales to maximise their fitness. However, animals sometimes prefer habitats of apparently low quality, especially when considering the costs associated with spatially heterogeneous human disturbance. We used spatial variation in human disturbance, and its consequences on lynx survival, a direct fitness component, to test the Hierarchical Habitat Selection hypothesis from a population of Eurasian lynx Lynx lynx in southern Norway. Data from 46 lynx monitored with telemetry indicated that a high proportion of forest strongly reduced the risk of mortality from legal hunting at the home range scale, while increasing road density strongly increased such risk at the finer scale within the home range. We found hierarchical effects of the impact of human disturbance, with a higher road density at a large scale reinforcing its negative impact at a fine scale. Conversely, we demonstrated that lynx shifted their habitat selection to avoid areas with the highest road densities within their home ranges, thus supporting a compensatory mechanism at fine scale enabling lynx to mitigate the impact of large-scale disturbance. Human impact, positively associated with high road accessibility, was thus a stronger driver of lynx space use at a finer scale, with home range characteristics nevertheless constraining habitat selection. Our study demonstrates the truly hierarchical nature of habitat selection, which aims at maximising fitness by selecting against limiting factors at multiple spatial scales, and indicates that scale-specific heterogeneity of the environment is driving individual spatial behaviour, by means of trade-offs across spatial scales.

  6. The total opportunity for sexual selection and the integration of pre- and post-mating episodes of sexual selection in a complex world.

    Science.gov (United States)

    Evans, J P; Garcia-Gonzalez, F

    2016-12-01

    It is well known that sexual selection can target reproductive traits during successive pre- and post-mating episodes of selection. A key focus of recent studies has been to understand and quantify how these episodes of sexual selection interact to determine overall variance in reproductive success. In this article, we review empirical developments in this field but also highlight the considerable variability in patterns of pre- and post-mating sexual selection, attributable to variation in patterns of resource acquisition and allocation, ecological and social factors, genotype-by-environment interaction and possible methodological factors that might obscure such patterns. Our aim is to highlight how (co)variances in pre- and post-mating sexually selected traits can be sensitive to changes in a range of ecological and environmental variables. We argue that failure to capture this variation when quantifying the opportunity for sexual selection may lead to erroneous conclusions about the strength, direction or form of sexual selection operating on pre- and post-mating traits. Overall, we advocate for approaches that combine measures of pre- and post-mating selection across contrasting environmental or ecological gradients to better understand the dynamics of sexual selection in polyandrous species. We also discuss some directions for future research in this area. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

  7. Within-season variation in sexual selection in a fish with dynamic sex roles.

    Science.gov (United States)

    Wacker, Sebastian; Amundsen, Trond; Forsgren, Elisabet; Mobley, Kenyon B

    2014-07-01

    The strength of sexual selection may vary between species, among populations and within populations over time. While there is growing evidence that sexual selection may vary between years, less is known about variation in sexual selection within a season. Here, we investigate within-season variation in sexual selection in male two-spotted gobies (Gobiusculus flavescens). This marine fish experiences a seasonal change in the operational sex ratio from male- to female-biased, resulting in a dramatic decrease in male mating competition over the breeding season. We therefore expected stronger sexual selection on males early in the season. We sampled nests and nest-holding males early and late in the breeding season and used microsatellite markers to determine male mating and reproductive success. We first analysed sexual selection associated with the acquisition of nests by comparing nest-holding males to population samples. Among nest-holders, we calculated the potential strength of sexual selection and selection on phenotypic traits. We found remarkable within-season variation in sexual selection. Selection on male body size related to nest acquisition changed from positive to negative over the season. The opportunity for sexual selection among nest-holders was significantly greater early in the season rather than late in the season, partly due to more unmated males. Overall, our study documents a within-season change in sexual selection that corresponds with a predictable change in the operational sex ratio. We suggest that many species may experience within-season changes in sexual selection and that such dynamics are important for understanding how sexual selection operates in the wild. © 2014 John Wiley & Sons Ltd.

  8. Socially selected ornaments and fitness: Signals of fighting ability in paper wasps are positively associated with survival, reproductive success, and rank.

    Science.gov (United States)

    Tibbetts, Elizabeth A; Forrest, Taylor; Vernier, Cassondra; Jinn, Judy; Madagame, Andrew

    2015-11-01

    Many animals have ornaments that mediate choice and competition in social and sexual contexts. Individuals with elaborate sexual ornaments typically have higher fitness than those with less elaborate ornaments, but less is known about whether socially selected ornaments are associated with fitness. Here, we test the relationship between fitness and facial patterns that are a socially selected signal of fighting ability in Polistes dominula wasps. We found wasps that signal higher fighting ability have larger nests, are more likely to survive harsh winters, and obtain higher dominance rank than wasps that signal lower fighting ability. In comparison, body weight was not associated with fitness. Larger wasps were dominant over smaller wasps, but showed no difference in nest size or survival. Overall, the positive relationship between wasp facial patterns and fitness indicates that receivers can obtain diverse information about a signaler's phenotypic quality by paying attention to socially selected ornaments. Therefore, there are surprisingly strong parallels between the information conveyed by socially and sexually selected signals. Similar fitness relationships in social and sexually selected signals may be one reason it can be difficult to distinguish the role of social versus sexual selection in ornament evolution. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

  9. Does sexual selection explain human sex differences in aggression?

    Science.gov (United States)

    Archer, John

    2009-08-01

    I argue that the magnitude and nature of sex differences in aggression, their development, causation, and variability, can be better explained by sexual selection than by the alternative biosocial version of social role theory. Thus, sex differences in physical aggression increase with the degree of risk, occur early in life, peak in young adulthood, and are likely to be mediated by greater male impulsiveness, and greater female fear of physical danger. Male variability in physical aggression is consistent with an alternative life history perspective, and context-dependent variability with responses to reproductive competition, although some variability follows the internal and external influences of social roles. Other sex differences, in variance in reproductive output, threat displays, size and strength, maturation rates, and mortality and conception rates, all indicate that male aggression is part of a sexually selected adaptive complex. Physical aggression between partners can be explained using different evolutionary principles, arising from the conflicts of interest between males and females entering a reproductive alliance, combined with variability following differences in societal gender roles. In this case, social roles are particularly important since they enable both the relatively equality in physical aggression between partners from Western nations, and the considerable cross-national variability, to be explained.

  10. Tales of two snails: sexual selection and sexual conflict in Lymnaea stagnalis and Helix aspersa.

    Science.gov (United States)

    Koene, Joris M

    2006-08-01

    Sexual selection and sexual conflict have been shown to play key roles in the evolution of species with separate sexes. Experimental evidence is accumulating that this is also true for simultaneous hermaphrodites. For example, many species of land snails forcefully stab their mating partners with love darts. In the brown garden snail (Helix aspersa, now called Cantareus asperses), this dart increases sperm storage and paternity, probably via the transfer of an allohormone that inhibits sperm digestion. A recent interspecies comparison of dart-possessing land snails revealed coevolution between darts and spermatophore-receiving organs that is consistent with counteradaptation against an allohormonal manipulation. The great pond snail (Lymnaea stagnalis) seems to use a seminal product to manipulate its partner and mates in the male role when enough seminal fluid is available in the prostate gland. Receipt of semen not only initiates egg laying in virgin animals, but also feminizes the mating partner later in life. These increases in the female function have been shown to go at the expense of growth and seminal fluid production of the sperm recipient. Although in Helix, and probably also Lymnaea, the sperm donor benefits from the induced changes through increased fertilization success, the sperm recipient may experience injury, imposed reallocation of resources, and altered sperm storage. These findings support the existence of sexual conflict in simultaneously hermaphroditic snails, and its importance for the evolution of mating behaviors and reproductive morphologies is discussed.

  11. Sexual selection and allometry: a critical reappraisal of the evidence and ideas.

    Science.gov (United States)

    Bonduriansky, Russell

    2007-04-01

    One of the most pervasive ideas in the sexual selection literature is the belief that sexually selected traits almost universally exhibit positive static allometries (i.e., within a sample of conspecific adults, larger individuals have disproportionally larger traits). In this review, I show that this idea is contradicted by empirical evidence and theory. Although positive allometry is a typical attribute of some sexual traits in certain groups, the preponderance of positively allometric sexual traits in the empirical literature apparently results from a sampling bias reflecting a fascination with unusually exaggerated (bizarre) traits. I review empirical examples from a broad range of taxa illustrating the diversity of allometric patterns exhibited by signal, weapon, clasping and genital traits, as well as nonsexual traits. This evidence suggests that positive allometry may be the exception rather than the rule in sexual traits, that directional sexual selection does not necessarily lead to the evolution of positive allometry and, conversely, that positive allometry is not necessarily a consequence of sexual selection, and that many sexual traits exhibit sex differences in allometric intercept rather than slope. Such diversity in the allometries of secondary sexual traits is to be expected, given that optimal allometry should reflect resource allocation trade-offs, and patterns of sexual and viability selection on both trait size and body size. An unbiased empirical assessment of the relation between sexual selection and allometry is an essential step towards an understanding of this diversity.

  12. Female homosexual behavior and inter-sexual mate competition in Japanese macaques: possible implications for sexual selection theory.

    Science.gov (United States)

    Vasey, Paul L; Leca, Jean-Baptiste; Gunst, Noëlle; VanderLaan, Doug P

    2014-10-01

    In this paper, we review research related to female homosexual behavior in Japanese macaques (Macaca fuscata), including our 20-year program of research on this species. Multiple lines of evidence indicate that female homosexual behavior in this species is sexually motivated. In contrast, many sociosexual hypotheses have been tested in relation to female homosexual behavior in Japanese macaques, but none have been supported. Female Japanese macaques sometimes engage in same-sex sexual activity even when motivated opposite-sex alternatives are available. Within this context of mate choice, males compete inter-sexually for opportunities to copulate with females above and beyond any intra-sexual competition that is required. Anecdotal evidence suggests that inter-sexual competition for female sexual partners has been observed in a number of other species, including humans. At present it is unclear whether inter-sexual competition for sexual partners influences patterns of reproduction. Our understanding of sexual selection and the evolution of mating systems may be improved by investigating whether inter-sexual mate competition influences the acquisition and maintenance of reproductive partners in those species in which such interactions occur. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Polyandry as a mediator of sexual selection before and after mating.

    Science.gov (United States)

    Kvarnemo, Charlotta; Simmons, Leigh W

    2013-03-05

    The Darwin-Bateman paradigm recognizes competition among males for access to multiple mates as the main driver of sexual selection. Increasingly, however, females are also being found to benefit from multiple mating so that polyandry can generate competition among females for access to multiple males, and impose sexual selection on female traits that influence their mating success. Polyandry can reduce a male's ability to monopolize females, and thus weaken male focused sexual selection. Perhaps the most important effect of polyandry on males arises because of sperm competition and cryptic female choice. Polyandry favours increased male ejaculate expenditure that can affect sexual selection on males by reducing their potential reproductive rate. Moreover, sexual selection after mating can ameliorate or exaggerate sexual selection before mating. Currently, estimates of sexual selection intensity rely heavily on measures of male mating success, but polyandry now raises serious questions over the validity of such approaches. Future work must take into account both pre- and post-copulatory episodes of selection. A change in focus from the products of sexual selection expected in males, to less obvious traits in females, such as sensory perception, is likely to reveal a greater role of sexual selection in female evolution.

  14. Darwin's beautiful notion: sexual selection and the plurality of moral codes.

    Science.gov (United States)

    Tipton, J A

    1999-01-01

    One of the explicit objectives of Darwin's Descent of Man, and Selection in Relation to Sex was to explain cultural differences seen in human beings. Such an explanation, Darwin believed, was to rest upon an understanding of sexual selection. I examine the role that the beautiful plays within the mechanism of sexual selection as it works to differentiate isolated groups. It is suggested that an examination of the relationship between sexual selection and artificial selection--a relationship mediated by the beautiful--will illuminate key issues of the Descent as well as contemporary debates regarding the relationship between evolution and ethics. The beautiful, originally rooted in sexual selection, can become de-coupled from sexual selection and utilized in some selective process which is conscious.

  15. Measuring sexual selection on females in sex-role-reversed Mormon crickets (Anabrus simplex, Orthoptera: Tettigoniidae).

    Science.gov (United States)

    Robson, L J; Gwynne, D T

    2010-07-01

    Although many studies examine the form of sexual selection in males, studies characterizing this selection in females remain sparse. Sexual selection on females is predicted for sex-role-reversed Mormon crickets, Anabrus simplex, where males are choosy of mates and nutrient-deprived females compete for matings and nutritious nuptial gifts. We used selection analyses to describe the strength and form of sexual selection on female morphology. There was no positive linear sexual selection on the female body size traits predicted to be associated with male preferences and female competition. Instead, we detected selection for decreasing head width and mandible length, with stabilizing selection as the dominant form of nonlinear selection. Additionally, we tested the validity of a commonly used instantaneous measure of mating success by comparing selection results with those determined using cumulative mating rate. The two fitness measures yielded similar patterns of selection, supporting the common sampling method comparing mated and unmated fractions.

  16. Postcopulatory sexual selection: Darwin's omission and its consequences.

    Science.gov (United States)

    Eberhard, William G

    2009-06-16

    In one of his few major oversights, Darwin failed to appreciate that male-male competition and sexual selection can continue even after copulation has begun. The postcopulatory equivalents of both direct male-male battles (sperm competition) and female choice (cryptic female choice) occur within the female's body. Recognition of this hidden, but intense, sexual competition provides new insights into a variety of fields. These include the hyperdiverse and paradoxically elaborate morphology of both sperm and male genitalia, the equally puzzling and elaborate morphology of nongenitalic male structures that are specialized to grasp and stimulate females, powerful manipulative effects of substances in male semen on female reproductive physiology, paradoxical male courtship behavior that occurs after copulation has already begun, variability in parental investments, and the puzzlingly complex and diverse interactions between sperm and female products that surround animal eggs and between male gametophytes and female tissues in flowering plants. Many bizarre traits are involved, including male genitalia that are designed to explode or fall apart during copulation leaving behind parts within the female, male genitalia that "sing" during copulation, potent seminal products that invade the female's body cavity and her nervous system to influence her behavior, and a virtual Kama Sutra of courtship behavior performed after rather than before genital coupling, including male-female dialogues during copulation.

  17. Operational sex ratio and density do not affect directional selection on male sexual ornaments and behavior.

    Science.gov (United States)

    Head, Megan L; Lindholm, Anna K; Brooks, Robert

    2008-01-01

    Demographic parameters including operational sex ratio (OSR) and population density may influence the opportunity for, and strength of sexual selection. Traditionally, male-biased OSRs and high population densities have been thought to increase the opportunity for sexual selection on male sexual traits due to increased male competition for mates. Recent experimental evidence, however, suggests that male-biased OSRs might reduce the opportunity for sexual selection due to increased sexual coercion experienced by females. How OSR, density, and any resultant changes in the opportunity for sexual selection actually affect selection on male sexual traits is unclear. In this study, we independently manipulated OSR and density in the guppy (Poecilia reticulata) without altering the number of males present. We recorded male and female behavior and used DNA microsatellite data to assign paternity to offspring and estimate male reproductive success. We then used linear selection analyses to examine the effects of OSR and density on directional sexual selection on male behavioral and morphological traits. We found that females were pursued more by males in male-biased treatments, despite no change in individual male behavior. There were no differences in sexual behavior experienced by females or performed by males in relation to density. Neither OSR nor density significantly altered the opportunity for sexual selection. Also, Although there was significant multivariate linear selection operating on males, neither OSR nor density altered the pattern of sexual selection on male traits. Our results suggest that differences in either OSR or density (independent of the number of males present) are unlikely to alter directional evolutionary change in male sexual traits.

  18. Quantitative genetic models of sexual selection by male choice.

    Science.gov (United States)

    Nakahashi, Wataru

    2008-09-01

    There are many examples of male mate choice for female traits that tend to be associated with high fertility. I develop quantitative genetic models of a female trait and a male preference to show when such a male preference can evolve. I find that a disagreement between the fertility maximum and the viability maximum of the female trait is necessary for directional male preference (preference for extreme female trait values) to evolve. Moreover, when there is a shortage of available male partners or variance in male nongenetic quality, strong male preference can evolve. Furthermore, I also show that males evolve to exhibit a stronger preference for females that are more feminine (less resemblance to males) than the average female when there is a sexual dimorphism caused by fertility selection which acts only on females.

  19. Sexual Selection and the Evolution of Human Sex Differences

    Directory of Open Access Journals (Sweden)

    David C. Geary

    2006-12-01

    Full Text Available Darwin’s (1871 theory of sexual selection and the associated mechanisms of intrasexual competition (e.g., male-male competition and intersexual choice (e.g., female choice of mates have guided the scientific study of sex differences in hundreds of non-human species. These mechanisms and several recent advances in our understanding of the evolution and expression of sex differences in non-human species are described. The usefulness of this theory for approaching the study human sex differences is illustrated with discussion of patterns of women’s mate preferences and choices and with discussion of men’s one-on-one and coalitional competition. A comparison of these aspects of intersexual choice and intrasexual competition in humans and non-human species is provided, as is discussion of cultural variation in the expression of these behaviors. cultural influences (Maccoby & Jacklin, 1974.

  20. The roles of life-history selection and sexual selection in the adaptive evolution of mating behavior in a beetle.

    Science.gov (United States)

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

    2010-05-01

    Although there is continuing debate about whether sexual selection promotes or impedes adaptation to novel environments, the role of mating behavior in such adaptation remains largely unexplored. We investigated the evolution of mating behavior (latency to mating, mating probability and duration) in replicate populations of seed beetles Callosobruchus maculatus subjected to selection on life-history ("Young" vs. "Old" reproduction) under contrasting regimes of sexual selection ("Monogamy" vs. "Polygamy"). Life-history selection is predicted to favor delayed mating in "Old" females, but sexual conflict under polygamy can potentially retard adaptive life-history evolution. We found that life-history selection yielded the predicted changes in mating behavior, but sexual selection regime had no net effect. In within-line crosses, populations selected for late reproduction showed equally reduced early-life mating probability regardless of mating system. In between-line crosses, however, the effect of life-history selection on early-life mating probability was stronger in polygamous lines than in monogamous ones. Thus, although mating system influenced male-female coevolution, removal of sexual selection did not affect the adaptive evolution of mating behavior. Importantly, our study shows that the interaction between sexual selection and life-history selection can result in either increased or decreased reproductive divergence depending on the ecological context.

  1. Multi-level sexual selection: individual and family-level selection for mating success in a historical human population.

    Science.gov (United States)

    Moorad, Jacob A

    2013-06-01

    Precopulatory sexual selection is the association between fitness and traits associated with mate acquisition. Although sexual selection is generally recognized to be a powerful evolutionary force, most investigations are limited to characters belonging to individuals. A broader multilevel perspective acknowledges that individual fitness can be affected by aspects of mating success that are characters of groups, such as families. Parental mating success in polygynous or polyandrous human societies may exemplify traits under group-level sexual selection. Using fitness measures that account for age-structure, I measure multilevel selection for mate number over 55 years in a human population with declining rates of polygyny. Sexual selection had three components: individual-level selection for ever-mating (whether an individual mated) and individual- and family-level selection for polyandry and polygyny. Family- and individual-level selection for polygyny was equally strong, three times stronger than family-level selection for polyandry and more than an order of magnitude stronger than individual-level selection for polyandry. However, individual-level selection for polyandry and polygyny was more effective at explaining relative fitness variance than family-level selection. Selection for ever-mating was the most important source of sexual selection for fitness; variation for ever-mating explained 23% of relative fitness variance. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

  2. Pre- and postcopulatory sexual selection favor aggressive, young males in polyandrous groups of red junglefowl.

    Science.gov (United States)

    McDonald, Grant C; Spurgin, Lewis G; Fairfield, Eleanor A; Richardson, David S; Pizzari, Tommaso

    2017-06-01

    A challenge in evolutionary biology is to understand the operation of sexual selection on males in polyandrous groups, where sexual selection occurs before and after mating. Here, we combine fine-grained behavioral information (>41,000 interactions) with molecular parentage data to study sexual selection in replicated, age-structured groups of polyandrous red junglefowl, Gallus gallus. Male reproductive success was determined by the number of females mated (precopulatory sexual selection) and his paternity share, which was driven by the polyandry of his female partners (postcopulatory sexual selection). Pre- and postcopulatory components of male reproductive success covaried positively; males with high mating success also had high paternity share. Two male phenotypes affected male pre- and postcopulatory performance: average aggressiveness toward rival males and age. Aggressive males mated with more females and more often with individual females, resulting in higher sexual exclusivity. Similarly, younger males mated with more females and more often with individual females, suffering less intense sperm competition than older males. Older males had a lower paternity share even allowing for their limited sexual exclusivity, indicating they may produce less competitive ejaculates. These results show that-in these populations-postcopulatory sexual selection reinforces precopulatory sexual selection, consistently promoting younger and more aggressive males. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

  3. Kin selection versus sexual selection: why the ends do not meet

    DEFF Research Database (Denmark)

    Boomsma, Jacobus J

    2007-01-01

    I redevelop the hypothesis that lifetime monogamy is a fundamental condition for the evolution of eusocial lineages with permanent non-reproductive castes, and that later elaborations--such as multiply-mated queens and multi-queen colonies--arose without the re-mating promiscuity that characterizes...... non-social and cooperative breeding. Sexually selected traits in eusocial lineages are therefore peculiar, and their evolution constrained. Indirect (inclusive) fitness benefits in cooperatively breeding vertebrates appear to be negatively correlated with promiscuity, corroborating that kin selection...

  4. The pathogen transmission avoidance theory of sexual selection

    Energy Technology Data Exchange (ETDEWEB)

    Loehle, C.

    1997-08-01

    The current theory that sexual selection results from female preference for males with good genes suffers from several problems. An alternative explanation, the pathogen transmission avoidance hypothesis, argues that the primary function of showy traits is to provide a reliable signal of current disease status, so that sick individuals can be avoided during mating. This study shows that a significant risk of pathogen transmission occurs during mating and that showy traits are reliable indicators of current disease status. The origin of female choosiness is argued to lie in a general tendency to avoid sick individuals, even in the absence of showy traits, which originate as exaggerations of normal traits that are indicative of good health (bright feathers, vigorous movement, large size). Thus, in this new model the origins of both showy traits and female choosiness are not problematic and there is no threshold effect. This model predicts that when the possession of male showy traits does not help to reduce disease in the female, showy traits are unlikely to occur. This case corresponds to thorough exposure of every animal to all group pathogens, on average, in large groups. Such species are shown with a large data set on birds to be less likely to exhibit showy traits. The good-genes model does not make this prediction. The pathogen transmission avoidance model can also lead to the evolution of showy traits even when selection is not effective against a given pathogen (e.g., when there is no heritable variation for resistance), but can result in selection for resistance if such genes are present. Monogamy is argued to reduce selection pressures for showy traits; data show monogamous species to be both less parasitized and less showy. In the context of reduction of pathogen transmission rates in showy populations, selection pressure becomes inversely frequency-dependent, which makes showy traits likely to be self-limiting rather than runaway.

  5. Sexual selection and the evolution of sperm quality.

    Science.gov (United States)

    Fitzpatrick, John L; Lüpold, Stefan

    2014-12-01

    Sperm experience intense and varied selection that dramatically impacts the evolution of sperm quality. Selection acts to ensure that sperm are fertilization-competent and able to overcome the many challenges experienced on their way towards eggs. However, simply being able to fertilize an egg is not enough to ensure male fertility in most species. Owing to the prevalence of female multiple mating throughout the animal kingdom, successful fertilization requires sperm to outcompete rival sperm. In addition, females can actively influence sperm quality, storage or utilization to influence male fertility. This review provides an overview of how these selective forces influence the evolution of sperm quality. After exploring the link between sperm traits and male fertility, we examine how post-mating competition between rival ejaculates influences the evolution of sperm quality. We then describe how complex genetic, social and sexual interactions influence sperm quality, focusing on the importance of seminal fluid and interactions between sperm and the female's reproductive tract. In light of the complexities of selection on sperm traits, greater use of multivariate approaches that incorporate male-male, sperm-sperm and sperm-female interactions to study sperm quality will enhance our understanding of how selection acts on sperm traits and factors influencing male fertility. Because the metric of male reproductive success--fertilization--is the same across the animal kingdom, we argue that information about sperm evolution gained from non-human animals has enormous potential to further our understanding of the factors that impact human fertility. © The Author 2014. 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.

  6. Sexual selection in language, music and birdsong - common themes and issues

    OpenAIRE

    Fisher, Sarah

    2006-01-01

    Sexual selection plays a major role in evolutionary biology, shaping some of nature's most spectacular beauties and intricate systems. The interplay between competition, display and choice is a major driving force in shaping the world around us Human beings are very sexual creatures, and display competition, selectiveness and jealousy when it comes to our partners. To what extent did sexual choice shape our evolutionary history ? Studies in the evolution of language have considered a ...

  7. Individual-based simulation of sexual selection: A quantitative genetic approach

    NARCIS (Netherlands)

    Dijk, D. van; Sloot, P.M.A.; Tay, J.C.; Schut, M.C.

    2010-01-01

    Sexual selection has been mathematically modeled using quantitative genetics as well as population genetics. Two-locus simulation models have been used to study the evolution of male display and female preference. We present an individual-based simulation model of sexual selection in a quantitative

  8. Timing as a sexually selected trait: the right mate at the right moment

    NARCIS (Netherlands)

    Hau, Michaela; Dominoni, D.M.; Casagrande, S.; Buck, Loren; Wagner, Gabriela; Hazlerigg, D.G.; Greives, Timothy J.; Hut, Roelof A

    2017-01-01

    Sexual selection favours the expression of traits in one sex that attract members of the opposite sex for mating. The nature of sexually selected traits such as vocalization, colour and ornamentation, their fitness benefits as well as their costs have received ample attention in field and laboratory

  9. Timing as a sexually selected trait : the right mate at the right moment

    NARCIS (Netherlands)

    Hau, Michaela; Dominoni, Davide; Casagrande, Stefania; Buck, C. Loren; Wagner, Gabriela; Hazlerigg, David; Greives, Timothy; Hut, Roelof A.

    2017-01-01

    Sexual selection favours the expression of traits in one sex that attract members of the opposite sex for mating. The nature of sexually selected traits such as vocalization, colour and ornamentation, their fitness benefits as well as their costs have received ample attention in field and laboratory

  10. Darwinian aesthetics: sexual selection and the biology of beauty.

    Science.gov (United States)

    Grammer, Karl; Fink, Bernhard; Møller, Anders P; Thornhill, Randy

    2003-08-01

    Current theoretical and empirical findings suggest that mate preferences are mainly cued on visual, vocal and chemical cues that reveal health including developmental health. Beautiful and irresistible features have evolved numerous times in plants and animals due to sexual selection, and such preferences and beauty standards provide evidence for the claim that human beauty and obsession with bodily beauty are mirrored in analogous traits and tendencies throughout the plant and animal kingdoms. Human beauty standards reflect our evolutionary distant and recent past and emphasize the role of health assessment in mate choice as reflected by analyses of the attractiveness of visual characters of the face and the body, but also of vocal and olfactory signals. Although beauty standards may vary between cultures and between times, we show in this review that the underlying selection pressures, which shaped the standards, are the same. Moreover we show that it is not the content of the standards that show evidence of convergence--it is the rules or how we construct beauty ideals that have universalities across cultures. These findings have implications for medical, social and biological sciences.

  11. Variance in male reproductive success and sexual size dimorphism in pinnipeds: testing an assumption of sexual selection theory

    OpenAIRE

    González-Suárez, M.; Cassini, Marcelo H.

    2014-01-01

    The theory of evolution by sexual selection for sexual size dimorphism (SSD) postulates that SSD primarily reflects the adaptation of males and females to their different reproductive roles. For example, competition among males for access to females increases male body size because larger males are better able to maintain dominant status than smaller males. Larger dominant males sire most offspring while smaller subordinate males are unsuccessful, leading to skew in reproductive success. Ther...

  12. [Selected sexuality features among married women--research results].

    Science.gov (United States)

    Wróbel, Beata

    2008-02-01

    Analysis of features describing sexuality and sexual behavior of married women, deeming their sexual life 'successful' or 'unsuccessful'. 217 women have been interviewed with the help of our original questionnaire about sexual life. All women in question had been married at the time of the interview. The results have been submitted for statistical analysis. Among 217 married women that had been interviewed, 190 (87.6%) described their sexual life as 'successful', while 25 (11.5%) as 'unsuccessful'. Two women were not sexually active and thus have been excluded from the study. 1. Women in failed marriages discuss the causes of their problems with their husbands less frequently, and more often have unrevealed sexual expectations and dreams, in comparison to the group of women in successful marriages. 2. Women who deemed their sexual life 'unsuccessful' have problems with accepting nudity, both theirs and their husbands. 3. Women describing their sexual life as 'unsuccessful' do not perceive sex as pleasure. 4. The belief that one has a 'successful' or 'unsuccessful' sexual life does not have influence on the attempts of undertaking sexual contacts, with or without the consent of a woman. 5. Almost a half of married women giving consent for intercourse against their will, both in 'happy' or 'failed' marriages, are of the opinion that a husband has the right to rape his wife. 6. 'Successful' sexual life in a marriage is not a guarantee of woman's faithfulness. 7. The type of contraceptive used does not have an influence on perceiving one's sexual life as 'successful' or 'unsuccessful'.

  13. Genomic Evidence that Sexual Selection Impedes Adaptation to a Novel Environment.

    Science.gov (United States)

    Chenoweth, Stephen F; Appleton, Nicholas C; Allen, Scott L; Rundle, Howard D

    2015-07-20

    Sexual selection is widely appreciated for generating remarkable phenotypic diversity, but its contribution to adaptation and the purging of deleterious mutations is unresolved. To provide insight into the impact of sexual selection on naturally segregating polymorphisms across the genome, we previously evolved 12 populations of Drosophila serrata in a novel environment employing a factorial manipulation of the opportunities for natural and sexual selection. Here, we genotype more than 1,400 SNPs in the evolved populations and reveal that sexual selection affected many of the same genomic regions as natural selection, aligning with it as often as opposing it. Intriguingly, more than half of the 80 SNPs showing treatment effects revealed an interaction between natural and sexual selection. For these SNPs, while sexual selection alone often caused a change in allele frequency in the same direction as natural selection alone, when natural and sexual selection occurred together, changes in allele frequency were greatly reduced or even reversed. This suggests an antagonism between natural and sexual selection arising from male-induced harm to females. Behavioral experiments showed that males preferentially courted and mated with high-fitness females, and that the harm associated with this increased male attention eliminated the female fitness advantage. During our experiment, females carrying otherwise adaptive alleles may therefore have disproportionally suffered male-induced harm due to their increased sexual attractiveness. These results suggest that a class of otherwise adaptive mutations may not contribute to adaptation when mating systems involve sexual conflict and male mate preferences. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Sexual selection as a consequence of pathogen avoidance behaviors

    Energy Technology Data Exchange (ETDEWEB)

    Loehle, C. [Argonne National Lab., IL (United States); Logofet, D.O. [Russian Academy of Sciences, Moscow (Russian Federation). Laboratory of Mathematical Ecology

    1997-08-01

    The current theory that sexual selection results from female choice for good genes suffers from several problems. An alternative explanation is proposed. The pathogen avoidance hypothesis argues that the primary function of showy traits is to provide a reliable signal of current disease status so that sick individuals may be avoided during mating. Our studies shown that a significant risk of pathogen transmission occurs during mating and that showy traits are reliable indicators of current disease status. The origin of female choosiness is argued to lie in a general tendency to avoid sick individuals, even in the absence of showy traits. The showy traits are argued to originate as simple exaggerations of normal traits that are indicative of good health (bright feathers; vigorous movement; large size). Thus the origins of both showy traits and female choosiness are not problematic in this theory. A game theory analysis is employed to formalize the theory. Results of the game theory model support the theory. In particular, when the possession of male showy traits does not help reduce disease in the female, then showy traits are unlikely to occur. This case corresponds to the situation in large flocks or herds in which every animal is thoroughly exposed to all group pathogens on average. Such species do not exhibit showy traits. The good genes model does not make this prediction. The pathogen avoidance model can also lead to the evolution of showy traits even when selection is not effective against a given pathogen (e.g., when there is no heritable variation for resistance) but will lead to selection for resistance if such genes are present. Overall, the pathogen avoidance hypothesis provides a complete alternative to the good genes theory.

  15. Clinical Impact of Selective and Non-selective Beta Blockers on Survival in Ovarian Cancer Patients

    Science.gov (United States)

    Watkins, Jack L.; Thaker, Premal H.; Nick, Alpa M.; Ramondetta, Lois M.; Kumar, Sanjeev; Urbauer, Diana L.; Matsuo, Koji; Squires, Kathryn; Lutgendorf, Susan K.; Ramirez, Pedro T.; Sood, Anil K.

    2015-01-01

    BACKGROUND Preclinical evidence suggests that sustained adrenergic activation can promote ovarian cancer growth and metastasis. We examined the impact of beta-adrenergic blockade on clinical outcome of women with epithelial ovarian, primary peritoneal or fallopian tube cancers (collectively, EOC). METHODS A multicenter review of 1,425 women with histopathologically confirmed EOC was performed. Comparisons were made between patients with documented beta blocker use during chemotherapy and those without beta blocker use. RESULTS The median age of patients in this study was 63 years (range, 21–93 years). The sample included 269 patients who received beta blockers. Of those, 193 (71.7%) were receiving beta-1 adrenergic receptor (ADRB1) selective agents, and the remaining patients were receiving non-selective beta antagonists. The primary indication for beta blocker use was hypertension but also included arrhythmia and post-myocardial infarction management. For patients receiving any beta blocker, the median overall survival (OS) was 47.8 months versus42 months (P = 0.04) for non-users. The median OS based on beta blocker receptor selectivity was 94.9 months for those receiving non-selective beta blockers versus 38 months for those receiving ADRB1 selective agents (P beta blocker had a longer median OS than non-users observed (38.2 vs 90 months, P beta blockers in epithelial ovarian cancer patients was associated with longer OS. These findings may have implications for new therapeutic approaches. PMID:26301456

  16. Unifying cornerstones of sexual selection: operational sex ratio, Bateman gradient and the scope for competitive investment.

    Science.gov (United States)

    Kokko, Hanna; Klug, Hope; Jennions, Michael D

    2012-11-01

    What explains variation in the strength of sexual selection across species, populations or differences between the sexes? Here, we show that unifying two well-known lines of thinking provides the necessary conceptual framework to account for variation in sexual selection. The Bateman gradient and the operational sex ratio (OSR) are incomplete in complementary ways: the former describes the fitness gain per mating and the latter the potential difficulty of achieving it. We combine this insight with an analysis of the scope for sexually selected traits to spread despite naturally selected costs. We explain why the OSR sometimes does not affect the strength of sexual selection. An explanation of sexual selection becomes more logical when a long 'dry time' ('time out', recovery after mating due to e.g. parental care) is understood to reduce the expected time to the next mating when in the mating pool (i.e. available to mate again). This implies weaker selection to shorten the wait. An integrative view of sexual selection combines an understanding of the origin of OSR biases with how they are reflected in the Bateman gradient, and how this can produce selection for mate acquisition traits despite naturally selected costs. © 2012 Blackwell Publishing Ltd/CNRS.

  17. Sexually selected traits predict patterns of species richness in a diverse clade of suboscine birds.

    Science.gov (United States)

    Seddon, Nathalie; Merrill, Richard M; Tobias, Joseph A

    2008-05-01

    Whether sexual selection acts as an "engine of speciation" is controversial. Some studies suggest that it promotes the evolution of reproductive isolation, while others find no relationship between sexual selection and species richness. However, the explanatory power of previous models may have been constrained because they employed coarse-scale, between-family comparisons and used mating systems and morphological cues as surrogates for sexual selection. In birds, an obvious missing predictor is song, a sexually selected trait that functions in mate choice and reproductive isolation. We investigated the extent to which plumage dichromatism and song structure predicted species richness in a diverse family of Neotropical suboscine birds, the antbirds (Thamnophilidae). These analyses revealed a positive relationship between the intensity of sexual selection and diversity: genera with higher levels of dichromatism and lower-pitched, more complex songs contained greater numbers of species. This relationship held when controlling for phylogeny and was strengthened by the inclusion of subspecies, suggesting that sexual selection has played a role in the diversification of antbirds. This is the first study to reveal correlations between song structure and species diversity, emphasizing the importance of acoustic signals, and within-family analyses, in comparative studies of sexual selection.

  18. Sexual selection on spontaneous mutations strengthens the between-sex genetic correlation for fitness.

    Science.gov (United States)

    Allen, Scott L; McGuigan, Katrina; Connallon, Tim; Blows, Mark W; Chenoweth, Stephen F

    2017-10-01

    A proposed benefit to sexual selection is that it promotes purging of deleterious mutations from populations. For this benefit to be realized, sexual selection, which is usually stronger on males, must purge mutations deleterious to both sexes. Here, we experimentally test the hypothesis that sexual selection on males purges deleterious mutations that affect both male and female fitness. We measured male and female fitness in two panels of spontaneous mutation-accumulation lines of the fly, Drosophila serrata, each established from a common ancestor. One panel of mutation accumulation lines limited both natural and sexual selection (LS lines), whereas the other panel limited natural selection, but allowed sexual selection to operate (SS lines). Although mutation accumulation caused a significant reduction in male and female fitness in both the LS and SS lines, sexual selection had no detectable effect on the extent of the fitness reduction. Similarly, despite evidence of mutational variance for fitness in males and females of both treatments, sexual selection had no significant impact on the amount of mutational genetic variance for fitness. However, sexual selection did reshape the between-sex correlation for fitness: significantly strengthening it in the SS lines. After 25 generations, the between-sex correlation for fitness was positive but considerably less than one in the LS lines, suggesting that, although most mutations had sexually concordant fitness effects, sex-limited, and/or sex-biased mutations contributed substantially to the mutational variance. In the SS lines this correlation was strong and could not be distinguished from unity. Individual-based simulations that mimick the experimental setup reveal two conditions that may drive our results: (1) a modest-to-large fraction of mutations have sex-limited (or highly sex-biased) fitness effects, and (2) the average fitness effect of sex-limited mutations is larger than the average fitness effect of

  19. Patterns of Parental Investment and Sexual Selection in Teleost Fishes: Do They Support Bateman's Principles?

    Science.gov (United States)

    Rios-Cardenas, Oscar

    2005-11-01

    Bateman demonstrated differences in variance for fertility and mating success between the sexes, with males usually having a greater variance than females. Thus in general, male reproductive success increases with number of mates acquired. These results have been referred to as "Bateman's principles" and taken together with other parameters (e.g., relative parental investment) have been proposed to estimate a component of sexual selection. For this review I examine patterns of parental care and sexual selection in teleost fishes (substrate brooding and with internal fertilization). I present data for the pumpkinseed sunfish Lepomis gibbosus, in which I estimated cost of paternal care and compared direct measures of the intensity of selection on possible sexually selected traits to measures of sexual selection based on Bateman's principles.Despite high levels of paternal care in substrate brooding fishes, sexual selection tends to act more strongly on males than on females, which suggests that maternal investment is higher than paternal investment and that parental care does not limit the reproductive rate for males. In pumpkinseed sunfish, selection favors parents with high levels of defense that may exclude predators more effectively and, as suggested by Bateman's measures, alternative reproductive strategies may decrease the opportunity for sexual selection within the parental strategy. In teleost fishes with internal fertilization, patterns of parental investment and intensity of sexual selection seem to support Bateman's principles, but further studies using these systems and these measures of selection will improve the understanding of factors affecting the intensity of sexual selection and its relation to mating systems.

  20. Sexual selection and diversification: reexamining the correlation between dichromatism and speciation rate in birds.

    Science.gov (United States)

    Huang, Huateng; Rabosky, Daniel L

    2014-11-01

    Theory predicts that sexual selection can serve as an important driver of speciation, but phylogenetic comparative analyses have failed to demonstrate a consistent effect of sexual selection on species richness at macroevolutionary scales. Sexual dichromatism in birds is an example of a phenotypic trait that is hypothesized to reflect the intensity of sexual selection, yet previous studies have reached ambiguous conclusions regarding its role in promoting species diversification. Here, we revisit this problem by pairing published spectrophotometer estimates of plumage dichromatism in the bird-visible range with a newly developed method for modeling speciation rates on phylogenetic trees that explicitly accounts for diversification rate variation through time and among clades. We find little evidence linking dichromatism to speciation across birds, using several measures of dichromatism and macroevolutionary diversification. These results suggest that sexual dichromatism plays a limited role in determining speciation rates at macroevolutionary scales in birds.

  1. A Paradox of Genetic Variance in Epigamic Traits: Beyond "Good Genes" View of Sexual Selection.

    Science.gov (United States)

    Radwan, Jacek; Engqvist, Leif; Reinhold, Klaus

    Maintenance of genetic variance in secondary sexual traits, including bizarre ornaments and elaborated courtship displays, is a central problem of sexual selection theory. Despite theoretical arguments predicting that strong sexual selection leads to a depletion of additive genetic variance, traits associated with mating success show relatively high heritability. Here we argue that because of trade-offs associated with the production of costly epigamic traits, sexual selection is likely to lead to an increase, rather than a depletion, of genetic variance in those traits. Such trade-offs can also be expected to contribute to the maintenance of genetic variation in ecologically relevant traits with important implications for evolutionary processes, e.g. adaptation to novel environments or ecological speciation. However, if trade-offs are an important source of genetic variation in sexual traits, the magnitude of genetic variation may have little relevance for the possible genetic benefits of mate choice.

  2. Why Creativity is Sexy: A Review of the Evidence of Sexual Selection for Creative Abilities in Humans

    Directory of Open Access Journals (Sweden)

    Stoyo Karamihalev

    2013-08-01

    Full Text Available Creativity is an essential human trait, yet there is no consensus among scholars as to why our species have developed creative abilities. Most evolutionary explanations rely on the survival value of such abilities, but generally fail to explain why other species have not evolved similar capacities or why so many human products of creativity have little to no practical value. Sexual selection is an evolutionary force which has the potential to shed new light on this investigation by regarding creativity as a fitness indicator that has evolved for the purposes of courtship and mating. The paper at hand reviews the empirical evidence in support of this hypothesis.

  3. [Selected psychosocial factors and the sexual development of girls].

    Science.gov (United States)

    Raboch, J; Raboch, J; Sindlár, M

    1997-01-01

    In a group of 771 Czech girls aged 16 to 18 years who were examined by means of an interview, the influence of three psychosocial factors on their sexual development was studied. Through statistical analysis of data it was found that probands living in towns had their first sexual intercourse significantly earlier (p development of students in comparison with girl-apprentices was highly significantly retarded (p development of 535 girls who lived in complete and stable families, and of 166 probands from divorced marriages was carried out. Sexual development in the later group was accelerated (p development of girls during their adolescence in different directions.

  4. Sexual selection and experimental evolution of chemical signals in Drosophila pseudoobscura.

    Science.gov (United States)

    Hunt, J; Snook, R R; Mitchell, C; Crudgington, H S; Moore, A J

    2012-11-01

    Our expectations for the evolution of chemical signals in response to sexual selection are uncertain. How are chemical signals elaborated? Does sexual selection result in complexity of the composition or in altered quantities of expression? We addressed this in Drosophila pseudoobscura by examining male and female cuticular hydrocarbons (CHs) after 82 generations of elevated (E) sexual selection or relaxed sexual selection through monogamy (M). The CH profile consisted of 18 different components. We extracted three eigenvectors using principal component analysis that explained 72% of the variation. principal component (PC)1 described the amount of CHs produced, PC2 the trade-off between short- and long-chain CHs and PC3 the trade-off between apparently arbitrary CHs. In both sexes, the amount of CHs produced was greater in flies from the E treatment. PC3 was also higher, indicating that sexual selection also influenced the evolution of CH composition. The sexes differed in all three PCs, indicating substantial sexual dimorphism in this species, although the magnitude of this dimorphism was not increased as a result of our experimental evolution. Collectively, our work provides direct evidence that sexual selection plays an important role in the evolution of CHs in D. pseudoobscura and that both increased quantity and overall composition are targeted. © 2012 The Authors. Journal of Evolutionary Biology © 2012 European Society For Evolutionary Biology.

  5. No evidence for pre-copulatory sexual selection on sperm length in a passerine bird.

    Science.gov (United States)

    Lifjeld, Jan T; Laskemoen, Terje; Kleven, Oddmund; Pedersen, A Tiril M; Lampe, Helene M; Rudolfsen, Geir; Schmoll, Tim; Slagsvold, Tore

    2012-01-01

    There is growing evidence that post-copulatory sexual selection, mediated by sperm competition, influences the evolution of sperm phenotypes. Evidence for pre-copulatory sexual selection effects on sperm traits, on the other hand, is rather scarce. A recent paper on the pied flycatcher, Ficedula hypoleuca, reported phenotypic associations between sperm length and two sexually selected male traits, i.e. plumage colour and arrival date, thus invoking pre-copulatory sexual selection for longer sperm. We were unable to replicate these associations with a larger data set from the same and two additional study populations; sperm length was not significantly related to either male plumage colour or arrival date. Furthermore, there was no significant difference in sperm length between populations despite marked differences in male plumage colour. We also found some evidence against the previously held assumption of longer sperm being qualitatively superior; longer sperm swam at the same speed as shorter sperm, but were less able to maintain speed over time. We argue that both empirical evidence and theoretical considerations suggest that the evolution of sperm morphology is not primarily associated with pre-copulatory sexual selection on male secondary sexual traits in this or other passerine bird species. The relatively large between-male variation in sperm length in this species is probably due to relaxed post-copulatory sexual selection.

  6. The geography of sex-specific selection, local adaptation, and sexual dimorphism.

    Science.gov (United States)

    Connallon, Tim

    2015-09-01

    Local adaptation and sexual dimorphism are iconic evolutionary scenarios of intraspecific adaptive differentiation in the face of gene flow. Although theory has traditionally considered local adaptation and sexual dimorphism as conceptually distinct processes, emerging data suggest that they often act concurrently during evolutionary diversification. Here, I merge theories of local adaptation in space and sex-specific adaptation over time, and show that their confluence yields several new predictions about the roles of context-specific selection, migration, and genetic correlations, in adaptive diversification. I specifically revisit two influential predictions from classical studies of clinal adaptation and sexual dimorphism: (1) that local adaptation should decrease with distance from the species' range center and (2) that opposing directional selection between the sexes (sexual antagonism) should inevitably accompany the evolution of sexual dimorphism. I show that both predictions can break down under clinally varying selection. First, the geography of local adaptation can be sexually dimorphic, with locations of relatively high local adaptation differing profoundly between the sexes. Second, the intensity of sexual antagonism varies across the species' range, with subpopulations near the range center representing hotspots for antagonistic selection. The results highlight the context-dependent roles of migration versus sexual conflict as primary constraints to adaptive diversification. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

  7. A Sexual Selection Theory Longitudinal Analysis of Sexual Segregation and Integration in Early Adolescence.

    Science.gov (United States)

    Pellegrini, Anthony D.; Long, Jeffrey D.

    2003-01-01

    This longitudinal study examined the ways middle school peer groups become sexually integrated and the factors that predict dating popularity. Findings indicated that although groups did not become more integrated with time, changes in peer group sexual integration co-varied with dating popularity. Findings also showed that dominance-related…

  8. Coping and survival skills: the role school personnel play regarding support for bullied sexual minority-oriented youth.

    Science.gov (United States)

    Marshall, Alexandra; Yarber, William L; Sherwood-Laughlin, Catherine M; Gray, Mary L; Estell, David B

    2015-05-01

    Research has shown that bullying has serious health consequences, and sexual minority-oriented youth are disproportionately affected. Sexual minority-oriented youth include lesbian, gay, bisexual, transgender, queer, or questioning (LGBTQ) individuals. This study examined the bullying experiences of sexual minority-oriented youth in a predominantly rural area of a Midwestern state. The purpose of this study was to have bullied youth describe their experiences and to present their perspectives. Using critical qualitative inquiry, 16 in-depth interviews were conducted in-person or online with youth, ages 15-20, who self-identified as having been bullied based on their perceived minority sexual orientation status. The role of supportive school personnel was found to be meaningful, and supportive school personnel were mentioned as assisting with the coping and survival among this group of bullied sexual minority youth. Supportive school personnel are crucial to the coping and survival of these youth. All school personnel need to be aware of the anti-bullying policies in their school corporations. They may then work to strengthen and enforce their policies for the protection of bullied youth. © 2015, American School Health Association.

  9. A combinatory approach for selecting prognostic genes in microarray studies of tumour survivals

    DEFF Research Database (Denmark)

    Tan, Qihua; Thomassen, Mads; Jochumsen, Kirsten M

    2009-01-01

    differential gene expression analysis with the Gram-Schmidt process to identify prognostic genes that are both statistically significant and highly informative for predicting tumour survival outcomes. Empirical application to leukemia and ovarian cancer survival data through-within- and cross-study validations...... for prediction. Unfortunately feature selection in literature of microarray study is predominated by the simple heuristic univariate gene filter paradigm that selects differentially expressed genes according to their statistical significances. We introduce a combinatory feature selection strategy that integrates...

  10. Sexual Selection on male cuticular hydrocarbons via male-male competition and female choice.

    Science.gov (United States)

    Lane, S M; Dickinson, A W; Tregenza, T; House, C M

    2016-07-01

    Traditional views of sexual selection assumed that male-male competition and female mate choice work in harmony, selecting upon the same traits in the same direction. However, we now know that this is not always the case and that these two mechanisms often impose conflicting selection on male sexual traits. Cuticular hydrocarbons (CHCs) have been shown to be linked to both social dominance and male attractiveness in several insect species. However, although several studies have estimated the strength and form of sexual selection imposed on male CHCs by female mate choice, none have established whether these chemical traits are also subject to sexual selection via male-male competition. Using a multivariate selection analysis, we estimate and compare sexual selection exerted by male-male competition and female mate choice on male CHC composition in the broad-horned flour beetle Gnatocerus cornutus. We show that male-male competition exerts strong linear selection on both overall CHC abundance and body size in males, while female mate choice exerts a mixture of linear and nonlinear selection, targeting not just the overall amount of CHCs expressed but the relative abundance of specific hydrocarbons as well. We discuss the potential implications of this antagonistic selection with regard to male reproductive success. © 2016 The Authors. Journal of Evolutionary Biology published by John Wiley & Sons Ltd on behalf of European Society for Evolutionary Biology.

  11. Survival of the fittest in cities: agglomeration, selection, and polarisation

    OpenAIRE

    Kristian Behrens; Frédéric Robert-Nicoud

    2008-01-01

    Empirical studies consistently report that labour productivity and TFP rise with city size. The reason is that cities attract the most productive agents, select the best of them, and make the selected ones even more productive via various agglomeration economies. This paper provides a microeconomically founded model of vertical city differentiation in which the latter two mechanisms (`agglomeration' and `selection') operate simultaneously. Our model is both rich and tractable enough to allow ...

  12. Sex-ratio control erodes sexual selection, revealing evolutionary feedback from adaptive plasticity.

    Science.gov (United States)

    Fawcett, Tim W; Kuijper, Bram; Weissing, Franz J; Pen, Ido

    2011-09-20

    Female choice is a powerful selective force, driving the elaboration of conspicuous male ornaments. This process of sexual selection has profound implications for many life-history decisions, including sex allocation. For example, females with attractive partners should produce more sons, because these sons will inherit their father's attractiveness and enjoy high mating success, thereby yielding greater fitness returns than daughters. However, previous research has overlooked the fact that there is a reciprocal feedback from life-history strategies to sexual selection. Here, using a simple mathematical model, we show that if mothers adaptively control offspring sex in relation to their partner's attractiveness, sexual selection is weakened and male ornamentation declines. This weakening occurs because the ability to determine offspring sex reduces the fitness difference between females with attractive and unattractive partners. We use individual-based, evolutionary simulations to show that this result holds under more biologically realistic conditions. Sexual selection and sex allocation thus interact in a dynamic fashion: The evolution of conspicuous male ornaments favors sex-ratio adjustment, but this conditional strategy then undermines the very same process that generated it, eroding sexual selection. We predict that, all else being equal, the most elaborate sexual displays should be seen in species with little or no control over offspring sex. The feedback process we have described points to a more general evolutionary principle, in which a conditional strategy weakens directional selection on another trait by reducing fitness differences.

  13. Sexual selection is ineffectual or inhibits the purging of deleterious mutations in Drosophila melanogaster.

    Science.gov (United States)

    Arbuthnott, Devin; Rundle, Howard D

    2012-07-01

    The effects of sexual selection on population mean fitness are unclear and a subject of debate. Recent models propose that, because reproductive success may be condition dependent, much of the genome may be a target of sexual selection. Under this scenario, mutations that reduce health, and thus nonsexual fitness, may also be deleterious with respect to reproductive success, meaning that sexual selection may contribute to the purging of deleterious alleles. We tested this hypothesis directly by subjecting replicate Drosophila melanogaster populations to two treatments that altered the opportunity for sexual selection and then tracked changes in the frequency of six separate deleterious alleles with recessive and visible phenotypic effects. While natural selection acted to decrease the frequency of all six mutations, the addition of sexual selection did not aid in the purging of any of them, and for three of them appears to have hampered it. Courtship and mating have harmful effects in this species and mate choice assays showed that males directed more courtship and mating behavior toward wild-type over mutant females, providing a likely explanation for sexual selection's cost. Whether this cost extends to other mutations (e.g., those lacking visible phenotypic effects) is an important topic for future research. © 2012 The Author(s).

  14. Testing for a genetic response to sexual selection in a wild Drosophila population.

    Science.gov (United States)

    Gosden, T P; Thomson, J R; Blows, M W; Schaul, A; Chenoweth, S F

    2016-06-01

    In accordance with the consensus that sexual selection is responsible for the rapid evolution of display traits on macroevolutionary scales, microevolutionary studies suggest sexual selection is a widespread and often strong form of directional selection in nature. However, empirical evidence for the contemporary evolution of sexually selected traits via sexual rather than natural selection remains weak. In this study, we used a novel application of quantitative genetic breeding designs to test for a genetic response to sexual selection on eight chemical display traits from a field population of the fly, Drosophila serrata. Using our quantitative genetic approach, we were able to detect a genetically based difference in means between groups of males descended from fathers who had either successfully sired offspring or were randomly collected from the same wild population for one of these display traits, the diene (Z,Z)-5,9-C27 : 2 . Our experimental results, in combination with previous laboratory studies on this system, suggest that both natural and sexual selection may be influencing the evolutionary trajectories of these traits in nature, limiting the capacity for a contemporary evolutionary response. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

  15. Sexual Selection and the differences between the sexes in Mandrills (Mandrillus sphinx).

    Science.gov (United States)

    Setchell, Joanna M

    2016-01-01

    Sexual selection has become a major focus in evolutionary and behavioral ecology. It is also a popular research topic in primatology. I use studies of mandrills (Mandrillus sphinx), a classic example of extravagant armaments and ornaments in animals, to exemplify how a long-term, multidisciplinary approach that integrates field observations with laboratory methods can contribute to on-going theoretical debates in the field of sexual selection. I begin with a brief summary of the main concepts of sexual selection theory and the differences between the sexes. I then introduce mandrills and the study population and review mandrill life history, the ontogeny of sex differences, and maternal effects. Next, I focus on male-male competition and female choice, followed by the less well-studied questions of female-female competition and male choice. This review shows how different reproductive priorities lead to very different life histories and divergent adaptations in males and females. It demonstrates how broadening traditional perspectives on sexual selection beyond the ostentatious results of intense sexual selection on males leads to an understanding of more subtle and cryptic forms of competition and choice in both sexes and opens many productive avenues in the study of primate reproductive strategies. These include the potential for studies of postcopulatory selection, female intrasexual competition, and male choice. These studies of mandrills provide comparison and, I hope, inspiration for studies of both other polygynandrous species and species with mating systems less traditionally associated with sexual selection. © 2016 Wiley Periodicals, Inc.

  16. Complementary effect of natural and sexual selection against immigrants maintains differentiation between locally adapted fish

    Science.gov (United States)

    Plath, Martin; Riesch, Rüdiger; Oranth, Alexandra; Dzienko, Justina; Karau, Nora; Schießl, Angela; Stadler, Stefan; Wigh, Adriana; Zimmer, Claudia; Arias-Rodriguez, Lenin; Schlupp, Ingo; Tobler, Michael

    2010-08-01

    Adaptation to ecologically heterogeneous environments can drive speciation. But what mechanisms maintain reproductive isolation among locally adapted populations? Using poeciliid fishes in a system with naturally occurring toxic hydrogen sulfide, we show that (a) fish from non-sulfidic sites ( Poecilia mexicana) show high mortality (95 %) after 24 h when exposed to the toxicant, while locally adapted fish from sulfidic sites ( Poecilia sulphuraria) experience low mortality (13 %) when transferred to non-sulfidic water. (b) Mate choice tests revealed that P. mexicana females exhibit a preference for conspecific males in non-sulfidic water, but not in sulfidic water, whereas P. sulphuraria females never showed a preference. Increased costs of mate choice in sulfidic, hypoxic water, and the lack of selection for reinforcement due to the low survival of P. mexicana may explain the absence of a preference in P. sulphuraria females. Taken together, our study may be the first to demonstrate independent—but complementary—effects of natural and sexual selection against immigrants maintaining differentiation between locally adapted fish populations.

  17. Sexual selection can both increase and decrease extinction probability: reconciling demographic and evolutionary factors.

    Science.gov (United States)

    Martínez-Ruiz, Carlos; Knell, Robert J

    2017-01-01

    Previous theoretical models of the effect of sexual selection on average individual fitness in a population have mostly predicted that sexually selected populations should adapt faster and clear deleterious mutations more quickly than populations where sexual selection is not operating. While some laboratory studies have supported these predictions, others have not and studies of field systems have tended to find negative effects of sexual selection, or no effect. The negative effects of sexual selection found in field and other studies are usually ascribed to the costs associated with strong sexual selection acting on the population. Here, using an individual-based model that allows feedback between demographic and evolutionary processes, we find that sexual selection can lead to both increases and decreases in population-level fitness measures such as extinction probability and adaptation rate. Whether fitness increases or decreases depends on a variety of environmental and demographic factors including the nature of environmental change, the carrying capacity of the environment, the average fecundity of the population in question and the strength of condition dependence. In many cases, our model predicts that sexual selection leads to higher extinction probability in small populations because of an increased risk of demographic stochasticity, but lower extinction probability in larger populations because of faster adaptation rates. This is consistent with field studies that have mostly focussed on very small populations such as recently introduced birds, and tend to find negative effects, and also with laboratory studies that tend to use larger populations and have tended to find positive effects. These findings go at least some way towards an understanding of the apparent contradictions between theoretical predictions, laboratory studies and field data. © 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological Society.

  18. Partitioning sexual selection into its mating success and fertilization success components.

    Science.gov (United States)

    Pischedda, Alison; Rice, William R

    2012-02-07

    Postcopulatory sexual selection due to sperm competition and/or cryptic female choice has been documented in a diversity of taxonomic groups and is considered a pivotal component of sexual selection. Despite this apparent importance, the relative contribution of postcopulatory fertilization success to overall sexual selection has not yet been measured in any species. Here, we used a laboratory-adapted population of the promiscuous fruit fly Drosophila melanogaster to partition the variance in male reproductive success into mating success (a major component of precopulatory sexual selection) and fertilization success (a major component of postcopulatory sexual selection). We found that fertilization success contributed nearly as strongly as mating success to a male's net performance in sexual selection, but that most of this postcopulatory component was attributable to variation in male mating order (the tendency to be the last male to mate a female). After adjusting for mating order, only ≈2% of the residual variation in male reproductive success was attributable to differential fertilization success. We found no correlation between male mating success and fertilization success in this system. Unlike natural populations of Drosophila, our laboratory population is adapted to a semelparous lifecycle, so our findings will be most applicable to other promiscuous species with strong sperm precedence and one short breeding period per year or lifetime. In these species, fertilization success may have as much influence on male reproductive success as mating success, but the timing of mating (mating order) may be the predominant factor contributing to variation in fertilization success.

  19. Know thine enemy : Intra-sexual selection and sympatric speciation in Lake Victoria cichlid fish

    NARCIS (Netherlands)

    Dijkstra, Peter Douwe

    2006-01-01

    Speciation by sexual selection research has traditionally concentrated on mechanisms for divergence driven via female mate choice (intersexual selection). The pivotal role of competition between members of the same sex (intrasexual selection) has been largely overlooked. In this thesis, I describe a

  20. Stronger sexual selection in warmer waters: the case of a sex role reversed pipefish.

    Directory of Open Access Journals (Sweden)

    Nuno M Monteiro

    Full Text Available In order to answer broader questions about sexual selection, one needs to measure selection on a wide array of phenotypic traits, simultaneously through space and time. Nevertheless, studies that simultaneously address temporal and spatial variation in reproduction are scarce. Here, we aimed to investigate the reproductive dynamics of a cold-water pipefish simultaneously through time (encompassing variation within each breeding cycle and as individuals grow and space (by contrasting populations experiencing distinct water temperature regimes in order to test hypothesized differences in sexual selection. Even though the sampled populations inhabited locations with very different water temperature regimes, they exhibited considerable similarities in reproductive parameters. The most striking was the existence of a well-defined substructure in reproductive activity, where larger individuals reproduce for longer periods, which seemed dependent on a high temperature threshold for breeding rather than on the low temperatures that vary heavily according to latitude. Furthermore, the perceived disparities among populations, such as size at first reproduction, female reproductive investment, or degree of sexual size dimorphism, seemed dependent on the interplay between seawater temperature and the operational sex ratio (OSR. Contrary to our expectations of an enhanced opportunity for sexual selection in the north, we found the opposite: higher female reproductive investment coupled with increased sexual size dimorphism in warmer waters, implying that a prolonged breeding season does not necessarily translate into reduced sexual selection pressure. In fact, if the limited sex has the ability to reproduce either continuously or recurrently during the entire breeding season, an increased opportunity for sexual selection might arise from the need to compete for available partners under strongly biased OSRs across protracted breeding seasons. A more general

  1. Sex-linked genomic variation and its relationship to avian plumage dichromatism and sexual selection.

    Science.gov (United States)

    Huang, Huateng; Rabosky, Daniel L

    2015-09-16

    Sexual dichromatism is the tendency for sexes to differ in color pattern and represents a striking form of within-species morphological variation. Conspicuous intersexual differences in avian plumage are generally thought to result from Darwinian sexual selection, to the extent that dichromatism is often treated as a surrogate for the intensity of sexual selection in phylogenetic comparative studies. Intense sexual selection is predicted to leave a footprint on genetic evolution by reducing the relative genetic diversity on sex chromosome to that on the autosomes. In this study, we test the association between plumage dichromatism and sex-linked genetic diversity using eight species pairs with contrasting levels of dichromatism. We estimated Z-linked and autosomal genetic diversity for these non-model avian species using restriction-site associated (RAD) loci that covered ~3 % of the genome. We find that monochromatic birds consistently have reduced sex-linked genomic variation relative to phylogenetically-paired dichromatic species and this pattern is robust to mutational biases. Our results are consistent with several interpretations. If present-day sexual selection is stronger in dichromatic birds, our results suggest that its impact on sex-linked genomic variation is offset by other processes that lead to proportionately lower Z-linked variation in monochromatic species. We discuss possible factors that may contribute to this discrepancy between phenotypes and genomic variation. Conversely, it is possible that present-day sexual selection -- as measured by the variance in male reproductive success -- is stronger in the set of monochromatic taxa we have examined, potentially reflecting the importance of song, behavior and other non-plumage associated traits as targets of sexual selection. This counterintuitive finding suggests that the relationship between genomic variation and sexual selection is complex and highlights the need for a more comprehensive survey

  2. Sexual selection on male body size, genital length and heterozygosity: Consistency across habitats and social settings.

    Science.gov (United States)

    Head, Megan L; Kahn, Andrew T; Henshaw, Jonathan M; Keogh, J Scott; Jennions, Michael D

    2017-10-01

    Spatial and temporal variation in environmental factors and the social setting can help to maintain genetic variation in sexually selected traits if it affects the strength of directional selection. A key social parameter which affects the intensity of, and sometimes predicts the response to, mating competition is the operational sex ratio (OSR; ratio of receptive males to females). How the OSR affects selection for specific male traits is poorly understood. It is also unclear how sexual selection is affected by interactions between the OSR and environmental factors, such as habitat complexity, that alter key male-female interactions such as mate encounter rates. Here, we experimentally manipulated the OSR and habitat complexity and quantified sexual selection on male mosquitofish (Gambusia holbrooki) by directly measuring male reproductive success (i.e. paternity). We show that despite a more equitable sharing of paternity (i.e. higher levels of multiple paternity) under a male-biased OSR, selection on focal male traits was unaffected by the OSR or habitat complexity. Instead, sexual selection consistently, and significantly, favoured smaller bodied males, males with higher genome wide heterozygosity (based on >3,000 SNP markers) and males with a relatively long gonopodium (intromittent organ). Our results show that sexual selection on male body size, relative genital size and heterozygosity in this system is consistent across environments that vary in ecological parameters that are expected to influence mate encounter rates. © 2017 The Authors. Journal of Animal Ecology © 2017 British Ecological Society.

  3. Qualitative evaluation of selected social factors that impact sexual ...

    African Journals Online (AJOL)

    2016-08-17

    Aug 17, 2016 ... In addition, students extensively discussed negative reactions from their parents when they tried to acquire information about sex. These judgements led young people to gravitate towards peers for advice about their sexual lives. Two respondents highlighted the extent of the lack of communication between.

  4. Qualitative evaluation of selected social factors that impact sexual ...

    African Journals Online (AJOL)

    Objectives: This study was designed to explore the sexual behaviour of students in a metropolitan Durban University of Technology in KwaZulu-Natal to understand the social factors underlying their risk of HIV infection. Methods: This is a qualitative study that used cluster sampling where the population was stratified by ...

  5. Correlated paternity measures mate monopolization and scales with the magnitude of sexual selection.

    Science.gov (United States)

    Dorken, M E; Perry, L E

    2017-02-01

    Indirect measures of sexual selection have been criticized because they can overestimate the magnitude of selection. In particular, they do not account for the degree to which mating opportunities can be monopolized by individuals of the sex that compete for mates. We introduce a measure of mate monopolization (m) based on the magnitude of correlated paternity and evaluate its ability to track changes in the magnitude of sexual selection. Simulation models were used to compare how well m tracked changes in the selection differential (s) for a trait regulating mating success. We further evaluated the association between m and s using ten replicate mating arrays of Sagittaria latifolia in which plants with contrasting alleles at microsatellite loci competed for siring opportunities. The computer models and mating arrays both demonstrated a positive linear association between m and s, supporting the utility of m as an index of sexual selection. Commonly used measures of sexual selection are not easily applied to organisms, such as the flowering plants, for which mating events are difficult to observe. The measure of mate monopolization introduced here could prove to be a useful addition to studies of sexual selection in these organisms. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

  6. Sexual selection predicts advancement of avian spring migration in response to climate change

    DEFF Research Database (Denmark)

    Spottiswoode, Claire N; Tøttrup, Anders P; Coppack, Timothy

    2006-01-01

    Global warming has led to earlier spring arrival of migratory birds, but the extent of this advancement varies greatly among species, and it remains uncertain to what degree these changes are phenotypically plastic responses or microevolutionary adaptations to changing environmental conditions. We...... suggest that sexual selection could help to understand this variation, since early spring arrival of males is favoured by female choice. Climate change could weaken the strength of natural selection opposing sexual selection for early migration, which would predict greatest advancement in species...... in the timing of first-arriving individuals, suggesting that selection has not only acted on protandrous males. These results suggest that sexual selection may have an impact on the responses of organisms to climate change, and knowledge of a species' mating system might help to inform attempts at predicting...

  7. Postcopulatory sexual selection reduces genetic diversity in experimental populations of Caenorhabditis elegans.

    Science.gov (United States)

    LaMunyon, Craig W; Bouban, Oussama; Cutter, Asher D

    2007-01-01

    Postcopulatory sexual selection affects the evolution of numerous features ranging from mating behavior to seminal fluid toxicity to the size of gametes. In an earlier study of the effect of sperm competition risk on sperm size evolution, experimental populations of the nematode Caenorhabditis elegans were maintained either by outcrossing (sperm competition present) or by selfing (no sperm competition), and after 60 generations, significantly larger sperm had evolved in the outcrossing populations. To determine the effects of this selection on population genetic variation, we assessed genetic diversity in a large number of loci using random amplification of polymorphic DNA-PCR. Nearly 80% of the alleles present in parental strain populations persisted in the 6 experimental populations after the 60 generations and, despite a 2.2-fold difference in expected heterozygosity, the resulting levels of genetic variation were equivalent between the outcrossing and selfing experimental populations. By inference, we conclude that genetic hitchhiking due to sexual selection in the experimental populations dramatically reduced genetic diversity. We use the levels of variation in the selfing populations as a control for the effects of drift, and estimate the strength of sexual selection to be strong in obligatorily outcrossing populations. Although sequential hermaphrodites like C. elegans probably experience little sexual selection in nature, these data suggest that sexual selection can profoundly affect diversity in outcrossing taxa.

  8. Exposure to sexualized media content and selective attention for sexual cues: An experimental study

    NARCIS (Netherlands)

    Doornwaard, Suzan; van den Eijnden, Regina; Johnson, Adam; ter Bogt, Tom

    2014-01-01

    This study examined whether exposure to sexualized media influences the subconscious process of attention allocation to subsequently encountered stimuli. One hundred twenty-three participants (61 females) between 18-23 years (M age = 19.99 years) watched a 3-minute video clip containing either

  9. Meiotic drive influences the outcome of sexually antagonistic selection at a linked locus.

    Science.gov (United States)

    Patten, M M

    2014-11-01

    Most meiotic drivers, such as the t-haplotype in Mus and the segregation distorter (SD) in Drosophila, act in a sex-specific manner, gaining a transmission advantage through one sex although suffering only the fitness costs associated with the driver in the other. Their inheritance is thus more likely through one of the two sexes, a property they share with sexually antagonistic alleles. Previous theory has shown that pairs of linked loci segregating for sexually antagonistic alleles are more likely to remain polymorphic and that linkage disequilibrium accrues between them. I probe this similarity between drive and sexual antagonism and examine the evolution of chromosomes experiencing these selection pressures simultaneously. Reminiscent of previous theory, I find that: the opportunity for polymorphism increases for a sexually antagonistic locus that is physically linked to a driving locus; the opportunity for polymorphism at a driving locus also increases when linked to a sexually antagonistic locus; and stable linkage disequilibrium accompanies any polymorphic equilibrium. Additionally, I find that drive at a linked locus favours the fixation of sexually antagonistic alleles that benefit the sex in which drive occurs. Further, I show that under certain conditions reduced recombination between these two loci is selectively favoured. These theoretical results provide clear, testable predictions about the nature of sexually antagonistic variation on driving chromosomes and have implications for the evolution of genomic architecture. © 2014 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

  10. Sex-ratio control erodes sexual selection, revealing evolutionary feedback from adaptive plasticity

    NARCIS (Netherlands)

    Fawcett, Tim W.; Kuijper, Bram; Weissing, Franz J.; Pen, Ido

    2011-01-01

    Female choice is a powerful selective force, driving the elaboration of conspicuous male ornaments. This process of sexual selection has profound implications for many life-history decisions, including sex allocation. For example, females with attractive partners should produce more sons, because

  11. Eggspot number and sexual selection in the cichlid fish Astatotilapia burtoni.

    Directory of Open Access Journals (Sweden)

    Frederico Henning

    Full Text Available Sexual selection on male coloration is one of the main mechanisms proposed to explain the explosive speciation rates in East African cichlid fish. True eggspots are color patterns characteristic of the most species-rich lineage of cichlids, the Haplochromini, and have been suggested to be causally related to the speciation processes. Eggspots are thought to have originated by sensory exploitation and subsequently gained several roles in sexual advertisement. However, for most of these functions the evidence is equivocal. In addition, the genetic architecture of this trait still is largely unknown. We conducted bidirectional selective breeding experiments for eggspot numbers in the model cichlid, Astatotilapia burtoni. After two generations, low lines responded significantly, whereas the high lines did not. Body size was both phenotypically and genotypically correlated with eggspot number and showed correlated response to selection. Males with higher numbers of eggspots were found to sire larger offspring. Despite the potential to act as honest indicators of fitness, the behavioral experiments showed no evidence of a role in either intra- or inter-sexual selection. Visual-based female preference was instead explained by courtship intensity. The evolution of this trait has been interpreted in light of adaptive theories of sexual selection, however the present and published results suggest the influence of non-adaptive factors such as sensory exploitation, environmental constraints and sexual antagonism.

  12. Bateman in nature: predation on offspring reduces the potential for sexual selection.

    Science.gov (United States)

    Byers, John; Dunn, Stacey

    2012-11-09

    Sexual selection is driven by competition for mates, and the advantage of a competitor is determined by the number of offspring it produces. Early experiments by Angus Bateman characterized this interaction, and the quantitative relationship between a male's number of mates and number of offspring is known as the Bateman slope. Sexual dimorphism, one of the most obvious results of sexual selection, largely requires a positive Bateman relationship, and the slope provides an estimate of the potential for sexual selection. However, natural selection from the environment can also influence male success, as can random effects, and some have argued for inclusion of the latter in calculations of mate success. Data from pronghorn (Antilocapra americana) reveal the presence of a positive Bateman slope in each year of a 10-year study. We found no evidence that random effects skewed male mating success; however, substantial yearly variation in the Bateman slope due to predation on fawns was evident. These results support the validity of the Bateman relationship, yet they also demonstrate that environmental or extrinsic influences can limit the potential for sexual selection.

  13. Are parental care trade-offs in shorebirds driven by parental investment or sexual selection?

    Science.gov (United States)

    Olson, V A; Webb, T J; Freckleton, R P; Székely, T

    2009-04-01

    Sexual selection, mating systems and parental behaviour are closely linked, although the exact nature of their relationship is controversial. The parental investment hypothesis (PIH) states that parental care disparity drives sexual selection intensity, because the sex providing less care competes for the sex that provides more. In contrast, the sexual selection hypothesis (SSH) asserts that more intense sexual selection on males leads to reduced male parental investment. We tested these hypotheses using directional phylogenetic comparative methods in shorebirds, which have an unusually diverse array of breeding systems. Changes in parental care and sexual selection intensity were tightly correlated, and we carried out three sets of analyses focusing on changes in male behaviour, female behaviour and in either sex. The results from the analyses were consistent with both PIH and SSH, although the patterns in male transition were sensitive to model values. We propose two explanations for these results. First, phylogenetic transitions may be idiosyncratic so that they depend on the ecological circumstances of individual species. Second, transitions in social traits, such as breeding systems, may be rapid and take place in ecological time, so directional phylogenetic methods that work through longer time scales may not infer accurately the timing and direction of all changes.

  14. Select interneuron clusters determine female sexual receptivity in Drosophila

    OpenAIRE

    Sakurai, Akira; Koganezawa, Masayuki; Yasunaga, Kei-ichiro; Emoto, Kazuo; Yamamoto, Daisuke

    2013-01-01

    Female Drosophila with the spinster mutation repel courting males and rarely mate. Here we show that the non-copulating phenotype can be recapitulated by the elimination of spinster functions from either spin-A or spin-D neuronal clusters, in the otherwise wild-type (spinster heterozygous) female brain. Spin-D corresponds to the olfactory projection neurons with dendrites in the antennal lobe VA1v glomerulus that is fruitless-positive, sexually dimorphic and responsive to fly odour. Spin-A is...

  15. Struggling to survive: sexual assault, poverty, and mental health outcomes of African American women.

    Science.gov (United States)

    Bryant-Davis, Thema; Ullman, Sarah E; Tsong, Yuying; Tillman, Shaquita; Smith, Kimberly

    2010-01-01

    A substantial body of research documents the mental health consequences of sexual assault including, but not limited to, depression, posttraumatic stress disorder, substance use, and suicidality. Far less attention has been given to the mental health effects of sexual assault for ethnic minority women or women living in poverty. Given African American women's increased risk for sexual assault and increased risk for persistent poverty, the current study explores the relationship between income and mental health effects within a sample of 413 African American sexual assault survivors. Hierarchical regression analyses revealed that after controlling for childhood sexual abuse there were positive relationships between poverty and mental health outcomes of depression, posttraumatic stress disorder, and illicit drug use. There was no significant relationship between poverty and suicidal ideation. Counseling and research implications are discussed.

  16. Survival

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data provide information on the survival of California red-legged frogs in a unique ecosystem to better conserve this threatened species while restoring...

  17. Select interneuron clusters determine female sexual receptivity in Drosophila.

    Science.gov (United States)

    Sakurai, Akira; Koganezawa, Masayuki; Yasunaga, Kei-ichiro; Emoto, Kazuo; Yamamoto, Daisuke

    2013-01-01

    Female Drosophila with the spinster mutation repel courting males and rarely mate. Here we show that the non-copulating phenotype can be recapitulated by the elimination of spinster functions from either spin-A or spin-D neuronal clusters, in the otherwise wild-type (spinster heterozygous) female brain. Spin-D corresponds to the olfactory projection neurons with dendrites in the antennal lobe VA1v glomerulus that is fruitless-positive, sexually dimorphic and responsive to fly odour. Spin-A is a novel local neuron cluster in the suboesophageal ganglion, which is known to process contact chemical pheromone information and copulation-related signals. A slight reduction in spinster expression to a level with a minimal effect is sufficient to shut off female sexual receptivity if the dominant-negative mechanistic target of rapamycin is simultaneously expressed, although the latter manipulation alone has only a marginal effect. We propose that spin-mediated mechanistic target of rapamycin signal transduction in these neurons is essential for females to accept the courting male.

  18. Sexuality and Autism: A Critical Review of Selected Literature Using a Social-Relational Model of Disability

    Science.gov (United States)

    Gougeon, Nathalie A.

    2010-01-01

    This article provides a summary of selected research conducted on the sexuality, as well as sexual knowledge and behaviors of individuals with autism over the past 20 years. The discussion section reviews the research according to the following recurrent themes: the importance of sexuality in the lives of individuals with autism, the discourse of…

  19. Variation in social organization influences the opportunity for sexual selection in a social lizard.

    Science.gov (United States)

    While, Geoffrey M; Uller, Tobias; Wapstra, Erik

    2011-02-01

    Social monogamy has traditionally been suggested to be maintained because of weak sexual selection on male partner acquisition. However, the ubiquitous incidence of extra-pair paternity suggests that sexual selection can be strong in monogamous systems, although studies partitioning variance in male reproductive success have come to mixed conclusions. Here, we use detailed field data to examine variance in male reproductive success and its implications for the maintenance of sociality in a population of the socially monogamous lizard Egernia whitii. We show that both within-pair and, to a lesser extent, extra-pair partner acquisition contribute to the variance in male reproductive success, resulting in considerable opportunity for sexual selection. Despite this, levels of multiple mating are lower in Egernia compared to other reptiles, suggesting that male partner acquisition is constrained. We suggest that this constraint may be a result of strong territoriality combined with sexual conflict over multiple mating generated by costs of extra-pair paternity to females as a result of facultative male care. This has the potential to limit sexual selection by reducing variance in male reproductive success and therefore contribute to the maintenance of complex social organization. © 2010 Blackwell Publishing Ltd.

  20. Sexual selection on receptor organ traits: younger females attract males with longer antennae

    Science.gov (United States)

    Johnson, Tamara L.; Symonds, Matthew R. E.; Elgar, Mark A.

    2017-06-01

    Sexual selection theory predicts that female choice may favour the evolution of elaborate male signals. Darwin also suggested that sexual selection can favour elaborate receiver structures in order to better detect sexual signals, an idea that has been largely ignored. We evaluated this unorthodox perspective by documenting the antennal lengths of male Uraba lugens Walker (Lepidoptera: Nolidae) moths that were attracted to experimentally manipulated emissions of female sex pheromone. Either one or two females were placed in field traps for the duration of their adult lives in order to create differences in the quantity of pheromone emissions from the traps. The mean antennal length of males attracted to field traps baited with a single female was longer than that of males attracted to traps baited with two females, a pattern consistent with Darwin's prediction assuming the latter emits higher pheromone concentrations. Furthermore, younger females attracted males with longer antennae, which may reflect age-specific changes in pheromone emission. These field experiments provide the first direct evidence of an unappreciated role for sexual selection in the evolution of sexual dimorphism in moth antennae and raise the intriguing possibility that females select males with longer antennae through strategic emission of pheromones.

  1. Evolution of sexual dimorphism and Rensch’s rule in the beetle genus Limnebius (Hydraenidae: is sexual selection opportunistic?

    Directory of Open Access Journals (Sweden)

    Andrey Rudoy

    2017-03-01

    Full Text Available Sexual size dimorphism (SSD is widespread among animals, with larger females usually attributed to an optimization of resources in reproduction and larger males to sexual selection. A general pattern in the evolution of SSD is Rensch’s rule, which states that SSD increases with body size in species with larger males but decreases when females are larger. We studied the evolution of SSD in the genus Limnebius (Coleoptera, Hydraenidae, measuring SSD and male genital size and complexity of ca. 80% of its 150 species and reconstructing its evolution in a molecular phylogeny with 71 species. We found strong support for a higher evolutionary lability of male body size, which had an overall positive allometry with respect to females and higher evolutionary rates measured over the individual branches of the phylogeny. Increases in SSD were associated to increases in body size, but there were some exceptions with an increase associated to changes in only one sex. Secondary sexual characters (SSC in the external morphology of males appeared several times independently, generally on species that had already increased their size. There was an overall significant correlation between SSD, male body size and male genital size and complexity, although some lineages with complex genitalia had low SSD, and some small species with complex genitalia had no SSD. Our results suggest that the origin of the higher evolutionary variance of male body size may be due to lack of constraints rather than to sexual selection, that may start to act in species with already larger males due to random variation.

  2. Bayesian Variable Selection in High Dimensional Survival Time Cancer Genomic Datasets using Nonlocal Priors

    OpenAIRE

    Nikooienejad, Amir; Wang, Wenyi; Johnson, Valen E.

    2017-01-01

    Variable selection in high dimensional cancer genomic studies has become very popular in the past decade, due to the interest in discovering significant genes pertinent to a specific cancer type. Censored survival data is the main data structure in such studies and performing variable selection for such data type requires certain methodology. With recent developments in computational power, Bayesian methods have become more attractive in the context of variable selection. In this article we i...

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

    Directory of Open Access Journals (Sweden)

    Sara Calhim

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

  4. Norwegian honey bees surviving Varroa destructor mite infestations by means of natural selection

    Directory of Open Access Journals (Sweden)

    Melissa A.Y. Oddie

    2017-10-01

    Full Text Available Background Managed, feral and wild populations of European honey bee subspecies, Apis mellifera, are currently facing severe colony losses globally. There is consensus that the ectoparasitic mite Varroa destructor, that switched hosts from the Eastern honey bee Apis cerana to the Western honey bee A. mellifera, is a key factor driving these losses. For >20 years, breeding efforts have not produced European honey bee colonies that can survive infestations without the need for mite control. However, at least three populations of European honey bees have developed this ability by means of natural selection and have been surviving for >10 years without mite treatments. Reduced mite reproductive success has been suggested as a key factor explaining this natural survival. Here, we report a managed A. mellifera population in Norway, that has been naturally surviving consistent V. destructor infestations for >17 years. Methods Surviving colonies and local susceptible controls were evaluated for mite infestation levels, mite reproductive success and two potential mechanisms explaining colony survival: grooming of adult worker bees and Varroa Sensitive Hygiene (VSH: adult workers specifically detecting and removing mite-infested brood. Results Mite infestation levels were significantly lower in surviving colonies and mite reproductive success was reduced by 30% when compared to the controls. No significant differences were found between surviving and control colonies for either grooming or VSH. Discussion Our data confirm that reduced mite reproductive success seems to be a key factor for natural survival of infested A. mellifera colonies. However, neither grooming nor VSH seem to explain colony survival. Instead, other behaviors of the adult bees seem to be sufficient to hinder mite reproductive success, because brood for this experiment was taken from susceptible donor colonies only. To mitigate the global impact of V. destructor, we suggest learning

  5. Population density mediates the interaction between pre- and post-mating sexual selection.

    Science.gov (United States)

    McCullough, Erin L; Buzatto, Bruno A; Simmons, Leigh W

    2018-02-17

    When females mate with more than one male, sexual selection acts both before and after mating. The interaction between pre- and post-mating episodes of selection is expected to be context dependent, but few studies have investigated how total sexual selection changes under different ecological conditions. We examined how population density mediates the interaction between pre- and post-mating sexual selection by establishing replicate populations of the horned dung beetle Onthophagus taurus at low, medium, and high densities, and using microsatellite-based parentage analyses to measure male fitness. We found that mating success and fertilization success were positively correlated at all three densities, but the strength of the correlation decreased with increasing density. We also found a shift from negative to positive linear selection on testes mass as density increased, and opposing selection on weapons and testes at high densities. These patterns suggest that the importance of post-mating processes increases with increasing population density, which reduces the selective advantage of weapons for pre-mating contest competition, and increases the selective advantage of large ejaculates for post-mating sperm competition. We expect that density-dependent selection on testes mass has contributed to the phenotypic variation observed between natural populations of O. taurus that differ in density. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  6. Immunocompetence index selection of broiler chicken lines for disease resistance and their impact on survival rate

    Directory of Open Access Journals (Sweden)

    Sanjeev Kumar

    2013-06-01

    Full Text Available Aim: This study was aimed to develop the disease resistance broiler chicken lines over two generations (G0 , G1 and G2 of selection for immunocompetence (IC index by targeting all the facets of immune response traits viz., humoral response (HR to Sheep red blood cells (SRBC, cell mediated immune response (CMI to phytohaeagglutination- Pmitogen (PHA-P, levels of serum serum immunoglobin- G (IgG and serum lysozyme (LZM level.Materials and Methods: The SDLSynthetic Dam Line (SDL broiler line consisting of 303, 204 and 300 birds in G0 , G1 and G2 generations, respectively were screened for immunocompetence traits such as humoral response to SRBCs, cell mediated immune response to PHA-Pand levels of serum lysozyme by Lysoplate assay and IgG by SRID method, and ranked based on their IC index values. Results: The percent survival rate up to 6 weeks of age in SDL broiler chicken lines were selected for high immunocompetence index (HIC and low immunocompetence index values (LIC over two generations (G1 , G1 and G2 of selection and observed that significant differences (P< 0.05 in percent survival pattern in the base population (n= 303 with the highest survivability of 100.00% was observed in 5-6 weeks of age followed by 99.37% and 97.23% in 4-5 and 0-4 weeks of age respectively. In the G1 generation, significant differences ( P<0.01 was noticed in the selected high and low index lines up to 6 weeks of age with the overall survival rate lower in high index lines (93.10% as compared to the low index lines (97.62%. Whereas the reverse trend was observed in the G2 generation that the high index line had significantly (P<0.05 higher survival percent (98.62% as compared to the low index lines (97.93%. Moreover, the overall survival rate was better substantially over the two generations of divergent immunocompetent index selection of SDL broiler chicken lines. The present investigation revealed that breeding for better immunocompetence status by selection index

  7. Legal size limit implies strong fisheries selection on sexually selected traits in a temperate wrasse providing male-only parental care

    Directory of Open Access Journals (Sweden)

    Kim Aleksander Tallaksen Halvorsen

    2015-12-01

    Full Text Available Corkwing wrasse (Symphodus melops is a temperate wrasse displaying both sex and male dimorphism and is targeted in a size selective commercial fishery which has increased dramatically since 2008. Wrasses are supplied alive to salmon farms as cleaner fish to combat infestations of Salmon lice. In previous studies, growth and maturation has been found to differ among male morphs and sexes and these groups might therefore be targeted unevenly by the size selective fishery. In the present study, we address this by comparing size regulations and fishing practice with data on sex specific growth and maturation from Western and Southern Norway, two regions varying in density and life histories. Two years of field data on density and length measures was used together with a subsample of otoliths to determine sex specific growth patterns. In the region with high density, nesting males were found to grow faster and mature later than sneaker males and females. Here, most nesting males will reach the minimum size as juveniles, one and two years before females and sneakers respectively. In contrast, sexual dimorphism was much less pronounced in the low density region, and relaxed male-male competition over nesting sites seems a likely explanation for this pattern. Intensive harvesting with selective removal of the larger nesting males could potentially lead to short term effect such as sperm limitation and reduced offspring survival and thus affect the productivity of juveniles. In addition, the current fishing regime may select for reduced growth rates and earlier maturation and oppose sexual selection.

  8. Neutral and selection-driven decay of sexual traits in asexual stick insects.

    Science.gov (United States)

    Schwander, Tanja; Crespi, Bernard J; Gries, Regine; Gries, Gerhard

    2013-08-07

    Environmental shifts and lifestyle changes may result in formerly adaptive traits becoming non-functional or maladaptive. The subsequent decay of such traits highlights the importance of natural selection for adaptations, yet its causes have rarely been investigated. To study the fate of formerly adaptive traits after lifestyle changes, we evaluated sexual traits in five independently derived asexual lineages, including traits that are specific to males and therefore not exposed to selection. At least four of the asexual lineages retained the capacity to produce males that display normal courtship behaviours and are able to fertilize eggs of females from related sexual species. The maintenance of male traits may stem from pleiotropy, or from these traits only regressing via drift, which may require millions of years to generate phenotypic effects. By contrast, we found parallel decay of sexual traits in females. Asexual females produced altered airborne and contact signals, had modified sperm storage organs, and lost the ability to fertilize their eggs, impeding reversals to sexual reproduction. Female sexual traits were decayed even in recently derived asexuals, suggesting that trait changes following the evolution of asexuality, when they occur, proceed rapidly and are driven by selective processes rather than drift.

  9. Sexual selection and the evolution of egg-sperm interactions in broadcast-spawning invertebrates.

    Science.gov (United States)

    Evans, Jonathan P; Sherman, Craig D H

    2013-08-01

    Many marine invertebrate taxa are broadcast spawners, where multiple individuals release their gametes into the water for external fertilization, often in the presence of gametes from heterospecifics. Consequently, sperm encounter the considerable challenges of locating and fertilizing eggs from conspecific females. To overcome these challenges, many taxa exhibit species-specific attraction of sperm toward eggs through chemical signals released from eggs (sperm chemotaxis) and species-specific gamete recognition proteins (GRPs) that mediate compatibility of gametes at fertilization. In this prospective review, we highlight these selective forces, but also emphasize the role that sexual selection, manifested through sperm competition, cryptic female choice, and evolutionary conflicts of interest between the sexes (sexual conflict), can also play in mediating the action of egg chemoattractants and GRPs, and thus individual reproductive fitness. Furthermore, we explore patterns of selection at the level of gametes (sperm phenotype, gamete plasticity, and egg traits) to identify putative traits targeted by sexual selection in these species. We conclude by emphasizing the excellent, but relatively untapped, potential of broadcast-spawning marine invertebrates as model systems to illuminate several areas of research in post-mating sexual selection.

  10. Polygyny and extra-pair paternity enhance the opportunity for sexual selection in blue tits

    NARCIS (Netherlands)

    Vedder, Oscar; Komdeur, Jan; van der Velde, Marco; Schut, Elske; Magrath, Michael J. L.

    Polygyny and extra-pair paternity are generally thought to enhance sexual selection. However, the extent to which these phenomena increase variance in male reproductive success will depend on the covariance between success at these two strategies. We analysed these patterns over four breeding

  11. Sexual selection and interacting phenotypes in experimental evolution: a study of Drosophila pseudoobscura mating behavior.

    Science.gov (United States)

    Bacigalupe, Leonardo D; Crudgington, Helen S; Slate, Jon; Moore, Allen J; Snook, Rhonda R

    2008-07-01

    Sexual selection requires social interactions, particularly between the sexes. When trait expression is influenced by social interactions, such traits are called interacting phenotypes and only recently have the evolutionary consequences of interacting phenotypes been considered. Here we investigated how variation in relative fitness, or the opportunity for sexual selection, affected the evolutionary trajectories of interacting phenotypes. We used experimentally evolved populations of the naturally promiscuous Drosophila pseudoobscura, in which the numbers of potential interactions between the sexes, and therefore relative fitness, were manipulated by altering natural levels of female promiscuity. We considered two different mating interactions between the sexes: mating speed and copulation duration. We investigated the evolutionary trajectories of means and (co)variances (P) and also the influence of genetic drift on the evolutionary response of these interactions. Our sexual selection treatments did not affect the means of either mating speed or copulation duration, but they did affect P. We found that the means of both traits differed among replicates within each selection treatment whereas the Ps did not. Changes as a consequence of genetic drift were excluded. Our results show that although variable potential strengths of sexual interactions influence the evolution of interacting phenotypes, the influence may be nonlinear.

  12. Strong sexual selection in males against a mutation load that reduces offspring production in seed beetles.

    Science.gov (United States)

    Grieshop, K; Stångberg, J; Martinossi-Allibert, I; Arnqvist, G; Berger, D

    2016-06-01

    Theory predicts that sexual reproduction can increase population viability relative to asexual reproduction by allowing sexual selection in males to remove deleterious mutations from the population without large demographic costs. This requires that selection acts more strongly in males than females and that mutations affecting male reproductive success have pleiotropic effects on population productivity, but empirical support for these assumptions is mixed. We used the seed beetle Callosobruchus maculatus to implement a three-generation breeding design where we induced mutations via ionizing radiation (IR) in the F0 generation and measured mutational effects (relative to nonirradiated controls) on an estimate of population productivity in the F1 and effects on sex-specific competitive lifetime reproductive success (LRS) in the F2 . Regardless of whether mutations were induced via F0 males or females, they had strong negative effects on male LRS, but a nonsignificant influence on female LRS, suggesting that selection is more efficient in removing deleterious alleles in males. Moreover, mutations had seemingly shared effects on population productivity and competitive LRS in both sexes. Thus, our results lend support to the hypothesis that strong sexual selection on males can act to remove the mutation load on population viability, thereby offering a benefit to sexual reproduction. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

  13. How sexual selection can drive the evolution of costly sperm ornamentation

    Science.gov (United States)

    Lüpold, Stefan; Manier, Mollie K.; Puniamoorthy, Nalini; Schoff, Christopher; Starmer, William T.; Luepold, Shannon H. Buckley; Belote, John M.; Pitnick, Scott

    2016-05-01

    Post-copulatory sexual selection (PSS), fuelled by female promiscuity, is credited with the rapid evolution of sperm quality traits across diverse taxa. Yet, our understanding of the adaptive significance of sperm ornaments and the cryptic female preferences driving their evolution is extremely limited. Here we review the evolutionary allometry of exaggerated sexual traits (for example, antlers, horns, tail feathers, mandibles and dewlaps), show that the giant sperm of some Drosophila species are possibly the most extreme ornaments in all of nature and demonstrate how their existence challenges theories explaining the intensity of sexual selection, mating-system evolution and the fundamental nature of sex differences. We also combine quantitative genetic analyses of interacting sex-specific traits in D. melanogaster with comparative analyses of the condition dependence of male and female reproductive potential across species with varying ornament size to reveal complex dynamics that may underlie sperm-length evolution. Our results suggest that producing few gigantic sperm evolved by (1) Fisherian runaway selection mediated by genetic correlations between sperm length, the female preference for long sperm and female mating frequency, and (2) longer sperm increasing the indirect benefits to females. Our results also suggest that the developmental integration of sperm quality and quantity renders post-copulatory sexual selection on ejaculates unlikely to treat male-male competition and female choice as discrete processes.

  14. Rapid loss of behavioral plasticity and immunocompetence under intense sexual selection.

    Science.gov (United States)

    van Lieshout, Emile; McNamara, Kathryn B; Simmons, Leigh W

    2014-09-01

    Phenotypic plasticity allows animals to maximize fitness by conditionally expressing the phenotype best adapted to their environment. Although evidence for such adjustment in reproductive tactics is common, little is known about how phenotypic plasticity evolves in response to sexual selection. We examined the effect of sexual selection intensity on phenotypic plasticity in mating behavior using the beetle Callosobruchus maculatus. Male genital spines harm females during mating and females exhibit copulatory kicking, an apparent resistance trait aimed to dislodge mating males. After exposing individuals from male- and female-biased experimental evolution lines to male- and female-biased sociosexual environments, we examined behavioral plasticity in matings with standard partners. While females from female-biased lines kicked sooner after exposure to male-biased sociosexual contexts, in male-biased lines this plasticity was lost. Ejaculate size did not diverge in response to selection history, but males from both treatments exhibited plasticity consistent with sperm competition intensity models, reducing size as the number of competitors increased. Analysis of immunocompetence revealed reduced immunity in both sexes in male-biased lines, pointing to increased reproductive costs under high sexual selection. These results highlight how male and female reproductive strategies are shaped by interactions between phenotypically plastic and genetic mechanisms of sexual trait expression. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

  15. Evolution of egg dummies in Tanganyikan cichlid fishes: the roles of parental care and sexual selection.

    Science.gov (United States)

    Amcoff, M; Gonzalez-Voyer, A; Kolm, N

    2013-11-01

    Sexual selection has been suggested to be an important driver of speciation in cichlid fishes of the Great Lakes of Africa, and the presence of male egg dummies is proposed to have played a key role. Here, we investigate how mouthbrooding and egg dummies have evolved in Tanganyikan cichlids, the lineage which seeded the other African radiations, with a special emphasis on the egg dummies. Using modern phylogenetic comparative analyses and a phylogeny including 86% of the 200 described species, we provide formal evidence demonstrating correlated evolution between mouthbrooding and egg dummies in Tanganyikan cichlids. These results concur with existing evidence, suggesting that egg dummies have evolved through sensory exploitation. We also demonstrate that there is a strong evolutionary correlation between the presence of egg dummies and both pre- and post-copulatory sexual selection. Moreover, egg dummy evolution was contingent on the intensity of pre- and post-copulatory sexual selection in Tanganyikan cichlids. In sum, our results provide evidence supporting the hypothesis of egg dummies evolving through sensory exploitation and highlight the role of sexual selection in favouring the evolution and maintenance of this trait. © 2013 The Authors. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology.

  16. The evolution of the sexually selected sword in Xiphophorus does not compromise aerobic locomotor performance.

    Science.gov (United States)

    Oufiero, Christopher E; Meredith, Robert W; Jugo, Kristine N; Tran, Paulina; Chappell, Mark A; Springer, Mark S; Reznick, David N; Garland, Theodore

    2014-06-01

    Sexual selection can increase morphological diversity within and among species. Little is known regarding how interspecific variation produced through sexual selection affects other functional systems. Here, we examine how morphological diversity resulting from sexual selection impacts aerobic locomotor performance. Using Xiphophorus (swordtail fish) and their close relatives (N = 19 species), we examined whether the evolution of a longer sexually selected sword affects critical swimming speed. We also examined the effect of other suborganismal, physiological, and morphological traits on critical swimming speed, as well as their relationship with sword length. In correlation analyses, we found no significant relationship between sword length and critical swimming speed. Unexpectedly, we found that critical swimming speed was higher in species with longer swords, after controlling for body size in multiple regression analyses. We also found several suborganismal and morphological predictors of critical swimming speed, as well as a significant negative relationship between sword length and heart and gill mass. Our results suggest that interspecific variation in sword length is not costly for this aspect of swimming performance, but further studies should examine potential costs for other types of locomotion and other components of Darwinian fitness (e.g., survivorship, life span). © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

  17. Sexual selection on land snail shell ornamentation: a hypothesis that may explain shell diversity

    NARCIS (Netherlands)

    Schilthuizen, M.

    2003-01-01

    Background: Many groups of land snails show great interspecific diversity in shell ornamentation, which may include spines on the shell and flanges on the aperture. Such structures have been explained as camouflage or defence, but the possibility that they might be under sexual selection has not

  18. Parasite-mediated sexual selection and species divergence in Lake Victoria cichlid fish

    NARCIS (Netherlands)

    Maan, Martine E.; Van Rooijen, Anne M. C.; Van Alphen, Jacques J. M.; Seehausen, Ole

    We investigate the role of parasite-mediated sexual selection in the divergence of two species of Lake Victoria cichlids. Pundamilia pundamilia and Pundamilia nyererei represent a common pattern of male nuptial colour divergence between haplochromine sister species: metallic grey-blue in P.

  19. On the origin of species by natural and sexual selection

    NARCIS (Netherlands)

    van Doorn, G. Sander; Edelaar, Pim; Weissing, Franz J.

    2009-01-01

    Ecological speciation is considered an adaptive response to selection for local adaptation. However, besides suitable ecological conditions, the process requires assortative mating to protect the nascent species from homogenization by gene flow. By means of a simple model, we demonstrate that

  20. A Combinatory Approach for Selecting Prognostic Genes in Microarray Studies of Tumour Survivals

    Directory of Open Access Journals (Sweden)

    Qihua Tan

    2009-01-01

    Full Text Available Different from significant gene expression analysis which looks for genes that are differentially regulated, feature selection in the microarray-based prognostic gene expression analysis aims at finding a subset of marker genes that are not only differentially expressed but also informative for prediction. Unfortunately feature selection in literature of microarray study is predominated by the simple heuristic univariate gene filter paradigm that selects differentially expressed genes according to their statistical significances. We introduce a combinatory feature selection strategy that integrates differential gene expression analysis with the Gram-Schmidt process to identify prognostic genes that are both statistically significant and highly informative for predicting tumour survival outcomes. Empirical application to leukemia and ovarian cancer survival data through-within- and cross-study validations shows that the feature space can be largely reduced while achieving improved testing performances.

  1. Prevalence of sexual disorders in a selection-free diabetic population (JEVIN).

    Science.gov (United States)

    Schiel, R; Müller, U A

    1999-05-01

    There is an extensive literature on sexual disorders among diabetic patients, but a shortage of studies on their prevalence in selection-free populations. In the present trial (JEVIN), 90% of all insulin-treated diabetic patients (IDDM/NIDDM, n = 127/117) aged 16-60 years and living in the city of Jena (100247 inhabitants) were studied. Each subject underwent a structured interview followed by a clinical and laboratory examination. The prevalence of sexual disorders was 32% in IDDM and 46% in NIDDM male patients. Patients with sexual disorders were older (IDDM 47.5 +/- 9.8 vs. 37.7 +/- 11.6, P = 0.0004; NIDDM 53.4 +/- 4.3 vs. 49.5 +/- 8.2 years, P = 0.04) and had longer diabetes duration (IDDM 23.1 +/- 13.8 vs. 13.5 +/- 11.1, P = 0.001; NIDDM 12.4 +/- 7.5 vs. 8.4 +/- 5.8 years, P = 0.03) than patients without sexual disorders. There were no significant differences (P diabetes long-term complications in men with versus men without sexual disorders (IDDM/NIDDM): retinopathy, 65/53% vs. 50/18% (P = 0.34/0.03); neuropathy, 58/48% vs. 9/34% (P = 0.001/0.47); nephropathy, 65/50% vs. 12/36% (P = 0.001/0.45). In addition, all the patients completed standardized questionnaires according to Bradley et al. and Lewis et al. to assess quality of life and treatment satisfaction, and one question concerning sexual disorders. The quality of life of IDDM patients with sexual disorders was lower than that of patients without sexual disorders (42.2 +/- 11.4 vs. 54.2 +/- 8.5, P = 0.0005), but there were no differences (P women, the prevalence of sexual disorders was 18/42% in IDDM and NIDDM. Comparing these data with the literature and with reports from healthy controls, mostly there is clearly an underestimation of the prevalence of sexual disorders in diabetic populations. Physicians must make more efforts to detect and treat sexual disorders, which may result in an improvement of patients' quality of life.

  2. Why mammalian lineages respond differently to sexual selection: metabolic rate constrains the evolution of sperm size.

    Science.gov (United States)

    Gomendio, Montserrat; Tourmente, Maximiliano; Roldan, Eduardo R S

    2011-10-22

    The hypothesis that sperm competition should favour increases in sperm size, because it results in faster swimming speeds, has received support from studies on many taxa, but remains contentious for mammals. We suggest that this may be because mammalian lineages respond differently to sexual selection, owing to major differences in body size, which are associated with differences in mass-specific metabolic rate. Recent evidence suggests that cellular metabolic rate also scales with body size, so that small mammals have cells that process energy and resources from the environment at a faster rate. We develop the 'metabolic rate constraint hypothesis' which proposes that low mass-specific metabolic rate among large mammals may limit their ability to respond to sexual selection by increasing sperm size, while this constraint does not exist among small mammals. Here we show that among rodents, which have high mass-specific metabolic rates, sperm size increases under sperm competition, reaching the longest sperm sizes found in eutherian mammals. By contrast, mammalian lineages with large body sizes have small sperm, and while metabolic rate (corrected for body size) influences sperm size, sperm competition levels do not. When all eutherian mammals are analysed jointly, our results suggest that as mass-specific metabolic rate increases, so does maximum sperm size. In addition, species with low mass-specific metabolic rates produce uniformly small sperm, while species with high mass-specific metabolic rates produce a wide range of sperm sizes. These findings support the hypothesis that mass-specific metabolic rates determine the budget available for sperm production: at high levels, sperm size increases in response to sexual selection, while low levels constrain the ability to respond to sexual selection by increasing sperm size. Thus, adaptive and costly traits, such as sperm size, may only evolve under sexual selection when metabolic rate does not constrain cellular

  3. Prolonging survival of corneal transplantation by selective sphingosine-1-phosphate receptor 1 agonist.

    Directory of Open Access Journals (Sweden)

    Min Gao

    Full Text Available Corneal transplantation is the most used therapy for eye disorders. Although the cornea is somewhat an immune privileged organ, immune rejection is still the major problem that reduces the success rate. Therefore, effective chemical drugs that regulate immunoreactions are needed to improve the outcome of corneal transplantations. Here, a sphingosine-1-phosphate receptor 1 (S1P1 selective agonist was systematically evaluated in mouse allogeneic corneal transplantation and compared with the commonly used immunosuppressive agents. Compared with CsA and the non-selective sphingosine 1-phosphate (S1P receptor agonist FTY720, the S1P1 selective agonist can prolong the survival corneal transplantation for more than 30 days with a low immune response. More importantly, the optimal dose of the S1P1 selective agonist was much less than non-selective S1P receptor agonist FTY720, which would reduce the dose-dependent toxicity in drug application. Then we analyzed the mechanisms of the selected S1P1 selective agonist on the immunosuppression. The results shown that the S1P1 selective agonist could regulate the distribution of the immune cells with less CD4+ T cells and enhanced Treg cells in the allograft, moreover the expression of anti-inflammatory cytokines TGF-β1 and IL-10 unregulated which can reduce the immunoreactions. These findings suggest that S1P1 selective agonist may be a more appropriate immunosuppressive compound to effectively prolong mouse allogeneic corneal grafts survival.

  4. Sexual selection on land snail shell ornamentation: a hypothesis that may explain shell diversity

    Directory of Open Access Journals (Sweden)

    Schilthuizen Menno

    2003-06-01

    Full Text Available Abstract Background Many groups of land snails show great interspecific diversity in shell ornamentation, which may include spines on the shell and flanges on the aperture. Such structures have been explained as camouflage or defence, but the possibility that they might be under sexual selection has not previously been explored. Presentation of the hypothesis The hypothesis that is presented consists of two parts. First, that shell ornamentation is the result of sexual selection. Second, that such sexual selection has caused the divergence in shell shape in different species. Testing the hypothesis The first part of the hypothesis may be tested by searching for sexual dimorphism in shell ornamentation in gonochoristic snails, by searching for increased variance in shell ornamentation relative to other shell traits, and by mate choice experiments using individuals with experimentally enhanced ornamentation. The second part of the hypothesis may be tested by comparing sister groups and correlating shell diversity with degree of polygamy. Implications of the hypothesis If the hypothesis were true, it would provide an explanation for the many cases of allopatric evolutionary radiation in snails, where shell diversity cannot be related to any niche differentiation or environmental differences.

  5. Intraspecific shape variation in horseshoe crabs: the importance of sexual and natural selection for local adaptation

    DEFF Research Database (Denmark)

    Faurby, Søren; Nielsen, Kasper Sauer Kollerup; Bussarawit, Somchai

    2011-01-01

    A morphometric analysis of the body shape of three species of horseshoe crabs was undertaken in order to infer the importance of natural and sexual selection. It was expected that natural selection would be most intense, leading to highest regional differentiation, in the American species Limulus...... polyphemus, which has the largest climatic differences between different populations. Local adaptation driven by sexual selection was expected in males but not females because horseshoe crab mating behaviour leads to competition between males, but not between females. Three hundred fifty-nine horseshoe crabs....... Differences in shape variation between sexes were tested with F-tests, which showed lower intrapopulation morphometric variation in males than females. These results indicate a lower degree of local adaptation on body shape in C. rotundicauda and T. gigas than in L. polyphemus and a lower degree of local...

  6. Sexual selection of human cooperative behaviour: an experimental study in rural Senegal.

    Directory of Open Access Journals (Sweden)

    Arnaud Tognetti

    Full Text Available Human cooperation in large groups and between non-kin individuals remains a Darwinian puzzle. Investigations into whether and how sexual selection is involved in the evolution of cooperation represent a new and important research direction. Here, 69 groups of four men or four women recruited from a rural population in Senegal played a sequential public-good game in the presence of out-group observers, either of the same sex or of the opposite sex. At the end of the game, participants could donate part of their gain to the village school in the presence of the same observers. Both contributions to the public good and donations to the school, which reflect different components of cooperativeness, were influenced by the sex of the observers. The results suggest that in this non-Western population, sexual selection acts mainly on men's cooperative behaviour with non-kin, whereas women's cooperativeness is mainly influenced by nonsexual social selection.

  7. Sexual and natural selection in the evolution of extended phenotypes: the use of green nesting material in starlings.

    Science.gov (United States)

    Rubalcaba, J G; Polo, V; Maia, R; Rubenstein, D R; Veiga, J P

    2016-08-01

    Although sexual selection is typically considered the predominant force driving the evolution of ritualized sexual behaviours, natural selection may also play an important and often underappreciated role. The use of green aromatic plants among nesting birds has been interpreted as a component of extended phenotype that evolved either via natural selection due to potential sanitary functions or via sexual selection as a signal of male attractiveness. Here, we compared both hypotheses using comparative methods in starlings, a group where this behaviour is widespread. We found that the use of green plants was positively related to male-biased size dimorphism and that it was most likely to occur among cavity-nesting species. These results suggest that this behaviour is likely favoured by sexual selection, but also related to its sanitary use in response to higher parasite loads in cavities. We speculate that the use of green plants in starlings may be facilitated by cavity nesting and was subsequently co-opted as a sexual signal by males. Our results represent an example of how an extended phenotypic component of males becomes sexually selected by females. Thus, both natural selection and sexual selection are necessary to fully understand the evolution of ritualized behaviours involved in courtship. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

  8. Sexual selection and mating chronology of Lesser Prairie-Chickens

    Science.gov (United States)

    Behney, Adam C.; Grisham, Blake A.; Boal, Clint W.; Whitlaw, Heather A.; Haukos, David A.

    2012-01-01

    Little is known about mate selection and lek dynamics of Lesser Prairie-Chickens (Tympanuchus pallidicinctus). We collected data on male territory size and location on leks, behavior, and morphological characteristics and assessed the importance of these variables on male Lesser Prairie-Chicken mating success during spring 2008 and 2009 in the Texas Southern High Plains. We used discrete choice models and found that males that were less idle were chosen more often for mating. Our results also suggest that males with smaller territories obtained more copulations. Morphological characteristics were weaker predictors of male mating success. Peak female attendance at leks occurred during the 1-week interval starting 13 April during both years of study. Male prairie-chickens appear to make exploratory movements to, and from, leks early in the lekking season; 13 of 19 males banded early (23 Feb–13 Mar) in the lekking season departed the lek of capture and were not reobserved (11 yearlings, 2 adults). Thirty-three percent (range  =  26–51%) of males on a lek mated (yearlings  =  44%, adults  =  20%) and males that were more active experienced greater mating success.

  9. Survival Prediction and Feature Selection in Patients with Breast Cancer Using Support Vector Regression

    Directory of Open Access Journals (Sweden)

    Shahrbanoo Goli

    2016-01-01

    Full Text Available The Support Vector Regression (SVR model has been broadly used for response prediction. However, few researchers have used SVR for survival analysis. In this study, a new SVR model is proposed and SVR with different kernels and the traditional Cox model are trained. The models are compared based on different performance measures. We also select the best subset of features using three feature selection methods: combination of SVR and statistical tests, univariate feature selection based on concordance index, and recursive feature elimination. The evaluations are performed using available medical datasets and also a Breast Cancer (BC dataset consisting of 573 patients who visited the Oncology Clinic of Hamadan province in Iran. Results show that, for the BC dataset, survival time can be predicted more accurately by linear SVR than nonlinear SVR. Based on the three feature selection methods, metastasis status, progesterone receptor status, and human epidermal growth factor receptor 2 status are the best features associated to survival. Also, according to the obtained results, performance of linear and nonlinear kernels is comparable. The proposed SVR model performs similar to or slightly better than other models. Also, SVR performs similar to or better than Cox when all features are included in model.

  10. Weibull regression with Bayesian variable selection to identify prognostic tumour markers of breast cancer survival.

    Science.gov (United States)

    Newcombe, P J; Raza Ali, H; Blows, F M; Provenzano, E; Pharoah, P D; Caldas, C; Richardson, S

    2017-02-01

    As data-rich medical datasets are becoming routinely collected, there is a growing demand for regression methodology that facilitates variable selection over a large number of predictors. Bayesian variable selection algorithms offer an attractive solution, whereby a sparsity inducing prior allows inclusion of sets of predictors simultaneously, leading to adjusted effect estimates and inference of which covariates are most important. We present a new implementation of Bayesian variable selection, based on a Reversible Jump MCMC algorithm, for survival analysis under the Weibull regression model. A realistic simulation study is presented comparing against an alternative LASSO-based variable selection strategy in datasets of up to 20,000 covariates. Across half the scenarios, our new method achieved identical sensitivity and specificity to the LASSO strategy, and a marginal improvement otherwise. Runtimes were comparable for both approaches, taking approximately a day for 20,000 covariates. Subsequently, we present a real data application in which 119 protein-based markers are explored for association with breast cancer survival in a case cohort of 2287 patients with oestrogen receptor-positive disease. Evidence was found for three independent prognostic tumour markers of survival, one of which is novel. Our new approach demonstrated the best specificity.

  11. SURVIVING SEXUAL ABUSE IN EVERYDAY LIFE: FORMS OF RESISTANCE USED BY CHILDREN AND ADOLESCENTS

    Directory of Open Access Journals (Sweden)

    Margaret Olinda de Souza Carvalho e Lira

    2017-01-01

    Full Text Available Objetivo: aprender formas de resistencia utilizadas por niños y adolescentes en un cotidiano familiar de abuso sexual. Método: investigación cualitativa desarrollada en un Centro de Atendimiento a la Mujer en Situación de Violencia en el Semiárido de Pernambuco, con datos recolectados entre junio y noviembre de 2014, por medio de entrevista con nueve mujeres. El proceso de análisis se fundamentó en nociones de la Sociología Comprensiva y del Cotidiano, con datos organizados por afinidad, interpretados y categorizados. Resultados: emergieron las categorías: ritualización del abuso sexual de niños y adolescentes en el cotidiano familiar: aceptación de la vida por la pasividad; camuflajes para sobrevivir a lo vivido sobre el abuso sexual: silencio, astucia y doble juego, y, entre lo oculto y la revelación del abuso sexual. Puede percibirse que los episodios de abuso ocurrían en secreto y bajo la amenaza de los abusadores a través de gestos o palabras intimidantes. Las víctimas no entraban en confrontación con ellos y para llamar la atención o pedir auxilio usaban artimañas como metáforas, risas y palabras irónicas, además de despistarlos con disculpas, escondiéndose, fingiendo dormir o escapándose para la calle. Conclusión: la centralidad subterránea presente en el abuso sexual desencadenó formas de resistencia en oposición a la opresión generada por el abusador en que, para la aceptación de la vida, las participantes desarrollaron diferentes mecanismos de sobrevivencia, además de encontrar en el trabajo voluntario, música y deporte, los respiraderos para aliviar el peso generado por la ocultación del abuso.

  12. The genomic signature of sexual selection in the genetic diversity of the sex chromosomes and autosomes.

    Science.gov (United States)

    Corl, Ammon; Ellegren, Hans

    2012-07-01

    Genomic levels of variation can help reveal the selective and demographic forces that have affected a species during its history. The relative amount of genetic diversity observed on the sex chromosomes as compared to the autosomes is predicted to differ among monogamous and polygynous species. Many species show departures from the expectation for monogamy, but it can be difficult to conclude that this pattern results from variation in mating system because forces other than sexual selection can act upon sex chromosome genetic diversity. As a critical test of the role of mating system, we compared levels of genetic diversity on the Z chromosome and autosomes of phylogenetically independent pairs of shorebirds that differed in their mating systems. We found general support for sexual selection shaping sex chromosome diversity because most polygynous species showed relatively reduced genetic variation on their Z chromosomes as compared to monogamous species. Differences in levels of genetic diversity between the sex chromosomes and autosomes may therefore contribute to understanding the long-term history of sexual selection experienced by a species. © 2012 The Author(s).

  13. Endocrine disruption of sexual selection by an estrogenic herbicide in the mealworm beetle (Tenebrio molitor).

    Science.gov (United States)

    McCallum, Malcolm L; Matlock, Makensey; Treas, Justin; Safi, Barroq; Sanson, Wendy; McCallum, Jamie L

    2013-12-01

    The role that endocrine disruption could play in sexual selection remains relatively untested, and although estrogens occur in insects, little information exists about their biological role in insect reproduction. Atrazine is a commonly applied herbicide that mimics estrogen in vertebrates. Tenebrio molitor were raised from egg to adult under a gradation of environmentally relevant atrazine exposures and a non-treated control. Atrazine was delivered in the drinking water ad libitum. Female T. molitor were provided with a choice between unrelated males raised under three levels of atrazine exposures. Female preference for males demonstrated a non-monotonic inverted U-shaped response to atrazine exposure. There was no significant difference between the control and the high exposure to atrazine. Excluding the control, female preference increased as exposure concentration increased. These results have important repercussions for nonlethal effects of endocrine disruption on populations, their capacity to interfere with sexual selection, and the role of estrogen in pheromone communication among insects.

  14. Fisher's sons' effect in sexual selection: absent, intermittent or just low experimental power?

    Science.gov (United States)

    Sharma, M D; Wilson, A J; Hosken, D J

    2016-12-01

    The Fisherian sexual selection paradigm has been called the null model of sexual selection. At its heart is the expectation of a genetic correlation (rG ) between female preference and male trait. However, recent meta-analysis has shown estimated correlations are often extremely weak and not statistically significant. We show here that systematic failure of studies to reject the null hypothesis that rG  = 0 is almost certainly due to the low power of most experimental designs used. We provide an easy way to assess experimental power a priori and suggest that current data make it difficult to definitively test a key component of the Fisher effect. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

  15. An Expression of Periodic Phenomena of Fashion on Sexual Selection Model with Conformity Genes and Memes

    Science.gov (United States)

    Mutoh, Atsuko; Tokuhara, Shinya; Kanoh, Masayoshi; Oboshi, Tamon; Kato, Shohei; Itoh, Hidenori

    It is generally thought that living things have trends in their preferences. The mechanism of occurrence of another trends in successive periods is concerned in their conformity. According to social impact theory, the minority is always exists in the group. There is a possibility that the minority make the transition to the majority by conforming agents. Because of agent's promotion of their conform actions, the majority can make the transition. We proposed an evolutionary model with both genes and memes, and elucidated the interaction between genes and memes on sexual selection. In this paper, we propose an agent model for sexual selection imported the concept of conformity. Using this model we try an environment where male agents and female agents are existed, we find that periodic phenomena of fashion are expressed. And we report the influence of conformity and differentiation on the transition of their preferences.

  16. Macroevolutionary patterns of bumblebee body size: detecting the interplay between natural and sexual selection

    Science.gov (United States)

    del Castillo, Raúl Cueva; Fairbairn, Daphne J

    2012-01-01

    Bumblebees and other eusocial bees offer a unique opportunity to analyze the evolution of body size differences between sexes. The workers, being sterile females, are not subject to selection for reproductive function and thus provide a natural control for parsing the effects of selection on reproductive function (i.e., sexual and fecundity selection) from other natural selection. Using a phylogenetic comparative approach, we explored the allometric relationships among queens, males, and workers in 70 species of bumblebees (Bombus sp.). We found hyperallometry in thorax width for males relative to workers, indicating greater evolutionary divergence of body size in males than in sterile females. This is consistent with the hypothesis that selection for reproductive function, most probably sexual selection, has caused divergence in male size among species. The slope for males on workers was significantly steeper than that for queens on workers and the latter did not depart from isometry, providing further evidence of greater evolutionary divergence in male size than female size, and no evidence that reproductive selection has accelerated divergence of females. We did not detect significant hyperallometry when male size was regressed directly on queen size and our results thus add the genus Bombus to the increasing list of clades that have female-larger sexual size dimorphism and do not conform to Rensch's rule when analyzed according to standard methodology. Nevertheless, by using worker size as a common control, we were able to demonstrate that bumblee species do show the evolutionary pattern underlying Rensch's rule, that being correlated evolution of body size in males and females, but with greater evolutionary divergence in males. PMID:22408725

  17. Selective pressures in the human bony pelvis: Decoupling sexual dimorphism in the anterior and posterior spaces.

    Science.gov (United States)

    Brown, Kirsten M

    2015-07-01

    Sexual dimorphism in the human bony pelvis is commonly assumed to be related to the intensity of obstetrical selective pressures. With intense obstetrical selective pressures, there should be greater shape dimorphism; with minimal obstetrical selective pressures, there should be reduced shape dimorphism. This pattern is seen in the nondimorphic anterior spaces and highly dimorphic posterior spaces. Decoupling sexual dimorphism in these spaces may in turn be related to the differential influence of other selective pressures, such as biomechanical ones. The relationship between sexual dimorphism and selective pressures in the human pelvis was examined using five skeletal samples (total female n = 101; male n = 103). Pelvic shape was quantified by collecting landmark coordinate data on articulated pelves. Euclidean distance matrix analysis was used to extract the distances that defined the anterior and posterior pelvic spaces. Sex and body mass were used as proxies for obstetrical and biomechanical selective pressures, respectively. MANCOVA analyses demonstrate significant effects of sex and body mass on distances in both the anterior and the posterior spaces. A comparison of the relative contribution of shape variance attributed to each of these factors suggests that the posterior space is more influenced by sex, and obstetrics by proxy, whereas the anterior space is more influenced by body mass, and biomechanics by proxy. Although the overall shape of the pelvis has been influenced by obstetrical and biomechanical selective pressures, there is a differential response within the pelvis to these factors. These results provide new insight into the ongoing debate on the obstetrical dilemma hypothesis. © 2015 Wiley Periodicals, Inc.

  18. Sexual selection and sex differences in the prevalence of childhood externalizing and adolescent internalizing disorders.

    Science.gov (United States)

    Martel, Michelle M

    2013-11-01

    Despite the well-established sex difference in prevalence of many childhood and adolescent psychopathological conditions, no integrative metatheory of sex differences in psychopathology exists. This review attempts to provide a metatheoretical framework to guide empirical examination of sex differences in prevalence of childhood-onset "externalizing" and adolescent-onset "internalizing" disorders, based on sexual selection evolutionary theory. Sexual selection theory suggests important between-sex differences in markers, mechanisms, etiology, and developmental timing of risk and resilience relevant to psychopathology. Namely, sexual selection theory hypothesizes that disinhibition and sensation-seeking may be important proximate risk markers for childhood-onset externalizing disorders in males. The theory suggests that these male-biased markers may be a product of their higher exposure to prenatal testosterone, which makes them more susceptible to prenatal stressors with downstream effects on dopaminergic neurotransmission, especially for those with genetic alleles associated with lower dopaminergic function. In contrast, sexual selection theory hypothesizes that negative emotionality, empathy, and cognitive rumination may be important proximate risk markers for adolescent-onset internalizing disorders in females. The theory suggests that these markers are propagated by rapidly rising levels of estradiol at puberty that interact with cortisol and oxytocin. These hormones exert downstream effects on the serotonergic system in such a way as to increase females' sensitivity to interpersonal stressors particularly at puberty and especially for those with lower functional serotonergic activity. Such a metatheory can help integrate prior ideas about sex differences and can also generate new predictions of sex differences in markers, etiology, mechanisms, and developmental timing of common forms of psychopathology. © 2013 American Psychological Association

  19. Sex in Murky Waters : Anthropogenic Disturbance of Sexual Selection in Pipefish

    OpenAIRE

    Sundin, Josefin

    2013-01-01

    Animals experience variation in their environment because of natural changes. However, due to anthropogenic disturbance, the speed and severity of these changes have recently increased. This thesis investigates how reproductive behaviours may be affected by human induced environmental change. In specific, I investigate how visual and chemical changes in the aquatic environment, caused by eutrophication, affect mating systems and sexual selection in fish. Broad-nosed- and straight-nosed pipefi...

  20. Coevolution of parental investment and sexually selected traits drives sex-role divergence

    OpenAIRE

    Fromhage, Lutz; Jennions, Michael D.

    2016-01-01

    Sex-role evolution theory attempts to explain the origin and direction of male–female differences. A fundamental question is why anisogamy, the difference in gamete size that defines the sexes, has repeatedly led to large differences in subsequent parental care. Here we construct models to confirm predictions that individuals benefit less from caring when they face stronger sexual selection and/or lower certainty of parentage. However, we overturn the widely cited claim that a ...

  1. Postnatal Sexual Concerns Regarding the Selection of Delivery Mode among Iranian Women: A Qualitative Content Analysis

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    Zahra Abbaspoor

    2016-04-01

    Full Text Available Background & aim: Several factors influence the choice of cesarean section and its increasing rate among pregnant women. It seems that sexual satisfaction after childbirth plays a pivotal role in the selection of delivery mode. This study aimed to describe the experiences of pregnant women regarding postnatal sexual concerns and delivery mode selection. Methods:This conventional qualitative content analysis was based on the study by Graneheim & Lundman (2004. Sample population consisted of 18 pregnant women undergoing natural vaginal delivery (NVD or elective cesarean section (CS at term in three hospitals and two healthcare centers of Tehran, Iran. Data collection and analysis were performed concurrently, and interviews continued until data saturation was achieved. Results: In this study, the main extracted theme was “decision-making influenced by socio-cultural childbirth beliefs.” One of the main categories comprising the content of the interviews was “meeting the sexual satisfaction of spouse" with subcategories of “spouse dissatisfaction after NVD” and “preserved sexual satisfaction after CS.” The other category was "preserving the original shape of genital organs” with subcategories of “necessity of cosmetic surgery after NVD” and “maintaining an intact genital system after CS.” Conclusion: According to the results of this study, sexual attitudes and beliefs in the Iranian society are essentially involved in women's preference of CS over NVD. Choice of CS by pregnant women is often influenced by the opinion of the spouse, family members, peers, and friends. Therefore, it is recommended that the knowledge of couples in this regard be enhanced through related educational programs.

  2. The expression of pre- and postcopulatory sexually selected traits reflects levels of dietary stress in guppies.

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    Md Moshiur Rahman

    Full Text Available Environmental and ecological conditions can shape the evolution of life history traits in many animals. Among such factors, food or nutrition availability can play an important evolutionary role in moderating an animal's life history traits, particularly sexually selected traits. Here, we test whether diet quantity and/or composition in the form of omega-3 long chain polyunsaturated fatty acids (here termed 'n3LC' influence the expression of pre- and postcopulatory traits in the guppy (Poecilia reticulata, a livebearing poeciliid fish. We assigned males haphazardly to one of two experimental diets supplemented with n3LC, and each of these diet treatments was further divided into two diet 'quantity' treatments. Our experimental design therefore explored the main and interacting effects of two factors (n3LC content and diet quantity on the expression of precopulatory (sexual behaviour and sexual ornamentation, including the size, number and spectral properties of colour spots and postcopulatory (the velocity, viability, number and length of sperm sexually selected traits. Our study revealed that diet quantity had significant effects on most of the pre- and postcopulatory traits, while n3LC manipulation had a significant effect on sperm traits and in particular on sperm viability. Our analyses also revealed interacting effects of diet quantity and n3LC levels on courtship displays, and the area of orange and iridescent colour spots in the males' colour patterns. We also confirmed that our dietary manipulations of n3LC resulted in the differential uptake of n3LC in body and testes tissues in the different n3LC groups. This study reveals the effects of diet quantity and n3LC on behavioural, ornamental and ejaculate traits in P. reticulata and underscores the likely role that diet plays in maintaining the high variability in these condition-dependent sexual traits.

  3. Fluctuating environments, sexual selection and the evolution of flexible mate choice in birds.

    Science.gov (United States)

    Botero, Carlos A; Rubenstein, Dustin R

    2012-01-01

    Environmentally-induced fluctuation in the form and strength of natural selection can drive the evolution of morphology, physiology, and behavior. Here we test the idea that fluctuating climatic conditions may also influence the process of sexual selection by inducing unexpected reversals in the relative quality or sexual attractiveness of potential breeding partners. Although this phenomenon, known as 'ecological cross-over', has been documented in a variety of species, it remains unclear the extent to which it has driven the evolution of major interspecific differences in reproductive behavior. We show that after controlling for potentially influential life history and demographic variables, there are significant positive associations between the variability and predictability of annual climatic cycles and the prevalence of infidelity and divorce within populations of a taxonomically diverse array of socially monogamous birds. Our results are consistent with the hypothesis that environmental factors have shaped the evolution of reproductive flexibility and suggest that in the absence of severe time constraints, secondary mate choice behaviors can help prevent, correct, or minimize the negative consequences of ecological cross-overs. Our findings also illustrate how a basic evolutionary process like sexual selection is susceptible to the increasing variability and unpredictability of climatic conditions that is resulting from climate change.

  4. Mechanisms and Evidence of Genital Coevolution: The Roles of Natural Selection, Mate Choice, and Sexual Conflict.

    Science.gov (United States)

    Brennan, Patricia L R; Prum, Richard O

    2015-07-01

    Genital coevolution between the sexes is expected to be common because of the direct interaction between male and female genitalia during copulation. Here we review the diverse mechanisms of genital coevolution that include natural selection, female mate choice, male-male competition, and how their interactions generate sexual conflict that can lead to sexually antagonistic coevolution. Natural selection on genital morphology will result in size coevolution to allow for copulation to be mechanically possible, even as other features of genitalia may reflect the action of other mechanisms of selection. Genital coevolution is explicitly predicted by at least three mechanisms of genital evolution: lock and key to prevent hybridization, female choice, and sexual conflict. Although some good examples exist in support of each of these mechanisms, more data on quantitative female genital variation and studies of functional morphology during copulation are needed to understand more general patterns. A combination of different approaches is required to continue to advance our understanding of genital coevolution. Knowledge of the ecology and behavior of the studied species combined with functional morphology, quantitative morphological tools, experimental manipulation, and experimental evolution have been provided in the best-studied species, all of which are invertebrates. Therefore, attention to vertebrates in any of these areas is badly needed. Copyright © 2015 Cold Spring Harbor Laboratory Press; all rights reserved.

  5. The accumulation of reproductive isolation in early stages of divergence supports a role for sexual selection.

    Science.gov (United States)

    Martin, M D; Mendelson, T C

    2016-04-01

    Models of speciation by sexual selection propose that male-female coevolution leads to the rapid evolution of behavioural reproductive isolation. Here, we compare the strength of behavioural isolation to ecological isolation, gametic incompatibility and hybrid inviability in a group of dichromatic stream fishes. In addition, we examine whether any of these individual barriers, or a combined measure of total isolation, is predicted by body shape differences, male colour differences, environmental differences or genetic distance. Behavioural isolation reaches the highest values of any barrier and is significantly greater than ecological isolation. No individual reproductive barrier is associated with any of the predictor variables. However, marginally significant relationships between male colour and body shape differences with ecological and behavioural isolation are discussed. Differences in male colour and body shape predict total reproductive isolation between species; hierarchical partitioning of these two variables' effects suggests a stronger role for male colour differences. Together, these results suggest an important role for divergent sexual selection in darter speciation but raise new questions about the mechanisms of sexual selection at play and the role of male nuptial ornaments. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology.

  6. Fluctuating environments, sexual selection and the evolution of flexible mate choice in birds.

    Directory of Open Access Journals (Sweden)

    Carlos A Botero

    Full Text Available Environmentally-induced fluctuation in the form and strength of natural selection can drive the evolution of morphology, physiology, and behavior. Here we test the idea that fluctuating climatic conditions may also influence the process of sexual selection by inducing unexpected reversals in the relative quality or sexual attractiveness of potential breeding partners. Although this phenomenon, known as 'ecological cross-over', has been documented in a variety of species, it remains unclear the extent to which it has driven the evolution of major interspecific differences in reproductive behavior. We show that after controlling for potentially influential life history and demographic variables, there are significant positive associations between the variability and predictability of annual climatic cycles and the prevalence of infidelity and divorce within populations of a taxonomically diverse array of socially monogamous birds. Our results are consistent with the hypothesis that environmental factors have shaped the evolution of reproductive flexibility and suggest that in the absence of severe time constraints, secondary mate choice behaviors can help prevent, correct, or minimize the negative consequences of ecological cross-overs. Our findings also illustrate how a basic evolutionary process like sexual selection is susceptible to the increasing variability and unpredictability of climatic conditions that is resulting from climate change.

  7. Sex-biased dispersal, kin selection and the evolution of sexual conflict.

    Science.gov (United States)

    Faria, Gonçalo S; Varela, Susana A M; Gardner, Andy

    2015-10-01

    There is growing interest in resolving the curious disconnect between the fields of kin selection and sexual selection. Rankin's (2011, J. Evol. Biol. 24, 71-81) theoretical study of the impact of kin selection on the evolution of sexual conflict in viscous populations has been particularly valuable in stimulating empirical research in this area. An important goal of that study was to understand the impact of sex-specific rates of dispersal upon the coevolution of male-harm and female-resistance behaviours. But the fitness functions derived in Rankin's study do not flow from his model's assumptions and, in particular, are not consistent with sex-biased dispersal. Here, we develop new fitness functions that do logically flow from the model's assumptions, to determine the impact of sex-specific patterns of dispersal on the evolution of sexual conflict. Although Rankin's study suggested that increasing male dispersal always promotes the evolution of male harm and that increasing female dispersal always inhibits the evolution of male harm, we find that the opposite can also be true, depending upon parameter values. © 2015 The Authors. Journal of Evolutionary Biology published by John Wiley & Sons Ltd on behalf of European Society for Evolutionary Biology.

  8. Sex differences in parental care: Gametic investment, sexual selection, and social environment.

    Science.gov (United States)

    Liker, András; Freckleton, Robert P; Remeš, Vladimir; Székely, Tamás

    2015-11-01

    Male and female parents often provide different type and amount of care to their offspring. Three major drivers have been proposed to explain parental sex roles: (1) differential gametic investment by males and females that precipitates into sex difference in care, (2) different intensity of sexual selection acting on males and females, and (3) biased social environment that facilitates the more common sex to provide more care. Here, we provide the most comprehensive assessment of these hypotheses using detailed parental care data from 792 bird species covering 126 families. We found no evidence for the gametic investment hypothesis: neither gamete sizes nor gamete production by males relative to females was related to sex difference in parental care. However, sexual selection correlated with parental sex roles, because the male share in care relative to female decreased with both extra-pair paternity and frequency of male polygamy. Parental sex roles were also related to social environment, because male parental care increased with male-biased adult sex ratios (ASRs). Taken together, our results are consistent with recent theories suggesting that gametic investment is not tied to parental sex roles, and highlight the importance of both sexual selection and ASR in influencing parental sex roles. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

  9. The evolution of autistic-like and schizotypal traits: A sexual selection hypothesis

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    Marco Del Giudice

    2010-08-01

    Full Text Available In this paper we present a new hypothesis on the evolution of autistic-like and schizotypal personality traits. We argue that autistic-like and schizotypal traits contribute in opposite ways to individual differences in reproductive and mating strategies, and have been maintained – at least in part – by sexual selection through mate choice. Whereas positive schizotypy can be seen as a psychological phenotype oriented to high mating effort and good genes displays in both sexes, autistic-like traits in their non-pathological form contribute to a male-typical strategy geared toward high parental investment, low mating effort, and long-term resource allocation. At the evolutionary-genetic level, this sexual selection hypothesis is consistent with Crespi and Badcock’s “imprinted brain” theory of autism and psychosis; the effect of offspring mating behavior on resource flow within the family connects sexual selection with genomic imprinting in the context of human biparental care. We conclude by presenting the results of an empirical study testing one of the predictions derived from our hypothesis. In a sample of 200 college students, autistic-like traits predicted lower interest in short-term mating, higher partner-specific investment, and stronger commitment to long-term romantic relations, whereas positive schizotypy showed the opposite pattern of effects.

  10. Quantifying episodes of sexual selection: Insights from a transparent worm with fluorescent sperm.

    Science.gov (United States)

    Marie-Orleach, Lucas; Janicke, Tim; Vizoso, Dita B; David, Patrice; Schärer, Lukas

    2016-02-01

    Sexual selection operates through consecutive episodes of selection that ultimately contribute to the observed variance in reproductive success between individuals. Understanding the relative importance of these episodes is challenging, particularly because the relevant postcopulatory fitness components are often difficult to assess. Here, we investigate different episodes of sexual selection on the male sex function, by assessing how (precopulatory) mating success, and (postcopulatory) sperm-transfer efficiency and sperm-fertilizing efficiency contribute to male reproductive success. Specifically, we used a transgenic line of the transparent flatworm, Macrostomum lignano, which expresses green fluorescent protein (GFP) in all cell types, including sperm cells, enabling in vivo sperm tracking and paternity analysis. We found that a large proportion of variance in male reproductive success arose from the postcopulatory episodes. Moreover, we also quantified selection differentials on 10 morphological traits. Testis size and seminal vesicle size showed significant positive selection differentials, which were mainly due to selection on sperm-transfer efficiency. Overall, our results demonstrate that male reproductive success in M. lignano is not primarily limited by the number of matings achieved, but rather by the ability to convert matings into successful fertilizations, which is facilitated by producing many sperm. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

  11. Spatial distribution of nests constrains the strength of sexual selection in a warbler.

    Science.gov (United States)

    Taff, C C; Freeman-Gallant, C R; Dunn, P O; Whittingham, L A

    2013-07-01

    In socially monogamous species, extra-pair paternity may increase the strength of intersexual selection by allowing males with preferred phenotypes to monopolize matings. Several studies have found relationships between male signals and extra-pair mating, but many others fail to explain variation in extra-pair mating success. A greater appreciation for the role that ecological contingencies play in structuring behavioural processes may help to reconcile contradictory results. We studied extra-pair mating in a spatial context in the common yellowthroat (Geothlypis trichas), a territorial wood warbler. Over the course of 6 years, we observed 158 breeding attempts by 99 males, resulting in a total of 369 nests and 520 sampled nestlings. The spatial distribution of territories varied greatly, with males having between 0 and 10 close neighbours and between three and 39 neighbouring nestlings close enough to represent extra-pair siring opportunities. Both within-pair and extra-pair reproductive success increased with breeding density, but the opportunity for sexual selection and strength of selection varied with density. Total variance in reproductive success was highest at low density and was mostly explained by variation in within-pair success. In contrast, at high density, both within-pair and extra-pair successes contributed substantially to variance in reproductive success. The relationships between plumage and extra-pair mating also varied by density; plumage was under strong sexual selection via extra-pair mating success at high density, but no selection was detected at low density. Thus, ecological factors that structure social interactions can drive patterns of sexual selection by facilitating or constraining the expression of mating preferences. © 2013 The Authors. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology.

  12. Condition-dependence, pleiotropy and the handicap principle of sexual selection in melanin-based colouration.

    Science.gov (United States)

    Roulin, Alexandre

    2016-05-01

    The signalling function of melanin-based colouration is debated. Sexual selection theory states that ornaments should be costly to produce, maintain, wear or display to signal quality honestly to potential mates or competitors. An increasing number of studies supports the hypothesis that the degree of melanism covaries with aspects of body condition (e.g. body mass or immunity), which has contributed to change the initial perception that melanin-based colour ornaments entail no costs. Indeed, the expression of many (but not all) melanin-based colour traits is weakly sensitive to the environment but strongly heritable suggesting that these colour traits are relatively cheap to produce and maintain, thus raising the question of how such colour traits could signal quality honestly. Here I review the production, maintenance and wearing/displaying costs that can generate a correlation between melanin-based colouration and body condition, and consider other evolutionary mechanisms that can also lead to covariation between colour and body condition. Because genes controlling melanic traits can affect numerous phenotypic traits, pleiotropy could also explain a linkage between body condition and colouration. Pleiotropy may result in differently coloured individuals signalling different aspects of quality that are maintained by frequency-dependent selection or local adaptation. Colouration may therefore not signal absolute quality to potential mates or competitors (e.g. dark males may not achieve a higher fitness than pale males); otherwise genetic variation would be rapidly depleted by directional selection. As a consequence, selection on heritable melanin-based colouration may not always be directional, but mate choice may be conditional to environmental conditions (i.e. context-dependent sexual selection). Despite the interest of evolutionary biologists in the adaptive value of melanin-based colouration, its actual role in sexual selection is still poorly understood.

  13. Sexual selection and the adaptive evolution of PKDREJ protein in primates and rodents.

    Science.gov (United States)

    Vicens, Alberto; Gómez Montoto, Laura; Couso-Ferrer, Francisco; Sutton, Keith A; Roldan, Eduardo R S

    2015-02-01

    PKDREJ is a testis-specific protein thought to be located on the sperm surface. Functional studies in the mouse revealed that loss of PKDREJ has effects on sperm transport and the ability to undergo an induced acrosome reaction. Thus, PKDREJ has been considered a potential target of post-copulatory sexual selection in the form of sperm competition. Proteins involved in reproductive processes often show accelerated evolution. In many cases, this rapid divergence is promoted by positive selection which may be driven, at least in part, by post-copulatory sexual selection. We analysed the evolution of the PKDREJ protein in primates and rodents and assessed whether PKDREJ divergence is associated with testes mass relative to body mass, which is a reliable proxy of sperm competition levels. Evidence of an association between the evolutionary rate of the PKDREJ gene and testes mass relative to body mass was not found in primates. Among rodents, evidence of positive selection was detected in the Pkdrej gene in the family Cricetidae but not in Muridae. We then assessed whether Pkdrej divergence is associated with episodes of sperm competition in these families. We detected a positive significant correlation between the evolutionary rates of Pkdrej and testes mass relative to body mass in cricetids. These findings constitute the first evidence of post-copulatory sexual selection influencing the evolution of a protein that participates in the mechanisms regulating sperm transport and the acrosome reaction, strongly suggesting that positive selection may act on these fertilization steps, leading to advantages in situations of sperm competition. © The Author 2014. 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.

  14. Long-term paternity skew and the opportunity for selection in a mammal with reversed sexual size dimorphism.

    Science.gov (United States)

    Rossiter, Stephen J; Ransome, Roger D; Faulkes, Christopher G; Dawson, Deborah A; Jones, Gareth

    2006-09-01

    Most mammalian groups are characterized by male-biased sexual size dimorphism, in which size-dependent male-male competition and reproductive skew are tightly linked. By comparison, little is known about the opportunity for sexual selection in mammalian systems without male-biased dimorphism, where the traits under sexual selection might be less obvious. We examined 10 years of parentage data in a colony of greater horseshoe bats (Rhinolophus ferrumequinum) to determine the magnitude of male reproductive skew and the opportunity for sexual selection in a mammal in which females are the larger sex. Annual paternity success was weakly skewed but consistent patterns led to strong longitudinal paternity skew among breeders. Just three males accounted for a third of all paternity assignments, representing at least a fifth of all colony offspring born in a decade. Paternity success was in part determined by age but was not influenced by dispersal status. Our results show that paternity skew and the opportunity for sexual selection in a species with reversed sexual size dimorphism can approach levels reported for classical examples of species with polygyny and male-biased dimorphism, even where the traits under sexual selection are not known.

  15. Rac1 selective activation improves retina ganglion cell survival and regeneration.

    Directory of Open Access Journals (Sweden)

    Erika Lorenzetto

    Full Text Available In adult mammals, after optic nerve injury, retinal ganglion cells (RGCs do not regenerate their axons and most of them die by apoptosis within a few days. Recently, several strategies that activate neuronal intracellular pathways were proposed to prevent such degenerative processes. The rho-related small GTPase Rac1 is part of a complex, still not fully understood, intracellular signaling network, mediating in neurons many effects, including axon growth and cell survival. However, its role in neuronal survival and regeneration in vivo has not yet been properly investigated. To address this point we intravitreally injected selective cell-penetrating Rac1 mutants after optic nerve crush and studied the effect on RGC survival and axonal regeneration. We injected two well-characterized L61 constitutively active Tat-Rac1 fusion protein mutants, in which a second F37A or Y40C mutation confers selectivity in downstream signaling pathways. Results showed that, 15 days after crush, both mutants were able to improve survival and to prevent dendrite degeneration, while the one harboring the F37A mutation also improved axonal regeneration. The treatment with F37A mutant for one month did not improve the axonal elongation respect to 15 days. Furthermore, we found an increase of Pak1 T212 phosphorylation and ERK1/2 expression in RGCs after F37A treatment, whereas ERK1/2 was more activated in glial cells after Y40C administration. Our data suggest that the selective activation of distinct Rac1-dependent pathways could represent a therapeutic strategy to counteract neuronal degenerative processes in the retina.

  16. Survival Outside Home: Sexual Behaviour of Homeless and Runaway Young Adults in Ghana

    Directory of Open Access Journals (Sweden)

    William Wilberforce Amoah

    2014-10-01

    Full Text Available Although homeless young adults are often seen on the streets of Ghana, little research had examined the nature of sexual behaviour among these homeless and runaway young adults. Due to the culturally sensitive nature of such studies in the Ghanaian setting, only fifty (50 respondents agreed to participate in the study. A thirty–five (35 item questionnaire, comprising of twenty-eight (28 closed-ended and seven (7 open-ended questions was used for data collection. The findings indicated poverty, inability of parents to cater for the young adult’s needs, peer pressure and lack of parental acceptance as the main causes of homelessness. Consequently, the findings also showed a trend of school dropout, teenage pregnancy and use of illicit drugs as effects of homelessness. These findings have implications for future studies, policy reform and care for homeless young adult.

  17. Sexual selection on cuticular hydrocarbons of male sagebrush crickets in the wild

    Science.gov (United States)

    Steiger, Sandra; Ower, Geoffrey D.; Stökl, Johannes; Mitchell, Christopher; Hunt, John; Sakaluk, Scott K.

    2013-01-01

    Cuticular hydrocarbons (CHCs) play an essential role in mate recognition in insects but the form and intensity of sexual selection on CHCs has only been evaluated in a handful of studies, and never in a natural population. We quantified sexual selection operating on CHCs in a wild population of sagebrush crickets, a species in which nuptial feeding by females imposes an unambiguous phenotypic marker on males. Multivariate selection analysis revealed a saddle-shaped fitness surface, suggesting a complex interplay between the total abundance of CHCs and specific CHC combinations in their influence on female choice. The fitness surface resulting from two axes of disruptive selection reflected a trade-off between short- and long-chained CHCs, suggesting that males may be sacrificing some level of desiccation resistance in favour of increased attractiveness. There was a significant correlation between male body size and total CHC abundance, suggesting that male CHCs provide females with a reliable cue for maximizing benefits obtained from males. Notwithstanding the conspicuousness of males’ acoustic signals, our results suggest that selection imposed on males via female mating preferences may be far more complex than previously appreciated and operating in multiple sensory modalities. PMID:24197415

  18. Experimental evolution of sperm quality via postcopulatory sexual selection in house mice.

    Science.gov (United States)

    Firman, Renée C; Simmons, Leigh W

    2010-05-01

    Individuals of many species copulate with multiple mates (polygamy). Multiple mating by females (polyandry) promotes sperm competition, which has broad implications for the evolution of the ejaculate. Multigenerational studies of polygamous insects have shown that the removal of sexual selection has profound fitness consequences for females, and can lead to an evolutionary divergence in ejaculate traits. However, the evolutionary implications of polygamous mating across successive generations have not before been demonstrated in a vertebrate. By manipulating the mating system we were able to reinstate postcopulatory sexual selection in a house mouse population that had a long history of enforced monogamy. Following eight generations of selection, we performed sperm quality assays on males from both the polygamous and monogamous selection lines. We applied a principal component analysis to summarize the variation among 12 correlated sperm traits, and found that males evolving under sperm competition had significantly larger scores on the first axis of variation, reflecting greater numbers of epididymal sperm and increased sperm motility, compared to males from lines under relaxed selection. Moreover, we found a correlated response in the size of litters born to females in lines subject to sperm competition. Thus, we present significant evidence that sperm competition has profound fitness consequences for both male and female house mice.

  19. Reproductive ageing and sexual selection on male body size in a wild population of antler flies (Protopiophila litigata)

    National Research Council Canada - National Science Library

    BONDURIANSKY, R; BRASSIL, C. E

    2005-01-01

    Little is known about the importance of trade‐offs between ageing and other life history traits, or the effects of ageing on sexual selection, particularly in wild populations suffering high extrinsic mortality rates...

  20. Survival of ART restorations assessed using selected FDI and modified ART restoration criteria.

    Science.gov (United States)

    Farag, Abeer; van der Sanden, Wil J M; Abdelwahab, Hisran; Frencken, Jo E

    2011-06-01

    A new set of criteria for assessing the quality of restorations using modern restorative materials, named FDI criteria, was recently introduced. This study tested the null hypothesis that there is no significant difference in survival estimate percentages of ART restorations assessed using selected FDI and modified ART criteria after 1 and 5 years. One operator placed a total of 60 class I and 30 Class II high-viscosity glass-ionomer ART restorations in ninety 14- to 15-year-olds. Two calibrated and independent evaluators using both criteria evaluated restorations on diestone replicas at baseline and after 1 and 5 years. Statistical analyses were done using the Kaplan-Meier method and log-rank test. The survival results of ART restorations assessed using both sets of criteria after 1 and 5 years (p = 0.27) did not differ significantly. Three ART restorations were assessed as failures according to the ART criteria, while they were assessed as survived using the FDI criteria. We conclude that the modified ART criteria enable reliable assessment of ART restorations in permanent teeth from diestone replicas and that there was no significant difference in survival estimates of ART restorations assessed using both sets of criteria. The null hypothesis was accepted.

  1. Allometry in damselfly ornamental and genital traits: solving some pitfalls of allometry and sexual selection.

    Science.gov (United States)

    Córdoba-Aguilar, A; López-Valenzuela, A; Brunel, O

    2010-12-01

    Static allometry of sexually selected traits has been the subject of intense research recently. However, some pitfalls for this kind of research are: (a) the functions of sexual traits are largely unknown; (b) more than one body size indicator must be measured; and, (c) allometry must be examined under different environmental circumstances to see whether allometric values change. Using Hetaerina americana damselflies, we investigated the type of allometry exhibited by a wing red spot and aedeagal width. These traits are positively selected during pre-copulatory male-male contests and post-copulatory female stimulation, respectively. As body size indicators, we used wing length and head width. It has been documented that expression of both sexual traits varies throughout the year. Thus, allometry was examined in different times of the year. We also investigated the allometry of aedeagal width and vaginal width at the zone where female stimulation takes place. We found no clear pattern of any allometric relationship for male and female traits and for both body size indicators at all times sampled. Our results contrast with patterns of negative allometry exhibited by genital traits in other animals.

  2. Mating portfolios: bet-hedging, sexual selection and female multiple mating.

    Science.gov (United States)

    Garcia-Gonzalez, Francisco; Yasui, Yukio; Evans, Jonathan P

    2015-01-07

    Polyandry (female multiple mating) has profound evolutionary and ecological implications. Despite considerable work devoted to understanding why females mate multiply, we currently lack convincing empirical evidence to explain the adaptive value of polyandry. Here, we provide a direct test of the controversial idea that bet-hedging functions as a risk-spreading strategy that yields multi-generational fitness benefits to polyandrous females. Unfortunately, testing this hypothesis is far from trivial, and the empirical comparison of the across-generations fitness payoffs of a polyandrous (bet hedger) versus a monandrous (non-bet hedger) strategy has never been accomplished because of numerous experimental constraints presented by most 'model' species. In this study, we take advantage of the extraordinary tractability and versatility of a marine broadcast spawning invertebrate to overcome these challenges. We are able to simulate multi-generational (geometric mean) fitness among individual females assigned simultaneously to a polyandrous and monandrous mating strategy. Our approaches, which separate and account for the effects of sexual selection and pure bet-hedging scenarios, reveal that bet-hedging, in addition to sexual selection, can enhance evolutionary fitness in multiply mated females. In addition to offering a tractable experimental approach for addressing bet-hedging theory, our study provides key insights into the evolutionary ecology of sexual interactions. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  3. Best lung function equations for the very elderly selected by survival analysis

    DEFF Research Database (Denmark)

    Miller, Martin R; Thinggaard, Mikael; Christensen, Kaare

    2014-01-01

    proportional hazard regression found lower FEV1SR was a predictor of mortality having controlled for MMSE, grip strength and sex. The US National Health and Nutrition Examination Survey (NHANES) III (1999) equations gave a better spread of median survival by FEV1SR quartile: 3.94, 3.65, 3.51 and 2.61 years...... with a hazard ratio for death of 1, 1.16, 1.32 and 1.60 respectively, compared with equations derived with the inclusion of elderly subjects.We conclude that extrapolating from NHANES III equations to predict lung function in nonagenarians gave better survival predictions from spirometry than when employing...... equations derived using very elderly subjects with possible selection bias. These findings can help inform how future lung function equations for the elderly are derived....

  4. Disruption of adult expression of sexually selected traits by developmental exposure to bisphenol A.

    Science.gov (United States)

    Jašarević, Eldin; Sieli, Paizlee T; Twellman, Erin E; Welsh, Thomas H; Schachtman, Todd R; Roberts, R Michael; Geary, David C; Rosenfeld, Cheryl S

    2011-07-12

    Exposure to endocrine disrupting compounds (EDCs), such as bisphenol A (BPA), may cause adverse health effects in wildlife and humans, but controversy remains as to what traits are most sensitive to EDCs and might serve as barometers of exposure. Expression of sexually selected traits that have evolved through intrasexual competition for mates and intersexual choice of mating partner are more dependent on developmental and physical condition of an animal than naturally selected traits and thus might be particularly vulnerable to disruption by developmental exposure to EDCs. We have used the deer mouse (Peromyscus maniculatus) as a model to test this hypothesis. Adult male-male competition for mates in this species is supported by enhanced spatial navigational and exploratory abilities, which enable males to search for prospective, widely dispersed females. Male deer mice exposed to BPA or ethinyl estradiol (EE) through maternal diet showed no changes in external phenotype, sensory development, or adult circulating concentrations of testosterone and corticosterone, but spatial learning abilities and exploratory behaviors were severely compromised compared with control males. Because these traits are not sexually selected in females, BPA exposure predictably had no effect, although EE-exposed females demonstrated enhanced spatial navigational abilities. Both BPA-exposed and control females preferred control males to BPA-exposed males. Our demonstration that developmental exposure to BPA compromises cognitive abilities and behaviors essential for males to reproduce successfully has broad implications for other species, including our own. Thus, sexually selected traits might provide useful biomarkers to assess risk of environmental contamination in animal and human populations.

  5. Time-Dependent Tree-Structured Survival Analysis with Unbiased Variable Selection through Permutation Tests

    Science.gov (United States)

    Wallace, M. L.

    2014-01-01

    Incorporating time-dependent covariates into tree-structured survival analysis (TSSA) may result in more accurate prognostic models than if only baseline values are used. Available time-dependent TSSA methods exhaustively test every binary split on every covariate; however, this approach may result in selection bias towards covariates with more observed values. We present a method that uses unbiased significance levels from newly proposed permutation tests to select the time-dependent or baseline covariate with the strongest relationship with the survival outcome. The specific splitting value is identified using only the selected covariate. Simulation results show that the proposed time-dependent TSSA method produces tree models of equal or greater accuracy as compared to baseline TSSA models, even with high censoring rates and large within-subject variability in the time-dependent covariate. To illustrate, the proposed method is applied to data from a cohort of bipolar youth to identify subgroups at risk for self-injurious behavior. PMID:25043382

  6. Positive genetic correlation between brain size and sexual traits in male guppies artificially selected for brain size.

    Science.gov (United States)

    Kotrschal, A; Corral-Lopez, A; Zajitschek, S; Immler, S; Maklakov, A A; Kolm, N

    2015-04-01

    Brain size is an energetically costly trait to develop and maintain. Investments into other costly aspects of an organism's biology may therefore place important constraints on brain size evolution. Sexual traits are often costly and could therefore be traded off against neural investment. However, brain size may itself be under sexual selection through mate choice on cognitive ability. Here, we use guppy (Poecilia reticulata) lines selected for large and small brain size relative to body size to investigate the relationship between brain size, a large suite of male primary and secondary sexual traits, and body condition index. We found no evidence for trade-offs between brain size and sexual traits. Instead, larger-brained males had higher expression of several primary and precopulatory sexual traits--they had longer genitalia, were more colourful and developed longer tails than smaller-brained males. Larger-brained males were also in better body condition when housed in single-sex groups. There was no difference in post-copulatory sexual traits between males from the large- and small-brained lines. Our data do not support the hypothesis that investment into sexual traits is an important limiting factor to brain size evolution, but instead suggest that brain size and several sexual traits are positively genetically correlated. © 2015 The Authors. Journal of Evolutionary Biology published by John Wiley & Sons Ltd on behalf of European Society for Evolutionary Biology.

  7. Runaway sexual selection without genetic correlations: social environments and flexible mate choice initiate and enhance the Fisher process.

    Science.gov (United States)

    Bailey, Nathan W; Moore, Allen J

    2012-09-01

    Female mating preferences are often flexible, reflecting the social environment in which they are expressed. Associated indirect genetic effects (IGEs) can affect the rate and direction of evolutionary change, but sexual selection models do not capture these dynamics. We incorporate IGEs into quantitative genetic models to explore how variation in social environments and mate choice flexibility influence Fisherian sexual selection. The importance of IGEs is that runaway sexual selection can occur in the absence of a genetic correlation between male traits and female preferences. Social influences can facilitate the initiation of the runaway process and increase the rate of trait elaboration. Incorporating costs to choice do not alter the main findings. Our model provides testable predictions: (1) genetic covariances between male traits and female preferences may not exist, (2) social flexibility in female choice will be common in populations experiencing strong sexual selection, (3) variation in social environments should be associated with rapid sexual trait divergence, and (4) secondary sexual traits will be more elaborate than previously predicted. Allowing feedback from the social environment resolves discrepancies between theoretical predictions and empirical data, such as why indirect selection on female preferences, theoretically weak, might be sufficient for preferences to become elaborated. © 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.

  8. Coevolution of parental investment and sexually selected traits drives sex-role divergence.

    Science.gov (United States)

    Fromhage, Lutz; Jennions, Michael D

    2016-08-18

    Sex-role evolution theory attempts to explain the origin and direction of male-female differences. A fundamental question is why anisogamy, the difference in gamete size that defines the sexes, has repeatedly led to large differences in subsequent parental care. Here we construct models to confirm predictions that individuals benefit less from caring when they face stronger sexual selection and/or lower certainty of parentage. However, we overturn the widely cited claim that a negative feedback between the operational sex ratio and the opportunity cost of care selects for egalitarian sex roles. We further argue that our model does not predict any effect of the adult sex ratio (ASR) that is independent of the source of ASR variation. Finally, to increase realism and unify earlier models, we allow for coevolution between parental investment and investment in sexually selected traits. Our model confirms that small initial differences in parental investment tend to increase due to positive evolutionary feedback, formally supporting long-standing, but unsubstantiated, verbal arguments.

  9. Survival of the fittest clone: Pro-apoptotic protein Noxa controls selection of lymphocytes under competitive conditions

    NARCIS (Netherlands)

    Wensveen, F.M.

    2010-01-01

    Darwinistic selection, or ‘survival of the fittest’, is based on intrinsic capacity, relative to that of its competitors in a given niche. This process drives the generation of species by allowing survival of organisms in with favorable, specialized characteristics for a certain niche. However, mere

  10. Facial attractiveness, sexual selection, and personnel selection : when evolved preferences matter

    NARCIS (Netherlands)

    Luxen, MF; Van de Vijver, FJR

    Using an evolutionary perspective, we looked at sex differences in the influence of facial attractiveness of applicants in hiring decisions, and determined whether expected contact intensity with applicants and experience in personnel selection moderated this influence. We found effects of evolved

  11. An introduction to genetic quality in the context of sexual selection.

    Science.gov (United States)

    Pitcher, Trevor E; Mays, Herman L

    2008-09-01

    This special issue of Genetica brings together empirical researchers and theoreticians to present the latest on the evolutionary ecology of genetic quality in the context of sexual selection. The work comes from different fields of study including behavioral ecology, quantitative genetics and molecular genetics on a diversity of organisms using different approaches from comparative studies, mathematical modeling, field studies and laboratory experiments. The papers presented in this special issue primarily focus on genetic quality in relation to (1) sources of genetic variation, (2) polyandry, (3) new theoretical developments and (4) comprehensive reviews.

  12. Temperature and biological soil effects on the survival of selected foodborne pathogens on a mortar surface.

    Science.gov (United States)

    Allan, J T; Yan, Z; Genzlinger, L L; Kornacki, J L

    2004-12-01

    The survival of three foodborne pathogens (Listeria monocytogenes, Yersinia enterocolitica, and Salmonella) attached to mortar surfaces, with or without biological soil (porcine serum) and incubated at either 4 or 10 degrees C in the presence of condensate, was evaluated. Soiled and unsoiled coupons were inoculated by immersion into a five-strain cocktail (approximately 10(7) CFU/ml) of each organism type and evaluated. Coupons were incubated at 25 degrees C for 2 h to allow attachment of cells, rinsed to remove unattached cells, and incubated at either 4 or 10 degrees C at high humidity to create condensate on the surface. Sonication was used to remove the attached cells, and bacteria (CFU per coupon) was determined at 9 to 10 sampling periods over 120 h. Yersinia populations decreased more than 5 log units in the presence of serum in a 24-h period. Listeria and Salmonella had better survival on mortar in the presence of serum than Yersinia throughout the 120-h incubation period. Populations of L. monocytogenes declined more rapidly at 10 than at 4 degree C after 24 h. In general, differences in temperature did not affect the survival of Salmonella or Yersinia. Serum had a protective effect on the survival of all three organisms, sustaining populations at significantly (P 0.05) among the mean number (CFU per coupon) of L. monocytogenes, Y. enterocolitica, or Salmonella on initial attachment onto the mortar surfaces (unsoiled). The results indicate relatively rapid destruction of selected pathogenic bacteria on unsoiled mortar surfaces compared with those that contained biological soil, thus highlighting the need for effective cleaning to reduce harborage of these microbes in the food factory environment.

  13. Bimodal Signaling of a Sexually Selected Trait: Gular Pouch Drumming in the Magnificent Frigatebird

    DEFF Research Database (Denmark)

    Madsen, V.; Balsby, T. J. S.; Dabelsteen, Torben

    2004-01-01

    courtship display, Fregata magnificens, Magnificent Frigatebird, secondary sexual trait, visual and acoustic signaling......courtship display, Fregata magnificens, Magnificent Frigatebird, secondary sexual trait, visual and acoustic signaling...

  14. Effect of encapsulation of selected probiotic cell on survival in simulated gastrointestinal tract condition

    Directory of Open Access Journals (Sweden)

    Hasiah Ayama

    2014-06-01

    Full Text Available The health benefits of probiotic bacteria have been led to their increasing use in foods. Encapsulation has been investigated to improve their survival. In this study, the selection, encapsulation and viability of lactic acid bacteria (LAB with probiotic properties in simulated gastrointestinal tract (GIT condition were investigated. One hundred and fifty isolates of LAB were obtained from 30 samples of raw cow and goat milk and some fermented foods. Nine isolates could survive under GIT condition and only 3 isolates exhibited an antimicrobial activity against all food-borne pathogenic bacteria. Among them, 2 isolates (CM21 and CM53 exhibited bile salt hydrolase activity on glycocholate and glycodeoxycholate agar plates and were identified as Lactobacillus plantarum. CM53 was selected for encapsulation using 1-3% alginate and 2% Hi-maize resistant starch by emulsion system. Viability and releasing ability of encapsulated CM53 in simulated GIT condition was increased in accordance to the alginate concentration and incubation time, respectively.

  15. Targeting Ras-Driven Cancer Cell Survival and Invasion through Selective Inhibition of DOCK1

    Directory of Open Access Journals (Sweden)

    Hirotada Tajiri

    2017-05-01

    Full Text Available Oncogenic Ras plays a key role in cancer initiation but also contributes to malignant phenotypes by stimulating nutrient uptake and promoting invasive migration. Because these latter cellular responses require Rac-mediated remodeling of the actin cytoskeleton, we hypothesized that molecules involved in Rac activation may be valuable targets for cancer therapy. We report that genetic inactivation of the Rac-specific guanine nucleotide exchange factor DOCK1 ablates both macropinocytosis-dependent nutrient uptake and cellular invasion in Ras-transformed cells. By screening chemical libraries, we have identified 1-(2-(3′-(trifluoromethyl-[1,1′-biphenyl]-4-yl-2-oxoethyl-5-pyrrolidinylsulfonyl-2(1H-pyridone (TBOPP as a selective inhibitor of DOCK1. TBOPP dampened DOCK1-mediated invasion, macropinocytosis, and survival under the condition of glutamine deprivation without impairing the biological functions of the closely related DOCK2 and DOCK5 proteins. Furthermore, TBOPP treatment suppressed cancer metastasis and growth in vivo in mice. Our results demonstrate that selective pharmacological inhibition of DOCK1 could be a therapeutic approach to target cancer cell survival and invasion.

  16. Coping and Survival Skills: The Role School Personnel Play Regarding Support for Bullied Sexual Minority-Oriented Youth

    Science.gov (United States)

    Marshall, Alexandra; Yarber, William L.; Sherwood-Laughlin, Catherine M.; Gray, Mary L.; Estell, David B.

    2015-01-01

    Background: Research has shown that bullying has serious health consequences, and sexual minority-oriented youth are disproportionately affected. Sexual minority-oriented youth include lesbian, gay, bisexual, transgender, queer, or questioning (LGBTQ) individuals. This study examined the bullying experiences of sexual minority-oriented youth in a…

  17. When are sexual difficulties distressing for women? The selective protective value of intimate relationships.

    Science.gov (United States)

    Stephenson, Kyle R; Meston, Cindy M

    2010-11-01

    Recent studies have shown that sexual functioning and sexually related personal distress are weakly related in women, with only a minority of sexual difficulties resulting in significant levels of distress. However, there has been little systematic research to date on which factors moderate the relationship between sexual functioning and sexual distress. To assess the degree to which relational intimacy and attachment anxiety moderate the association between sexual functioning and sexual distress in college-age women. Two hundred women (mean age=20.25) completed surveys assessing sexual functioning, relational intimacy, attachment anxiety, and sexual distress. Participants completed the Sexual Satisfaction Scale for Women, the Female Sexual Function Index, the Dimensions of Relationship Quality Scale, and the Revised Experiences in Close Relationships Measure of Adult Romantic Attachment. Relational intimacy and attachment anxiety moderated the association between multiple aspects of sexual functioning and sexual distress. For lubrication and sexual pain, functioning was more strongly associated with distress in low-intimacy vs. high-intimacy relationships, but only for women with high levels of attachment anxiety. Results regarding desire were mixed and neither intimacy nor attachment anxiety interacted with subjective arousal or orgasm in predicting distress. Both relational intimacy and attachment anxiety are important moderators of the association between sexual functioning and subjective sexual distress in women. Theoretical and practical implications are discussed. © 2010 International Society for Sexual Medicine.

  18. Crowd control: sex ratio affects sexually selected cuticular hydrocarbons in male Drosophila serrata.

    Science.gov (United States)

    Gershman, S N; Rundle, H D

    2017-03-01

    Although it is advantageous for males to express costly sexually selected signals when females are present, they may also benefit from suppressing these signals to avoid costly interactions with rival males. Cuticular chemical profiles frequently function as insect sexual signals; however, few studies have asked whether males alter these signals in response to their social environment. In Drosophila serrata, an Australian fly, there is sexual selection for a multivariate combination of male cuticular hydrocarbons (CHCs). Here, we show that the ratio of females to males that an adult male experiences has a strong effect on his CHC expression, with female-biased adult sex ratios eliciting greater expression of CHC profiles associated with higher male mating success. Classical models predict that male reproductive investment should be highest when there is a small but nonzero number of rivals, but we found that males expressed the most attractive combination of CHCs when there were no rivals. We found that male CHCs were highly sensitive to adult sex ratio, with males expressing higher values of CHC profiles associated with greater mating success as the ratio of females to males increased. Moreover, sex ratio has a stronger effect on male CHC expression than adult density. Finally, we explore whether sex ratio affects the variance among a group of males in their CHC expression, as might be expected if individuals respond differently to a given social environment, but find little effect. Our results reveal that subtle differences in social environment can induce plasticity in male chemical signal expression. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

  19. Relationship between number of sexual intercourse partners and selected health risk behaviors among public high school adolescents.

    Science.gov (United States)

    Valois, R F; Oeltmann, J E; Waller, J; Hussey, J R

    1999-11-01

    To examine the relationship between number of sexual partners and selected health risk behaviors in a statewide sample of public high school students. The Centers for Disease Control and Prevention Youth Risk Behavior Survey was used to secure usable sexual risk-taking, substance use, and violence/aggression data from 3805 respondents. Because simple polychotomous logistic regression analysis revealed a significant Race x Gender interaction, subsequent multivariate models were constructed separately for each race-gender group. Odds ratios and 95% confidence intervals was calculated from polychotomous logistic regression models for number of sexual intercourse partners and their potential risk behavior correlates. An increased number of sexual intercourse partners were correlated with a cluster of risk behaviors that place adolescents at risk for unintended pregnancy, human immunodeficiency virus/acquired immunodeficiency syndrome, and other sexually transmitted infections. For Black females, alcohol, tobacco, marijuana use, and dating violence behaviors were the strongest predictors of an increased number of sexual partners; white females had similar predictors with the addition of physical fighting. For white males, alcohol, tobacco, marijuana use, physical fighting, carrying weapons, and dating violence were the strongest predictors of an increased number of sexual intercourse partners. Black males had similar predictors with the addition of binge alcohol use. Prevention of adolescent sexual and other health risk behaviors calls for creative approaches in school and community settings and will require long-term intervention strategies focused on adolescent behavior changes and environmental modifications.

  20. A Review and Treatment Selection Model for Individuals with Developmental Disabilities Who Engage in Inappropriate Sexual Behavior.

    Science.gov (United States)

    Davis, Tonya N; Machalicek, Wendy; Scalzo, Rachel; Kobylecky, Alicia; Campbell, Vincent; Pinkelman, Sarah; Chan, Jeffrey Michael; Sigafoos, Jeff

    2016-12-01

    Some individuals with developmental disabilities develop inappropriate sexual behaviors such as public masturbation, disrobing, and touching others in an unwanted sexual manner. Such acts are problematic given the taboo nature of the behaviors and the potential for significant negative consequences, such as restricted community access, injury, and legal ramifications. Therefore, it is necessary to equip caregivers and practitioners with effective treatment options. The purpose of this paper is to review studies that have evaluated behavioral treatments to reduce inappropriate sexual behavior in persons with developmental disabilities. The strengths and weaknesses of each treatment are reviewed, and a model for treatment selection is provided.

  1. Can sexual selection theory inform genetic management of captive populations? A review

    Science.gov (United States)

    Chargé, Rémi; Teplitsky, Céline; Sorci, Gabriele; Low, Matthew

    2014-01-01

    Captive breeding for conservation purposes presents a serious practical challenge because several conflicting genetic processes (i.e., inbreeding depression, random genetic drift and genetic adaptation to captivity) need to be managed in concert to maximize captive population persistence and reintroduction success probability. Because current genetic management is often only partly successful in achieving these goals, it has been suggested that management insights may be found in sexual selection theory (in particular, female mate choice). We review the theoretical and empirical literature and consider how female mate choice might influence captive breeding in the context of current genetic guidelines for different sexual selection theories (i.e., direct benefits, good genes, compatible genes, sexy sons). We show that while mate choice shows promise as a tool in captive breeding under certain conditions, for most species, there is currently too little theoretical and empirical evidence to provide any clear guidelines that would guarantee positive fitness outcomes and avoid conflicts with other genetic goals. The application of female mate choice to captive breeding is in its infancy and requires a goal-oriented framework based on the needs of captive species management, so researchers can make honest assessments of the costs and benefits of such an approach, using simulations, model species and captive animal data. PMID:25553072

  2. Postmating sexual selection and the enigmatic jawed genitalia of Callosobruchus subinnotatus

    Directory of Open Access Journals (Sweden)

    Merel M. Van Haren

    2017-07-01

    Full Text Available Insect genitalia exhibit rapid divergent evolution. Truly extraordinary structures have evolved in some groups, presumably as a result of postmating sexual selection. To increase our understanding of this phenomenon, we studied the function of one such structure. The male genitalia of Callosobruchus subinnotatus (Coleoptera: Bruchinae contain a pair of jaw-like structures with unknown function. Here, we used phenotypic engineering to ablate the teeth on these jaws. We then experimentally assessed the effects of ablation of the genital jaws on mating duration, ejaculate weight, male fertilization success and female fecundity, using a double-mating experimental design. We predicted that copulatory wounding in females should be positively related to male fertilization success; however, we found no significant correlation between genital tract scarring in females and male fertilization success. Male fertilization success was, however, positively related to the amount of ejaculate transferred by males and negatively related to female ejaculate dumping. Ablation of male genital jaws did not affect male relative fertilization success but resulted in a reduction in female egg production. Our results suggest that postmating sexual selection in males indeed favors these genital jaws, not primarily through an elevated relative success in sperm competition but by increasing female egg production.

  3. Sex-specific effects of natural and sexual selection on the evolution of life span and ageing in Drosophila simulans

    NARCIS (Netherlands)

    Archer, C.R.; Duffy, E.; Hosken, D.J.; Mokkonen, M.; Okada, K.; Oku, K.; Sharma, M.D.; Hunt, J.

    2015-01-01

    1. Variation in the strength of age-dependent natural selection shapes differences in ageing rates across species and populations. Likewise, sexual selection can promote divergent patterns of senescence across the sexes. However, the effects of these processes on the evolution of ageing have largely

  4. Experimental selection for Drosophila survival in extremely low O(2 environment.

    Directory of Open Access Journals (Sweden)

    Dan Zhou

    2007-05-01

    Full Text Available Cellular hypoxia, if severe enough, results usually in injury or cell death. Our research in this area has focused on the molecular mechanisms underlying hypoxic tissue injury to explore strategies to prevent injury or enhance tolerance. The current experiments were designed to determine the genetic basis for adaptation to long term low O(2 environments.With long term experimental selection over many generations, we obtained a Drosophila melanogaster strain that can live perpetually in extremely low, normally lethal, O(2 condition (as low as 4% O(2. This strain shows a dramatic phenotypic divergence from controls, including a decreased recovery time from anoxic stupor, a higher rate of O(2 consumption in hypoxic conditions, and a decreased body size and mass due to decreased cell number and size. Expression arrays showed that about 4% of the Drosophila genome altered in expression and about half of the alteration was down-regulation. The contribution of some altered transcripts to hypoxia tolerance was examined by testing the survival of available corresponding P-element insertions (and their excisions under extremely low O(2 conditions. We found that down-regulation of several candidate genes including Best1, broad, CG7102, dunce, lin19-like and sec6 conferred severe hypoxia tolerance in Drosophila.We have identified a number of genes that play an important role in the survival of a selected Drosophila strain in extremely low O(2 conditions, selected by decreasing O(2 availability over many generations. Because of conservation of pathways, we believe that such genes are critical in hypoxia adaptation in physiological or pathological conditions not only in Drosophila but also in mammals.

  5. Sexual selection by female immunity against paternal antigens can fix loss of function alleles.

    Science.gov (United States)

    Ghaderi, Darius; Springer, Stevan A; Ma, Fang; Cohen, Miriam; Secrest, Patrick; Taylor, Rachel E; Varki, Ajit; Gagneux, Pascal

    2011-10-25

    Humans lack the common mammalian cell surface molecule N-glycolylneuraminic acid (Neu5Gc) due to a CMAH gene inactivation, which occurred approximately three million years ago. Modern humans produce antibodies specific for Neu5Gc. We hypothesized that anti-Neu5Gc antibodies could enter the female reproductive tract and target Neu5Gc-positive sperm or fetal tissues, reducing reproductive compatibility. Indeed, female mice with a human-like Cmah(-/-) mutation and immunized to express anti-Neu5Gc antibodies show lower fertility with Neu5Gc-positive males, due to prezygotic incompatibilities. Human anti-Neu5Gc antibodies are also capable of targeting paternally derived antigens and mediate cytotoxicity against Neu5Gc-bearing chimpanzee sperm in vitro. Models of populations polymorphic for such antigens show that reproductive incompatibility by female immunity can drive loss-of-function alleles to fixation from moderate initial frequencies. Initially, the loss of a cell-surface antigen can occur due to drift in isolated populations or when natural selection favors the loss of a receptor exploited by pathogens, subsequently the same loss-of-function allele can come under sexual selection because it avoids being targeted by the female immune system. Thus, we provide evidence of a link between sexual selection and immune function: Antigenicity in females can select against foreign paternal antigens on sperm and rapidly fix loss-of-function alleles. Similar circumstances existed when the CMAH null allele was polymorphic in ancestral hominins, just before the divergence of Homo from australopithecines.

  6. Whole-genome resequencing uncovers molecular signatures of natural and sexual selection in wild bighorn sheep.

    Science.gov (United States)

    Kardos, Marty; Luikart, Gordon; Bunch, Rowan; Dewey, Sarah; Edwards, William; McWilliam, Sean; Stephenson, John; Allendorf, Fred W; Hogg, John T; Kijas, James

    2015-11-01

    The identification of genes influencing fitness is central to our understanding of the genetic basis of adaptation and how it shapes phenotypic variation in wild populations. Here, we used whole-genome resequencing of wild Rocky Mountain bighorn sheep (Ovis canadensis) to >50-fold coverage to identify 2.8 million single nucleotide polymorphisms (SNPs) and genomic regions bearing signatures of directional selection (i.e. selective sweeps). A comparison of SNP diversity between the X chromosome and the autosomes indicated that bighorn males had a dramatically reduced long-term effective population size compared to females. This probably reflects a long history of intense sexual selection mediated by male-male competition for mates. Selective sweep scans based on heterozygosity and nucleotide diversity revealed evidence for a selective sweep shared across multiple populations at RXFP2, a gene that strongly affects horn size in domestic ungulates. The massive horns carried by bighorn rams appear to have evolved in part via strong positive selection at RXFP2. We identified evidence for selection within individual populations at genes affecting early body growth and cellular response to hypoxia; however, these must be interpreted more cautiously as genetic drift is strong within local populations and may have caused false positives. These results represent a rare example of strong genomic signatures of selection identified at genes with known function in wild populations of a nonmodel species. Our results also showcase the value of reference genome assemblies from agricultural or model species for studies of the genomic basis of adaptation in closely related wild taxa. © 2015 John Wiley & Sons Ltd.

  7. Clinical impact of selective and nonselective beta-blockers on survival in patients with ovarian cancer.

    Science.gov (United States)

    Watkins, Jack L; Thaker, Premal H; Nick, Alpa M; Ramondetta, Lois M; Kumar, Sanjeev; Urbauer, Diana L; Matsuo, Koji; Squires, Kathryn C; Coleman, Robert L; Lutgendorf, Susan K; Ramirez, Pedro T; Sood, Anil K

    2015-10-01

    Preclinical evidence has suggested that sustained adrenergic activation can promote ovarian cancer growth and metastasis. The authors examined the impact of beta-adrenergic blockade on the clinical outcome of women with epithelial ovarian, primary peritoneal, or fallopian tube cancers (collectively, epithelial ovarian cancer [EOC]). A multicenter review of 1425 women with histopathologically confirmed EOC was performed. Comparisons were made between patients with documented beta-blocker use during chemotherapy and those without beta-blocker use. The median age of patients in the current study was 63 years (range, 21-93 years). The sample included 269 patients who received beta-blockers. Of those, 193 (71.7%) were receiving beta-1-adrenergic receptor selective agents, and the remaining patients were receiving nonselective beta antagonists. The primary indication for beta-blocker use was hypertension but also included arrhythmia and postmyocardial infarction management. For patients receiving any beta-blocker, the median overall survival (OS) was 47.8 months versus 42 months for nonusers (P =.04). The median OS based on beta-blocker receptor selectivity was 94.9 months for those receiving nonselective beta-blockers versus 38 months for those receiving beta-1-adrenergic receptor selective agents (Pbeta-blocker compared with nonusers (38.2 months vs 90 months; Pbeta-blockers in patients with EOC was associated with longer OS. These findings may have implications for new therapeutic approaches. Cancer 2015;121:3435-43. © 2015 American Cancer Society. © 2015 American Cancer Society.

  8. p38α negatively regulates survival and malignant selection of transformed bronchioalveolar stem cells.

    Directory of Open Access Journals (Sweden)

    Edwige Voisset

    Full Text Available Lung cancer is the cause of most cancer-related deaths in the Western world. Non-small cell lung cancer accounts for almost 80% of all lung cancers, and 50% of this type are adenocarcinomas. The cellular and molecular origin of this type of lung cancer remains elusive and the mechanisms are poorly known. It is known that K-Ras mutations appear in 25-30% of lung adenocarcinomas and it is the best known single mutation that can be related to lung cancers. Recently, it has been suggested that a putative population of mouse bronchioalveolar stem cells could be considered as the cell of origin of adenocarcinomas. These cells are expanded in the early stages of lung tumorigenesis. We have isolated a population of mouse bronchioalveolar stem cells and induced their transformation by oncogenic K-RasG12. Different approaches have shown that an intracellular network linking the p38α MAPK and the PI3K-Pdk1 pathways is involved in regulating the survival and malignant progression of the transformed cells. Absence of p38α catalytic activity leads to further Pdk1 activation (independent of Akt and Erk activity, enhancing the survival and proliferation of the more malignant lung cancer cells. This specifically selects high Sca-1/Sox9 cells that harbour a stronger colonizing potential, as they maintain their capacity to produce secondary tumors after serial transplantations.

  9. Does students' exposure to gender discrimination and sexual harassment in medical school affect specialty choice and residency program selection?

    Science.gov (United States)

    Stratton, Terry D; McLaughlin, Margaret A; Witte, Florence M; Fosson, Sue E; Nora, Lois Margaret

    2005-04-01

    To examine the role of gender discrimination and sexual harassment in medical students' choice of specialty and residency program. Anonymous, self-administered questionnaires were distributed in 1997 to fourth-year students enrolled in 14 public and private U.S. medical schools. In addition to reporting the frequency of gender discrimination and sexual harassment encountered during preclinical coursework, core clerkships, elective clerkships, and residency selection, students assessed the impact of these exposures (none, a little, some, quite a bit, the deciding factor) on their specialty choices and rankings of residency programs. A total of 1,314 (69%) useable questionnaires were returned. Large percentages of men (83.2%) and women (92.8%) experienced, observed, or heard about at least one incident of gender discrimination and sexual harassment during medical school, although more women reported such behavior across all training contexts. Compared with men, significantly (p sexual harassment influenced their specialty choices (45.3% versus 16.4%) and residency rankings (25.3% versus 10.9%). Across all specialties, more women than men experienced gender discrimination and sexual harassment during residency selection, with one exception: a larger percentage of men choosing obstetrics and gynecology experienced such behavior. Among women, those choosing general surgery were most likely to experience gender discrimination and sexual harassment during residency selection. Interestingly, correlations between exposure to gender discrimination and sexual harassment and self-assessed impact on career decisions tended to be larger for men, suggesting that although fewer men are generally affected, they may weigh such experiences more heavily in their choice of specialty and residency program. This study suggests that exposure to gender discrimination and sexual harassment during undergraduate education may influence some medical students' choice of specialty and, to a

  10. Structure of social networks in a passerine bird: consequences for sexual selection and the evolution of mating strategies.

    Science.gov (United States)

    Oh, Kevin P; Badyaev, Alexander V

    2010-09-01

    The social environment is a critical determinant of fitness and, in many taxa, is shaped by an individual's behavioral discrimination among social contexts, suggesting that animals can actively influence the selection they experience. In competition to attract females, males may modify sexual selection by choosing social environments in which they are more attractive relative to rivals. Across the population, such behaviors should influence sexual selection patterns by altering the relationship between male mating success and sexual ornament elaboration. Here we use network analysis to examine patterns of male social behavior in relation to plumage ornamentation and mating success in a free-living population of house finches. During the nonbreeding season, less elaborate males changed associations with distinct social groups more frequently, compared to more elaborate males that showed greater fidelity to a single social group. By the onset of pair formation, socially labile males effectively increased their attractiveness relative to other males in the same flocks. Consequently, males that frequently moved between social groups had greater pairing success than less social individuals with equivalent sexual ornamentation. We discuss these results in relation to conditional mating tactics and the role of social behavior in evolutionary change by sexual selection.

  11. Exploring the Evolution of Music and Language: Social versus Sexual Selection. Evidence from an Emotional Priming Study

    OpenAIRE

    Kiker, Alexander James

    2012-01-01

    Connections between language and music have been made for over a century, and their origins are thought to be closely linked, but the selection mechanisms of the first precursors to music and language are still largely unknown, and it is debated whether they would have been either sexually or socially selected for. The present study presents the results of an emotional priming experiment in an attempt to shed light on the selection mechanisms which would have been at work on the evolution of ...

  12. Environmentally realistic exposure to the herbicide atrazine alters some sexually selected traits in male guppies.

    Directory of Open Access Journals (Sweden)

    Kausalya Shenoy

    Full Text Available Male mating signals, including ornaments and courtship displays, and other sexually selected traits, like male-male aggression, are largely controlled by sex hormones. Environmental pollutants, notably endocrine disrupting compounds, can interfere with the proper functioning of hormones, thereby impacting the expression of hormonally regulated traits. Atrazine, one of the most widely used herbicides, can alter sex hormone levels in exposed animals. I tested the effects of environmentally relevant atrazine exposures on mating signals and behaviors in male guppies, a sexually dimorphic freshwater fish. Prolonged atrazine exposure reduced the expression of two honest signals: the area of orange spots (ornaments and the number of courtship displays performed. Atrazine exposure also reduced aggression towards competing males in the context of mate competition. In the wild, exposure levels vary among individuals because of differential distribution of the pollutants across habitats; hence, differently impacted males often compete for the same mates. Disrupted mating signals can reduce reproductive success as females avoid mating with perceptibly suboptimal males. Less aggressive males are at a competitive disadvantage and lose access to females. This study highlights the effects of atrazine on ecologically relevant mating signals and behaviors in exposed wildlife. Altered reproductive traits have important implications for population dynamics, evolutionary patterns, and conservation of wildlife species.

  13. Childhood sexual abuse, selective attention for sexual cues and the effects of testosterone with or without Vardenafil on physiological sexual arousal in women with sexual dysfunction: a pilot study

    NARCIS (Netherlands)

    van der Made, F.; Bloemers, J.; van Ham, D.; El Yassem, W.; Kleiverda, G.; Everaerd, W.; Olivier, B.; Tuiten, A.

    2009-01-01

    INTRODUCTION: Female sexual dysfunction (FSD) may be associated with reduced central sensitivity for sexual cues. A single dose of testosterone might induce an increase in sensitivity for sexual stimuli, which in turn allows a PDE5 inhibitor to be effective in boosting the physiological sexual

  14. SEXUAL SELECTION. Irrationality in mate choice revealed by túngara frogs.

    Science.gov (United States)

    Lea, Amanda M; Ryan, Michael J

    2015-08-28

    Mate choice models derive from traditional microeconomic decision theory and assume that individuals maximize their Darwinian fitness by making economically rational decisions. Rational choices exhibit regularity, whereby the relative strength of preferences between options remains stable when additional options are presented. We tested female frogs with three simulated males who differed in relative call attractiveness and call rate. In binary choice tests, females' preferences favored stimulus caller B over caller A; however, with the addition of an inferior "decoy" C, females reversed their preferences and chose A over B. These results show that the relative valuation of mates is not independent of inferior alternatives in the choice set and therefore cannot be explained with the rational choice models currently used in sexual selection theory. Copyright © 2015, American Association for the Advancement of Science.

  15. Low fertilization rates in a pelagic copepod caused by sexual selection?

    DEFF Research Database (Denmark)

    Ceballos, Sara; Sichlau, Mie Hylstofte; Heuschele, Jan

    2014-01-01

    We studied female fertilization status in North Sea summer populations and laboratory cultures of the marine copepod Temora longicornis and found fractions of fertilized females in both field and laboratory populations that were much smaller (... random mating. Such low fertilization rates are normally related to environmental factors such as poor food or low densities, which we could not confirm in our experiment. Male density was negatively related to fertilization rate, and a large fraction of males did not mate in laboratory incubations. We...... therefore suggest that sexual selection, through mate choice or male–male competition could account for low fertilization rates of females in populations of pelagic copepods during some periods of the year...

  16. Attractive Skin Coloration: Harnessing Sexual Selection to Improve Diet and Health

    Directory of Open Access Journals (Sweden)

    Ross D. Whitehead

    2012-12-01

    Full Text Available In this paper we review the mechanisms through which carotenoid coloration could provide a sexually selected cue to condition in species with elaborate color vision. Skin carotenoid pigmentation induced by fruit and vegetable consumption may provide a similar cue to health in humans (particularly light-skinned Asians and Caucasians. Evidence demonstrates that carotenoid-based skin coloration enhances apparent health, and that dietary change can perceptibly impact skin color within weeks. We find that the skin coloration associated with increased fruit and vegetable consumption benefits apparent health to a greater extent than melanin pigmentation. We argue that the benefits to appearance may motivate individuals to improve their diet and that this line of appearance research reveals a potentially powerful strategy for motivating a healthy lifestyle.

  17. Target inhibition networks: predicting selective combinations of druggable targets to block cancer survival pathways.

    Directory of Open Access Journals (Sweden)

    Jing Tang

    Full Text Available A recent trend in drug development is to identify drug combinations or multi-target agents that effectively modify multiple nodes of disease-associated networks. Such polypharmacological effects may reduce the risk of emerging drug resistance by means of attacking the disease networks through synergistic and synthetic lethal interactions. However, due to the exponentially increasing number of potential drug and target combinations, systematic approaches are needed for prioritizing the most potent multi-target alternatives on a global network level. We took a functional systems pharmacology approach toward the identification of selective target combinations for specific cancer cells by combining large-scale screening data on drug treatment efficacies and drug-target binding affinities. Our model-based prediction approach, named TIMMA, takes advantage of the polypharmacological effects of drugs and infers combinatorial drug efficacies through system-level target inhibition networks. Case studies in MCF-7 and MDA-MB-231 breast cancer and BxPC-3 pancreatic cancer cells demonstrated how the target inhibition modeling allows systematic exploration of functional interactions between drugs and their targets to maximally inhibit multiple survival pathways in a given cancer type. The TIMMA prediction results were experimentally validated by means of systematic siRNA-mediated silencing of the selected targets and their pairwise combinations, showing increased ability to identify not only such druggable kinase targets that are essential for cancer survival either individually or in combination, but also synergistic interactions indicative of non-additive drug efficacies. These system-level analyses were enabled by a novel model construction method utilizing maximization and minimization rules, as well as a model selection algorithm based on sequential forward floating search. Compared with an existing computational solution, TIMMA showed both enhanced

  18. [Sexual and contraceptive behavior of teenagers and young adults. Selected results of the BZgA study "Youth Sexuality 2010"].

    Science.gov (United States)

    Heßling, A; Bode, H

    2013-02-01

    The BZgA study "Youth Sexuality 2010" clarifies the changes that have occurred in the sexual and contraceptive behavior of teenagers and young adults over the last 30 years. Among young Germans, there is now more gender similarity regarding both the age at which intercourse first takes place and contraceptive behavior. The proportion of German teenagers who take no contraceptive precautions when they have intercourse for the first time is now 8%, a lower figure than ever previously recorded. Communication about contraception, both at home and between the partners, is making a substantial contribution to responsible contraceptive behavior on the part of teenagers and young adults. Alongside education about sexuality in the family and at school, there are also structural influences on the positive developments witnessed in Germany. And yet there are still target groups that are inadequately reached. Many migrants are less well informed about bodily processes, their contraceptive practice is not as good, and their religious background tends to exclude them from access to information. Disabled teenagers and young adults constitute a target group about which to date we have insufficient knowledge. Education and social deprivation continue to be important factors in the differences seen in sexual and contraceptive behavior. In this area, proactive efforts are necessary.

  19. Evolution of the structure of tail feathers: implications for the theory of sexual selection.

    Science.gov (United States)

    Aparicio, José Miguel; Bonal, Raúl; Cordero, Pedro J

    2003-02-01

    Bird tails are extraordinarily variable in length and functionality. In some species, males have evolved exaggeratedly long tails as a result of sexual selection. Changes in tail length should be associated with changes in feather structure. The study of the evolution of feather structure in bird tails could give insight to understand the causes and means of evolution in relation to processes of sexual selection. In theory, three possible means of tail length evolution in relation to structural components might be expected: (1) a positive relationship between the increase in length and size of structural components maintaining the mechanical properties of the feather; (2) no relationship; that is, enlarging feather length without changes in the structural components; and (3) a negative relationship; that is, enlarging feather length by reducing structural components. These hypotheses were tested using phylogenetic analyses to examine changes in both degree of exaggeration in tail length and structural characteristics of tail feathers (rachis width and density of barbs) in 36 species, including those dimorphic and nondimorphic in tail length. The degree of sexual dimorphism in tail length was negatively correlated with both rachis width and density of barbs in males but not in females. Reinforcing this result, we found that dimorphism in tail length was negatively associated with dimorphism in tail feather structure (rachis width and density of barbs). These results support the third hypothesis, in which the evolution of long feathers occurs at the expense of making them simpler and therefore less costly to produce. However, we do not know the effects of enfeeblement on the costs of bearing. If the total costs increased, the enfeeblement of feathers could be explained as a reinforcement of the honesty of the signal. Alternatively, if total costs were reduced, the strategy could be explained by cheating processes. The study of female preferences for fragile tail

  20. A lover or a fighter? Opposing sexual selection pressures on men's vocal pitch and facial hair.

    Science.gov (United States)

    Saxton, Tamsin K; Mackey, Lauren L; McCarty, Kristofor; Neave, Nick

    2016-01-01

    The traditional assumption within the research literature on human sexually dimorphic traits has been that many sex differences have arisen from intersexual selection. More recently, however, there has been a shift toward the idea that many male features, including male lower-pitched voices and male beard growth, might have arisen predominantly through intrasexual selection: that is, to serve the purpose of male-male competition instead of mate attraction. In this study, using a unique set of video stimuli, we measured people's perceptions of the dominance and attractiveness of men who differ both in terms of voice pitch (4 levels from lower to higher pitched) and beard growth (4 levels from clean shaven to a month's hair growth). We found a nonlinear relationship between lower pitch and increased attractiveness; men's vocal attractiveness peaked at around 96 Hz. Beard growth had equivocal effects on attractiveness judgments. In contrast, perceptions of men's dominance simply increased with increasing masculinity (i.e., with lower-pitched voices and greater beard growth). Together, these results suggest that the optimal level of physical masculinity might differ depending on whether the outcome is social dominance or mate attraction. These dual selection pressures might maintain some of the documented variability in male physical and behavioral masculinity that we see today.

  1. Transformation of sexually transmitted infection-causing serovars of chlamydia trachomatis using Blasticidin for selection.

    Directory of Open Access Journals (Sweden)

    Honglei Ding

    Full Text Available Plasmid-free Chlamydia trachomatis serovar L2 organisms have been transformed with chlamydial plasmid-based shuttle vectors pGFP::SW2 and pBRCT using β-lactamase as a selectable marker. However, the recommendation of amoxicillin, a β-lactam antibiotics, as one of the choices for treating pregnant women with cervicitis due to C. trachomatis infection has made the existing shuttle vectors unsuitable for transforming sexually transmitted infection (STI-causing serovars of C. trachomatis. Thus, in the current study, we modified the pGFP::SW2 plasmid by fusing a blasticidin S deaminase gene to the GFP gene to establish blasticidin resistance as a selectable marker and replacing the β-lactamase gene with the Sh ble gene to eliminate the penicillin resistance. The new vector termed pGFPBSD/Z::SW2 was used for transforming plasmid-free C. trachomatis serovar D organisms. Using blasticidin for selection, stable transformants were obtained. The GFP-BSD fusion protein was detected in cultures infected with the pGFPBSD/Z::SW2-trasnformed serovar D organisms. The transformation restored the plasmid property to the plasmid-free serovar D organisms. Thus, we have successfully modified the pGFP::SW2 transformation system for studying the biology and pathogenesis of other STI-causing serovars of C. trachomatis.

  2. Effects of basal area on survival and growth of longleaf pine when practicing selection silviculture

    Energy Technology Data Exchange (ETDEWEB)

    Kara, F.; Loewenstein, E.F.; Brockway, D.G.

    2017-11-01

    Aim of study: Uneven-aged (UEA) management systems can achieve multiple-use objectives, however, use of UEA techniques to manage longleaf pine (Pinus palustris Mill.) forests are still open to question, because of the species’ intolerance of competition. It was our aim to examine the influence of different levels (9.2, 13.8 and 18.4 m2 ha-1) of residual basal area (RBA) on longleaf pine seedling survival and growth following three growing seasons. Area of study: This study was conducted at the Escambia Experimental Forest, located on the Southern Coastal Plain of Alabama, in the southeastern United States. Material and Methods: Selection silviculture was implemented with the Proportional-Basal Area (Pro-B) method. Prescribed burning was conducted before seed dispersal and in the second year after germination. Photosynthetically active radiation (PAR) was measured under the canopy in the study plots. Survival and growth of longleaf pine seedlings were observed for three growing seasons. Main results: An inverse relationship was found between the number of germinants and RBA, but the mortality of germinants and planted seedlings was not affected by RBA. At age three, an inverse relationship was observed between root-collar diameter (RCD) growth of the germinants and RBA, but RCD growth of planted seedlings was not affected by RBA. Most of the study plots contained more than the projected number of seedlings needed to sustain the target diameter structure. Research highlights: Long-term continuous monitoring of seedling development and recruitment into canopy is required to determine the efficacy of UEA management. However, current data suggest that UEA methods may be a viable alternative to the use of even-aged (EA) methods in longleaf ecosystems.

  3. The adverse effect of selective cyclooxygenase-2 inhibitor on random skin flap survival in rats.

    Directory of Open Access Journals (Sweden)

    Haiyong Ren

    Full Text Available BACKGROUND: Cyclooxygenase-2(COX-2 inhibitors provide desired analgesic effects after injury or surgery, but evidences suggested they also attenuate wound healing. The study is to investigate the effect of COX-2 inhibitor on random skin flap survival. METHODS: The McFarlane flap model was established in 40 rats and evaluated within two groups, each group gave the same volume of Parecoxib and saline injection for 7 days. The necrotic area of the flap was measured, the specimens of the flap were stained with haematoxylin-eosin(HE for histologic analysis. Immunohistochemical staining was performed to analyse the level of VEGF and COX-2 . RESULTS: 7 days after operation, the flap necrotic area ratio in study group (66.65 ± 2.81% was significantly enlarged than that of the control group(48.81 ± 2.33%(P <0.01. Histological analysis demonstrated angiogenesis with mean vessel density per mm(2 being lower in study group (15.4 ± 4.4 than in control group (27.2 ± 4.1 (P <0.05. To evaluate the expression of COX-2 and VEGF protein in the intermediate area II in the two groups by immunohistochemistry test .The expression of COX-2 in study group was (1022.45 ± 153.1, and in control group was (2638.05 ± 132.2 (P <0.01. The expression of VEGF in the study and control groups were (2779.45 ± 472.0 vs (4938.05 ± 123.6(P <0.01.In the COX-2 inhibitor group, the expressions of COX-2 and VEGF protein were remarkably down-regulated as compared with the control group. CONCLUSION: Selective COX-2 inhibitor had adverse effect on random skin flap survival. Suppression of neovascularization induced by low level of VEGF was supposed to be the biological mechanism.

  4. Selected Coordination Motor Abilities of Students of the University of Physical Education During Survival Training

    Directory of Open Access Journals (Sweden)

    Tomczak Andrzej

    2017-06-01

    Full Text Available Introduction. Taking up emergency actions when fighting various types of natural disasters requires appropriate psychophysical preparation. Thanks to the development of technique, coordination motor abilities have gained greater importance than physical strength and endurance in such activities. The purpose of the present work was to assess the impact of 36 hours of survival activities and sleep deprivation on selected coordination motor abilities in students of the University of Physical Education. Material and methods. The study involved 12 male students of the University of Physical Education in Warsaw, specialising in “Physical Education in Uniformed Services”. The age of the participants was 21.0 ± 0.74 years, their body height was 179.5 ± 5.6 cm, and their body mass was 74.6 ± 8.0 kg. The assessment was performed based on the following coordination motor ability tests: a test measuring the differentiation of the use of forearm muscle strength, a running motor adjustment test, and a measurement of divided attention. A test involving shooting from a pneumatic gun and a measurement of the maximal force of the forearm were also carried out. Tests and trials were conducted before training (P1, after 24 hours of training (P2, after completing the training - that is after 36 hours of training (P3, and after 12 hours of rest (P4. During the training, the participants completed 12 km on foot, paddled for approximately 6 hours, rowed kayaks for about 4 hours, and performed survival tasks. Results. The analysis of the results of the study of maximal force and the ability to differentiate forearm muscle strength showed that the forearm muscle strength remained at the same level during the entire training. The ability to differentiate forearm muscle strength deteriorated after night training. There were no statistically significant differences in the results of the running motor adjustment tests and in shooting performance between individual

  5. Can sexual selection and disassortative mating contribute to the maintenance of a shell color polymorphism in an intertidal marine snail?

    Directory of Open Access Journals (Sweden)

    E. ROLÁN-ALVAREZ, M.SAURA, A. P. DIZ, M. J. RIVAS, M. ALVAREZ, B. Cortés, A. de COO, D. ESTÉVEZ, L. IGLESIAS

    2012-06-01

    Full Text Available Littorina fabalis is an intertidal snail commonly living on the brown algae Fucus vesiculosus and showing frequent shell-color polymorphisms in the wild. The evolutionary mechanism underlying this polymorphism is currently unknown. Shell color variation was studied in mated and non-mated specimens of this species from different microareas in one locality from NW Spain, in order to estimate sexual selection and assortative mating that may (still be operating in this population. The analyses across microareas allowed us to investigate frequency-dependent selection and assortative mating components, mechanisms that could maintain the polymorphism. The presence of shell scars caused by crab attacks, an environmental variable not related with sexual selection or assortative mating, was used as experimental control. This study provides new evidence of significant disassortative mating and some degree of sexual selection against some shell colors, supporting the results found 21 years ago in a similar study, i.e. in the same species and locality. The similarity of these estimates during the studied period suggests that this experimental approach is consistent and valid to be extended to other populations and organisms. In addition, sexual selection and assortative mating estimates did not change across microareas differing in shell color frequencies, suggesting than the polymorphism can not be maintained by a frequency-dependent (sexual selection-based mechanism. Our main hypothesis is that negative assortative mating could contribute to the maintenance of the polymorphism, perhaps by males showing distinct female color preferences when searching for mates [Current Zoology 58 (3: 460–471, 2012].

  6. Intra-sexual selection in cooperative mammals and birds: why are females not bigger and better armed?

    Science.gov (United States)

    Young, Andrew J; Bennett, Nigel C

    2013-01-01

    In cooperatively breeding mammals and birds, intra-sexual reproductive competition among females may often render variance in reproductive success higher among females than males, leading to the prediction that intra-sexual selection in such species may have yielded the differential exaggeration of competitive traits among females. However, evidence to date suggests that female-biased reproductive variance in such species is rarely accompanied by female-biased sexual dimorphisms. We illustrate the problem with data from wild Damaraland mole-rat, Fukomys damarensis, societies: the variance in lifetime reproductive success among females appears to be higher than that among males, yet males grow faster, are much heavier as adults and sport larger skulls and incisors (the weapons used for fighting) for their body lengths than females, suggesting that intra-sexual selection has nevertheless acted more strongly on the competitive traits of males. We then consider potentially general mechanisms that could explain these disparities by tempering the relative intensity of selection for competitive trait exaggeration among females in cooperative breeders. Key among these may be interactions with kin selection that could nevertheless render the variance in inclusive fitness lower among females than males, and fundamental aspects of the reproductive biology of females that may leave reproductive conflict among females more readily resolved without overt physical contests.

  7. Testing the prediction from sexual selection of a positive genetic correlation between human mate preferences and corresponding traits

    NARCIS (Netherlands)

    Verweij, C.J.H.; Burri, A.V.; Zietsch, B.P.

    2014-01-01

    Sexual selection can cause evolution in traits that affect mating success, and it has thus been implicated in the evolution of human physical and behavioural traits that influence attractiveness. We use a large sample of identical and nonidentical female twins to test the prediction from mate choice

  8. Brain size evolution in pipefishes and seahorses: the role of feeding ecology, life history and sexual selection.

    Science.gov (United States)

    Tsuboi, M; Lim, A C O; Ooi, B L; Yip, M Y; Chong, V C; Ahnesjö, I; Kolm, N

    2017-01-01

    Brain size varies greatly at all taxonomic levels. Feeding ecology, life history and sexual selection have been proposed as key components in generating contemporary diversity in brain size across vertebrates. Analyses of brain size evolution have, however, been limited to lineages where males predominantly compete for mating and females choose mates. Here, we present the first original data set of brain sizes in pipefishes and seahorses (Syngnathidae) a group in which intense female mating competition occurs in many species. After controlling for the effect of shared ancestry and overall body size, brain size was positively correlated with relative snout length. Moreover, we found that females, on average, had 4.3% heavier brains than males and that polyandrous species demonstrated more pronounced (11.7%) female-biased brain size dimorphism. Our results suggest that adaptations for feeding on mobile prey items and sexual selection in females are important factors in brain size evolution of pipefishes and seahorses. Most importantly, our study supports the idea that sexual selection plays a major role in brain size evolution, regardless of on which sex sexual selection acts stronger. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

  9. The role of multilevel selection in the evolution of sexual conflict in the water strider aquarius remigis.

    Science.gov (United States)

    Eldakar, Omar Tonsi; Wilson, David Sloan; Dlugos, Michael J; Pepper, John W

    2010-11-01

    In evolution, exploitative strategies often create a paradox in which the most successful individual strategy "within" the group is also the most detrimental strategy "for" the group, potentially resulting in extinction. With regard to sexual conflict, the overexploitation of females by harmful males can yield similar consequences. Despite these evolutionary implications, little research has addressed why sexual conflict does not ultimately drive populations to extinction. One possibility is that groups experiencing less sexual conflict are more productive than groups with greater conflict. However, most studies of sexual conflict are conducted in a single isolated group, disregarding the potential for selection among groups. We observed Aquarius remigis water striders in a naturalistic multigroup pool in which individuals could freely disperse among groups. The free movement of individuals generated variation in aggression and sex-ratio among groups, thereby increasing the importance of between-group selection compared to within-group selection. Females dispersed away from local aggression, creating more favorable mating environments for less-aggressive males. Furthermore, the use of contextual analysis revealed that individual male aggression positively predicted fitness whereas aggression at the group level negatively predicted fitness, empirically demonstrating the conflict between levels of selection acting on mating aggression. © 2010 The Author(s). Evolution© 2010 The Society for the Study of Evolution.

  10. Population genetics of sexual conflict in the genomic era.

    Science.gov (United States)

    Mank, Judith E

    2017-12-01

    Sexual conflict occurs when selection acts in opposing directions on males and females. Case studies in both vertebrates and invertebrates indicate that sexual conflict maintains genetic diversity through balancing selection, which might explain why many populations show more genetic variation than expected. Recent population genomic approaches based on different measures of balancing selection have suggested that sexual conflict can arise over survival, not just reproductive fitness as previously thought. A fuller understanding of sexual conflict will provide insight into its contribution to adaptive evolution and will reveal the constraints it might impose on populations.

  11. Postcopulatory sexual selection results in spermatozoa with more uniform head and flagellum sizes in rodents.

    Directory of Open Access Journals (Sweden)

    María Varea-Sánchez

    Full Text Available Interspecific comparative studies have shown that, in most taxa, postcopulatory sexual selection (PCSS in the form of sperm competition drives the evolution of longer and faster swimming sperm. Work on passserine birds has revealed that PCSS also reduces variation in sperm size between males at the intraspecific level. However, the influence of PCSS upon intra-male sperm size diversity is poorly understood, since the few studies carried out to date in birds have yielded contradictory results. In mammals, PCSS increases sperm size but there is little information on the effects of this selective force on variations in sperm size and shape. Here, we test whether sperm competition associates with a reduction in the degree of variation of sperm dimensions in rodents. We found that as sperm competition levels increase males produce sperm that are more similar in both the size of the head and the size of the flagellum. On the other hand, whereas with increasing levels of sperm competition there is less variation in head length in relation to head width (ratio CV head length/CV head width, there is no relation between variation in head and flagellum sizes (ratio CV head length/CV flagellum length. Thus, it appears that, in addition to a selection for longer sperm, sperm competition may select more uniform sperm heads and flagella, which together may enhance swimming velocity. Overall, sperm competition seems to drive sperm components towards an optimum design that may affect sperm performance which, in turn, will be crucial for successful fertilization.

  12. A lover or a fighter? Opposing sexual selection pressures on men?s vocal pitch and facial hair

    OpenAIRE

    Saxton, Tamsin; Mackey, Lauren; McCarty, Kristofor; Neave, Nick

    2015-01-01

    The traditional assumption within the research literature on human sexually dimorphic traits has been that many sex differences have arisen from intersexual selection. More recently however, there has been a shift towards the idea that many male features, including for example male lower-pitched voices, and male beard growth, might have arisen predominantly through intrasexual selection: that is, to serve the purpose of male-male competition instead of mate attraction. In this study, using a ...

  13. Intermittent hypoxia selects for genotypes and phenotypes that increase survival, invasion, and therapy resistance.

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    Daniel Verduzco

    Full Text Available Hypoxia in tumors correlates with greater risk of metastases, increased invasiveness, and resistance to systemic and radiation therapy. The evolutionary dynamics that links specific adaptations to hypoxia with these observed tumor properties have not been well investigated. While some tumor populations may experience fixed hypoxia, cyclical and stochastic transitions from normoxia to hypoxia are commonly observed in vivo. Although some phenotypic adaptations to this cyclic hypoxia are likely reversible, we hypothesize that some adaptations may become fixed through mutations promoted by hypoxia-induced genomic instability. Here we seek to identify genetic alterations and corresponding stable phenotypes that emerge following cyclic hypoxia. Although these changes may originate as adaptations to this specific environmental stress, their fixation in the tumor genome may result in their observation in tumors from regions of normoxia, a condition known as pseudohypoxia. We exposed several epithelial cell lines to 50 cycles of hypoxia-normoxia, followed by culture in normoxia over a period of several months. Molecular analyses demonstrated permanent changes in expression of several oncogenes and tumor-suppressors, including p53, E-cadherin, and Hif-1α. These changes were associated with increased resistance to multiple cytotoxins, increased survival in hypoxia and increased anchorage-independent growth. These results suggest cycles of hypoxia encountered in early cancers can select for specific and stable genotypic and phenotypic properties that persist even in normoxic conditions, which may promote tumor progression and resistance to therapy.

  14. Phenology of scramble polygyny in a wild population of chrysomelid beetles: the opportunity for and the strength of sexual selection [corrected].

    Science.gov (United States)

    Baena, Martha Lucía; Macías-Ordóñez, Rogelio

    2012-01-01

    Recent debate has highlighted the importance of estimating both the strength of sexual selection on phenotypic traits, and the opportunity for sexual selection. We describe seasonal fluctuations in mating dynamics of Leptinotarsa undecimlineata (Coleoptera: Chrysomelidae). We compared several estimates of the opportunity for, and the strength of, sexual selection and male precopulatory competition over the reproductive season. First, using a null model, we suggest that the ratio between observed values of the opportunity for sexual selections and their expected value under random mating results in unbiased estimates of the actual nonrandom mating behavior of the population. Second, we found that estimates for the whole reproductive season often misrepresent the actual value at any given time period. Third, mating differentials on male size and mobility, frequency of male fighting and three estimates of the opportunity for sexual selection provide contrasting but complementary information. More intense sexual selection associated to male mobility, but not to male size, was observed in periods with high opportunity for sexual selection and high frequency of male fights. Fourth, based on parameters of spatial and temporal aggregation of female receptivity, we describe the mating system of L. undecimlineata as a scramble mating polygyny in which the opportunity for sexual selection varies widely throughout the season, but the strength of sexual selection on male size remains fairly weak, while male mobility inversely covaries with mating success. We suggest that different estimates for the opportunity for, and intensity of, sexual selection should be applied in order to discriminate how different behavioral and demographic factors shape the reproductive dynamic of populations.

  15. Fluorescent sperm in a transparent worm: validation of a GFP marker to study sexual selection.

    Science.gov (United States)

    Marie-Orleach, Lucas; Janicke, Tim; Vizoso, Dita B; Eichmann, Micha; Schärer, Lukas

    2014-06-30

    Sexual selection has initially been thought to occur exclusively at the precopulatory stage in terms of contests among males and female mate choice, but research over the last four decades revealed that it often continues after copulation through sperm competition and cryptic female choice. However, studying these postcopulatory processes remains challenging because they occur internally and therefore are often difficult to observe. In the transparent free-living flatworm Macrostomum lignano, a recently established transgenic line that expresses green fluorescent protein (GFP) in all cell types, including sperm, offers a unique opportunity to non-invasively visualise and quantify the sperm of a GFP-expressing donor inside the reproductive tract of wild-type recipients in vivo. We here test several aspects of the reproductive performance of the transgenic individuals and the accuracy of the techniques involved in assessing the GFP-expressing worms and their sperm. We then show the usefulness of these methods in a study on sperm displacement. GFP-expressing worms do not differ from wild-type worms in terms of morphology, mating rate and reproductive success. In addition, we show that the GFP signal is reliably and unequivocally expressed by all GFP-expressing individuals observed under epifluorescence illumination. However, the intensity of the GFP signal emitted by sperm of GFP expressing donors can vary (which we show to be at least in part due to sperm ageing) and the GFP marker is inherited according to Mendel's laws in most, but not all, of the individuals. Nevertheless, we argue these two issues can be addressed with an appropriate experimental design. Finally, we demonstrate the value of the GFP-techniques by comparing the number of GFP-expressing sperm in a wild-type recipient before and after mating with a competing sperm donor, providing clear experimental evidence for sperm displacement in M. lignano. This result suggests that sperm donors can displace

  16. Mortality selection among adults in Brazil: The survival advantage of Air Force officers

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    Vanessa di Lego

    2017-10-01

    Full Text Available Background: The impact of extreme conditions on survival has been the focus of mortality studies using military data. However, in countries at peace, the military live in favorable conditions, being positively selected with respect to health. In this type of context, military data may help to improve our understanding of mortality differentials, particularly in countries where defective vital systems are still cumbersome for mortality studies. Methods: We estimate death rates for Brazilian Air Force (BAF officers through Poisson regression models, compute life expectancies, and compare them with those of average Brazilians and people in low-mortality countries. We also examine causes of death and mortality differentials through a competing risks framework and Fine and Gray regression models. Results: BAF life expectancy is higher than that of the average Brazilian and comparable to Sweden, France, and Japan in 2000. Younger pilots have a higher risk of dying on duty when compared with other officers but experience lower mortality rates from other causes at advanced ages. Conclusions: BAF officers are a population subgroup in Brazil with a life expectancy comparable to the one in advanced societies. There is no association between mortality and place of birth, which indicates that different childhood backgrounds did not affect BAF mortality differentials later in life. Contribution: This paper takes a novel approach focusing on a specific subgroup with lower mortality rates than the general population and good-quality longitudinal information available, a rarity in developing countries. We argue that this approach can be an interesting strategy to study mortality differentials in developing countries.

  17. Sepsis-induced selective loss of NMDA receptors modulates hippocampal neuropathology in surviving septic mice.

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    Shuibing Zhang

    Full Text Available Sepsis-induced neuroinflammation plays an important role in sepsis-related brain dysfunction. However, the molecules that are targeted during neuroinflammation resulting from sepsis-induced brain dysfunction remain unclear. Herein, we tried to investigate the expression and roles of NMDA receptor subunits during sepsis-related brain dysfunction.Sepsis was induced by cecal ligation and perforation (CLP or by a single intraperitoneal injection of lipopolysaccharide (LPS, 8 mg/kg in C57BL/6J mice. The NMDA receptor co-agonist D-serine was injected intraperitoneally for 3 days (500 mg/kg/day to compensate for the loss of NMDA receptors. The behaviors of mice were tested in the Barnes maze and in the open field test. The mice were euthanized at the indicated time points. The brains were collected to detect the following: the levels of synaptophysin and NMDA receptor subunits GluN2A, GluN2B and GluN1 (by Western blot and RT-PCR; the number of CA1 neurons (by Nissl staining; neuronal activity (by p-CREB staining; neuroinflammation (by staining of Iba-1 and inflammatory factors IL-1β, TNF-α, NLRP3; and the levels of oxidative stress [by dihydroethidium (DHE].Sepsis selectively decreased the protein and mRNA levels of GluN2A, GluN2B and GluN1 but not the levels of synaptophysin or the neuronal number in the hippocampus of mice in either of the classic CLP-induced or LPS-induced sepsis models during the first 7 days after sepsis. Intraperitoneal injection of D-serine obviously limited the lipopolysaccharide-induced changes, including the impairment of learning and memory, the loss of NMDA receptor subunits, robust neuroinflammation, the levels of ROS stress and the decrease of p-CREB in the hippocampus of mice.These data suggest that the sepsis-induced selective loss of NMDA receptors modulates hippocampal neuropathology in the mice that survived sepsis, and the data show that NMDA receptors are potential targets for the improvement of brain dysfunction

  18. Birdsong Acquisition Model by Sexual Selection Focused on the Habitat Density

    Science.gov (United States)

    Fujita, Yohei; Mutoh, Atsuko; Kato, Shohei

    We describe a simulation model based on an avian ecosystem for determining what causes birdsong evolution. It is already known that songbirds communicate with a “birdsong.” This birdsong is used in territorial and courtship behaviors. Some previous researches have suggested that songs related to territorial behaviors should have simple structures while those related to courtship behaviors should have complex ones. We suspect that birdsongs are constantly evolving to achieve a suitable balance between the two behaviors while considering the surrounding environment. We consider avian habitat density to be one of the most important environmental factors influencing birdsong evolution and therefore created different densities in a simulation model. In this paper, we propose a birdsong acquisition model by sexual selection that contains both territorial and courtship behaviors. We conducted simulations with the proposed model and determined that the evolution of birdsongs differs depending on a bird's habitat density. The experimental results suggest that a bird's habitat density influences the structure of birdsongs, as well.

  19. Directional postcopulatory sexual selection is associated with female sperm storage in Trinidadian guppies.

    Science.gov (United States)

    Devigili, Alessandro; Di Nisio, Andrea; Grapputo, Alessandro; Pilastro, Andrea

    2016-08-01

    Female sperm storage (FSS) is taxonomically widespread and often associated with intense sperm competition, yet its consequences on postcopulatory sexual selection (PCSS) are poorly known. Theory predicts that FSS will reduce the strength of PCSS, because sperm characteristics favored before and after FSS may be traded-off, and opportunities for nondirectional PCSS should increase. We explored these questions in the guppy (Poecilia reticulata), by allowing females to mate multiply and by comparing the paternity pattern in two successive broods. Contrary to predictions, the variance in male fertilization success increased after FSS, driven by a change in male paternity share across broods. This change was positively associated with sperm velocity (measured before FSS) but not with the duration of FSS, indirectly suggesting that faster sperm were better in entering female storage organs, rather than in persisting within them. Other male traits, such as male size and orange color, heterozygosity, and relatedness to the female, did not influence paternity after FSS. These results indicate that processes associated with FSS tend to reinforce the strength of PCSS in guppies, rather than weaken it. Further work is necessary to test whether this pattern changes in case of more prolonged FSS. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

  20. Evaluation of sexual maturity of young bulls from different breeds selected for post-weaning weight

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    Fabio Morato Monteiro

    2011-01-01

    Full Text Available Sperm traits of 243 young bulls from Caracu (n=62, Gir (n=23, Guzerá (n=59 and Nellore (n=99 breeds, with 20-25 months of age, from the Breeding Program of Estação Experimental de Zootecnia de Sertãozinho, were analyzed. On the day of breeding soundness evaluation animals were weighed, the scrotal circumference was measured and the semen was collected by electroejaculation. The sperm motility, vigor and morphology were assessed and the animals were classified according to the andrological classification by points (CAP. No difference was observed among breeds for any seminal trait evaluated, although Nelore presented lower scrotal circumference average than the other breeds. When the animals were classified by body weight, it was observed that the heavier animals presented greater scrotal circumference, better seminal characteristics and, consequently, greater percentage of these animals were considered sexually mature comparing with the other body weight groups. It was concluded that the animals selected for post-weaning and reared on pasture from the taurine adapted breed Caracu and from the zebu breeds Gir, Guzerá and Nelore have proved able to reproduction at 23.2, 23.4, 22.7 and 22.8 months, respectively, corresponding to age which reached an average weight of 452, 422, 470 and 467 kg respectively.

  1. Sexuality Education Can Make a Difference. Reference Sheet 1 and Bibliography of Selected Resources.

    Science.gov (United States)

    Planned Parenthood Federation of America, Inc., New York, NY. Education Dept.

    This document contains a reference sheet and an annotated bibliography concerned with sexuality education. The reference sheet provides a brief overview of the results of sexuality education programs as reported in the literature. The annotated bibliography contains the relevant information for each article, study, or book citation included in the…

  2. Movements, cover-type selection, and survival of fledgling Ovenbirds in managed deciduous and mixed coniferous-deciduous forests

    Science.gov (United States)

    Streby, Henry M.; Andersen, David E.

    2013-01-01

    We used radio telemetry to monitor movements, cover-type selection, and survival for fledglings of the mature-forest nesting Ovenbird (Seiurus aurocapilla) at two managed forest sites in north-central Minnesota. Both sites contained forested wetlands, regenerating clearcut stands of various ages, and logging roads, but differed in mature forest composition; one deciduous with open understory, and the other mixed coniferous-deciduous with dense understory. We used compositional analysis, modified to incorporate age-specific limitations in fledgling movements, to assess cover-type selection by fledglings throughout the dependent (on adult care) post-fledging period. Compared to those that were depredated, fledglings from nests in deciduous forest that survived the early post-fledging period had more older (sapling-dominated) clearcut available, directed movements toward older clearcuts and forested wetlands, and used older clearcuts more than other cover types relative to availability. Fledglings that were depredated had more young (shrub-dominated) clearcut and unpaved logging road available, and used mature forest and roads more than expected based on availability. For birds from nests in mixed mature forest with dense understory, movements and cover-type selection were similar between fledglings that survived and those that were depredated. However, fledglings that were depredated at that site also had more young clearcut available than fledglings that survived. We conclude that Ovenbird fledgling survival is influenced by distance of their nest to various non-nesting cover types, and by the subsequent selection among those cover types, but that the influence of non-nesting cover types varies depending on the availability of dense understory vegetation in mature forest.

  3. Enhancing selective breeding for growth, slaughter traits and overall survival in rainbow trout (Oncorhynchus mykiss)

    NARCIS (Netherlands)

    Sae-Lim, P.; Komen, J.; Kause, A.; Martin, K.E.; Crooijmans, R.P.M.A.; Arendonk, van J.A.M.; Parsons, J.E.

    2013-01-01

    Enhancing selection using two-stage selection is normally implemented by pre-selection for tagging weight (BWT) and by final selection for ungutted harvest weight (BWH) and thermal growth coefficient from tagging to harvest (TGCTH). However, selection on harvest traits, i.e., gutted weight (GBWH),

  4. Sexual selection has minimal impact on effective population sizes in species with high rates of random offspring mortality: An empirical demonstration using fitness distributions.

    Science.gov (United States)

    Pischedda, Alison; Friberg, Urban; Stewart, Andrew D; Miller, Paige M; Rice, William R

    2015-10-01

    The effective population size (N(e)) is a fundamental parameter in population genetics that influences the rate of loss of genetic diversity. Sexual selection has the potential to reduce N(e) by causing the sex-specific distributions of individuals that successfully reproduce to diverge. To empirically estimate the effect of sexual selection on N(e), we obtained fitness distributions for males and females from an outbred, laboratory-adapted population of Drosophila melanogaster. We observed strong sexual selection in this population (the variance in male reproductive success was ∼14 times higher than that for females), but found that sexual selection had only a modest effect on N(e), which was 75% of the census size. This occurs because the substantial random offspring mortality in this population diminishes the effects of sexual selection on N(e), a result that necessarily applies to other high fecundity species. The inclusion of this random offspring mortality creates a scaling effect that reduces the variance/mean ratios for male and female reproductive success and causes them to converge. Our results demonstrate that measuring reproductive success without considering offspring mortality can underestimate Ne and overestimate the genetic consequences of sexual selection. Similarly, comparing genetic diversity among different genomic components may fail to detect strong sexual selection. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

  5. Genetic architecture of sexual selection: QTL mapping of male song and female receiver traits in an acoustic moth.

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    Denis Limousin

    Full Text Available Models of indirect (genetic benefits sexual selection predict linkage disequilibria between genes that influence male traits and female preferences, owing to non-random mate choice or physical linkage. Such linkage disequilibria can accelerate the evolution of traits and preferences to exaggerated levels. Both theory and recent empirical findings on species recognition suggest that such linkage disequilibria may result from physical linkage or pleiotropy, but very little work has addressed this possibility within the context of sexual selection. We studied the genetic architecture of sexually selected traits by analyzing signals and preferences in an acoustic moth, Achroia grisella, in which males attract females with a train of ultrasound pulses and females prefer loud songs and a fast pulse rhythm. Both male signal characters and female preferences are repeatable and heritable traits. Moreover, female choice is based largely on male song, while males do not appear to provide direct benefits at mating. Thus, some genetic correlation between song and preference traits is expected. We employed a standard crossing design between inbred lines and used AFLP markers to build a linkage map for this species and locate quantitative trait loci (QTL that influence male song and female preference. Our analyses mostly revealed QTLs of moderate strength that influence various male signal and female receiver traits, but one QTL was found that exerts a major influence on the pulse-pair rate of male song, a critical trait in female attraction. However, we found no evidence of specific co-localization of QTLs influencing male signal and female receiver traits on the same linkage groups. This finding suggests that the sexual selection process would proceed at a modest rate in A. grisella and that evolution toward exaggerated character states may be tempered. We suggest that this equilibrium state may be more the norm than the exception among animal species.

  6. A link between altruism and sexual selection: genetic influence on altruistic behaviour and mate preference towards it.

    Science.gov (United States)

    Phillips, Tim; Ferguson, Eamonn; Rijsdijk, Fruhling

    2010-11-01

    Altruistic behaviour raises major questions for psychology and biology. One hypothesis proposes that human altruistic behaviour evolved as a result of sexual selection. Mechanisms that seek to explain how sexual selection works suggest genetic influence acting on both the mate preference for the trait and the preferred trait itself. We used a twin study to estimate whether genetic effects influenced responses to psychometric scales measuring mate preference towards altruistic traits (MPAT) and the preferred trait (i.e., 'altruistic personality'). As predicted, we found significant genetic effects influencing variation in both. We also predicted that individuals expressing stronger MPAT and 'altruistic personality' would have mated at a greater frequency in ancestral populations. We found evidence for this in that 67% of the covariance in the phenotypic correlation between the two scales was associated with significant genetic effects. Both sets of findings are thus consistent with the hypothesized link between sexual selection and human altruism towards non-kin. We discuss how this study contributes to our understanding of altruistic behaviour and how further work might extend this understanding.

  7. As the sword grows: individual variation and ontogenetic effects of a sexually selected trait on locomotor performance in Xiphophorus hellerii.

    Science.gov (United States)

    Oufiero, Christopher E; Jugo, Kristine; Tran, Paulina; Garland, Theodore

    2012-01-01

    Previous studies aimed at detecting costs of sexually selected traits have yielded mixed results partly because of variable methods. We present a novel approach: a repeated-measures design to examine individual variation in locomotor performance of male Xiphophorus hellerii as the sexually selected sword develops ontogenetically and to determine whether the growth of a sexually selected trait alters consistency of performance. Individual differences in sprint speed, critical swimming speed (stamina), and relative sword length were statistically repeatable over 9 wk. However, using the Akaike Information Criterion corrected for small sample sizes, the best-fit predictive models for swimming performance did not include sword length or relative sword length. Furthermore, in less supported models and within-week comparisons, there was no statistically significant effect of sword length on performance. These results suggest little effect of the sword on locomotor abilities, which is inconsistent with results from some previous experimental manipulations, possibly because compensatory traits develop ontogenetically in parallel with the sword. However, our results are consistent with correlational studies of natural variation that suggest no locomotor cost of the sword. These results do not necessarily imply a complete lack of a cost to the sword but rather lack of a functional cost for swimming performance.

  8. Female guppies agree to differ: phenotypic and genetic variation in mate-choice behavior and the consequences for sexual selection.

    Science.gov (United States)

    Brooks, R; Endler, J A

    2001-08-01

    Variation among females in mate choice may influence evolution by sexual selection. The genetic basis of this variation is of interest because the elaboration of mating preferences requires additive genetic variation in these traits. Here we measure the repeatability and heritability of two components of female choosiness (responsiveness and discrimination) and of female preference functions for the multiple ornaments borne by male guppies (Poecilia reticulata). We show that there is significant repeatable variation in both components of choosiness and in some preference functions but not in others. There appear to be several male ornaments that females find uniformly attractive and others for which females differ in preference. One consequence is that there is no universally attractive male phenotype. Only responsiveness shows significant additive genetic variation. Variation in responsiveness appears to mask variation in discrimination and some preference functions and may be the most biologically relevant source of phenotypic and genetic variation in mate-choice behavior. To test the potential evolutionary importance of the phenotypic variation in mate choice that we report, we estimated the opportunity for and the intensity of sexual selection under models of mate choice that excluded and that incorporated individual female variation. We then compared these estimates with estimates based on measured mating success. Incorporating individual variation in mate choice generally did not predict the outcome of sexual selection any better than models that ignored such variation.

  9. A Summary of Selective Experimental Research on Psychosocial Interventions for Sexually Abused Children.

    Science.gov (United States)

    Kim, Sunah; Noh, Dabok; Kim, Hyunlye

    2016-07-01

    This study was conducted to explore current trends in psychosocial interventions for sexually abused children through a review of recent research. Our comprehensive review is limited to published (quasi) experimental studies in the English language over a period of 2000-2013. It provides a detailed analysis of the final 18 articles that met our inclusion criteria, from the 670 potentially relevant articles that were identified. Reviewers analyzed candidate articles to determine whether they met inclusion or exclusion criteria. The retrieved studies reported positive results with respect to improvements in the negative psychosocial sequelae of child sexual abuse following the use of a diverse set of treatment strategies. Of the various interventions, cognitive behavioral therapy was shown to be the most promising type of intervention for sexually abused children. In this review, we discuss some of the implications of psychosocial interventions for victims of child sexual abuse, citing both the methodological and ethical issues that should be considered.

  10. A prime determinant in selecting dialysis modality: peritoneal dialysis patient survival

    Directory of Open Access Journals (Sweden)

    Hyunwook Kim

    2017-03-01

    Full Text Available The number of patients with end-stage renal disease (ESRD has rapidly increased, as has the cost of dialysis. Peritoneal dialysis (PD is an established treatment for ESRD patients worldwide; it has a variety of advantages, including autonomy and flexibility, as well as economic benefits in many countries compared to hemodialysis (HD. However, the long-term survival rate of PD remains poor. Although direct comparison of survival rate between the dialysis modalities by randomized controlled trials is difficult due to the ethical issues, it has always been a crucial point when deciding which dialysis modality should be recommended to patients. Recently, in many countries, including the United States, Brazil, Spain, Australia, and New Zealand, the survival rate in PD patients has significantly improved. PD patient survival in Korea has also improved, but Korean PD patients are known to have higher risk of mortality and major adverse cardiovascular, cerebrovascular events than HD patients. Herein, we further evaluate why Korean PD patients had worse outcomes; we suggest that special attention should be paid to patients with diabetes, coronary artery disease, or congestive heart failure when they choose PD as the first dialysis modality in order to reduce mortality risk.

  11. Survival benefits select for group living in a social spider despite reproductive costs.

    Science.gov (United States)

    Bilde, T; Coates, K S; Birkhofer, K; Bird, T; Maklakov, A A; Lubin, Y; Avilés, L

    2007-11-01

    The evolution of cooperation requires benefits of group living to exceed costs. Hence, some components of fitness are expected to increase with increasing group size, whereas others may decrease because of competition among group members. The social spiders provide an excellent system to investigate the costs and benefits of group living: they occur in groups of various sizes and individuals are relatively short-lived, therefore life history traits and Lifetime Reproductive Success (LRS) can be estimated as a function of group size. Sociality in spiders has originated repeatedly in phylogenetically distant families and appears to be accompanied by a transition to a system of continuous intra-colony mating and extreme inbreeding. The benefits of group living in such systems should therefore be substantial. We investigated the effect of group size on fitness components of reproduction and survival in the social spider Stegodyphus dumicola in two populations in Namibia. In both populations, the major benefit of group living was improved survival of colonies and late-instar juveniles with increasing colony size. By contrast, female fecundity, female body size and early juvenile survival decreased with increasing group size. Mean individual fitness, estimated as LRS and calculated from five components of reproduction and survival, was maximized for intermediate- to large-sized colonies. Group living in these spiders thus entails a net reproductive cost, presumably because of an increase in intra-colony competition with group size. This cost is traded off against survival benefits at the colony level, which appear to be the major factor favouring group living. In the field, many colonies occur at smaller size than expected from the fitness curve, suggesting ecological or life history constraints on colony persistence which results in a transient population of relatively small colonies.

  12. Increased survival of western corn rootworm on transgenic corn within three generations of on-plant greenhouse selection.

    Science.gov (United States)

    Meihls, Lisa N; Higdon, Matthew L; Siegfried, Blair D; Miller, Nicholas J; Sappington, Thomas W; Ellersieck, Mark R; Spencer, Terence A; Hibbard, Bruce E

    2008-12-09

    To delay evolution of insect resistance to transgenic crops producing Bacillus thuringiensis (Bt) toxins, nearby "refuges" of host plants not producing Bt toxins are required in many regions. Such refuges are expected to be most effective in slowing resistance when the toxin concentration in Bt crops is high enough to kill all or nearly all insects heterozygous for resistance. However, Bt corn, Zea mays, introduced recently does not meet this "high-dose" criterion for control of western corn rootworm (WCR), Diabrotica virgifera virgifera. A greenhouse method of rearing WCR on transgenic corn expressing the Cry3Bb1 protein was used in which approximately 25% of previously unexposed larvae survived relative to isoline survival (compared to 1-4% in the field). After three generations of full larval rearing on Bt corn (Constant-exposure colony), WCR larval survival was equivalent on Bt corn and isoline corn in greenhouse trials, and the LC(50) was 22-fold greater for the Constant-exposure colony than for the Control colony in diet bioassays with Cry3Bb1 protein on artificial diet. After six generations of greenhouse selection, the ratio of larval recovery on Bt corn to isoline corn in the field was 11.7-fold greater for the Constant-exposure colony than the Control colony. Removal from selection for six generations did not decrease survival on Bt corn in the greenhouse. The results suggest that rapid response to selection is possible in the absence of mating with unexposed beetles, emphasizing the importance of effective refuges for resistance management.

  13. The effect of selected factors on the survival of Bacillus cereus in the human gastrointestinal tract.

    Science.gov (United States)

    Berthold-Pluta, Anna; Pluta, Antoni; Garbowska, Monika

    2015-05-01

    Bacillus cereus is a Gram-positive bacterium widely distributed in soil and vegetation. This bacterial species can also contaminate raw or processed foods. Pathogenic B. cereus strains can cause a range of infections in humans, as well as food poisoning of an emetic (intoxication) or diarrheal type (toxico-infection). Toxico-infections are due to the action of the Hbl toxin, Nhe toxin, and cytotoxin K produced by the microorganism in the gastrointestinal tract. This occurs once the spores or vegetative B. cereus cells survive the pH barrier of the stomach and reach the small intestine where they produce toxins in sufficient amounts. This article discusses the effect of various factors on the survival of B. cereus in the gastrointestinal tract, including low pH and the presence of digestive enzymes in the stomach, bile salts in the small intestine, and indigenous microflora in the lower parts of the gastrointestinal tract. Additional aspects also reported to affect B. cereus survival and virulence in the gastrointestinal tract include the interaction of the spores and vegetative cells with enterocytes. In vitro studies revealed that both vegetative B. cereus and spores can survive in the gastrointestinal tract suggesting that the biological form of the microorganism may have less influence on the occurrence of the symptoms of infection than was once believed. It is most likely the interaction between the pathogen and enterocytes that is necessary for the diarrheal form of B. cereus food poisoning to develop. The adhesion of B. cereus to the intestinal epithelium allows the bacterium to grow and produce enterotoxins in the proximity of the epithelium. Recent studies suggest that the human intestinal microbiota inhibits the growth of vegetative B. cereus cells considerably. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Survival benefits select for group living in a social spider despite reproductive costs

    DEFF Research Database (Denmark)

    Bilde, T.; Coates, K.S.; Birkhofer, K.

    2007-01-01

    The evolution of cooperation requires benefits of group living to exceed costs. Hence, some components of fitness are expected to increase with increasing group size, whereas others may decrease because of competition among group members. The social spiders provide an excellent system to investig......The evolution of cooperation requires benefits of group living to exceed costs. Hence, some components of fitness are expected to increase with increasing group size, whereas others may decrease because of competition among group members. The social spiders provide an excellent system...... to investigate the costs and benefits of group living: they occur in groups of various sizes and individuals are relatively short-lived, therefore life history traits and Lifetime Reproductive Success (LRS) can be estimated as a function of group size. Sociality in spiders has originated repeatedly...... and survival in the social spider Stegodyphus dumicola in two populations in Namibia. In both populations, the major benefit of group living was improved survival of colonies and late-instar juveniles with increasing colony size. By contrast, female fecundity, female body size and early juvenile survival...

  15. The relative nature of fertilization success: Implications for the study of post-copulatory sexual selection

    Directory of Open Access Journals (Sweden)

    García-González Francisco

    2008-05-01

    Full Text Available Abstract Background The determination of genetic variation in sperm competitive ability is fundamental to distinguish between post-copulatory sexual selection models based on good-genes vs compatible genes. The sexy-sperm and the good-sperm hypotheses for the evolution of polyandry require additive (intrinsic effects of genes influencing sperm competitiveness, whereas the genetic incompatibility hypothesis invokes non-additive genetic effects. A male's sperm competitive ability is typically estimated from his fertilization success, a measure that is dependent on the ability of rival sperm competitors to fertilize the ova. It is well known that fertilization success may be conditional to genotypic interactions among males as well as between males and females. However, the consequences of effects arising from the random sampling of sperm competitors upon the estimation of genetic variance in sperm competitiveness have been overlooked. Here I perform simulations of mating trials performed in the context of sibling analysis to investigate whether the ability to detect additive genetic variance underlying the sperm competitiveness phenotype is hindered by the relative nature of fertilization success measurements. Results Fertilization success values render biased sperm competitive ability values. Furthermore, asymmetries among males in the errors committed when estimating sperm competitive abilities are likely to exist as long as males exhibit variation in sperm competitiveness. Critically, random effects arising from the relative nature of fertilization success lead to an underestimation of underlying additive genetic variance in sperm competitive ability. Conclusion The results show that, regardless of the existence of genotypic interactions affecting the output of sperm competition, fertilization success is not a perfect predictor of sperm competitive ability because of the stochasticity of the background used to obtain fertilization success

  16. Female discrimination thresholds frequently exceed local male display variation: implications for mate choice dynamics and sexual selection.

    Science.gov (United States)

    Höbel, G

    2016-03-01

    Among the factors that can influence female mate choice decisions is the degree to which females differentiate among similar displays: as differences decrease, females are expected to eventually stop discriminating. This discrimination threshold, in conjunction with the magnitude of male trait variation females regularly encounter while making mate choice decisions, may have important consequences for sexual selection. If local display variation is above the discrimination threshold, female preferences should translate into higher mating success for the more attractive male. But if display variation is frequently below the threshold, the resulting increased pattern of random mating may obscure the existence of female mate choice. I investigated the interplay between female discrimination and male display variation in green treefrogs (Hyla cinerea) and found that call trait differences between nearest neighbour males were frequently smaller than what females are expected to discriminate. This finding has two important consequences for our understanding of sexual selection in the wild: first, low display variation should weaken the strength of selection on male display traits, but the direction of selection should mirror the one predicted from females choice trials. Second, caution is needed when interpreting data on realized mating success in the wild: a pattern of random mating with respect to male display traits does not always mean that female preferences are weak or that conditions are too challenging for females to express their preferences. Rather, insufficient display variation can generate the same pattern. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology.

  17. Sexual differences in microhabitat selection of breeding little bustards Tetrax tetrax: Ecological segregation based on vegetation structure

    Science.gov (United States)

    Morales, M. B.; Traba, J.; Carriles, E.; Delgado, M. P.; de la Morena, E. L. García

    2008-11-01

    We examined sexual differences in patterns of vegetation structure selection in the sexually dimorphic little bustard. Differences in vegetation structure between male, female and non-used locations during reproduction were examined and used to build a presence/absence model for each sex. Ten variables were measured in each location, extracting two PCA factors (PC1: a visibility-shelter gradient; PC2: a gradient in food availability) used as response variables in GLM explanatory models. Both factors significantly differed between female, male and control locations. Neither study site nor phenology was significant. Logistic regression was used to model male and female presence/absence. Female presence was positively associated to cover of ground by vegetation litter, as well as overall vegetation cover, and negatively to vegetation density over 30 cm above ground. Male presence was positively related to litter cover and short vegetation and negatively to vegetation density over 30 cm above ground. Models showed good global performance and robustness. Female microhabitat selection and distribution seems to be related to the balance between shelter and visibility for surveillance. Male microhabitat selection would be related mainly to the need of conspicuousness for courtship. Accessibility to food resources seems to be equally important for both sexes. Differences suggest ecological sexual segregation resulting from different ecological constraints. These are the first detailed results on vegetation structure selection in both male and female little bustards, and are useful in designing management measures addressing vegetation structure irrespective of landscape composition. Similar microhabitat approaches can be applied to manage the habitat of many declining farmland birds.

  18. Genetic and non-genetic factors affecting rabbit doe sexual receptivity as estimated from one generation of divergent selection

    Directory of Open Access Journals (Sweden)

    M. Theau.Clément

    2015-09-01

    Full Text Available Sexual receptivity of rabbit does at insemination greatly influences fertility and is generally induced by hormones or techniques known as “biostimulation”. Searching for more sustainable farming systems, an original alternative would be to utilise the genetic pathway to increase the does’receptivity. The purpose of the present study was to identify genetic and non-genetic factors that influence rabbit doe sexual receptivity, in the context of a divergent selection experiment over 1 generation. The experiment spanned 2 generations: the founder generation (G0 consisting of 140 rabbit does, and the G1 generation comprising 2 divergently selected lines (L and H lines with 70 does each and 2 successive batches from each generation. The selection rate of the G0 females to form the G1 lines was 24/140. The selection tests consisted of 16 to 18 successive receptivity tests at the rate of 3 tests per week. On the basis of 4716 tests from 275 females, the average receptivity was 56.6±48.2%. A batch effect and a test operator effect were revealed. The contribution of females to the total variance was 20.0%, whereas that of bucks was only 1.1%. Throughout the experiment, 18.2% of does expressed a low receptivity (< 34%, 50.7% a medium one and 33.1% a high one (>66%. Some does were frequently receptive, whereas others were rarely receptive. The repeatability of sexual receptivity was approximately 20%. The results confirmed the high variability of sexual receptivity of non-lactating rabbit does maintained without any biostimulation or hormonal treatment. A lack of selection response on receptivity was observed. Accordingly, the heritability of receptivity was estimated at 0.01±0.02 from an animal model and at 0.02±0.03 from a  sire and dam model. The heritability of the average receptivity of a doe was calculated as 0.04. In agreement with the low estimated heritability, the heritability determined was no different from zero

  19. Psychological, Sexual, Social and Vocational Aspects of Spinal Cord Injury. A Selected Bibliography.

    Science.gov (United States)

    Scarlett, Sharon, Comp.; And Others

    Presented is a bibliography with approximately 700 citations referring to research in the area of spinal cord injury. Entries are listed alphabetically by author under the following sections: psychological aspects (236 entries), sexual aspects (170 entries), social aspects (152 entries), and vocational aspects (134 entries). Information for each…

  20. The selective estrogen receptor-alpha coactivator, RPL7, and sexual differentiation of the songbird brain.

    Science.gov (United States)

    Duncan, Kelli A; Jimenez, Pedro; Carruth, Laura L

    2009-12-01

    The brain and behavior of the Australian zebra finch (Taeniopygia guttata) are sexually dimorphic. Only males sing courtship songs and the regions of the brain involved in the learning and production of song are significantly larger in males than females. Therefore the zebra finch serves as an excellent model for studying the mechanisms that influence brain sexual differentiation, and the majority of past research on this system has focused on the actions of steroid hormones in the development of these sex differences. Coregulators, such as coactivators and corepressors, are proteins and RNA activators that work by enhancing or depressing the transcriptional activity of the nuclear steroid receptor with which they associate, and thereby modulating the development of sex-specific brain morphologies and behaviors. The actions of these proteins may help elucidate the hormonal mechanisms that underlie song nuclei development. Research described in this review focus on the role of estrogen receptor coactivators in the avian brain; more specifically we will focus on the role of RPL7 (ribosomal protein L7; also known as L7/SPA) on sexual differentiation of the zebra finch song system. Collectively, these studies provide information about the role of steroid receptor coactivators on development of the zebra finch song system as well as on sexual differentiation of brain.

  1. Responding to Parental Objections to School Sexuality Education: A Selection of 12 Objections

    Science.gov (United States)

    Goldman, Juliette D. G.

    2008-01-01

    Sexuality education for school-aged young people is a crucial component of all quality education systems. It prepares young people for participation in society as responsible, mature and community-minded citizens. Most contemporary school education curricula generally aim to enhance young people's knowledge, skills and understandings of the world,…

  2. Adolescents' and their friends' sexual behavior and intention : Selection effects of personality dimensions

    NARCIS (Netherlands)

    Baams, Laura; Overbeek, Geertjan; van de Bongardt, Daphne; Reitz, Ellen; Dubas, Judith Semon; van Aken, Marcel A G

    2015-01-01

    Using simulation investigation for empirical network analyses (in RSiena) we examined how personality and sexual behavior and intention were related to peer processes in Dutch adolescents. Our main research questions were: (a) do adolescents cluster together in friendship networks based on

  3. Adolescents' and their friends' sexual behavior and intention: Selection effects of personality dimensions

    NARCIS (Netherlands)

    Baams, L.; Overbeek, G.; van de Bongardt, D.; Reitz, E.; Dubas, J.S.; van Aken, M.A.G.

    2015-01-01

    Using simulation investigation for empirical network analyses (in RSiena) we examined how personality and sexual behavior and intention were related to peer processes in Dutch adolescents. Our main research questions were: (a) do adolescents cluster together in friendship networks based on

  4. Disgust sensitivity selectively predicts attitudes toward groups that threaten (or uphold) traditional sexual morality

    NARCIS (Netherlands)

    Crawford, J.; Inbar, Y.; Malony, V.

    2014-01-01

    Previous research has linked disgust sensitivity to negative attitudes toward gays and lesbians. We extend this existing research by examining the extent to which disgust sensitivity predicts attitudes more generally toward groups that threaten or uphold traditional sexual morality. In a sample of

  5. Mutual ornamentation, sexual selection, and social dominance in the black swan

    NARCIS (Netherlands)

    Kraaijeveld, K; Gregurke, J; Hall, C; Komdeur, J; Mulder, RA

    We investigated the adaptive significance of a sexually monomorphic ornament in the black swan Cygnus atratus. Both sexes grow curled feathers on their wings (range 7-22 curled feathers per wing), which are displayed prominently in a range of social interactions. The number of curled feathers

  6. Sexual dimorphic expression of dnd in germ cells during sex reversal and its requirement for primordial germ cell survival in protogynous hermaphroditic grouper.

    Science.gov (United States)

    Sun, Zhi-Hui; Zhou, Li; Li, Zhi; Liu, Xiao-Chun; Li, Shui-Sheng; Wang, Yang; Gui, Jian-Fang

    2017-06-01

    Dead end (dnd), vertebrate-specific germ cell marker, had been demonstrated to be essential for primordial germ cell (PGC) migration and survival, and the link between PGC number and sex change had been revealed in some teleost species, but little is known about dnd in hermaphroditic vertebrates. In the present study, a protogynous hermaphroditic orange-spotted grouper (Epinephelus coioides) dnd homologue (Ecdnd) was identified and characterized. Quantitative real-time PCR and in situ hybridization analysis revealed a dynamic and sexually dimorphic expression pattern in PGCs and germ cells of gonads. During sex changing, the Ecdnd transcript sharply increased in early transitional gonad, reached the highest level at late transitional gonad stage, and decreased after testis maturation. Visualization of zebrafish PGCs by injecting with RFP-Ecdnd-3'UTR RNA and GFP-zfnanos3-3'UTR RNA confirmed importance of Ecdnd 3'UTR for the PGC distribution. In addition, knockdown of EcDnd by using antisense morpholinos (MO) caused the ablation of PGCs in orange-spotted grouper. Therefore, the current data indicate that Ecdnd is essential for PGCs survival and may serve as a useful germ cell marker during gametogenesis in hermaphroditic grouper. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. The form of sexual selection arising from male-male competition depends on the presence of females in the social environment.

    Science.gov (United States)

    Procter, D S; Moore, A J; Miller, C W

    2012-05-01

    Sexual selection arises from social interactions, and if social environments vary so too should sexual selection. For example, male-male competition often occurs either in the presence or in the absence of females, and such changes in the social environment could affect the form and strength of sexual selection. Here we examine how the presence of a female influences selection arising from male-male competition in a leaf-footed cactus bug, Narnia femorata, which has a resource defence mating system. Males compete for territories on cacti because females lay eggs on the cactus plants. Females are not always present when this competition first occurs; however, the presence or absence of the female matters. We found that both the form and strength of selection on male traits, those traits that influenced success in intrasexual competition, depended on the social context. When a female was not present, male size and the area of the sexually dimorphic hind legs was only marginally important to winning a contest. However, males with larger overall size and leg area were more likely to win in the presence of a female. There was also positive quadratic selection on these traits when a female was present with both the largest and the smallest males winning. The implication is unexpected alternative strategies when females are present. Our results support the notion that sexual selection should be studied under all relevant social contexts. © 2012 The Authors. Journal of Evolutionary Biology © 2012 European Society For Evolutionary Biology.

  8. Differences in the Selection Bottleneck between Modes of Sexual Transmission Influence the Genetic Composition of the HIV-1 Founder Virus.

    Directory of Open Access Journals (Sweden)

    Damien C Tully

    2016-05-01

    Full Text Available Due to the stringent population bottleneck that occurs during sexual HIV-1 transmission, systemic infection is typically established by a limited number of founder viruses. Elucidation of the precise forces influencing the selection of founder viruses may reveal key vulnerabilities that could aid in the development of a vaccine or other clinical interventions. Here, we utilize deep sequencing data and apply a genetic distance-based method to investigate whether the mode of sexual transmission shapes the nascent founder viral genome. Analysis of 74 acute and early HIV-1 infected subjects revealed that 83% of men who have sex with men (MSM exhibit a single founder virus, levels similar to those previously observed in heterosexual (HSX transmission. In a metadata analysis of a total of 354 subjects, including HSX, MSM and injecting drug users (IDU, we also observed no significant differences in the frequency of single founder virus infections between HSX and MSM transmissions. However, comparison of HIV-1 envelope sequences revealed that HSX founder viruses exhibited a greater number of codon sites under positive selection, as well as stronger transmission indices possibly reflective of higher fitness variants. Moreover, specific genetic "signatures" within MSM and HSX founder viruses were identified, with single polymorphisms within gp41 enriched among HSX viruses while more complex patterns, including clustered polymorphisms surrounding the CD4 binding site, were enriched in MSM viruses. While our findings do not support an influence of the mode of sexual transmission on the number of founder viruses, they do demonstrate that there are marked differences in the selection bottleneck that can significantly shape their genetic composition. This study illustrates the complex dynamics of the transmission bottleneck and reveals that distinct genetic bottleneck processes exist dependent upon the mode of HIV-1 transmission.

  9. Differences in the Selection Bottleneck between Modes of Sexual Transmission Influence the Genetic Composition of the HIV-1 Founder Virus.

    Science.gov (United States)

    Tully, Damien C; Ogilvie, Colin B; Batorsky, Rebecca E; Bean, David J; Power, Karen A; Ghebremichael, Musie; Bedard, Hunter E; Gladden, Adrianne D; Seese, Aaron M; Amero, Molly A; Lane, Kimberly; McGrath, Graham; Bazner, Suzane B; Tinsley, Jake; Lennon, Niall J; Henn, Matthew R; Brumme, Zabrina L; Norris, Philip J; Rosenberg, Eric S; Mayer, Kenneth H; Jessen, Heiko; Kosakovsky Pond, Sergei L; Walker, Bruce D; Altfeld, Marcus; Carlson, Jonathan M; Allen, Todd M

    2016-05-01

    Due to the stringent population bottleneck that occurs during sexual HIV-1 transmission, systemic infection is typically established by a limited number of founder viruses. Elucidation of the precise forces influencing the selection of founder viruses may reveal key vulnerabilities that could aid in the development of a vaccine or other clinical interventions. Here, we utilize deep sequencing data and apply a genetic distance-based method to investigate whether the mode of sexual transmission shapes the nascent founder viral genome. Analysis of 74 acute and early HIV-1 infected subjects revealed that 83% of men who have sex with men (MSM) exhibit a single founder virus, levels similar to those previously observed in heterosexual (HSX) transmission. In a metadata analysis of a total of 354 subjects, including HSX, MSM and injecting drug users (IDU), we also observed no significant differences in the frequency of single founder virus infections between HSX and MSM transmissions. However, comparison of HIV-1 envelope sequences revealed that HSX founder viruses exhibited a greater number of codon sites under positive selection, as well as stronger transmission indices possibly reflective of higher fitness variants. Moreover, specific genetic "signatures" within MSM and HSX founder viruses were identified, with single polymorphisms within gp41 enriched among HSX viruses while more complex patterns, including clustered polymorphisms surrounding the CD4 binding site, were enriched in MSM viruses. While our findings do not support an influence of the mode of sexual transmission on the number of founder viruses, they do demonstrate that there are marked differences in the selection bottleneck that can significantly shape their genetic composition. This study illustrates the complex dynamics of the transmission bottleneck and reveals that distinct genetic bottleneck processes exist dependent upon the mode of HIV-1 transmission.

  10. Sexual selection and maintenance of sex: evidence from comparisons of rates of genomic accumulation of mutations and divergence of sex-related genes in sexual and hermaphroditic species of Caenorhabditis.

    Science.gov (United States)

    Artieri, Carlo G; Haerty, Wilfried; Gupta, Bhagwati P; Singh, Rama S

    2008-05-01

    Several hypotheses have been proposed to explain the persistence of dioecy despite the reproductive advantages conferred to hermaphrodites, including greater efficiency at purging deleterious mutations in the former. Dioecy can benefit from both mutation purging and accelerated evolution by bringing together beneficial mutations in the same individual via recombination and shuffling of genotypes. In addition, mathematical treatment has shown that sexual selection is also capable of mitigating the cost of maintaining separate sexes by increasing the overall fitness of sexual populations, and genomic comparisons have shown that sexual selection can lead to accelerated evolution. Here, we examine the advantages of dioecy versus hermaphroditism by comparing the rate of evolution in sex-related genes and the rate of accumulation of deleterious mutations using a large number of orthologs (11,493) in the dioecious Caenorhabditis remanei and the hermaphroditic Caenorhabditis briggsae. We have used this data set to estimate the deleterious mutation rate per generation, U, in both species and find that although it is significantly higher in hermaphrodites, both species are at least 2 orders of magnitude lower than the value required to explain the persistence of sex by efficiency at purging deleterious mutations alone. We also find that genes expressed in sperm are evolving rapidly in both species; however, they show a greater increase in their rate of evolution relative to genes expressed in other tissues in C. remanei, suggesting stronger sexual selection pressure acting on these genes in dioecious species. Interestingly, the persistence of a signal of rapid evolution of sperm genes in C. briggsae suggests a recent evolutionary origin of hermaphrodism in this lineage. Our results provide empirical evidence of increased sexual selection pressure in dioecious animals, supporting the possibility that sexual selection may play an important role in the maintenance of sexual

  11. Effect of increased ovulation rate on embryo and foetal survival as a model for selection by ovulation rate in rabbits

    Directory of Open Access Journals (Sweden)

    A.Y. Badawy

    2016-06-01

    Full Text Available Selection for ovulation rate in prolific species has not improved litter size, due to an increase in prenatal mortality, with most mortality observed in the foetal period. The aim of this study was to investigate the magnitude and timing of embryo and early foetal survival in females with high ovulation rate using hormonal treatment as a model for selection by ovulation rate. Two groups of females (treated and untreated were used. Treated females were injected with 50 IU equine chorionic gonadotropin 48 h before mating. Females were slaughtered at 18 d of gestation. Ovulation rate (OR, number of implanted embryos (IE, number of live foetuses at 12 and 18 d (LF12 and LF18, respectively were recorded. In addition, embryo survival (ES=IE/OR, foetal survival at 18 d of gestation (FSLF18=LF18/IE, foetal survival between 12 and 18 d of gestation (FSLF18/LF12=LF18/LF12 and prenatal survival (PSLF18=LF18/OR were estimated. For each female, the mean and variability of the weight for live foetuses (LFWm and LFWv, respectively and their placentas (LFPWm and LFPWv, respectively were calculated. Treated females had a higher ovulation rate (+3.02 ova than untreated females, with a probability of 0.99. An increase in the differences (D between treated and untreated females was observed from implantation to 18 d of gestation (D=–0.33, –0.70 and –1.28 for IE, LF12 and LF18, respectively. These differences had a low accuracy and the probability that treated females would have a lower number of foetuses also increased throughout gestation (0.60, 0.70 and 0.86 for IE, LF12 and LF18, respectively. According to the previous results for OR and LF18, treated females showed a lower survival rate from ovulation to 18 d of gestation (D=–0.12, P=0.98 for PSLF18. Treated females also had lower embryo and foetal survival (D=–0.10 and P=0.94 for ES and D=–0.08 and P=0.93 for FSLF18. Main differences in foetal survival appeared from 12 to 18 d of gestation (D=–0

  12. Patterns of paternity skew among polyandrous social insects: what can they tell us about the potential for sexual selection?

    Science.gov (United States)

    Jaffé, Rodolfo; Garcia-Gonzalez, Francisco; den Boer, Susanne P A; Simmons, Leigh W; Baer, Boris

    2012-12-01

    Monogamy results in high genetic relatedness among offspring and thus it is generally assumed to be favored by kin selection. Female multiple mating (polyandry) has nevertheless evolved several times in the social Hymenoptera (ants, bees, and wasps), and a substantial amount of work has been conducted to understand its costs and benefits. Relatedness and inclusive fitness benefits are, however, not only influenced by queen mating frequency but also by paternity skew, which is a quantitative measure of paternity biases among the offspring of polyandrous females. We performed a large-scale phylogenetic analysis of paternity skew across polyandrous social Hymenoptera. We found a general and significant negative association between paternity frequency and paternity skew. High paternity skew, which increases relatedness among colony members and thus maximizes inclusive fitness gains, characterized species with low paternity frequency. However, species with highly polyandrous queens had low paternity skew, with paternity equalized among potential sires. Equal paternity shares among fathers are expected to maximize fitness benefits derived from genetic diversity among offspring. We discuss the potential for postcopulatory sexual selection to influence patterns of paternity in social insects, and suggest that sexual selection may have played a key, yet overlooked role in social evolution. © 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.

  13. Establishment, survival, site selection and development of Leptorhynchoides thecatus in largemouth bass, Micropterus salmoides.

    Science.gov (United States)

    Leadabrand, C C; Nickol, B B

    1993-06-01

    Establishment, survival and distribution of Leptorhynchoides thecatus (Acanthocephala) were investigated in largemouth bass, Micropterus salmoides, fed 10, 25, or 40 cystacanths and examined at 1, 3 or 5 weeks post-infection. Worms established widely in the alimentary tracts of bass but by 5 weeks post-infection had localized in the pyloric caeca and intercaecal region. Other individuals moved to parenteral sites where they remained immature, though viable. In the 10- and 25-level exposures, establishment and survivorship in the alimentary tract were roughly proportional to the dose of cystacanths. After 1 week post-infection in the 40-level exposure class, numbers of worms in the alimentary tract decreased significantly and parenteral occurrence increased significantly. Total survival of L. thecatus appeared to be density-independent. Maturation of worms was retarded temporarily as intensity of infection increased, but by 5 weeks post-infection worms from all doses were at roughly the same stage of development within sex. The caeca and intercaecal area apparently did not differ in their suitability for maturation.

  14. The form of sexual selection on male genitalia cannot be inferred from within-population variance and allometry - a case study in Aquarius remigis.

    Science.gov (United States)

    Bertin, Angéline; Fairbairn, Daphne J

    2007-04-01

    Male genital morphology in insects and arachnids is characterized by static hypoallometry and low intrapopulational levels of phenotypic variation relative to other male traits. The one-size-fits-all model of genital evolution attributes these patterns to stabilizing sexual selection. This model relies on the assumption that the observed patterns of variation and allometry reflect the form of sexual selection acting these traits. We test this by examining the patterns of scaling and trait variation for a set of genitalic and somatic morphological traits in male water striders (Aquarius remigis). This suite of traits is of particular interest because previous work has shown that the genitalic traits are under strong directional selection whereas the somatic traits are under either weak directional or stabilizing selection. Because the selection regime for these traits is known, we can, for the first time, test the purported relationship between trait variation, scaling, and the form of sexual selection. We show that the patterns of variation and scaling of these traits differ sharply from those predicted for traits experiencing strong directional sexual selection. Specifically, the male genital structures show static hypoallometry and low intrapopulational levels of phenotypic variation relative to other male traits, in spite of consistent, strong, directional sexual selection. These scaling relationships and levels of variation are typical of genital traits in other insect species, where they have been presumed to reflect stabilizing sexual selection. Our data clearly refute the assumption of the one-size-fits-all hypothesis that hypoallometric scaling of genitalic traits implies stabilizing selection. We discuss the implications of this finding and propose future directions for improving our current understanding of genital evolution in arthropods.

  15. Survival and growth of selected pathogens in fermented kocho (Ensete ventricosum).

    Science.gov (United States)

    Nigatu, A; Gashe, B A

    1994-08-01

    A study was conducted to investigate the antagonistic potential of fermented kocho, aqueous extract of fermented kocho and spent media from lactic acid bacteria (LAB) isolated from it on Salmonella sp, Pseudomonas aeruginosa, Klebsiella sp, Bacillus cereus and Staphylococcus aureus. Fermented kocho (pH 4.3) inhibited growth of the test bacteria soon after their introduction into the food. The spent media from all of the four LAB, isolated from fermented kocho, namely Pediococcus sp, Leuconostoc sp, Lactobacillus sp and Streptococcus sp prevented the survival and growth of the test bacteria. The spent medium from Streptococcus sp showed the best antagonistic effect amongst all the LAB isolates. In all cases the inhibitory effects were independent of pH.

  16. The effect of selected fungicides on survival of Agrobacterium tumefaciens in various kinds of soils

    Directory of Open Access Journals (Sweden)

    Stanisław Barczyński

    2013-12-01

    Full Text Available The effect of 10 fungicides on survival of A. tumefaciens in various types of soils was studied. In fertile, nonsterile soil Dithane M-45 (mancozeb, Euparen 50 WP (tolyfluanid, Kaptan 50 WP (captan and Ridomil Gold 80 WP (metalaxyl at concentration of 1000 ppm showed the highest antibacterial activity. Similar trends in activity of these fungicides occurred in fertile, sterile soil, however a little lower in case of Kaptan and Euparen. In most of investigated soils Befran 25 SL (imimnoctadyne, Syllit 65 WP (dodine and Thiram Granulfo 80 WG (thiram increased bacteria number. In sandy acidic soil (pH 3,5 all tested fungicides totally eliminated bacteria. On the other hand in sandy neutral soil only Dithane, Euparen, Kaptan and Ridomil showed such activity. Ten fold decrease of fungicides concentration generally did not influence Kaptan and Ridomil effectiveness but it decreased the activity of Dithane and Euparen.

  17. Evolutionary dynamics of a sexual ornament in the house sparrow (Passer domesticus): the role of indirect selection within and between sexes.

    Science.gov (United States)

    Jensen, Henrik; Steinsland, Ingelin; Ringsby, Thor Harald; Saether, Bernt-Erik

    2008-06-01

    The relative contribution of sexual and natural selection to evolution of sexual ornaments has rarely been quantified under natural conditions. In this study we used a long-term dataset of house sparrows in which parents and offspring were matched genetically to estimate the within- and across-sex genetic basis for variation and covariation among morphological traits. By applying two-sex multivariate "animal models" to estimate genetic parameters, we estimated evolutionary changes in a male sexual ornament, badge size, from the contribution of direct and indirect selection on correlated traits within males and females, after accounting for overlapping generations and age-structure. Indirect natural selection on genetically correlated traits in males and females was the major force causing evolutionary change in the male ornament. Thus, natural selection on female morphology may cause indirect evolutionary changes in male ornaments. We observed however no directional phenotypic change in the ornament size of one-year-old males during the study period. On the other hand, changes were recorded in other morphological characters of both sexes. Our analyses of evolutionary dynamics in sexual characters require application of appropriate two-sex models to account for how selection on correlated traits in both sexes affects the evolutionary outcome of sexual selection.

  18. An Assessment of Religious Threats to Security and Survival of Democracy in Nigeria: A Case Study of the Incessant Killings of Igbos in Some Selected Northern States

    National Research Council Canada - National Science Library

    Christian Chima Chukwu

    2014-01-01

    Religious threats continue to pose a real threat to security and survival of the nascent democracy in Nigeria, especially with the widespread and incessant killings of Igbos in some selected Northern States...

  19. Sexually Selected Sex Differences in Competitiveness Explain Sex Differences in Changes in Drinking Game Participation

    Directory of Open Access Journals (Sweden)

    Liana S. E. Hone

    2015-04-01

    Full Text Available Drinking games are a risk factor for behavioral and health problems among university students. Previous cross-sectional research by Hone, Carter, and McCullough (2013 replicated well-established sex differences in drinking game behaviors (i.e., that men are more active drinking game participants than are women and university drinking problems more generally. Hone et al. (2013 also found that these male-specific behavioral patterns are attributable in part to the fact that men's generally unrestricted sexual strategies, plus their social competitiveness, motivate them to participate in drinking games to display their fortitude and compete with same-sex rivals. Here, the authors conducted a study to evaluate with greater causal rigor whether sex differences in sexual restrictedness and social competitiveness—and sex differences in motivations for participating in drinking games in particular—are partially responsible for the sex differences in university students' drinking game behaviors and drinking problems. Sex differences in changes in frequency of drinking game participation were partially mediated by competitive motivations for participating in drinking games and by the effects of social competitiveness on competitive drinking game motivation. These findings lend additional support to the proposition that participation in drinking games is motivated in part by their suitability as a venue for sexual competition in university students' day-to-day lives.

  20. Reconstructing the origin of Helianthus deserticola: Survival and selection on the desert floor

    NARCIS (Netherlands)

    Gross, B.L.; Kane, D.L.; Lexer, C.; Ludwig, F.; Rosenthal, D.R.; Donovan, L.A.; Rieseberg, L.H.

    2004-01-01

    The diploid hybrid species Helianthus deserticola inhabits the desert floor, an extreme environment relative to its parental species Helianthus annuus and Helianthus petiolaris. Adaptation to the desert floor may have occurred via selection acting on transgressive, or extreme, traits in early

  1. Sexual selection in the squirrel treefrog Hyla squirella: the role of multimodal cue assessment in female choice

    Science.gov (United States)

    Taylor, Ryan C.; Buchanan, Bryant W.; Doherty, Jessie L.

    2007-01-01

    Anuran amphibians have provided an excellent system for the study of animal communication and sexual selection. Studies of female mate choice in anurans, however, have focused almost exclusively on the role of auditory signals. In this study, we examined the effect of both auditory and visual cues on female choice in the squirrel treefrog. Our experiments used a two-choice protocol in which we varied male vocalization properties, visual cues, or both, to assess female preferences for the different cues. Females discriminated against high-frequency calls and expressed a strong preference for calls that contained more energy per unit time (faster call rate). Females expressed a preference for the visual stimulus of a model of a calling male when call properties at the two speakers were held the same. They also showed a significant attraction to a model possessing a relatively large lateral body stripe. These data indicate that visual cues do play a role in mate attraction in this nocturnal frog species. Furthermore, this study adds to a growing body of evidence that suggests that multimodal signals play an important role in sexual selection.

  2. Habitat selection of stone and starry flounders in an estuary in relation to feeding and survival

    Science.gov (United States)

    Tomiyama, Takeshi; Omori, Michio

    2008-09-01

    Juveniles of both stone flounder Platichthys bicoloratus and starry flounder Platichthys stellatus utilize estuaries as nursery grounds. To understand their habitat selection and the functions of habitats such as food supply, we defined the seasonal distribution of recently settled fish of these species in shallow nursery areas and investigated their feeding habits in the Natori River estuary, Japan. Distribution of stone flounder was limited to the lower estuary (olivacea and the mysid Neomysis awatschensis, respectively; however, 1- and 2-yr-old fish of both stone and starry flounders fed mainly on the bivalve siphons. These results indicate that habitat selections of juvenile stone and starry flounders enable utilization of preferred prey and predator avoidance, respectively, and that non-overlap of these species' habitats results in avoidance of inter-specific competition for food between these two species.

  3. Survival of the Friendliest: Homo sapiens Evolved via Selection for Prosociality.

    Science.gov (United States)

    Hare, Brian

    2017-01-03

    The challenge of studying human cognitive evolution is identifying unique features of our intelligence while explaining the processes by which they arose. Comparisons with nonhuman apes point to our early-emerging cooperative-communicative abilities as crucial to the evolution of all forms of human cultural cognition, including language. The human self-domestication hypothesis proposes that these early-emerging social skills evolved when natural selection favored increased in-group prosociality over aggression in late human evolution. As a by-product of this selection, humans are predicted to show traits of the domestication syndrome observed in other domestic animals. In reviewing comparative, developmental, neurobiological, and paleoanthropological research, compelling evidence emerges for the predicted relationship between unique human mentalizing abilities, tolerance, and the domestication syndrome in humans. This synthesis includes a review of the first a priori test of the self-domestication hypothesis as well as predictions for future tests.

  4. EFFECT OF WATER EXTRACT FROM MINT ON SELECTED CROP PESTS FEEDING AND SURVIVAL

    Directory of Open Access Journals (Sweden)

    Barbara Biniaś

    2017-03-01

    Full Text Available The aim of the study was to determine the effect of aqueous extracts of dried mint (Mentha piperita L. in concentrations of 2%, 5% and 10%, and fresh parts of this plant, in concentrations of 10%, 20% and 30% on feeding of pea leaf weevil (Sitona lineatus L. and survival of black bean aphid (Aphis fabae Scop. on the leaves of broad bean (Vicia faba L. variety "Bartek". In the studies of the effects of aqueous extracts of mint on the dynamics of Sitona lineatus feeding on the beans leaves, 9 laboratory’s observations in 12-hour intervals was made. Leaves injuries on their edge surface caused by adult individuals were measured. Observations were carried out in 6 replicates divided into males and females. In these researches on impact of water extracts from mint on mortality of wingless females and larvae of black bean aphids, 14 laboratory’s observations in the 8-hour intervals was made. Aqueous extracts of dry and fresh peppermint significantly limited the feeding of pea leaf weevil females, and the extracts from dried material were more effective. Extracts from peppermint to a greater extent caused mortality of black bean aphid larvae compared to wingless females, and the higher the concentration of the extract the more beneficial effect was observed. An extract from dried material at a concentration of 2% was too weak to effectively combat the larvae of A. fabae, while in the case of aphid females, an effectiveness was only demonstrated for the extracts at the highest concentrations, i.e., 10% of dried and 30% of fresh peppermint.

  5. Statistical methods in detecting differential expressed genes, analyzing insertion tolerance for genes and group selection for survival data

    Science.gov (United States)

    Liu, Fangfang

    The thesis is composed of three independent projects: (i) analyzing transposon-sequencing data to infer functions of genes on bacteria growth (chapter 2), (ii) developing semi-parametric Bayesian method for differential gene expression analysis with RNA-sequencing data (chapter 3), (iii) solving group selection problem for survival data (chapter 4). All projects are motivated by statistical challenges raised in biological research. The first project is motivated by the need to develop statistical models to accommodate the transposon insertion sequencing (Tn-Seq) data, Tn-Seq data consist of sequence reads around each transposon insertion site. The detection of transposon insertion at a given site indicates that the disruption of genomic sequence at this site does not cause essential function loss and the bacteria can still grow. Hence, such measurements have been used to infer the functions of each gene on bacteria growth. We propose a zero-inflated Poisson regression method for analyzing the Tn-Seq count data, and derive an Expectation-Maximization (EM) algorithm to obtain parameter estimates. We also propose a multiple testing procedure that categorizes genes into each of the three states, hypo-tolerant, tolerant, and hyper-tolerant, while controlling false discovery rate. Simulation studies show our method provides good estimation of model parameters and inference on gene functions. In the second project, we model the count data from RNA-sequencing experiment for each gene using a Poisson-Gamma hierarchical model, or equivalently, a negative binomial (NB) model. We derive a full semi-parametric Bayesian approach with Dirichlet process as the prior for the fold changes between two treatment means. An inference strategy using Gibbs algorithm is developed for differential expression analysis. We evaluate our method with several simulation studies, and the results demonstrate that our method outperforms other methods including the popularly applied ones such as edge

  6. Immune Investment Is Explained by Sexual Selection and Pace-of-Life, but Not Longevity in Parrots (Psittaciformes)

    Science.gov (United States)

    Edwards, Darryl B.

    2012-01-01

    Investment in current reproduction should come at the expense of traits promoting future reproduction, such as immunity and longevity. To date, comparative studies of pace-of-life traits have provided some support for this, with slower paced species having greater immune function. Another means of investment in current reproduction is through secondary sexual characters (SSC). Investment in SSC's is considered costly, both in terms of immunity and longevity, with greater costs being borne by species with more elaborate traits. Yet within species, females prefer more ornate males and those males are typically immunologically superior. Because of this, predictions about the relationship between immunity and SSC's across species are not clear. If traits are costly, brighter species should have reduced immune function, but the opposite is true if SSC's arise from selection for more immunocompetent individuals. My approach was to investigate immune investment in relation to SSC's, pace-of-life and longevity while considering potentially confounding ecological factors. To do so I assessed leukocyte counts from in a novel group, the Psittaciformes. Investment in SSC's best explained investment in immunity: species with brighter plumage had higher leukocyte counts and those with a greater degree of sexual dichromatism had fewer. Ecological variables and pace-of-life models tended to be poor predictors of immune investment. However, shorter incubation periods were associated with lower leukocyte counts supporting the notion that species with a fast pace-of-life invest less in immunity. These results suggest that investment in reproduction in terms of fast pace-of-life and sexual dichromatism results in reduced immunity; however, investment in plumage colour per se does not impose a cost on immunity across species. PMID:23300862

  7. Immune investment is explained by sexual selection and pace-of-life, but not longevity in parrots (Psittaciformes.

    Directory of Open Access Journals (Sweden)

    Darryl B Edwards

    Full Text Available Investment in current reproduction should come at the expense of traits promoting future reproduction, such as immunity and longevity. To date, comparative studies of pace-of-life traits have provided some support for this, with slower paced species having greater immune function. Another means of investment in current reproduction is through secondary sexual characters (SSC. Investment in SSC's is considered costly, both in terms of immunity and longevity, with greater costs being borne by species with more elaborate traits. Yet within species, females prefer more ornate males and those males are typically immunologically superior. Because of this, predictions about the relationship between immunity and SSC's across species are not clear. If traits are costly, brighter species should have reduced immune function, but the opposite is true if SSC's arise from selection for more immunocompetent individuals. My approach was to investigate immune investment in relation to SSC's, pace-of-life and longevity while considering potentially confounding ecological factors. To do so I assessed leukocyte counts from in a novel group, the Psittaciformes. Investment in SSC's best explained investment in immunity: species with brighter plumage had higher leukocyte counts and those with a greater degree of sexual dichromatism had fewer. Ecological variables and pace-of-life models tended to be poor predictors of immune investment. However, shorter incubation periods were associated with lower leukocyte counts supporting the notion that species with a fast pace-of-life invest less in immunity. These results suggest that investment in reproduction in terms of fast pace-of-life and sexual dichromatism results in reduced immunity; however, investment in plumage colour per se does not impose a cost on immunity across species.

  8. Mental health selection and income support dynamics: multiple spell discrete-time survival analyses of welfare receipt.

    Science.gov (United States)

    Kiely, Kim M; Butterworth, Peter

    2014-04-01

    The higher occurrence of common psychiatric disorders among welfare recipients has been attributed to health selection, social causation and underlying vulnerability. The aims of this study were to test for the selection effects of mental health problems on entry and re-entry to working-age welfare payments in respect to single parenthood, unemployment and disability. Nationally representative longitudinal data were drawn from the Household Income and Labour Dynamics in Australia survey. Multiple spell discrete-time survival analyses were conducted using multinomial logistic regression models to test if pre-existing mental health problems predicted transitions to welfare. Analyses were stratified by sex and multivariate adjusted for mental health problems, father's occupation, socioeconomic position, marital status, employment history, smoking status and alcohol consumption, physical function and financial hardship. All covariates were modelled as either lagged effects or when a respondent was first observed to be at risk of income support. Mental health problems were associated with increased risk of entry and re-entry to disability, unemployment and single parenting payments for women, and disability and unemployment payments for men. These associations were attenuated but remained significant after adjusting for contemporaneous risk factors. Although we do not control for reciprocal causation, our findings are consistent with a health selection hypothesis and indicate that mental illness may be a contributing factor to later receipt of different types of welfare payments. We argue that mental health warrants consideration in the design and targeting of social and economic policies.

  9. Effects of a selective regimen of dry cow therapy on intramammary infection and on antibiotic sensitivity of surviving pathogens.

    Science.gov (United States)

    Schultze, W D

    1983-04-01

    Selective dry cow therapy with 1 million U of procaine penicillin G and 1 g of dihydrostreptomycin in a slow-release base was administered to all quarters of cows currently infected or treated for mastitis in the previous lactation. All other cows in the herd that were dried off during the experimental period were left untreated. Milk samples were cultured for detection of intramammary infection at drying off, 1 wk later (at time of treatment), and after next calving from 227 treated and 143 untreated cows. Isolants were tested for sensitivity to 12 antibiotics including penicillin and streptomycin. Although treatment resulted in clearance of Staphylococcus aureus, Staphylococcus epidermidis, streptococci other than agalactiae, and coliforms from 78, 82, 88, and 87% of infected glands, the net effect on udder health of the herd was a gain of 1.4% in infected quarters. Incidences of new infection in the early dry period (1 wk) were 18.1 and 12.3% among treated and untreated cows. Therapy failed to control new infection in the late dry and peripartum periods; incidence was about 18% of quarters among both long and short dry periods. Among 46 instances of apparent survival of an intramammary pathogen through a treated dry period, 7 of 10 strains previously sensitive to streptomycin became resistant and 8 of 10 strains previously sensitive to penicillin became resistant. The surviving pathogen population was not large enough to be considered a threat to herd udder health in the next lactation.

  10. Effects of 17beta-estradiol on survival, growth, sexual development and molting cycles of the marine crustacean mysid shrimp, Americamysis bahia.

    Science.gov (United States)

    Hirano, Masashi; Ishibashi, Hiroshi; Watanabe, Naoko; Matsumura, Naomi; Watanabe, Akiko; Onikura, Norio; Kishi, Katsuyuki; Shiratsuchi, Hideki; Arizono, Koji

    2004-01-01

    A 14-day partial life-cycle test was performed to assess the effects of 17beta-estradiol (E2) on the survival, growth, sexual development and molting cycles of a marine crustacean mysid shrimp (Americamysis bahia). Seven-day-old mysids were exposed to the nominal E2 concentrations of 31.3, 62.5, 125, 250 and 500 microg/l for 14 days. The total length and the body weight of mysids significantly decreased relative to the controls when exposed to 62.5, 250 and 500 microg/l E2 for 14 days. Moreover, the carapace length significantly decreased in the 500 microg/l E2 treatment groups. No significant differences were observed in sex ratio with the appearance of secondary sex characteristics in the all treatment groups including the control and solvent control groups. However, the percentage of females with eggs in the oviduct or brood sac decreased significantly in mysids treated with E2 at 62.5, 125, 250 and 500 microg/l. The cumulative total number of molting cycles when exposed to E2 for 14 days significantly decreased in the treatment groups at 500 microg/l relative to the controls. These results suggest that concentrations of E2 over 62.5 microg/l may cause growth suppression in mysid shrimp, and that the disruption of molting cycles may result in alterations in growth due to a sublethal response to toxicant exposure.

  11. Survival of the Curviest: Noise-Driven Selection for Synergistic Epistasis.

    Directory of Open Access Journals (Sweden)

    Jon F Wilkins

    2016-04-01

    Full Text Available A major goal of human genetics is to elucidate the genetic architecture of human disease, with the goal of fueling improvements in diagnosis and the understanding of disease pathogenesis. The degree to which epistasis, or non-additive effects of risk alleles at different loci, accounts for common disease traits is hotly debated, in part because the conditions under which epistasis evolves are not well understood. Using both theory and evolutionary simulation, we show that the occurrence of common diseases (i.e. unfit phenotypes with frequencies on the order of 1% can, under the right circumstances, be expected to be driven primarily by synergistic epistatic interactions. Conditions that are necessary, collectively, for this outcome include a strongly non-linear phenotypic landscape, strong (but not too strong selection against the disease phenotype, and "noise" in the genotype-phenotype map that is both environmental (extrinsic, time-correlated and developmental (intrinsic, uncorrelated and, in both cases, neither too little nor too great. These results suggest ways in which geneticists might identify, a priori, those disease traits for which an "epistatic explanation" should be sought, and in the process better focus ongoing searches for risk alleles.

  12. Postmating sexual selection favors males that sire offspring with low fitness

    DEFF Research Database (Denmark)

    Bilde, T.; Foged, Anne; Schilling, Nadia

    2009-01-01

    and offspring fitness in a seed beetle and then tested whether fertilization success was biased in favor of high-quality male genotypes in double mating experiments. Contrary to expectations, high-quality male genotypes consistently had a lower postmating fertilization success in two independent assays. Our......Despite the costs of mating, females of most taxa mate with multiple males. Polyandrous females are hypothesized to gain genetic benefits for their offspring, but this assumes paternity bias favoring male genotypes that enhance offspring viability. We determined net male genetic effects on female...... results imply that sexually antagonistic adaptations have a major and unappreciated influence on male postmating fertilization success. Such genetic variation renders indirect genetic benefits an unlikely driver of the evolution of polyandry....

  13. Mutants of Sexual Maturity in PARAMECIUM CAUDATUM Selected by Erythromycin Resistance

    Science.gov (United States)

    Myohara, Koji; Hiwatashi, Koichi

    1978-01-01

    Cells of Paramecium caudatum, syngen 3 usually become sexually mature about 50 fissions after conjugation. In order to study the genetic mechanisms that control fission-dependent expression of maturity, an attempt was made to obtain early mature mutants by treatment with N-methyl-N'-nitro-N-nitro-soguanidine. A new cytoplasmic marker, erythromycin resistance, was used to eliminate nonconjugant and macronuclear regeneration clones. Twenty early mature clones were obtained from five different mutagenized cultures. Three of them were genetically analyzed by crosses to wild-type stocks. The results show all three mutants to be controlled by incompletely dominant genes, i.e., the homozygotes became mature 20-25 fissions and the heterozygotes 15 fissions earlier than the wild-type clones. At least two different loci are suggested for the early maturity. PMID:730047

  14. Sexually selected traits evolve positive allometry when some matings occur irrespective of the trait.

    Science.gov (United States)

    Fromhage, Lutz; Kokko, Hanna

    2014-05-01

    Positive allometry of secondary sexual traits (whereby larger individuals have disproportionally larger traits than smaller individuals) has been called one of the most pervasive and poorly understood regularities in the study of animal form and function. Its widespread occurrence is in contrast with theoretical predictions that it should evolve only under rather special circumstances. Using a combination of mathematical modeling and simulations, here we show that positive allometry is predicted to evolve under much broader conditions than previously recognized. This result hinges on the assumption that mating success is not necessarily zero for males with the lowest trait values: for example, a male who lacks horns or antlers might still be able to copulate if encountering an unguarded female. We predict the strongest positive allometry when males typically (but not always) compete in large groups, and when trait differences decisively determine the outcome of competitive interactions. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

  15. An expressed sequence tag (EST library for Drosophila serrata, a model system for sexual selection and climatic adaptation studies

    Directory of Open Access Journals (Sweden)

    McGraw Elizabeth A

    2009-01-01

    Full Text Available Abstract Background The native Australian fly Drosophila serrata belongs to the highly speciose montium subgroup of the melanogaster species group. It has recently emerged as an excellent model system with which to address a number of important questions, including the evolution of traits under sexual selection and traits involved in climatic adaptation along latitudinal gradients. Understanding the molecular genetic basis of such traits has been limited by a lack of genomic resources for this species. Here, we present the first expressed sequence tag (EST collection for D. serrata that will enable the identification of genes underlying sexually-selected phenotypes and physiological responses to environmental change and may help resolve controversial phylogenetic relationships within the montium subgroup. Results A normalized cDNA library was constructed from whole fly bodies at several developmental stages, including larvae and adults. Assembly of 11,616 clones sequenced from the 3' end allowed us to identify 6,607 unique contigs, of which at least 90% encoded peptides. Partial transcripts were discovered from a variety of genes of evolutionary interest by BLASTing contigs against the 12 Drosophila genomes currently sequenced. By incorporating into the cDNA library multiple individuals from populations spanning a large portion of the geographical range of D. serrata, we were able to identify 11,057 putative single nucleotide polymorphisms (SNPs, with 278 different contigs having at least one "double hit" SNP that is highly likely to be a real polymorphism. At least 394 EST-associated microsatellite markers, representing 355 different contigs, were also found, providing an additional set of genetic markers. The assembled EST library is available online at http://www.chenowethlab.org/serrata/index.cgi. Conclusion We have provided the first gene collection and largest set of polymorphic genetic markers, to date, for the fly D. serrata. The EST

  16. Correlated responses to long-term divergent selection for 8-week body weight in female White Plymouth Rock chickens: Sexual maturity.

    Science.gov (United States)

    Jambui, M; Honaker, C F; Siegel, P B

    2017-09-01

    Reported here are correlated responses for reproductive traits to long-term divergent selection (54 generations) for 8-week body weight (BW8). Comparisons involved both selected and relaxed lines. Traits measured were age at first egg (AFE), body weight at first egg (WFE), and ratio of body weight and age at first egg (WAFE). Although sexual maturity was delayed in the selected lines, the effect was more pronounced in the low than high selected and relaxed lines. Selection for low BW resulted in decreases in WFE and WAFE. Correlated responses to selection for high BW were increased WFE and WAFE. Minimum AFE, WFE, and WAFE in relation to sexual maturity were line specific and influenced by selection for BW8. WAFE provided a "yardstick" for target body weights that were optimum for successful attainment of sexual maturity and higher reproductive rates. Such may be line specific. There was opposition between relaxed and artificial selection, resulting in a higher reproductive performance and fitness for the former. © 2017 Poultry Science Association Inc.

  17. Sexual Identity, Sex of Sexual Contacts, and Health-Related Behaviors Among Students in Grades 9-12 - United States and Selected Sites, 2015.

    Science.gov (United States)

    Kann, Laura; Olsen, Emily O'Malley; McManus, Tim; Harris, William A; Shanklin, Shari L; Flint, Katherine H; Queen, Barbara; Lowry, Richard; Chyen, David; Whittle, Lisa; Thornton, Jemekia; Lim, Connie; Yamakawa, Yoshimi; Brener, Nancy; Zaza, Stephanie

    2016-08-12

    Sexual identity and sex of sexual contacts can both be used to identify sexual minority youth. Significant health disparities exist between sexual minority and nonsexual minority youth. However, not enough is known about health-related behaviors that contribute to negative health outcomes among sexual minority youth and how the prevalence of these health-related behaviors compare with the prevalence of health-related behaviors among nonsexual minorities. September 2014-December 2015. The Youth Risk Behavior Surveillance System (YRBSS) monitors six categories of priority health-related behaviors among youth and young adults: 1) behaviors that contribute to unintentional injuries and violence; 2) tobacco use; 3) alcohol and other drug use; 4) sexual behaviors related to unintended pregnancy and sexually transmitted infections, including human immunodeficiency virus infection; 5) unhealthy dietary behaviors; and 6) physical inactivity. In addition, YRBSS monitors the prevalence of obesity and asthma and other priority health-related behaviors. YRBSS includes a national school-based Youth Risk Behavior Survey (YRBS) conducted by CDC and state and large urban school district school-based YRBSs conducted by state and local education and health agencies. For the 2015 YRBSS cycle, a question to ascertain sexual identity and a question to ascertain sex of sexual contacts was added for the first time to the national YRBS questionnaire and to the standard YRBS questionnaire used by the states and large urban school districts as a starting point for their YRBS questionnaires. This report summarizes results for 118 health-related behaviors plus obesity, overweight, and asthma by sexual identity and sex of sexual contacts from the 2015 national survey, 25 state surveys, and 19 large urban school district surveys conducted among students in grades 9-12. Across the 18 violence-related risk behaviors nationwide, the prevalence of 16 was higher among gay, lesbian, and bisexual

  18. Steller sex: infidelity and sexual selection in a social Corvid (Cyanocitta stelleri).

    Science.gov (United States)

    Overeem, Katlin R; Gabriel, Pia O; Zirpoli, Jeff A; Black, Jeffrey M

    2014-01-01

    Genetic analysis of avian mating systems has revealed that more than 70% of monogamous species show incidence of offspring parentage that does not match the social partner. Extra-pair parentage (EPP) has been linked to a variety of factors, including size and symmetry of ornamental traits, coloration, resource availability, and local conspecific density. We examined how ornamental plumage traits of individual Steller's jays (Cyanocitta stelleri) and territory characteristics influence genetic fidelity of socially monogamous pairs. We used seven highly polymorphic microsatellite markers to assign paternity to 79 offspring, and identified 12 (15.2%) as extra-pair young (EPY). Steller's jays with extra-pair young had significantly lower values of feather brightness and hue, indicating more ultraviolet-blue shifted coloration, and nested in closer proximity to the forest edge than Steller's jays with no detected EPY. Body size, crest height, asymmetry of ornamental crest stripes, as well as vegetative composition of territories and their proximity to supplemental feeders appeared to have little relationship to EPP. These results indicate that extra-pair parentage plays a role in the evolution of secondary sexual characteristics in both sexes, and suggest local density and availability of resources may influence Steller's jay mating dynamics.

  19. Steller sex: infidelity and sexual selection in a social Corvid (Cyanocitta stelleri.

    Directory of Open Access Journals (Sweden)

    Katlin R Overeem

    Full Text Available Genetic analysis of avian mating systems has revealed that more than 70% of monogamous species show incidence of offspring parentage that does not match the social partner. Extra-pair parentage (EPP has been linked to a variety of factors, including size and symmetry of ornamental traits, coloration, resource availability, and local conspecific density. We examined how ornamental plumage traits of individual Steller's jays (Cyanocitta stelleri and territory characteristics influence genetic fidelity of socially monogamous pairs. We used seven highly polymorphic microsatellite markers to assign paternity to 79 offspring, and identified 12 (15.2% as extra-pair young (EPY. Steller's jays with extra-pair young had significantly lower values of feather brightness and hue, indicating more ultraviolet-blue shifted coloration, and nested in closer proximity to the forest edge than Steller's jays with no detected EPY. Body size, crest height, asymmetry of ornamental crest stripes, as well as vegetative composition of territories and their proximity to supplemental feeders appeared to have little relationship to EPP. These results indicate that extra-pair parentage plays a role in the evolution of secondary sexual characteristics in both sexes, and suggest local density and availability of resources may influence Steller's jay mating dynamics.

  20. Pharmacophagy of methyl eugenol by males enhances sexual selection of Bactrocera carambolae.

    Science.gov (United States)

    Wee, Suk-Ling; Tan, Keng-Hong; Nishida, Ritsuo

    2007-06-01

    After pharmacophagy of methyl eugenol (ME), males of Bactrocera carambolae (Diptera: Tephritidae) produced (E)-coniferyl alcohol (CF) along with its endogenously synthesized pheromonal compounds. CF was shown to be released into the air by the ME-fed males only during the courtship period at dusk and attracted significantly more males and females than the ME-deprived males in wind tunnel assays. However, earlier onset of sexual attraction and a higher mating success were observed only in the wind tunnel and field cage assays on the third day posttreatment of ME. Field cage observations on the male-to-male interaction indicated that the ME-deprived males did not exhibit aggregation behavior, but that ME feeding promoted aggregation behavior in B. carambolae. Field cage observations revealed that the ME-deprived males were not only attracted to the ME-fed males, but also appeared to feed on their anal secretions. The secretions were subsequently confirmed to contain CF along with endogenously produced pheromonal compounds. Results obtained for B. carambolae were compared to those previously obtained from its sibling species, Bactrocera dorsalis, and are discussed in light of species advancement in fruit fly-plant relationships.

  1. Survival of the fittest before the beginning of life: selection of the first oligonucleotide-like polymers by UV light

    Directory of Open Access Journals (Sweden)

    Cherepanov Dmitry A

    2003-05-01

    Full Text Available Abstract Background A key event in the origin of life on this planet has been formation of self-replicating RNA-type molecules, which were complex enough to undergo a Darwinian-type evolution (origin of the "RNA world". However, so far there has been no explanation of how the first RNA-like biopolymers could originate and survive on the primordial Earth. Results As condensation of sugar phosphates and nitrogenous bases is thermodynamically unfavorable, these compounds, if ever formed, should have undergone rapid hydrolysis. Thus, formation of oligonucleotide-like structures could have happened only if and when these structures had some selective advantage over simpler compounds. It is well known that nitrogenous bases are powerful quenchers of UV quanta and effectively protect the pentose-phosphate backbones of RNA and DNA from UV cleavage. To check if such a protection could play a role in abiogenic evolution on the primordial Earth (in the absence of the UV-protecting ozone layer, we simulated, by using Monte Carlo approach, the formation of the first oligonucleotides under continuous UV illumination. The simulations confirmed that UV irradiation could have worked as a selective factor leading to a relative enrichment of the system in longer sugar-phosphate polymers carrying nitrogenous bases as UV-protectors. Partial funneling of the UV energy into the condensation reactions could provide a further boost for the oligomerization. Conclusion These results suggest that accumulation of the first polynucleotides could be explained by their abiogenic selection as the most UV-resistant biopolymers.

  2. Distinguishing the effects of familiarity, relatedness, and color pattern rarity on attractiveness and measuring their effects on sexual selection in guppies (Poecilia reticulata).

    Science.gov (United States)

    Zajitschek, Susanne R K; Brooks, Robert C

    2008-12-01

    Mate choice is often based on multiple signal traits and can be influenced by context-dependent factors. Understanding the importance of these signals and factors can be difficult because they are often correlated and might interact. Here, we experimentally disentangle the effects of familiarity, kinship, pattern rarity, and ornament patterns on mate choice in guppies. We estimate whether these factors alter sexual selection on six phenotypic traits known to influence male attractiveness. Rarity of the male's phenotype is the only context-dependent factor that significantly influenced female mating decisions, with common patterns being least attractive. This preference for rare male patterns is a source of negative frequency-dependent selection that may contribute to maintaining the extreme polymorphism in male guppy coloration. Neither visual familiarity nor relatedness between mating partners had any significant effect on mate choice decisions. There was significant linear and nonlinear sexual selection on ornamental traits, but this was not influenced by the context-dependent measures. Our approach highlights the complexity of female mate choice and sexual selection, as well as the value of combining multifactorial experiments with multivariate selection analyses. Our study shows that both negative frequency-dependent selection and disruptive selection contribute to the maintenance of extreme polymorphism in guppies.

  3. Balancing Instrumental and Identity Goals in Relationships: The Role of Request Directness and Request Persistence in the Selection of Sexual Resistance Strategies.

    Science.gov (United States)

    Afifi, Walid A.; Lee, Josephine W.

    2000-01-01

    Applies the general frameworks of Politeness Theory and Planning Theory to explain the selection of sexual resistance strategies among undergraduates following both initial and persisting requests. Investigates contingent effects of request directness on characteristics of the resistance message. Tests influence of resister sex on strategy choice.…

  4. Not all sex ratios are equal: the Fisher condition, parental care and sexual selection.

    Science.gov (United States)

    Jennions, Michael D; Fromhage, Lutz

    2017-09-19

    The term 'sex roles' encapsulates male-female differences in mate searching, competitive traits that increase mating/fertilization opportunities, choosiness about mates and parental care. Theoretical models suggest that biased sex ratios drive the evolution of sex roles. To model sex role evolution, it is essential to note that in most sexually reproducing species (haplodiploid insects are an exception), each offspring has one father and one mother. Consequently, the total number of offspring produced by each sex is identical, so the mean number of offspring produced by individuals of each sex depends on the sex ratio (Fisher condition). Similarly, the total number of heterosexual matings is identical for each sex. On average, neither sex can mate nor breed more often when the sex ratio is even. But equally common in which sex ratio? The Fisher condition only applies to some reproductive measures (e.g. lifetime offspring production or matings) for certain sex ratios (e.g. operational or adult sex ratio; OSR, ASR). Here, we review recent models that clarify whether a biased OSR, ASR or sex ratio at maturation (MSR) have a causal or correlational relationship with the evolution of sex differences in parental care and competitive traits-two key components of sex roles. We suggest that it is more fruitful to understand the combined effect of the MSR and mortality rates while caring and competing than that of the ASR itself. In short, we argue that the ASR does not have a causal role in the evolution of parental care. We point out, however, that the ASR can be a cue for adaptive phenotypic plasticity in how each sex invests in parental care.This article is part of the themed issue 'Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies'. © 2017 The Author(s).

  5. Mate Choice in Soldier Beetles: Field & Laboratory Experiments that Demonstrate Sexual Selection in Action

    Science.gov (United States)

    Eason, Perri K.; Sherman, Peter T.

    2003-01-01

    Although the theory of evolution is the foundation of modern biology, students too rarely have an opportunity to watch selection operate in natural populations of animals. This lack may be partially responsible for the unfortunate ignorance of many people regarding the significance of evolution in biology. Laboratory exercises that directly study…

  6. Sexual selection promotes colonial breeding in shell-brooding cichlid fish

    NARCIS (Netherlands)

    Schuetz, Dolores; Ocana, Sabine Wirtz; Maan, martine E.; Taborsky, Michael

    Colonial species breed in densely aggregated territories containing no resources other than nest sites. This behaviour is usually explained by natural selection, for instance through benefits resulting from reduced predation risk. An alternative hypothesis suggests that, as in lek breeding systems,

  7. Neutral and selection-driven decay of sexual traits in asexual stick insects

    NARCIS (Netherlands)

    Schwander, Tanja; Crespi, Bernard J.; Gries, Regine; Gries, Gerhard

    2013-01-01

    Environmental shifts and lifestyle changes may result in formerly adaptive traits becoming non-functional or maladaptive. The subsequent decay of such traits highlights the importance of natural selection for adaptations, yet its causes have rarely been investigated. To study the fate of formerly

  8. Genomic association for sexual precocity in beef heifers using pre-selection of genes and haplotype reconstruction.

    Directory of Open Access Journals (Sweden)

    Luciana Takada

    Full Text Available Reproductive traits are of the utmost importance for any livestock farming, but are difficult to measure and to interpret since they are influenced by various factors. The objective of this study was to detect associations between known polymorphisms in candidate genes related to sexual precocity in Nellore heifers, which could be used in breeding programs. Records of 1,689 precocious and non-precocious heifers from farms participating in the Conexão Delta G breeding program were analyzed. A subset of single nucleotide polymorphisms (SNP located in the region of the candidate genes at a distance of up to 5 kb from the boundaries of each gene, were selected from the panel of 777,000 SNPs of the High-Density Bovine SNP BeadChip. Linear mixed models were used for statistical analysis of early heifer pregnancy, relating the trait with isolated SNPs or with haplotype groups. The model included the contemporary group (year and month of birth as fixed effect and parent of the animal (sire effect as random effect. The fastPHASE® and GenomeStudio® were used for reconstruction of the haplotypes and for analysis of linkage disequilibrium based on r2 statistics. A total of 125 candidate genes and 2,024 SNPs forming haplotypes were analyzed. Statistical analysis after Bonferroni correction showed that nine haplotypes exerted a significant effect (p<0.05 on sexual precocity. Four of these haplotypes were located in the Pregnancy-associated plasma protein-A2 gene (PAPP-A2, two in the Estrogen-related receptor gamma gene (ESRRG, and one each in the Pregnancy-associated plasma protein-A gene (PAPP-A, Kell blood group complex subunit-related family (XKR4 and mannose-binding lectin genes (MBL-1 genes. Although the present results indicate that the PAPP-A2, PAPP-A, XKR4, MBL-1 and ESRRG genes influence sexual precocity in Nellore heifers, further studies are needed to evaluate their possible use in breeding programs.

  9. Sexual Jealousy

    Directory of Open Access Journals (Sweden)

    David M. Buss

    2013-09-01

    Full Text Available Sexual jealousy is a basic emotion. Although it lacks a distinctive facial expression and is unlikely to solve problems of survival, it evolved because it solves adaptive problems of mating. Some adaptive functions are similar in men and women at one level of abstraction, such as warding off potential mate poachers and deterring relationship defection. Other functions are sex-differentiated, such as increasing paternity probability for men and monopolizing a mate's economic commitments for women. Dozens of studies have documented sex-differentiated design features of jealousy: The relative upset about sexual and emotional aspects of infidelity; processing speed and memorial recall of sexual and emotional infidelity cues; physiological distress to sexual and emotional infidelity cues; qualities of same-sex rivals that evoke jealousy, such as superior job prospects versus greater physical attractiveness; triggers of mate retention tactics; jealous interrogations following the discovery of infidelity; and whether an infidelity produces forgiveness or breakup. Although showing all the hallmarks of evolved functionality, sexual jealousy also leads to tremendous destruction, from humiliation to homicide. By these scientific theoretical and empirical criteria, sexual jealousy is properly considered not only "basic" but also "one of the most important emotions".

  10. The Survival of Bifidobacterium infantis 20088 and Physicochemical Changes During Refrigeration Storage of Selected Fermented Traditional Sudanese Fruit Beverages

    Directory of Open Access Journals (Sweden)

    Wala Salah Elden Babekir

    2015-11-01

    Full Text Available This study was carried out to evaluate survival of Bifidobacterium infantis 20088 in fermented beverage formulated from selected traditional Sudanese fruits Gudaim and dom. The viable counts of the strain and physiochemical changes during refrigeration were determined. 10% beverages (w/v were prepared from dom and gudaim powder. 2.5% (w/w skim milk was supplemented to each formulation to provide the required nutrient for bacteria growth during the fermentation. After sterilization and cooling, the mixture was inoculated with a 10% culture of B. infants 20088 followed by incubation for 36 h at 37°C. Reconstituted skim milk was used as control. Fermented beverages were held at refrigeration (4°C for a period of 2 weeks. During the refrigeration storage of the fermented beverages there was significant reduction in Bifidobacterium infantis of all fermented beverages. Nevertheless, the strain was maintained high; fulfill the number required to presence in probiotic foods, which was at least 6 log CFU/ml fermented product. There was no significantly difference in TSS and pH as compared to their initial at the beginning of fermentation except in pH of fermented gudaim. Therefore gudaim and dom are suitable carrier to deliver Bifidobacterium infantis 20088 to consumer.

  11. Sexual behaviour of Cape Town high-school students | Flisher ...

    African Journals Online (AJOL)

    Objectives. To document prevalence rates for selected aspects of sexual behaviour among Cape Town high-school students and to conduct a survival analysis of age at first intercourse. Design. Cross-sectional survey. Setting. State high schools in Cape Town. Subjects. A multistage cluster sample of 2 740 grade 8 and 11 ...

  12. Untold stories: biases and selection effects in research with victims of trafficking for sexual exploitation.

    Science.gov (United States)

    Brunovskis, Anette; Surtees, Rebecca

    2010-01-01

    Recent discussions of trafficking research have included calls for more innovative studies and new methodologies in order to move beyond the current trafficking narrative, which is often based on unrepresentative samples and overly simplified images. While new methods can potentially play a role in expanding the knowledge base on trafficking, this article argues that the solution is not entirely about applying new methods, but as much about using current methods to greater effect and with careful attention to their limitations and ethical constraints. Drawing on the authors' experience in researching trafficking issues in a number of projects over the past decade, the article outlines and exemplifies some of the methodological and ethical issues to be considered and accommodated when conducting research with trafficked persons -- including unrepresentative samples; access to respondents; selection biases by "gatekeepers" and self selection by potential respondents. Such considerations should inform not only how research is undertaken but also how this information is read and understood. Moreover, many of these considerations equally apply when considering the application of new methods within this field. The article maintains that a better understanding of how these issues come into play and inform trafficking research will translate into tools for conducting improved research in this field and, by implication, new perspectives on human trafficking.

  13. Qualitative evaluation of selected social factors that impact sexual risk-taking behaviour among African students in Kwazulu-Natal, South Africa.

    Science.gov (United States)

    Ngidi, Ndumiso Daluxolo; Moyo, Sibusiso; Zulu, Thobile; Adam, Jamila Khatoon; Krishna, Suresh Babu Naidu

    2016-12-01

    The incidence of HIV and AIDS continues to be a source of great concern within universities in South Africa. Furthermore, university students constitute an important community in the intervention against the HIV/AIDS epidemic. Students in the age group of 15-24 years are at a greater risk of HIV infection than any other group in the country; yet, little is known about why they continue to engage in risky sexual practices. This study was designed to explore the sexual behaviour of students in a metropolitan Durban University of Technology in KwaZulu-Natal to understand the social factors underlying their risk of HIV infection. This is a qualitative study that used cluster sampling where the population was stratified by campus and faculty. The study population was selected using a standard randomization technique. This was a part of a multi-phased research project aimed at providing a sero-prevalence baseline and an analysis of risk-taking behaviour at a Durban University of Technology in the eThekwini Metropolitan Municipality area. The study highlights peer pressure among students as an influence in promoting high-risk sexual behaviour. Within this context, the findings revealed that university students lack the ability to negotiate risk-aware decisions especially regarding sexual relationships. This study draws attention to the perspectives of African university students regarding their risk-taking sexual practices and selected factors which influence such behaviour. The findings are not exhaustive in exploring contextual antecedents that shape students' sexual practices. However, they provide an important basis in understanding key factors which expose students to HIV infections. The study provides insights into opportunities for further studies as well as preventative implications.

  14. Selection bias influences reported contralateral breast cancer incidence and survival in high risk non-BRCA1/2 patients

    NARCIS (Netherlands)

    Tilanus-Linthorst, Madeleine M. A.; Bartels, Karina C. M.; Alves, Celina; Bakri, Bonnie; Crepin, Ellen; van den Ouweland, Ans; Klijn, Jan G. M.; Meijers-Heijboer, Hanne; Brekelmans, Cecile T. M.

    2006-01-01

    The results of studies comparing survival in familial and sporadic breast cancer (BC) are inconsistent. A higher incidence of contralateral breast cancer (CBC) has been reported in familial BC. Ascertainment bias may influence both the reported familial CBC and survival. We assessed CBC incidence,

  15. Renal Transplant Register of Andalusia, 2010 Report: survival in relation to the factors used in recipient selection.

    Science.gov (United States)

    Gentil, M A; Pérez-Valdivia, M A; Rodriguez-Benot, A; Sola, E; Osuna, A; Mazuecos, M A; Bedoya, R; Borrego, J; Castro, P; Alonso, M

    2010-10-01

    Kidney transplantation is the best therapeutic alternative for patients suffering from end-stage renal disease (ESRD). In recent years a significant advance has been made in Andalusia in graft and recipient survival as seen in our 2009 publication. In the current work we analyzed 2989 kidney transplantations performed between January 1, 2000 and December 31, 2009 based on data obtained from the Renal Transplant Registry of Andalusia. We studied the influence on graft and patient survival of factors, such as donor and recipient age, HLA matching, HLA immunization, and duration of previous renal replacement therapy. Patient survival was influenced by age at the time of transplantation and by donor age; the younger the donor, the more it was improved. Graft survival was determined by the donor age group, with no differences at each level according to the recipient age group. No significant differences were observed in patient survival or graft or death-censored graft survival according to HLA matching. Patient and graft survivals were significantly affected by the duration of the previous renal replacement therapy. Despite this being a preliminary study, we have shown the importance of nonmodifiable factors in transplant survival, such as donor and recipient age, with HLA matching having a limited effect. These latter findings should be confirmed in the future by multivariate analyses. Copyright © 2010 Elsevier Inc. All rights reserved.

  16. Sexual selection in cane toads Rhinella marina: A male’s body size affects his success and his tactics

    Directory of Open Access Journals (Sweden)

    Haley BOWCOCK, Gregory P. BROWN, Richard SHINE

    2013-12-01

    Full Text Available Male body size can play an important role in the mating systems of anuran amphibians. We conducted laboratory-based trials with cane toads Rhinella (Bufo marina from an invasive population in the wet-dry tropics of northern Australia, to clarify the effects of a male's body size on his reproductive success and behavior (mate choice. Males were stimulated with a synthetic hormone to induce reproductive readiness. Larger body size enhanced a male toad's ability to displace a smaller rival from amplexus, apparently because of physical strength: more force was required to dislodge a larger than a smaller amplectant male. A male’s body size also affected his mate-choice criteria. Males of all body sizes were as likely to attempt amplexus with another male as with a female of the same size, and preferred larger rather than smaller sexual targets. However, this size preference was stronger in larger males and hence, amplexus was size-assortative. This pattern broke down when males were given access to already-amplectant male-female pairs: males of all body sizes readily attempted amplexus with the pair, with no size discrimination. An amplectant pair provides a larger visual stimulus, and prolonged amplexus provides a strong cue for sex identification (one of the individuals involved is almost certainly a female. Thus, a male cane toad’s body size affects both his ability to defeat rivals in physical struggles over females, and the criteria he uses when selecting potential mates, but the impacts of that selectivity depend upon the context in which mating occurs [Current Zoology 59 (6: 747–753, 2013].

  17. Administration of the selective cyclooxygenase (COX)-2 inhibitor etodolac prolongs cardiac allograft survival in a mouse model.

    Science.gov (United States)

    Matsuyama, Masahide; Yoshimura, Rikio; Hase, Taro; Chargui, Jamel; Yoshimura, Norio; Touraine, Jean-Louis

    2010-01-01

    Etodolac, a selective cyclooxygenase-2 (COX-2) inhibitor, is a non-steroidal anti-inflammatory drug. COX-2 is a key factor in the progression of inflammation. Although inflammation is an essential pathologic feature of cardiac allograft rejection, the role of COX-2 in this process remains unclear. The aim of this study was to investigate the expression of COX and the effects of etodolac in a mouse cardiac allograft model. Balb/c mice (H-2d) were used as recipients and C57BL/6 (H-2b) mice as heart donors. Heart function was evaluated daily after transplantation by regular abdominal palpation of the heart and by laparotomy in cases where the beating became weak. Rejection was defined as total cessation of cardiac muscle contraction. COX-2 expression was analyzed by immunohistochemistry. Cardiac isograft was well tolerated (>150 days, n=5), while non-treated cardiac allograft was rapidly rejected (mean 10.9±2.4, n=7). In the etodolac-treated cardiac allograft (10 mg/kg/day by hypodermic injection), survival was extended to 18.53±2.1 days (n=7). The necrotic area and the grade of COX-2 immunostaining were more significantly reduced in the etodolac-treated cardiac allograft than in the non-treated cardiac allograft at day 14. These results indicate that etodolac contributes to protection against rejection after heart transplantation. Etodolac could therefore be used to suppress graft rejection by means of its anti-inflammatory properties.

  18. Screening in a Lactobacillus delbrueckii subsp. bulgaricus collection to select a strain able to survive to the human intestinal tract.

    Science.gov (United States)

    Vázquez, Clotilde; Botella-Carretero, José I; García-Albiach, Raimundo; Pozuelo, María J; Rodríguez-Baños, Mercedes; Baquero, Fernando; Baltadjieva, María A; del Campo, Rosa

    2013-01-01

    Genetic diversity and resistance of Lactobacillus bulgaricus sbsp. delbrueckii collection with 100 isolates from different home-made yogurt in rural Bulgarian areas were determined. The strain K98 was the most resistant to bile salts and low pH. Survival and effects on short chain fatty acids production were tested in 20 healthy volunteers. High genetic diversity was observed in the L. bulgaricus collection by RAPD, whereas the ability of tolerate high deoxycholic acid concentrations, and different acid pHs was variable. The strain K98 was selected and used to prepare a homemade yogurt which was administered to 20 healthy volunteers (500 ml/day during 15d). A basal faecal sample and another after yogurt intake were recovered. DGGE experiments, using both universal and Lactic Acid Bacteria (LAB) primers, demonstrated no significant changes in the qualitative composition of gut microbiota. A band corresponding to L. bulgaricus was observed in all 20 samples. Viable L. bulgaricus K98 strain was only recovered in one volunteer. After yogurt intake we found an increase of LAB and Clostridium perfringens, and a decrease of Bacteroides- Prevotella-Porphyromonas. In addition, increases of acetic, butyric and 2-hydroxy-butyric acids in faeces were detected. Genetic diversity of L. delbrueckii subsp. bulgaricus especie is high We have isolated a probiotic resistant strain to bile and high acidity, L. delbrueckii subsp. bulgaricus-K98. Qualitative and quantitative changes in the intestinal microbiota are found after ingestion of a homemade yogurt containing this strain, with a concomitant increase in faecal SCFA. Our findings support the interest in developing further studies providing different amounts of L. delbrueckii subsp. bulgaricus-K98, and should evaluate its clinical effects in human disease. Copyright © AULA MEDICA EDICIONES 2013. Published by AULA MEDICA. All rights reserved.

  19. Adult Perpetrator Gender Asymmetries in Child Sexual Assault Victim Selection: Results from the 2000 National Incident-Based Reporting System

    Science.gov (United States)

    McCloskey, Kathy A.; Raphael, Desreen N.

    2005-01-01

    Data from the 2000 National Incident-Based Reporting System (NIBRS) show that while males make up about nine out of every 10 adult sexual assault perpetrators, totaling about 26,878 incidents within the reporting period, females account for about one out of 10 perpetrators, totaling about 1,162 incidents. Male sexual assault perpetrators offend…

  20. Effect of divergent selection for uterine capacity on embryonic survival and development at 30 h post-mating in unilaterally ovariectomized rabbit females

    Directory of Open Access Journals (Sweden)

    R. Peiro

    2015-12-01

    Full Text Available Uterine capacity has been proposed as an indirect way to increase litter size. The aim of this work is to study the effect of a divergent selection for uterine capacity (UC on reproductive traits at 30 h post mating in unilaterally ovariectomized (ULO females. A total of 62 ULO females from the high line (selected to increase UC and 39 ULO females from the low line (selected to decrease UC were used. Ovulation rate was estimated as the number of corpora haemorrhagica and early embryonic survival was estimated as the ratio between number of embryos and ovulation rate. No differences in ovulation rate and early embryonic survival at 30 h post mating were found between high and low lines. Selection for UC did not change the embryonic stage of development either, the majority of embryos being at 4-cell stage. Additionally, the embryos were evaluated according to morphological criteria and more than 95% of the embryos were evaluated as good or fair quality. No differences in embryonic morphological criteria between high and low lines were found either. Thus, selection for UC did not modify the early embryonic survival and development in ULO females at 30 h post mating.

  1. Fgfr1 signalling in the development of a sexually selected trait in vertebrates, the sword of swordtail fish.

    Science.gov (United States)

    Offen, Nils; Blum, Nicola; Meyer, Axel; Begemann, Gerrit

    2008-10-09

    One of Darwin's chosen examples for his idea of sexual selection through female choice was the "sword", a colourful extension of the caudal fin of male swordtails of the genus Xiphophorus. Platyfish, also members of the genus Xiphophorus, are thought to have arisen from within the swordtails, but have secondarily lost the ability to develop a sword. The sustained increase of testosterone during sexual maturation initiates sword development in male swordtails. Addition of testosterone also induces sword-like fin extensions in some platyfish species, suggesting that the genetic interactions required for sword development may be dormant, rather than lost, within platyfish. Despite considerable interest in the evolution of the sword from a behavioural or evolutionary point of view, little is known about the developmental changes that resulted in the gain and secondary loss of the sword. Up-regulation of msxC had been shown to characterize the development of both swords and the gonopodium, a modified anal fin that serves as an intromittent organ, and prompted investigations of the regulatory mechanisms that control msxC and sword growth. By comparing both development and regeneration of caudal fins in swordtails and platyfish, we show that fgfr1 is strongly up-regulated in developing and regenerating sword and gonopodial rays. Characterization of the fin overgrowth mutant brushtail in a platyfish background confirmed that fin regeneration rates are correlated with the expression levels of fgfr1 and msxC. Moreover, brushtail re-awakens the dormant mechanisms of sword development in platyfish and activates fgfr1/msxC-signalling. Although both genes are co-expressed in scleroblasts, expression of msxC in the distal blastema may be independent of fgfr1. Known regulators of Fgf-signalling in teleost fins, fgf20a and fgf24, are transiently expressed only during regeneration and thus not likely to be required in developing swords. Our data suggest that Fgf-signalling is

  2. Sexual and reproductive health status and related problems of young people with disabilities in selected associations of people with disability, Addis Ababa, Ethiopia.

    Science.gov (United States)

    Alemu, Tigist; Fantahun, Mesganaw

    2011-04-01

    Young people in Ethiopia face many sexual and reproductive health problems. In particular young people with disability are among the most stigmatized, poorest, and least educated. To date, very little is known about the sexuality of disabled youth, in general the reproductive health need and related problems of this group. The aim of this study is to assess the sexual reproductive health status and associated problems of young people with disability at selected associations of people with disability in Addis Ababa. A cross-sectional survey was conducted from Feb 11-17, 2008 to assess disabled youth reproductive health status and related problems. Data were collected by trained interviewers using a structured questionnaire and two complementary focus group discussions were also conducted guided by semi-structured questions. A total of 384 young people with disability were selected using systematic sampling technique. The sociodemographic and the sexual reproductive health characteristics of the respondents were described and appropriate statistical methods including chi-square test, crude and adjusted odds ratio were used to make comparisons A total 174 (45.3%) of respondents in the study ever had sexual intercourse; out of which 100 (57.5%) and 74 (42.5%) were males and females respectively. Seventy three (42.0%) started sex between the age of 15-19 years and only 9.2% were married Only 45.4% of the sexually experienced respondents had used some kind of contraceptive during their first sexual encounter. The prevalence of unintended pregnancy was 62.5% among young disabled females who had ever been pregnant and 50% of them had history of abortion, 87.5% of this abortion was induced type. In this study, 58.6% of the sexually active respondents had multiple life time sexual partners, 20.7% had a casual sex partner and 18.0% of sexually active males had a commercial sex partner in the past 12 months period prior to the survey. The prevalence of history of ever having

  3. HIV transmission and pre-exposure prophylaxis in a high risk MSM population: A simulation study of location-based selection of sexual partners

    Science.gov (United States)

    Velter, Annie; Barin, Francis; Boelle, Pierre-Yves

    2017-01-01

    Objective In France, indications for pre-exposure prophylaxis (PrEP) for HIV prevention are based on individual-level risk factors for HIV infection. However, the risk of HIV infection may also depend on characteristics of sexual partnerships. Here we study how place-based selection of partners change transmission and the overall efficiency of PrEP. Methods We used the PREVAGAY survey of sexual behavior and HIV serostatus in men who have sex with men (MSM) in a Parisian district to look for associations between sexual network characteristics and HIV infection. We then simulated HIV transmission in a high-risk MSM population. We used information about venues visited to meet casual sexual partners (clubs, backrooms or saunas) to define sexual networks. We then simulated HIV transmission in these networks and assessed the impact of PrEP in this population. Results In the PREVAGAY study, we found that HIV serostatus changed with the type of venues visited, in addition to other individual risk factors. In simulations, we found similar differences in HIV incidence when the choice of venues visited was not random. The use of PrEP allowed reducing incidence, irrespective of the venues visited by PrEP users. However, with the same amount of PrEP, the number of infections adverted could almost double depending on network structure and venues visited by PrEP users. Conclusion This study shows that characteristics of the sexual network structure can strongly impact the effectiveness of PrEP interventions. These should be considered further to refine individual risk assessment and maximize the effect of individual-based prevention policies. PMID:29190784

  4. Ischemic flap survival improvement by composition-selective fat grafting with novel adipose tissue derived product - stromal vascular fraction gel.

    Science.gov (United States)

    Zhang, Pan; Feng, Jingwei; Liao, Yunjun; Cai, Junrong; Zhou, Tao; Sun, Mingliang; Gao, Jianhua; Gao, Kai

    2017-11-30

    Flap necrosis due to insufficient blood supply is a common postoperative complication in random pattern flaps. Stem cell therapies have emerged as promising biologics for tissue ischemia. A novel fat derived product, stromal vascular fraction gel (SVF-gel), can be prepared with lipoaspirate through simple mechanical processing, removing only the lipid content. SVF-gel enriches adipose-derived stem cells and potentially beneficial for flap necrosis. Nude mice ischemic flaps were treated with human SVF-gel, stromal vascular fraction (SVF) cell suspension or saline (n = 10). They were injected to the flap recipient beds, and necrosis and vascularization was assessed on postoperative day 14. We harvested the necrosis-free distal to evaluated skin healthiness and neovasculogenesis by Masson's trichrome stain and immunofluorescence, etc. Pro-angiogenic factors were assessed with tissue qRT-PCR. Finally, we traced the grafted human tissue with immunofluorescence. SVF-gel-treated flaps have the smallest necrotic zones (22.05% ± 0.0438) compared with the saline controls (53.78% ± 0.1412) or SVF-treated ones (35.54% ± 0.0850, p = 0.039). Numerous functional musculocutaneous perforators were developed around SVF-gel grafts. The SVF-gel-treated skin had the best fat restoration (231.3 ± 48.1 μm) among three groups (F = 10.83, p = 0.0102) while saline-treated flap distal appeared fibrotic. SVF-gel-treated flaps also had ∼43% more CD31 + capillaries (p = 0.0152) with ∼3 folds more gene expression of angiogenic cytokines of VEGF and bFGF (p = 0.0310 and 0.0303, respectively) than saline-treated controls. Furthermore, we found hSVF-gel cells (hGolgi+) had directly engrafted as vessel component (α-smooth muscle actin, α-SMA+) to the flap. Adipose cellular matrix enhanced flap neovascularization partly by direct incorporation, improved flap survival and fat restoration. The composition-selective fat grafting with SVF-gel demonstrated efficacy

  5. Leaf Photosynthesis and Respiration of High CO2-Grown Tobacco Plants Selected for Survival under CO2 Compensation Point Conditions 1

    Science.gov (United States)

    Delgado, Esteban; Azcón-Bieto, Joaquim; Aranda, Xavier; Palazón, Javier; Medrano, Hipólito

    1992-01-01

    Four self-pollinated, doubled-haploid tobacco, (Nicotiana tabacum L.) lines (SP422, SP432, SP435, and SP451), selected as haploids by survival in a low CO2 atmosphere, and the parental cv Wisconsin-38 were grown from seed in a growth room kept at high CO2 levels (600-700 parts per million). The selected plants were much larger (especially SP422, SP432, and SP451) than Wisconsin-38 nine weeks after planting. The specific leaf dry weight and the carbon (but not nitrogen and sulfur) content per unit area were also higher in the selected plants. However, the chlorophyll, carotenoid, and alkaloid contents and the chlorophyll a/b ratio varied little. The net CO2 assimilation rate per unit area measured in the growth room at high CO2 was not higher in the selected plants. The CO2 assimilation rate versus intercellular CO2 curve and the CO2 compensation point showed no substantial differences among the different lines, even though these plants were selected for survival under CO2 compensation point conditions. Adult leaf respiration rates were similar when expressed per unit area but were lower in the selected lines when expressed per unit dry weight. Leaf respiration rates were negatively correlated with specific leaf dry weight and with the carbon content per unit area and were positively correlated with nitrogen and sulfur content of the dry matter. The alternative pathway was not involved in respiration in the dark in these leaves. The better carbon economy of tobacco lines selected for low CO2 survival was not apparently related to an improvement of photosynthesis rate but could be related, at least partially, to a significantly reduced respiration (mainly cytochrome pathway) rate per unit carbon. ImagesFigure 1 PMID:16668769

  6. Multiple paternity and postcopulatory sexual selection in a hermaphrodite: what influences sperm precedence in the garden snail Helix aspersa?

    Science.gov (United States)

    Evanno, Guillaume; Madec, Luc; Arnaud, Jean-François

    2005-03-01

    Sperm competition has been studied in many gonochoric animals but little is known about its occurrence in simultaneous hermaphrodites, especially in land snails. The reproductive behaviour of the land snail Helix aspersa involves several features, like multiple mating, long-term sperm storage and dart-shooting behaviour, which may promote sperm competition. Cryptic female choice may also occur through a spermatheca subdivided into tubules, which potentially allows compartmentalized sperm storage of successive mates. In order to determine the outcome of postcopulatory sexual selection in this species, we designed a cross-breeding experiment where a recipient ('female') mated with two sperm donors ('males'). Mates came from either the same population as the recipient or from a distinct one. To test for the influence a recipient can have on the paternity of its offspring, we excluded the effects of dart shooting by using only virgin snails as sperm donors because they do not shoot any dart before their first copulation. We measured the effects of size of mates as well as time to first and second mating on second mate sperm precedence (P2; established using microsatellite markers). Multiple paternity was detected in 62.5% of clutches and overall there was first-mate sperm precedence with a mean P2 of 0.24. Generalized linear modelling revealed that the best predictors of paternity were the time between matings and the time before first mating. Overall, both first and second mates that copulated quickly got greater parentage, which may suggest that postcopulatory events influence patterns of sperm precedence in the garden snail.

  7. Sexual selection in true fruit flies (Diptera: Tephritidae): transcriptome and experimental evidences for phytochemicals increasing male competitive ability.

    Science.gov (United States)

    Kumaran, Nagalingam; Prentis, Peter J; Mangalam, Kalimuthu P; Schutze, Mark K; Clarke, Anthony R

    2014-09-01

    In male tephritid fruit flies of the genus Bactrocera, feeding on secondary plant compounds (sensu lato male lures = methyl eugenol, raspberry ketone and zingerone) increases male mating success. Ingested male lures alter the male pheromonal blend, normally making it more attractive to females and this is considered the primary mechanism for the enhanced mating success. However, the male lures raspberry ketone and zingerone are known, across a diverse range of other organisms, to be involved in increasing energy metabolism. If this also occurs in Bactrocera, then this may represent an additional benefit to males as courtship is metabolically expensive and lure feeding may increase a fly's short-term energy. We tested this hypothesis by performing comparative RNA-seq analysis between zingerone-fed and unfed males of Bactrocera tryoni. We also carried out behavioural assays with zingerone- and cuelure-fed males to test whether they became more active. RNA-seq analysis revealed, in zingerone-fed flies, up-regulation of 3183 genes with homologues transcripts to those known to regulate intermale aggression, pheromone synthesis, mating and accessory gland proteins, along with significant enrichment of several energy metabolic pathways and gene ontology terms. Behavioural assays show significant increases in locomotor activity, weight reduction and successful mating after mounting; all direct/indirect measures of increased activity. These results suggest that feeding on lures leads to complex physiological changes, which result in more competitive males. These results do not negate the pheromone effect, but do strongly suggest that the phytochemical-induced sexual selection is governed by both female preference and male competitive mechanisms. © 2014 John Wiley & Sons Ltd.

  8. Sexual Identity, Sex of Sexual Contacts, and Health-Related Behaviors among Students in Grades 9-12--United States and Selected Sites, 2015. Morbidity and Mortality Weekly Report. Surveillance Summaries. Volume 65, Number 9

    Science.gov (United States)

    Kann, Laura; Olsen, Emily O'Malley; McManus, Tim; Harris, William A.; Shanklin, Shari L.; Flint, Katherine H.; Queen, Barbara; Lowry, Richard; Chyen, David; Whittle, Lisa; Thornton, Jemekia; Lim, Connie; Yamakawa, Yoshimi; Brener, Nancy; Zaza, Stephanie

    2016-01-01

    Problem: Sexual identity and sex of sexual contacts can both be used to identify sexual minority youth. Significant health disparities exist between sexual minority and nonsexual minority youth. However, not enough is known about health-related behaviors that contribute to negative health outcomes among sexual minority youth and how the prevalence…

  9. Bill redness is positively associated with reproduction and survival in male and female zebra finches.

    Directory of Open Access Journals (Sweden)

    Mirre J P Simons

    Full Text Available Sexual traits can serve as honest indicators of phenotypic quality when they are costly. Brightly coloured yellow to red traits, which are pigmented by carotenoids, are relatively common in birds, and feature in sexual selection. Carotenoids have been linked to immune and antioxidant function, and the trade-off between ornamentation and these physiological functions provides a potential mechanism rendering carotenoid based signals costly. Mutual ornamentation is also common in birds and can be maintained by mutual mate choice for this ornament or by a correlated response in one sex to selection on the other sex. When selection pressures differ between the sexes this can cause intralocus sexual conflict. Sexually antagonistic selection pressures have been demonstrated for few sexual traits, and for carotenoid-dependent traits there is a single example: bill redness was found to be positively associated with survival and reproductive output in male zebra finches, but negatively so in females. We retested these associations in our captive zebra finch population without two possible limitations of this earlier study. Contrary to the earlier findings, we found no evidence for sexually antagonistic selection. In both sexes, individuals with redder bills showed higher survival. This association disappeared among the females with the reddest bills. Furthermore, females with redder bills achieved higher reproductive output. We conclude that bill redness of male and female zebra finches honestly signals phenotypic quality, and discuss the possible causes of the differences between our results and earlier findings.

  10. Dimensions of racism and their impact on partner selection among men of colour who have sex with men: understanding pathways to sexual risk.

    Science.gov (United States)

    Ro, Annie; Ayala, George; Paul, Jay; Choi, Kyung-Hee

    2013-01-01

    While many studies have established the relationship between experiences of racism and sexual risk among men of colour who have sex with men, the pathways by which this occurs are underdeveloped. To address this gap, we must better investigate the lived realities of racism in the gay community. In this study, we had the unique opportunity to examine experiences of racism among African American, Asian/Pacific Islander and Latino men who have sex with men living in Los Angeles through focus groups and individual in-depth interviews. We found three themes of racism: exclusion from West Hollywood and the mainstream gay community, sexual rejection based on race/ethnicity and sexual stereotypes. There were differences across the three racial groups in the experiences of each theme, however. We then considered how racism impacted partner selection and found that race played a salient role in determining power differentials within mixed-race partnerships. Finally, we discussed several future areas for research that can better establish pathways between racism and sexual risk.

  11. Dimensions of Racism and their Impact on Partner Selection among Men who have Sex with Men of Colour: Understanding Pathways to Sexual Risk

    Science.gov (United States)

    Ayala, George; Paul, Jay; Choi, Kyung-Hee

    2013-01-01

    While many studies have established the relationship between experiences of racism and sexual risk among men who have sex with men of colour, the pathways by which this occurs are underdeveloped. To address this gap, we must better investigate the lived realities of racism in the gay community. In this study, we had the unique opportunity to examine experiences of racism among African American, Latino and Asian/Pacific Islander men who have sex with men living in Los Angeles through focus groups and individual in-depth interviews. We found three themes of racism: exclusion from West Hollywood and the mainstream gay community, sexual rejection based on race/ethnicity, and sexual stereotypes. There were differences across the three racial groups in the experiences of each theme, however. We then considered how racism impacted partner selection and found that race played a salient role in determining power differentials within mixed-race partnerships. Finally, we discussed several future areas for research that can better establish pathways between racism and sexual risk. PMID:23659363

  12. Assessment of the impact of the London Olympics 2012 on selected non-genitourinary medicine clinic sexual health services.

    Science.gov (United States)

    Hartley, A; Foster, R; Brook, M G; Cassell, J A; Mercer, C H; Coyne, K; Hughes, G; Crook, P

    2015-04-01

    With minimal information on sexual health provision during mass-gathering events, our aim was to describe the use of sexual health, contraceptive, sex worker and sexual assault services during the London 2012 Olympics. We analysed data from five sources. One contraceptive service provider reported a 10% increase in attendance during the main Games, while emergency contraception prescriptions rose during the main Olympics, compared to the week before, but were similar or lower than at the beginning and end of the summer period. A health telephone advice line reported a 16% fall in sexual health-related calls during the main Olympics, but a 33% increase subsequently. London sexual assault referral centres reported that 1.8% of sexual assaults were Olympics-linked. A service for sex workers reported that 16% started working in the sex industry and 7% moved to London to work during the Olympics. Fifty-eight per cent and 45% of sex workers reported fewer clients and an increase in police crack-downs, respectively. Our results show a change in activity across these services during the 2012 summer, which may be associated with the Olympics. Our data are a guide to other services when anticipating changes in service activity and planning staffing for mass-gathering events. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  13. Differential selection on pollen and pistil traits in relation to pollen competition in the context of a sexual conflict over timing of stigma receptivity.

    Science.gov (United States)

    Lankinen, Åsa; Strandh, Maria

    2016-01-01

    Sexual conflict and its evolutionary consequences are understudied in plants, but the theory of sexual conflict may help explain how selection generates and maintains variability. Here, we investigated selection on pollen and pistil traits when pollen arrives sequentially to partially receptive pistils in relation to pollen competition and a sexual conflict over timing of stigma receptivity in the mixed-mating annual Collinsia heterophylla (Plantaginaceae). In this species the conflict is generated by early fertilizing pollen that reduces seed production, which is counteracted by delaying receptivity in the recipient. We performed sequential two-donor pollinations at early floral developmental stages involving two pollen deposition schedules (with or without a time lag of 1 day), using only outcross or self and outcross pollen. We investigated pollen and pistil traits in relation to siring success (male fitness) and seed production (female fitness). In contrast to previous findings in receptive pistils in C. heterophylla and in other species, last arriving pollen donors showed highest siring success in partially receptive pistils. The last male advantage was weaker when self pollen was the first arriving donor. Two measures of germination rate (early and late) and pollen tube growth rate of first arriving donors were important for siring success in crosses with a time lag, while only late germination rate had an effect in contemporary crosses. Curiously, late stigma receptivity was negatively related to seed production in our contemporary crosses, which was opposite to expectation. Our results in combination with previous studies suggest that pollen and pistil traits in C. heterophylla are differentially advantageous depending on stage of floral development and varying pollen deposition schedules. Variation in success of these traits over floral development time may result from sexually antagonistic selection. © The Authors 2016. Published by Oxford University

  14. Premating isolation is determined by larval rearing substrates in cactophilic Drosophila mojavensis. IX. Host plant and population specific epicuticular hydrocarbon expression influences mate choice and sexual selection.

    Science.gov (United States)

    Havens, J A; Etges, W J

    2013-03-01

    Sexual signals in cactophilic Drosophila mojavensis include cuticular hydrocarbons (CHCs), contact pheromones that mediate female discrimination of males during courtship. CHCs, along with male courtship songs, cause premating isolation between diverged populations, and are influenced by genotype × environment interactions caused by different host cacti. CHC profiles of mated and unmated adult flies from a Baja California and a mainland Mexico population of D. mojavensis reared on two host cacti were assayed to test the hypothesis that male CHCs mediate within-population female discrimination of males. In multiple choice courtship trials, mated and unmated males differed in CHC profiles, indicating that females prefer males with particular blends of CHCs. Mated and unmated females significantly differed in CHC profiles as well. Adults in the choice trials had CHC profiles that were significantly different from those in pair-mated adults from no-choice trials revealing an influence of sexual selection. Females preferred different male CHC blends in each population, but the influence of host cactus on CHC variation was significant only in the mainland population indicating population-specific plasticity in CHCs. Different groups of CHCs mediated female choice-based sexual selection in each population suggesting that geographical and ecological divergence has the potential to promote divergence in mate communication systems. © 2012 The Authors. Journal of Evolutionary Biology © 2012 European Society For Evolutionary Biology.

  15. Characteristics of patients who survived 2 years after surgery for spinal metastases : Can we avoid inappropriate patient selection?

    NARCIS (Netherlands)

    Verlaan, Jorrit Jan; Choi, David; Versteeg, Anne; Albert, Todd; Arts, Mark; Balabaud, Laurent; Bunger, Cody; Buchowski, Jacob Maciej; Chung, Chung Kee; Coppes, Maarten Hubert; Crockard, Hugh Alan; Depreitere, Bart; Fehlings, Michael George; Harrop, James; Kawahara, Norio; Kim, Eun Sang; Lee, Chong Suh; Leung, Yee; Liu, Zhongjun; Martin-Benlloch, Antonio; Massicotte, Eric Maurice; Mazel, Christian; Meyer, Bernhard; Peul, Wilco; Quraishi, Nasir A.; Tokuhashi, Yasuaki; Tomita, Katsuro; Ulbricht, Christian; Wang, Michael; Oner, F. Cumhur

    2016-01-01

    Purpose Survival after metastatic cancer has improved at the cost of increased presentation with metastatic spinal disease. For patients with pathologic spinal fractures and/or spinal cord compression, surgical intervention may relieve pain and improve quality of life. Surgery is generally

  16. Factors affecting route selection and survival of steelhead kelts at Snake River dams in 2012 and 2013

    Energy Technology Data Exchange (ETDEWEB)

    Harnish, Ryan A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Colotelo, Alison H. A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Li, Xinya [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Fu, Tao [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ham, Kenneth D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Deng, Zhiqun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Green, Ethan D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-03-31

    In 2012 and 2013, Pacific Northwest National Laboratory (PNNL) conducted a study that summarized the passage route proportions and route-specific survival rates of steelhead kelts that passed through Federal Columbia River Power System (FCRPS) dams. To accomplish this, a total of 811 steelhead kelts were tagged with Juvenile Salmon Acoustic Telemetry System (JSATS) transmitters. Acoustic receivers, both autonomous and cabled, were deployed throughout the FCRPS to monitor the downstream movements of tagged kelts. Kelts were also tagged with passive integrated transponder tags to monitor passage through juvenile bypass systems (JBS) and detect returning fish. The current study evaluated data collected in 2012 and 2013 to identify environmental, temporal, operational, individual, and behavioral variables that were related to forebay residence time, route of passage, and survival of steelhead kelts at FCRPS dams on the Snake River. Multiple approaches, including 3-D tracking, bivariate and multivariable regression modeling, and decision tree analyses were used to identify the environmental, temporal, operational, individual, and behavioral variables that had the greatest effect on forebay residence time, route of passage, and route-specific and overall dam passage survival probabilities for tagged kelts at Lower Granite (LGR), Little Goose (LGS), and Lower Monumental (LMN) dams. In general, kelt behavior and discharge appeared to work independently to affect forebay residence times. Kelt behavior, primarily approach location, migration depth, and “searching” activities in the forebay, was found to have the greatest influence on their route of passage. The condition of kelts was the single most important factor affecting their survival. The information gathered in this study may be used by dam operators and fisheries managers to identify potential management actions to improve in-river survival of kelts or collection methods for kelt reconditioning programs to aid

  17. Site selection and nest survival of the Bar-Headed Goose (Anser indicus) on the Mongolian Plateau

    Science.gov (United States)

    Batbayar, Nyambayar; Takekawa, John Y.; Natsagdorj, Tseveenmyadag; Spragens, Kyle A.; Xiao, Xiamgming

    2014-01-01

    Waterbirds breeding on the Mongolian Plateau in Central Asia must find suitable wetland areas for nesting in a semiarid region characterized by highly variable water conditions. The first systematic nesting study of a waterbird dependent on this region for breeding was conducted on the Bar-headed Goose (Anser indicus). The purpose of this study was to document Bar-headed Goose nesting locations, characterize nests and nesting strategies, and estimate daily nest survival (n = 235 nests) from eight areas of west-central Mongolia across three summers (2009–2011) using a modified Mayfield estimator. Bar-headed Goose daily nest survival ranged from 0.94 to 0.98, with a 3-year average nest success of 42.6% during incubation. Bar-headed Geese were found to primarily nest on isolated pond and lake islands as previously reported, but were also documented regularly, though less frequently, along rocky cliffs in several regions of west-central Mongolia. Daily nest survival was higher for cliff nests than for island nests. Information-theoretic models indicated that nest survival decreased with nest age and varied annually with changing environmental conditions. Results of this study suggest that while Bar-headed Geese primarily rely on nesting island sites these sites may be more susceptible to anthropogenic disturbance and predation events influenced by seasonal variation in environmental conditions, and that higher daily nest survival values documented for the less frequent cliff nest strategy may provide an important alternative strategy during poor island nest success years. Thus, conservation efforts for this and other waterbird species in the semiarid region should be focused on conserving nesting islands and protecting them from disturbance in areas of high livestock densities experiencing a rapidly warming climate.

  18. Survival and Associated Risk Factors of Selective Caries Removal Treatments in Primary Teeth: A Retrospective Study in a High Caries Risk Population.

    Science.gov (United States)

    Melgar, Ximena C; Opdam, Niek J M; Britto Correa, Marcos; Franzon, Renata; Demarco, Flávio Fernando; Araujo, Fernando B; Casagrande, Luciano

    2017-01-01

    The aim of this retrospective study was to analyze the survival probability of selective caries removal (SCR) treatments in the primary teeth of children with high caries experience and factors potentially associated with treatment failure. The sample included SCR treatments conducted in anterior and posterior teeth without sedation or general anesthesia among children attending a university dental service. Kaplan-Meier survival analysis was used to estimate the longevity of restorations and multivariate Cox regression with shared frailty was used to assess risk factors. A total of 284 SCR treatments in 88 children (aged 5.2 ± 1.91 years) with high caries experience (mean dmft/DMFT = 11.1 ± 5.04) were analyzed. The 3-year survival reached 48.8%, with an annual failure rate of 21.2%. Restorative failures (n = 60) were found more frequently compared to pulp complications (n = 12). SCR performed in anterior primary teeth were more prone to failure (hazard ratio = 3.6, 95% CI: 1.94; 6.71). Patients with a higher amount of visible plaque experienced more failures in SCR treatments (hazard ratio 3.0, 95% CI:1.27; 7.07). In this retrospective study, SCR showed restricted survival when compared to other prospective clinical trials. Patient-related factors, especially the young age and high caries experience of the children, may represent a challenge for restoration survival. Regardless of the caries removal technique or restorative material, cariogenic biofilm has a negative effect on the survival of restorations, probably by acting directly on material deterioration and, particularly, on the development of new caries lesions of rapid progression. © 2017 S. Karger AG, Basel.

  19. Sexual sadism.

    Science.gov (United States)

    Berner, Wolfgang; Berger, Peter; Hill, Andreas

    2003-08-01

    Definitions of sexual sadism in ICD-10 and DSM-IV will be presented as well as the historical routes of the concept. Today studies on differently selected clinical samples reveal a different distribution of sexual sadism versus masochism with masochism prevailing in general especially outpatient psychiatric facilities, and sadism prevailing in forensic settings, thus corroborating the concept of two separated diagnoses sadism versus masochism. In forensic settings the diagnosis of a sadistic character disorder (sadistic personality disorder [SPD] according DSM-III-R) is found to a much higher degree than in other clinical samples (50-fold). Our own follow-up study on a forensic sample implies that sadism as a paraphilia is of relevance for relapse-rates of sex-offenders. Symptoms of SPD can be combined with sexual sadism, or occur independently. This may corroborate arguments in favor of a dimensional concept of sexual sadism. Symptoms of SPD may then be a sign of generalization of sadistic traits at least in some cases. A concept of two factors contributing to sadistic pleasure is suggested, one taking the aspect of bodily gratification by sexual-aggressive stimuli as decisive, and the other taking inner representation of hostile objects into consideration (stressing the antisocial-anger-rage aspect).

  20. Factors Affecting Route Selection and Survival of Steelhead Kelts at Snake River Dams in 2012 and 2013

    Energy Technology Data Exchange (ETDEWEB)

    Harnish, Ryan A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Colotelo, Alison HA [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Li, Xinya [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ham, Kenneth D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Deng, Zhiqun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-12-01

    In 2012 and 2013, Pacific Northwest National Laboratory conducted a study that summarized the passage proportions and route-specific survival rates of steelhead kelts that passed through Federal Columbia River Power System (FCRPS) dams. To accomplish this, a total of 811 steelhead kelts were tagged with Juvenile Salmon Acoustic Telemetry System (JSATS) transmitters. Acoustic receivers, both autonomous and cabled, were deployed throughout the FCRPS to monitor the downstream movements of tagged-kelts. Kelts were also tagged with Passive Integrated Transponder tags to monitor passage through juvenile bypass systems and detect returning fish. The current study evaluated data collected in 2012 and 2013 to identify individual, behavioral, environmental and dam operation variables that were related to passage and survival of steelhead kelts that passed through FCRPS dams. Bayesian model averaging of multivariable logistic regression models was used to identify the environmental, temporal, operational, individual, and behavioral variables that had the highest probability of influencing the route of passage and the route-specific survival probabilities for kelts that passed Lower Granite (LGR), Little Goose (LGS), and Lower Monumental (LMN) dams in 2012 and 2013. The posterior probabilities of the best models for predicting route of passage ranged from 0.106 for traditional spill at LMN to 0.720 for turbine passage at LGS. Generally, the behavior (depth and near-dam searching activity) of kelts in the forebay appeared to have the greatest influence on their route of passage. Shallower-migrating kelts had a higher probability of passing via the weir and deeper-migrating kelts had a higher probability of passing via the JBS and turbines than other routes. Kelts that displayed a higher level of near-dam searching activity had a higher probability of passing via the spillway weir and those that did less near-dam searching had a higher probability of passing via the JBS and

  1. Effect of antibiotics selection on survival rate of nodal explant and gene transformation in Anthurium andraeanum cv. Sonate

    Directory of Open Access Journals (Sweden)

    Te-chato, S.

    2007-05-01

    Full Text Available The effects of various concentrations of hygromycin antibiotic supplemented in modified Murashige and Skoog (MMS on the survival rate of nodal explant of Anthurium andraeanum cv. Sonate were determined.The use of hygromycin at 50 mg/l caused absolute death of nodal tissue after 4 weeks of culture. Dipping nodal explant with agrobacterium, EHA 105 containing pCAMBIA1301 for 15 min followed by co-cultureon filter paper laid on MMS with 0.5 mg/l benzyladenine (BA, 0.5 mg/l thidiazuron (TDZ and 200 mg/l cefotaxime for 2 days then transferring the explant to culture on MMS supplemented with the abovephytohormones and 50 mg/l hygromycin resulted in the highest survival rate at 26.6% with 4 shoots/callus. Histochemical analysis of gus activity was found in callus after 6 weeks of nodal culture and in leaf fromshoot derived from the callus.

  2. Investigation on possibility of survival and growth enhancing by selected seaweeds from Persian Gulf in post larvae shrimp Litopenaeus vannamei

    OpenAIRE

    Dashtiannasab, Aghil

    2015-01-01

    The use of antibiotics in aquaculture has been limited. Scientifics seeking for natural substitutes to prevent of aquatic animals diseases. Considering seaweeds are rich of nutritions and bioactive compounds, the purpose of this study is: investigation the potential and use possibility of native seaweeds from Persian Gulf in shrimp aquculture industry to improve growth, survival of postlarvae and to resistance against pathogens such as vibriosis. For this propose 7 macroalgae species from Bus...

  3. Selective Infection of Antigen-Specific B Lymphocytes by Salmonella Mediates Bacterial Survival and Systemic Spreading of Infection

    Science.gov (United States)

    de Wit, Jelle; Martinoli, Chiara; Zagato, Elena; Janssen, Hans; Jorritsma, Tineke; Bar-Ephraïm, Yotam E.; Rescigno, Maria; Neefjes, Jacques; van Ham, S. Marieke

    2012-01-01

    Background The bacterial pathogen Salmonella causes worldwide disease. A major route of intestinal entry involves M cells, providing access to B cell-rich Peyer’s Patches. Primary human B cells phagocytose Salmonella typhimurium upon recognition by the specific surface Ig receptor (BCR). As it is unclear how Salmonella disseminates systemically, we studied whether Salmonella can use B cells as a transport device for spreading. Methodology/Principal Findings Human primary B cells or Ramos cell line were incubated with GFP-expressing Salmonella. Intracellular survival and escape was studied in vitro by live cell imaging, flow cytometry and flow imaging. HEL-specific B cells were transferred into C57BL/6 mice and HEL-expressing Salmonella spreading in vivo was analyzed investigating mesenteric lymph nodes, spleen and blood. After phagocytosis by B cells, Salmonella survives intracellularly in a non-replicative state which is actively maintained by the B cell. Salmonella is later excreted followed by reproductive infection of other cell types. Salmonella-specific B cells thus act both as a survival niche and a reservoir for reinfection. Adoptive transfer of antigen-specific B cells before oral infection of mice showed that these B cells mediate in vivo systemic spreading of Salmonella to spleen and blood. Conclusions/Significance This is a first example of a pathogenic bacterium that abuses the antigen-specific cells of the adaptive immune system for systemic spreading for dissemination of infection. PMID:23209805

  4. Prediction error variance and expected response to selection, when selection is based on the best predictor - for Gaussian and threshold characters, traits following a Poisson mixed model and survival traits

    DEFF Research Database (Denmark)

    Andersen, Anders Holst; Korsgaard, Inge Riis; Jensen, Just

    2002-01-01

    In this paper, we consider selection based on the best predictor of animal additive genetic values in Gaussian linear mixed models, threshold models, Poisson mixed models, and log normal frailty models for survival data (including models with time-dependent covariates with associated fixed or ran...... of the model (heritability on the normally distributed level of the model) or a generalised version of heritability plays a central role in these formulas...

  5. Sexual Identity, Sex of Sexual Contacts, and Health-Risk Behaviors among Students in Grades 9-12--Youth Risk Behavior Surveillance, Selected Sites, United States, 2001-2009. Morbidity and Mortality Weekly Report. Early Release. Volume 60

    Science.gov (United States)

    Kann, Laura; O'Malley Olsen, Emily; McManus, Tim; Kinchen, Steve; Chyen, David; Harris, William A.; Wechsler, Howell

    2011-01-01

    Problem: Sexual minority youths are youths who identify themselves as gay or lesbian, bisexual, or unsure of their sexual identity or youths who have only had sexual contact with persons of the same sex or with both sexes. Population-based data on the health-risk behaviors practiced by sexual minority youths are needed at the state and local…

  6. Factors Contributing to Sexual Violence at Selected Schools for Learners with Mild Intellectual Disability in South Africa

    Science.gov (United States)

    Nyokangi, Doris; Phasha, Nareadi

    2016-01-01

    Background: This paper reports part of the findings of a study which exposed sexual violence in schools for learners with mild intellectual disability in South Africa. Special attention was paid on factors contributing to such a problem. Methods: Data were collected using focus groups and individual interviews with 16 learners with mild…

  7. Media Portrayals of Love, Marriage & Sexuality for Child Audiences: A Select Content Analysis of Walt Disney Animated Family Films.

    Science.gov (United States)

    Junn, Ellen N.

    This study examined the portrayal of love, marriage, and sexuality in 11 romantic and nonromantic Disney animated films. Results showed that four out of five of the nonromantic films had male leads, with males occupying significantly more screen time than females. Half of the romantic films had female leads, who occupied significantly more screen…

  8. "I Didn't Understand the Damage It Did": Narrative Factors Influencing the Selection of Sexual Abuse as Epiphany.

    Science.gov (United States)

    Gasker, Janice A.

    2001-01-01

    Argues that the classification of life experiences as epiphanies is a task critical to personal growth. Uses narrative analysis to illuminate the factors that seem to influence the choice of events as epiphanies for survivors of sexual abuse. Examines such narratives from the life and work of D.H. Lawrence, as well as modern narratives from…

  9. The effects of ozonation on select waterborne steroid hormones in recirculation aquaculture systems containing sexually mature Atlantic salmon Salmo salar

    Science.gov (United States)

    A controlled 3-month study was conducted in 6 replicated water recirculation aquaculture systems (RAS) containing a mixture of sexually mature and immature Atlantic salmon Salmo salar to determine whether water ozonation is associated with a reduction in waterborne hormones. Post-smolt Atlantic salm...

  10. Greater sage-grouse (Centrocercus urophasianus) nesting and brood-rearing microhabitat in Nevada and California—Spatial variation in selection and survival patterns

    Science.gov (United States)

    Coates, Peter S.; Brussee, Brianne E.; Ricca, Mark A.; Dudko, Jonathan E.; Prochazka, Brian G.; Espinosa, Shawn P.; Casazza, Michael L.; Delehanty, David J.

    2017-08-10

    Greater sage-grouse (Centrocercus urophasianus; hereinafter, "sage-grouse") are highly dependent on sagebrush (Artemisia spp.) dominated vegetation communities for food and cover from predators. Although this species requires the presence of sagebrush shrubs in the overstory, it also inhabits a broad geographic distribution with significant gradients in precipitation and temperature that drive variation in sagebrush ecosystem structure and concomitant shrub understory conditions. Variability in understory conditions across the species’ range may be responsible for the sometimes contradictory findings in the scientific literature describing sage-grouse habitat use and selection during important life history stages, such as nesting. To help understand the importance of this variability and to help guide management actions, we evaluated the nesting and brood-rearing microhabitat factors that influence selection and survival patterns in the Great Basin using a large dataset of microhabitat characteristics from study areas spanning northern Nevada and a portion of northeastern California from 2009 to 2016. The spatial and temporal coverage of the dataset provided a powerful opportunity to evaluate microhabitat factors important to sage-grouse reproduction, while also considering habitat variation associated with different climatic conditions and areas affected by wildfire. The summary statistics for numerous microhabitat factors, and the strength of their association with sage-grouse habitat selection and survival, are provided in this report to support decisions by land managers, policy-makers, and others with the best-available science in a timely manner.

  11. Sexual Health

    Science.gov (United States)

    ... Youth Risk Behavior Survey Newest CDC data on teen risk behaviors Publications Check here to find the latest sexual ... Health (Medline Plus) Teen Sexual Health (Medline Plus) Teen Sexual Risk Behaviors Sexual Health and HIV/AIDS [1] WHO working ...

  12. Survival of the fittest: positive selection of CD4+ T cells expressing a membrane-bound fusion inhibitor following HIV-1 infection.

    Directory of Open Access Journals (Sweden)

    Janine Kimpel

    2010-08-01

    Full Text Available Although a variety of genetic strategies have been developed to inhibit HIV replication, few direct comparisons of the efficacy of these inhibitors have been carried out. Moreover, most studies have not examined whether genetic inhibitors are able to induce a survival advantage that results in an expansion of genetically-modified cells following HIV infection. We evaluated the efficacy of three leading genetic strategies to inhibit HIV replication: 1 an HIV-1 tat/rev-specific small hairpin (sh RNA; 2 an RNA antisense gene specific for the HIV-1 envelope; and 3 a viral entry inhibitor, maC46. In stably transduced cell lines selected such that >95% of cells expressed the genetic inhibitor, the RNA antisense envelope and viral entry inhibitor maC46 provided the strongest inhibition of HIV-1 replication. However, when mixed populations of transduced and untransduced cells were challenged with HIV-1, the maC46 fusion inhibitor resulted in highly efficient positive selection of transduced cells, an effect that was evident even in mixed populations containing as few as 1% maC46-expressing cells. The selective advantage of the maC46 fusion inhibitor was also observed in HIV-1-infected cultures of primary T lymphocytes as well as in HIV-1-infected humanized mice. These results demonstrate robust inhibition of HIV replication with the fusion inhibitor maC46 and the antisense Env inhibitor, and importantly, a survival advantage of cells expressing the maC46 fusion inhibitor both in vitro and in vivo. Evaluation of the ability of genetic inhibitors of HIV-1 replication to confer a survival advantage on genetically-modified cells provides unique information not provided by standard techniques that may be important in the in vivo efficacy of these genes.

  13. Escherichia coli MazF leads to the simultaneous selective synthesis of both "death proteins" and "survival proteins".

    Directory of Open Access Journals (Sweden)

    Shahar Amitai

    2009-03-01

    Full Text Available The Escherichia coli mazEF module is one of the most thoroughly studied toxin-antitoxin systems. mazF encodes a stable toxin, MazF, and mazE encodes a labile antitoxin, MazE, which prevents the lethal effect of MazF. MazF is an endoribonuclease that leads to the inhibition of protein synthesis by cleaving mRNAs at ACA sequences. Here, using 2D-gels, we show that in E. coli, although MazF induction leads to the inhibition of the synthesis of most proteins, the synthesis of an exclusive group of proteins, mostly smaller than about 20 kDa, is still permitted. We identified some of those small proteins by mass spectrometry. By deleting the genes encoding those proteins from the E. coli chromosome, we showed that they were required for the death of most of the cellular population. Under the same experimental conditions, which induce mazEF-mediated cell death, other such proteins were found to be required for the survival of a small sub-population of cells. Thus, MazF appears to be a regulator that induces downstream pathways leading to death of most of the population and the continued survival of a small sub-population, which will likely become the nucleus of a new population when growth conditions become less stressful.

  14. Rapid diversification of sexual signals in Hawaiian Nesosydne planthoppers (Hemiptera: Delphacidae): The relative role of neutral and selective forces

    OpenAIRE

    Goodman, KR; Kelley, JP; Welter, SC; Roderick, GK; Elias, DO

    2015-01-01

    © 2015 European Society For Evolutionary Biology. Changes in sexual signals have the potential to promote rapid divergence and reproductive isolation among populations of animals. Thus, identifying processes contributing to variation in signals is key to understanding the drivers of speciation. However, it is difficult to identify the processes initiating changes in signals in empirical systems because (1) the demographic history of populations under study is usually unclear, and (2) there is...

  15. Human papilloma virus status evaluation and survival description in selected oropharyngeal and laryngeal squamous cell carcinoma patients from Hungary.

    Science.gov (United States)

    Reka Fejer, Eniko; Abram, Zoltan; Zs Egyed, Jiahe; Voidazan, Septimiu; Toth, Erika; Szentirmay, Zoltan; Kasler, Miklos

    2016-01-01

    Many patients with oropharyngeal squamous cell carcinomas do not have any of the traditional risk factors associated with head and neck squamous cell cancers (HNSCC). Epidemiologic and molecular studies have identified human papillomavirus (HPV) as a causative agent, viral tumors presenting a better survival and being important risk factors together with the long established ones, tobacco and alcohol consumption, in head and neck cancers. The purpose of this study was to establish the incidence of HPV-associated HNSCCs, to identify the most frequent HPV type and to evaluate the overall survival and recurrence rates of HPV-positive cases in comparison with HPV-negative HNSCCs. A retrospective analysis from the database of the National Institute of Oncology from Budapest was performed and the following parameters were analyzed: age, age at diagnosis, gender, primary tumor location, tumor histopathology, TNM stage, HPV status, date of recurrence, last visit and date of death. Out of 81 patients with HNSCCs 55 (67.9%) were male and 26 (32.1%) female. HNSCCs were more frequent in men (2.11:1) and the majority of the patients (81.7%) were diagnosed in advanced stages (TNM III and IV). HPV status was evaluated in nearly half (48.14%) of the patients and HNSCCs were positive for HPV in 43.6% of the cases. These were more frequent in patients over 50 years (76.66%), in men (76.47%) and in oropharyngeal location (94.1%). HPV-16 type was associated with malignancy in 82.35% of the cases. Disease recurrence was more frequent in HPV-negative (31.81%) vs HPV-positive cases (29.41%) and mortality rate was inferior in HPV-positive 33.33% vs negative (38.09%) tumors (p=0.52). In Hungary HNSCCs are more frequent in men than in women. HPV positivity is higher in men vs women and in oropharyngeal vs laryngeal location. Overall survival rate was superior in HPV-positive vs HPV-negative cases. Disease recurrence was more frequent in HPV-negative vs HPV-positive cases.

  16. Survival Rate without Brain Abnormalities on Postnatal Ultrasonography among Monochorionic Twins after Fetoscopic Laser Photocoagulation for Selective Intrauterine Growth Restriction with Concomitant Oligohydramnios.

    Science.gov (United States)

    Ishii, Keisuke; Wada, Seiji; Takano, Mayumi; Nakata, Masahiko; Murakoshi, Takeshi; Sago, Haruhiko

    2018-02-20

    We aimed to clarify the survival rate without brain abnormalities (BA) after fetoscopic laser photoco-agulation (FLP) for monochorionic diamniotic twin gestations (MCDA) with selective intrauterine growth restriction (sIUGR) accompanied by abnormal umbilical artery (UA) Doppler waveforms and isolated oligohydramnios in the sIUGR twin. This retrospective study included 52 cases that underwent FLP. The main outcome was survival rate without BA of the twins at age 28 days. BA was defined as severe intraventricular hemorrhage and periventricular leukomalacia on postnatal ultrasonography. Median gestational age at FLP was 20 (16-24) weeks. Ten cases were classified as type III based on Doppler for the UA. For all cases, including 20 cases of anterior placenta, FLP was completed without major intraoperative complications. Amnioinfusion was required in 49 cases for better fetoscopic visualization. Fetal loss occurred in 29 sIUGR twins and two larger twins, whereas one larger twin experienced neonatal death. Survival rates without BA were 44% (n = 23) for sIUGR twins and 94% (n = 49) for the larger twins. FLP for MCDA with sIUGR presenting with oligohydramnios in the sIUGR twin might be considered a prenatal treatment option. © 2018 S. Karger AG, Basel.

  17. Diffusion-weighted magnetic resonance imaging predicts survival in patients with liver-predominant metastatic colorectal cancer shortly after selective internal radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Schmeel, Frederic Carsten; Simon, Birgit; Luetkens, Julian Alexander; Traeber, Frank; Schmeel, Leonard Christopher; Schild, Hans Heinz; Hadizadeh, Dariusch Reza [University Hospital Bonn, Rheinische-Friedrich-Wilhelms-Universitaet Bonn, Department of Radiology, Bonn (Germany); Sabet, Amir [University Hospital Bonn, Rheinische-Friedrich-Wilhelms-Universitaet Bonn, Department of Nuclear Medicine, Bonn (Germany); University Hospital Essen, Universitaet Duisburg-Essen, Department of Nuclear Medicine, Essen (Germany); Ezziddin, Samer [University Hospital Bonn, Rheinische-Friedrich-Wilhelms-Universitaet Bonn, Department of Nuclear Medicine, Bonn (Germany); University Hospital Saarland, Universitaet des Saarlandes, Department of Nuclear Medicine, Homburg (Germany)

    2017-03-15

    To investigate whether quantifications of apparent diffusion coefficient (ADC) on diffusion-weighted imaging (DWI) can predict overall survival (OS) in patients with liver-predominant metastatic colorectal cancer (CRC) following selective internal radiation therapy with {sup 90}Yttrium-microspheres (SIRT). Forty-four patients underwent DWI 19 ± 16 days before and 36 ± 10 days after SIRT. Tumour-size and intratumoral minimal ADC (minADC) values were measured for 132 liver metastases on baseline and follow-up DWI. Optimal functional imaging response to treatment was determined by receiver operating characteristics and defined as ≥22 % increase in post-therapeutic minADC. Survival analysis was performed with the Kaplan-Meier method and Cox-regression comparing various variables with potential impact on OS. Median OS was 8 months. The following parameters were significantly associated with median OS: optimal functional imaging response (18 vs. 5 months; p < 0.001), hepatic tumour burden <50 % (8 vs. 5 months; p = 0.018), Eastern Cooperative Oncology Group performance scale <1 (10 vs. 4 months; p = 0.012) and progressive disease according to Response and Evaluation Criteria in Solid Tumours (8 vs. 3 months; p = 0.001). On multivariate analysis, optimal functional imaging response and hepatic tumour burden remained independent predictors of OS. Functional imaging response assessment using minADC changes on DWI may predict survival in CRC shortly after SIRT. (orig.)

  18. Transcriptomics of two evolutionary novelties: how to make a sperm-transfer organ out of an anal fin and a sexually selected "sword" out of a caudal fin.

    Science.gov (United States)

    Kang, Ji Hyoun; Manousaki, Tereza; Franchini, Paolo; Kneitz, Susanne; Schartl, Manfred; Meyer, Axel

    2015-02-01

    Swords are exaggerated male ornaments of swordtail fishes that have been of great interest to evolutionary biologists ever since Darwin described them in the Descent of Man (1871). They are a novel sexually selected trait derived from modified ventral caudal fin rays and are only found in the genus Xiphophorus. Another phylogenetically more widespread and older male trait is the gonopodium, an intromittent organ found in all poeciliid fishes, that is derived from a modified anal fin. Despite many evolutionary and behavioral studies on both traits, little is known so far about the molecular mechanisms underlying their development. By investigating transcriptomic changes (utilizing a RNA-Seq approach) in response to testosterone treatment in the swordtail fish, Xiphophorus hellerii, we aimed to better understand the architecture of the gene regulatory networks underpinning the development of these two evolutionary novelties. Large numbers of genes with tissue-specific expression patterns were identified. Among the "sword genes" those involved in embryonic organ development, sexual character development and coloration were highly expressed, while in the gonopodium rather more morphogenesis-related genes were found. Interestingly, many genes and genetic pathways are shared between both developing novel traits derived from median fins: the sword and the gonopodium. Our analyses show that a larger set of gene networks was co-opted during the development and evolution of the "older" gonopodium than in the "younger," and morphologically less complex trait, the sword. We provide a catalog of candidate genes for future efforts to dissect the development of those sexually selected exaggerated male traits in swordtails.

  19. Examination of 12-lipoxygenase (12-LOX) as a therapeutic target in non-small cell lung cancer (NSCLC): Mechanisms controlling survival and induction of apoptosis following selective inhibition

    LENUS (Irish Health Repository)

    Cathcart, Mary Clare

    2011-06-01

    Background: Platelet-type 12-LOX is an arachidonic acid metabolising enzyme resulting in the formation of 12(S)-HETE, which stimulates tumour cell adhesion, invasion and metastasis. This study aimed to examine the expression profile and role of this enzyme in NSCLC, and determine if it is a potential target for intervention. Methods: A panel of retrospective resected lung tumours was stained for 12-LOX expression by IHC. Levels of the 12-LOX metabolite, 12(S)-HETE, were examined in 50 NSCLC serum samples, and correlated with serum VEGF. A panel of NSCLC cell lines were treated with baicalein (10 uM), a selective inhibitor of 12-LOX, or 12(S)-HETE (100 ng\\/ml) and cell survival\\/proliferation examined by BrdU. Apoptosis following 12-LOX inhibition was examined by HCS and validated by FACS and DNA laddering. The effect of 12-LOX inhibition on NSCLC tumour growth and survival was examined in-vivo using an athymic nude mouse model. Gene alterations following 12-LOX inhibition in NSCLC cell lines were assessed by qPCR arrays and validated by RT-PCR. Transient transfection methods were used to examine the effects of 12-LOX overexpression in NSCLC cells. Results: 12-LOX expression was observed to a varying degree in human lung cancers of varying histological subtypes. 12(S)-HETE levels were correlated (p<0.05) with those of VEGF. Baicalein inhibited proliferation\\/survival in all cell lines, while 12(S)-HETE increased proliferation. 12-LOX inhibition increased apoptosis, indicated by a reduction in f-actin content and mitochondrial mass potential. Treatment with baicalein significantly reduced the growth of NSCLC tumours and increased overall survival in athymic nude mice. qPCR array data implicated a number of apoptosis\\/angiogenesis genes regulating these effects, including bcl-2, VEGF, integrin A2 and A4. 12-LOX overexpression resulted in an increase in VEGF secretion, confirming qPCR observations. Conclusions: 12-LOX is a survival factor\\/potential target in

  20. Mating systems, reproductive success, and sexual selection in secretive species: a case study of the western diamond-backed rattlesnake, Crotalus atrox.

    Science.gov (United States)

    Clark, Rulon W; Schuett, Gordon W; Repp, Roger A; Amarello, Melissa; Smith, Charles F; Herrmann, Hans-Werner

    2014-01-01

    Long-term studies of individual animals in nature contribute disproportionately to our understanding of the principles of ecology and evolution. Such field studies can benefit greatly from integrating the methods of molecular genetics with traditional approaches. Even though molecular genetic tools are particularly valuable for species that are difficult to observe directly, they have not been widely adopted. Here, we used molecular genetic techniques in a 10-year radio-telemetric investigation of the western diamond-backed rattlesnake (Crotalus atrox) for an analysis of its mating system and to measure sexual selection. Specifically, we used microsatellite markers to genotype 299 individuals, including neonates from litters of focal females to ascertain parentage using full-pedigree likelihood methods. We detected high levels of multiple paternity within litters, yet found little concordance between paternity and observations of courtship and mating behavior. Larger males did not father significantly more offspring, but we found evidence for size-specific male-mating strategies, with larger males guarding females for longer periods in the mating seasons. Moreover, the spatial proximity of males to mothers was significantly associated with reproductive success. Overall, our field observations alone would have been insufficient to quantitatively measure the mating system of this population of C. atrox, and we thus urge more widespread adoption of molecular tools by field researchers studying the mating systems and sexual selection of snakes and other secretive taxa.

  1. Mating systems, reproductive success, and sexual selection in secretive species: a case study of the western diamond-backed rattlesnake, Crotalus atrox.

    Directory of Open Access Journals (Sweden)

    Rulon W Clark

    Full Text Available Long-term studies of individual animals in nature contribute disproportionately to our understanding of the principles of ecology and evolution. Such field studies can benefit greatly from integrating the methods of molecular genetics with traditional approaches. Even though molecular genetic tools are particularly valuable for species that are difficult to observe directly, they have not been widely adopted. Here, we used molecular genetic techniques in a 10-year radio-telemetric investigation of the western diamond-backed rattlesnake (Crotalus atrox for an analysis of its mating system and to measure sexual selection. Specifically, we used microsatellite markers to genotype 299 individuals, including neonates from litters of focal females to ascertain parentage using full-pedigree likelihood methods. We detected high levels of multiple paternity within litters, yet found little concordance between paternity and observations of courtship and mating behavior. Larger males did not father significantly more offspring, but we found evidence for size-specific male-mating strategies, with larger males guarding females for longer periods in the mating seasons. Moreover, the spatial proximity of males to mothers was significantly associated with reproductive success. Overall, our field observations alone would have been insufficient to quantitatively measure the mating system of this population of C. atrox, and we thus urge more widespread adoption of molecular tools by field researchers studying the mating systems and sexual selection of snakes and other secretive taxa.

  2. Critical Reflections on Evolutionary Psychology and Sexual Selection Theory as Explanatory Account of Emergence of Sex Differences in Psychopathology: Comment on Martel (2013)

    Science.gov (United States)

    Hankin, Benjamin L.

    2014-01-01

    Martel (2013) proposed a meta-theory, based on sexual selection theory and broad evolutionary psychological (EP) principles, to account for well-known sex differences in the emergence of common behavioral and certain internalizing disorders across childhood and adolescence, respectively. This Comment first enumerates several strengths and then offers two primary critiques about Martel’s proposal. Martel provides an exceptional, integrative review that organizes several disparate literatures that hold promise to enhance understanding of such sex differences. At the same time, I raise critical questions regarding EP generally, and sexual selection theory specifically, as the meta-theoretical framework chosen to bind together these different influences and mechanisms as drivers of the sex difference in different psychopathologies. Indeed, it is not clear that EP is necessary—nor does it provide unique explanatory power—to explicate the emergence of sex differences in internalizing and externalizing disorders among youth. Moreover, Martel’s EP-based proposal pertains to adolescent-onset depression and social phobia but does not provide an explanation for known sex differences in other common childhood-onset and early adult-onset anxiety disorders. PMID:24188421

  3. Run for your life, but bite for your rights? How interactions between natural and sexual selection shape functional morphology across habitats

    Science.gov (United States)

    Gomes, Verónica; Carretero, Miguel A.; Kaliontzopoulou, Antigoni

    2018-02-01

    A central issue in evolutionary biology is how morphology, performance, and habitat use coevolve. If morphological variation is tightly associated with habitat use, then differences in morphology should affect fitness through their effect on performance within specific habitats. In this study, we investigate how evolutionary forces mold morphological traits and performance differently given the surrounding environment, at the intraspecific level. For this purpose, we selected populations of the lizard Podarcis bocagei from two different habitat types, agricultural walls and dunes, which we expected to reflect saxicolous vs ground-dwelling habits. In the laboratory, we recorded morphological traits as well as performance traits by measuring sprint speed, climbing capacity, maneuverability, and bite force. Our results revealed fast-evolving ecomorphological variation among populations of P. bocagei, where a direct association existed between head morphology and bite performance. However, we could not establish links between limb morphology and locomotor performance at the individual level. Lizards from walls were better climbers than those from dunes, suggesting a very fast evolutionary response. Interestingly, a significant interaction between habitat and sex was detected in climbing performance. In addition, lizards from dunes bit harder than those from walls, although sexual differentiation was definitely the main factor driving variation in head functional morphology. Taking into account all the results, we found a complex interaction between natural and sexual selection on whole-organism performance, which are, in some cases, reflected in morphological variation.

  4. Critical reflections on evolutionary psychology and sexual selection theory as explanatory account of emergence of sex differences in psychopathology: comment on Martel (2013).

    Science.gov (United States)

    Hankin, Benjamin L

    2013-11-01

    Martel (2013) proposed a metatheory, based on sexual selection theory and broad evolutionary psychological (EP) principles, to account for well-known sex differences in the emergence of common behavioral and certain internalizing disorders across childhood and adolescence, respectively. In this comment, I first enumerate several strengths and then offer 2 primary critiques about Martel's proposal. Martel provides an exceptional, integrative review that organizes several disparate literatures that hold promise to enhance understanding of such sex differences. At the same time, I raise critical questions regarding EP generally, and sexual selection theory specifically, as the metatheoretical framework chosen to bind together these different influences and mechanisms as drivers of the sex difference in different psychopathologies. Indeed, it is not clear that EP is necessary--nor does it provide unique explanatory power-to explicate the emergence of sex differences in internalizing and externalizing disorders among youth. Moreover, Martel's EP-based proposal pertains to adolescent-onset depression and social phobia but does not provide an explanation for known sex differences in other common childhood-onset and early adult-onset anxiety disorders. © 2013 American Psychological Association

  5. Darwin vs. Wallace: When Poetry Dies and When Poetry Survives in the Not-so-Natural Selection of Memetic Evolution

    Science.gov (United States)

    Christensen, Bryce

    2011-01-01

    The theory of memetic evolution--explaining the reproduction of cultural units called "memes"--illuminates the decline of poetry as a cultural presence by clarifying the contrasting attitudes towards poetry manifested by the co-discoverers of natural selection: Charles Darwin and Alfred Wallace. Darwin's eventual indifference to poetry…

  6. The male–female health–survival paradox: A survey and register study of the impact of sex-specific selection and information bias

    Science.gov (United States)

    Oksuzyan, Anna; Petersen, Inge; Stovring, Henrik; Bingley, Paul; Vaupel, James W.; Christensen, Kaare

    2009-01-01

    Purpose The present study examined whether the health–survival paradox could partially be due to sex-specific selection and information bias in surveys. Methods The study is based on the linkage of three population-based surveys of 15,330 Danes aged 46–102 years with health registers covering the total Danish population regarding hospitalizations within the last 2 years and prescription medicine within 6 months prior to the baseline surveys. Results Men had higher participation rates than women at all ages. Hospitalized women and women taking medications had higher participation rate compared with non-hospitalized women (difference 0.7–3.0%) and female non-users (difference 0.8–7.6%), respectively, while no consistent pattern was found among men according to hospitalization or medication use status. Men used fewer medications than women, but they under-reported medication use to a similar degree as did women. Conclusions Hospitalized women, as well as women using prescription medicine, were slightly overrepresented in the surveys. Hence, the study found some evidence that selection bias in surveys may contribute to the explanation of the health–survival paradox, but its contribution is likely to be small. However, there was no evidence for sex-specific reporting of medication use among study participants. PMID:19457685

  7. The cure: design and evaluation of a crowdsourcing game for gene selection for breast cancer survival prediction.

    Science.gov (United States)

    Good, Benjamin M; Loguercio, Salvatore; Griffith, Obi L; Nanis, Max; Wu, Chunlei; Su, Andrew I

    2014-07-29

    Molecular signatures for predicting breast cancer prognosis could greatly improve care through personalization of treatment. Computational analyses of genome-wide expression datasets have identified such signatures, but these signatures leave much to be desired in terms of accuracy, reproducibility, and biological interpretability. Methods that take advantage of structured prior knowledge (eg, protein interaction networks) show promise in helping to define better signatures, but most knowledge remains unstructured. Crowdsourcing via scientific discovery games is an emerging methodology that has the potential to tap into human intelligence at scales and in modes unheard of before. The main objective of this study was to test the hypothesis that knowledge linking expression patterns of specific genes to breast cancer outcomes could be captured from players of an open, Web-based game. We envisioned capturing knowledge both from the player's prior experience and from their ability to interpret text related to candidate genes presented to them in the context of the game. We developed and evaluated an online game called The Cure that captured information from players regarding genes for use as predictors of breast cancer survival. Information gathered from game play was aggregated using a voting approach, and used to create rankings of genes. The top genes from these rankings were evaluated using annotation enrichment analysis, comparison to prior predictor gene sets, and by using them to train and test machine learning systems for predicting 10 year survival. Between its launch in September 2012 and September 2013, The Cure attracted more than 1000 registered players, who collectively played nearly 10,000 games. Gene sets assembled through aggregation of the collected data showed significant enrichment for genes known to be related to key concepts such as cancer, disease progression, and recurrence. In terms of the predictive accuracy of models trained using this

  8. Sigma Virus (DMelSV Incidence in Lines of Drosophila melanogaster Selected for Survival following Infection with Bacillus cereus

    Directory of Open Access Journals (Sweden)

    Meghan L. Bentz

    2017-01-01

    Full Text Available The immune response of Drosophila melanogaster is complex and involves both specific and general responses to parasites. In this study we tested for cross-immunity for bacteria and viruses by scoring the incidence of infection with the vertically transmitted Sigma virus (DMelSV in the progeny of a cross between females transmitting DMelSV at high frequencies and males from lines subjected to three selection regimes related to resistance to Bacillus cereus. There was no significant difference in transmission of DMelSV among selection regimes, though results suggest that the B. cereus selected lines had lower rates of infection by DMelSV. We found a significant difference in viral infection with respect to the sex of the progeny, with males consistently less likely to be infected than females. Given a finite energy budget, flies that have experienced immune system challenge may show alterations in other life history traits. Later eclosing progeny were also less likely to be infected than earlier eclosing progeny, indicating a relationship with development time. Finally, there was a significant interaction between the timing of collection and the sex of the progeny, such that later eclosing males were the most resistant group. Increased development time is sometimes associated with increased energy acquisition; from this perspective, increased development time may be associated with acquiring sufficient resources for effective resistance.

  9. The Impact and Oxidation Survival of Selected Meteoritic Compounds: Signatures of Asteroid Organic Material on Planetary Surfaces

    Science.gov (United States)

    Cooper, George; Horz, Fred; Oleary, Alanna; Chang, Sherwood

    2013-01-01

    Polar, non-volatile organic compounds may be present on the surfaces (or near surfaces) of multiple Solar System bodies. If found, by current or future missions, it would be desirable to determine the origin(s) of such compounds, e.g., asteroidal or in situ. To test the possible survival of meteoritic compounds both during impacts with planetary surfaces and under subsequent (possibly) harsh ambient conditions, we subjected known meteoritic compounds to relatively high impact-shock pressures and/or to varying oxidizing/corrosive conditions. Tested compounds include sulfonic and phosphonic acids (S&P), polyaromatic hydrocarbons (PAHs) amino acids, keto acids, dicarboxylic acids, deoxy sugar acids, and hydroxy tricarboxylic acids (Table 1). Meteoritic sulfonic acids were found to be relatively abundant in the Murchison meteorite and to possess unusual S-33 isotope anomalies (non mass-dependent isotope fractionations). Combined with distinctive C-S and C-P bonds, the S&P are potential signatures of asteroidal organic material.

  10. Prediction error variance and expected response to selection, when selection is based on the best predictor – for Gaussian and threshold characters, traits following a Poisson mixed model and survival traits

    Directory of Open Access Journals (Sweden)

    Jensen Just

    2002-05-01

    Full Text Available Abstract In this paper, we consider selection based on the best predictor of animal additive genetic values in Gaussian linear mixed models, threshold models, Poisson mixed models, and log normal frailty models for survival data (including models with time-dependent covariates with associated fixed or random effects. In the different models, expressions are given (when these can be found – otherwise unbiased estimates are given for prediction error variance, accuracy of selection and expected response to selection on the additive genetic scale and on the observed scale. The expressions given for non Gaussian traits are generalisations of the well-known formulas for Gaussian traits – and reflect, for Poisson mixed models and frailty models for survival data, the hierarchal structure of the models. In general the ratio of the additive genetic variance to the total variance in the Gaussian part of the model (heritability on the normally distributed level of the model or a generalised version of heritability plays a central role in these formulas.

  11. Sexual conflict in plants

    Indian Academy of Sciences (India)

    In dioecious species, the two sexes often make different investments in reproduction, or have different reproductive strategies, leading to divergent selection pressures across sexes. This, combined with a shared genome, can poten- tially result in an intragenomic conflict called sexual conflict. (Chapman et al. 2003). Sexual ...

  12. A preference for a sexual signal keeps females safe.

    Directory of Open Access Journals (Sweden)

    Tae Won Kim

    Full Text Available Predation is generally thought to constrain sexual selection by female choice and limit the evolution of conspicuous sexual signals. Under high predation risk, females usually become less choosy, because they reduce their exposure to their predators by reducing the extent of their mate searching. However, predation need not weaken sexual selection if, under high predation risk, females exhibit stronger preferences for males that use conspicuous signals that help females avoid their predators. We tested this prediction in the fiddler crab Uca terpsichores by increasing females' perceived predation risk from crab-eating birds and measuring the attractiveness of a courtship signal that females use to find mates. The sexual signal is an arching mound of sand that males build at the openings of their burrows to which they attract females for mating. We found that the greater the risk, the more attractive were males with those structures. The benefits of mate preferences for sexual signals are usually thought to be linked to males' reproductive contributions to females or their young. Our study provides the first evidence that a female preference for a sexual signal can yield direct survival benefits by keeping females safe as they search for mates.

  13. Scavenging superoxide selectively in mouse forebrain is associated with improved cardiac function and survival following myocardial infarction.

    Science.gov (United States)

    Lindley, Timothy E; Infanger, David W; Rishniw, Mark; Zhou, Yi; Doobay, Marc F; Sharma, Ram V; Davisson, Robin L

    2009-01-01

    Dysregulation in central nervous system (CNS) signaling that results in chronic sympathetic hyperactivity is now recognized to play a critical role in the pathogenesis of heart failure (HF) following myocardial infarction (MI). We recently demonstrated that adenovirus-mediated gene transfer of cytoplasmic superoxide dismutase (Ad-Cu/ZnSOD) to forebrain circumventricular organs, unique sensory structures that lack a blood-brain barrier and link peripheral blood-borne signals to central nervous system cardiovascular circuits, inhibits both the MI-induced activation of these central signaling pathways and the accompanying sympathoexcitation. Here, we tested the hypothesis that this forebrain-targeted reduction in oxidative stress translates into amelioration of the post-MI decline in myocardial function and increase in mortality. Adult C57BL/6 mice underwent left coronary artery ligation or sham surgery along with forebrain-targeted gene transfer of Ad-Cu/ZnSOD or a control vector. The results demonstrate marked MI-induced increases in superoxide radical formation in one of these forebrain regions, the subfornical organ (SFO). Ad-Cu/ZnSOD targeted to this region abolished the increased superoxide levels and led to significantly improved myocardial function compared with control vector-treated mice. This was accompanied by diminished levels of cardiomyocyte apoptosis in the Ad-Cu/ZnSOD but not the control vector-treated group. These effects of superoxide scavenging with Ad-Cu/ZnSOD in the forebrain paralleled increased post-MI survival rates compared with controls. This suggests that oxidative stress in the SFO plays a critical role in the deterioration of cardiac function following MI and underscores the promise of CNS-targeted antioxidant therapy for the treatment of MI-induced HF.

  14. DCE-MRI prediction of survival time for patients with glioblastoma multiforme: using an adaptive neuro-fuzzy-based model and nested model selection technique.

    Science.gov (United States)

    Dehkordi, Azimeh N V; Kamali-Asl, Alireza; Wen, Ning; Mikkelsen, Tom; Chetty, Indrin J; Bagher-Ebadian, Hassan

    2017-09-01

    This pilot study investigates the construction of an Adaptive Neuro-Fuzzy Inference System (ANFIS) for the prediction of the survival time of patients with glioblastoma multiforme (GBM). ANFIS is trained by the pharmacokinetic (PK) parameters estimated by the model selection (MS) technique in dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) data analysis, and patient age. DCE-MRI investigations of 33 treatment-naïve patients with GBM were studied. Using the modified Tofts model and MS technique, the following physiologically nested models were constructed: Model 1, no vascular leakage (normal tissue); Model 2, leakage without efflux; Model 3, leakage with bidirectional exchange (influx and efflux). For each patient, the PK parameters of the three models were estimated as follows: blood plasma volume (vp ) for Model 1; vp and volume transfer constant (K(trans) ) for Model 2; vp , K(trans) and rate constant (kep ) for Model 3. Using Cox regression analysis, the best combination of the estimated PK parameters, together with patient age, was identified for the design and training of ANFIS. A K-fold cross-validation (K = 33) technique was employed for training, testing and optimization of ANFIS. Given the survival time distribution, three classes of survival were determined and a confusion matrix for the correct classification fraction (CCF) of the trained ANFIS was estimated as an accuracy index of ANFIS's performance. Patient age, kep and ve (K(trans) /kep ) of Model 3, and K(trans) of Model 2, were found to be the most effective parameters for training ANFIS. The CCF of the trained ANFIS was 84.8%. High diagonal elements of the confusion matrix (81.8%, 90.1% and 81.8% for Class 1, Class 2 and Class 3, respectively), with low off-diagonal elements, strongly confirmed the robustness and high performance of the trained ANFIS for predicting the three survival classes. This study confirms that DCE-MRI PK analysis, combined with the MS technique and ANFIS

  15. Wired on steroids: sexual differentiation of the brain and its role in the expression of sexual partner preferences.

    Science.gov (United States)

    Alexander, Brenda M; Skinner, Donal C; Roselli, Charles E

    2011-01-01

    The preference to seek out a sexual partner of the opposite sex is robust and ensures reproduction and survival of the species. Development of female-directed partner preference in the male is dependent on exposure of the developing brain to gonadal steroids synthesized during critical periods of sexual differentiation of the central nervous system. In the absence of androgen exposure, a male-directed partner preference develops. The development and expression of sexual partner preference has been extensively studied in rat, ferret, and sheep model systems. From these models it is clear that gonadal testosterone, often through estrogenic metabolites, cause both masculinization and defeminization of behavior during critical periods of brain development. Changes in the steroid environment during these critical periods result in atypical sexual partner preference. In this manuscript, we review the major findings which support the hypothesis that the organizational actions of sex steroids are responsible for sexual differentiation of sexual partner preferences in select non-human species. We also explore how this information has helped to frame our understanding of the biological influences on human sexual orientation and gender identity.

  16. Wired on steroids: Sexual differentiation of the brain and its role in the expression of sexual partner preferences

    Directory of Open Access Journals (Sweden)

    Brenda Mae Alexander

    2011-10-01

    Full Text Available The preference to seek out a sexual partner of the opposite sex is robust and ensures reproduction and survival of the species. Development of female-directed partner preference in the male is dependent on exposure of the developing brain to gonadal steroids synthesized during critical periods of sexual differentiation of the central nervous system. In the absence of androgen exposure, a male-directed partner preference develops. The development and expression of sexual partner preference has been extensively studied in rats, ferrets, and sheep model systems. From these models it is clear that gonadal testosterone, often through estrogenic metabolites, cause both masculinization and defeminization of behavior during critical periods of brain development. Changes in the steroid environment during these critical periods results in atypical sexual partner preference. In this manuscript, we review the major findings which support the hypothesis that the organizational actions of sex steroids are responsible for sexual differentiation of sexual partner preferences in select non-human species. We also explore how this information has helped to frame our understanding of the biological influences on human sexual orientation and gender identity.

  17. Blue and green egg-color intensity is associated with parental effort and mating system in passerines: support for the sexual selection hypothesis.

    Science.gov (United States)

    Soler, Juan J; Moreno, Juan; Avilés, Jesús M; Møller, Anders P

    2005-03-01

    Among several adaptive explanations proposed to account for variation in avian egg color, that related to sexual selection is of particular interest because of its possible generality. Briefly, it proposes that because biliverdin (the pigment responsible for blue-green eggshell coloration) is an antioxidant, deposition in the eggshell by laying females may signal the capacity of females to control free radicals, despite the handicap of removing this antioxidant from their body. If males adjust parental effort in response to the intensity of the blue coloration of eggs, thereby investing more in the offspring of high-quality mates, blue eggs may represent a postmating sexually selected signal in females. Here, by image and spectrophotometric analyses of the eggs of European passerines, we tested two different predictions of the hypothesis. First, variables related to intraspecific variation in parental effort (i.e., the duration of the nestling period controlled for body mass) should be positively related to the intensity of blue-green color of the eggshell across species. Second, there should be a positive relationship between intensity of blue-green color of eggs and degree of polygyny. These predictions were supported: intensity of blue-green coloration (i.e., chroma) was significantly related to the duration of the nestling period and to degree of polygyny after controlling for possible confounding variables (i.e., body mass, incubation period, and nest type) and similarity due to common descent. Nest type (hole or nonhole) also explained a significant proportion of variation in egg chroma, perhaps reflecting different selection pressures (i.e., light conditions, risk of parasitism) affecting species with the two types of nests.

  18. Associations between youth homelessness, sexual offenses, sexual victimization, and sexual risk behaviors: a systematic literature review.

    Science.gov (United States)

    Heerde, Jessica A; Scholes-Balog, Kirsty E; Hemphill, Sheryl A

    2015-01-01

    Homeless youth commonly report engaging in sexual risk behaviors. These vulnerable young people also frequently report being sexually victimized. This systematic review collates, summarizes, and appraises published studies of youth investigating relationships between homelessness, perpetration of sexual offenses, experience of sexual victimization, and engagement in sexual risk behavior. A systematic search of seventeen psychology, health, and social science electronic databases was conducted. Search terms included "homeless*," "youth," "offend*," "victimization," "crime," "rape," "victim*," and "sex crimes." Thirty-eight studies were identified that met the inclusion criteria. Findings showed homeless youth commonly report being raped and sexually assaulted, fear being sexually victimized, and engage in street prostitution and survival sex. Rates of victimization and sexual risk behavior were generally higher for females. Given the paucity of longitudinal studies and limitations of current studies, it is unclear whether homelessness is prospectively associated with sexual victimization or engagement in sexual risk behavior, and whether such associations vary cross nationally and as a function of time and place. Future prospective research examining the influence of the situational context of homelessness is necessary to develop a better understanding of how homelessness influences the perpetration of sexual offenses, experience of sexual victimization, and engagement in sexual risk behavior among homeless youth.

  19. Association of brain-derived neurotrophic factor valine to methionine polymorphism with sexual dysfunction following selective serotonin reuptake inhibitor treatment in female patients with major depressive disorder.

    Science.gov (United States)

    Nazree, Nur Elia; Mohamed, Zahurin; Reynolds, Gavin P; Mohd Zain, Shamsul; Masiran, Ruziana; Sidi, Hatta; Chong, Lu Ann; Hway, Anne Yee; Adlan, Aida Syarinaz; Zainal, Nor Zuraida

    2016-12-01

    The occurrence of female sexual dysfunction (FSD) in patients with major depressive disorder (MDD) receiving selective serotonin reuptake inhibitors (SSRIs) treatment gives negative impacts on patients' quality of life and causes treatment discontinuation. We aimed to investigate whether genetic polymorphism of identified candidate gene is associated with FSD in our study population. This is a cross-sectional study. A total of 95 female patients with MDD who met the criteria of the study were recruited and were specifically assessed on the sexual function by trained psychiatrists. Patients' DNA was genotyped for BDNF Val66Met polymorphism using real-time polymerase chain reaction. The prevalence of FSD in this study is 31.6%. In the FSD group, patients with problematic marriage were significantly more frequent compared with patients who did not have problematic marriage (P = 0.009). Significant association was detected in the lubrication domain with BDNF Val66Met polymorphism (P = 0.030) using additive genetic model, with even stronger association when using the recessive model (P = 0.013). This study suggested that there was no significant association between BDNF Val66Met with FSD. However, this polymorphism is significantly associated with lubrication disorder in patients treated with SSRIs. © 2015 Wiley Publishing Asia Pty Ltd.

  20. How Setswana Cultural Beliefs and Practices on Sexuality Affect Teachers' and Adolescents' Sexual Decisions, Practices, and Experiences as well as HIV/AIDS and STI Prevention in Select Botswanan Secondary Schools.

    Science.gov (United States)

    Nleya, Paul T; Segale, Emelda

    2015-01-01

    The article reports on the aspects of a Botswana Ministry of Education and Skills Development (MoE & SD) HIV/AIDS Instructional Television (ITV) project modeled on a similar HIV/AIDS program implemented in Brazil. This Teacher Capacity Building Project (TCBP) in Botswana is in its initial years of implementation. Its overall goal is to contribute to the prevention and mitigation of the impact of HIV and AIDS by strengthening the capacity of the education and communication sectors to deliver interactive, distance HIV/AIDS education primarily to teachers so that they act as agents of behavior change among the in-school youth. One of the components of the TCBP program is a live teacher education television HIV/AIDS program called Talk Back program. Talk Back is a collaborative effort of the MoE & SD and the Botswana national television station. The Talk Back program involves development and implementation of weekly 1 hour live HIV/AIDS education interactive TV broadcasts for teachers. The development of the live programs is guided by a curriculum that provides a wide range of themes related to HIV/AIDS and education. This article reports the results of a survey of a sample of teachers and students at junior secondary schools and senior secondary schools, first, on their views and opinions regarding the Talk Back program as a TCBP. Second, how Setswana cultural beliefs, myths, and practices on sexuality affect teachers' and adolescents' sexual decisions, practices, and experiences as well as HIV/AIDS and sexually transmitted infection prevention. A questionnaire survey and focus group interviews were used as data collection instruments in selected secondary schools. The findings of the study suggest that the Talk Back program has not met much success as a TCBP. The findings further suggest that several myths, beliefs, misconceptions, and attitudes about HIV/AIDS exist among Botswana teachers and students and thus make it difficult for the Talk Back program to impart

  1. Preparing for adulthood--patterns of physical growth, sexual maturity and menarche of adolescent girls in selected urban slums and rural areas.

    Science.gov (United States)

    Gupta, Neeru; Singh, M P; Dhillon, B S; Saxena, N C

    2007-03-01

    Adolescent girls are the future mothers. Height less than 145 cm and weight less than 45 kg are considered to be high obstetric risk factor for adverse maternal and perinatal outcome including low birth weight. Teenage pregnancy is another problem in our country. This study aimed to study height and weight of girls of vulnerable urban slums and rural areas. It also studied the pattern of onset of menarche and attainment of sexual maturity in relation to age. The longitudinal, multicentric, descriptive observational study was carried out by the Indian Council of Medical Research during the period of 1986 to 1991 in selected rural (Chandigarh, Hyderabad, Jabalpur, Varanasi, Vellore) and two urban slum areas (Vellore and Delhi) in different regions of India. Girls of ages 10-12 years were followed up till 16 years for their height and weight. Weight increased from 22.3 to 39.4 kg in rural and 23.4 to 41.9 kg in urban areas from 10 to 16 years. Height increased from 126.2 cm to 150.2 cm in rural and 128.2 to 153.0 cm in urban areas. Large variations from centre to centre were observed in ages for appearance of sexual characteristic and the order in which these appeared. Pubic hair was the first sexual characteristic to appear in majority of the girls in all the centres. The mean age at stages II, III and IV of breast development in girls varied between 11.3 to 12.3 years, 12.3 to 13.2 years and 13.3 to 14.1 years respectively. The percentage of girls who had attained menarche by the age of 15 years, ranged from 30 to 100 per cent between centres. Those children in whom the sexual characteristics had appeared earlier than others had higher mean body weight and height as compared to others at the same age points. The data on physical growth parameters during adolescence revealed that girls from rural areas, were shorter and weighed less compared to those from urban slums. Adolescent girls are undernourished in urban slums and rural areas.

  2. Evolution and human sexuality.

    Science.gov (United States)

    Gray, Peter B

    2013-12-01

    The aim of this review is to put core features of human sexuality in an evolutionary light. Toward that end, I address five topics concerning the evolution of human sexuality. First, I address theoretical foundations, including recent critiques and developments. While much traces back to Darwin and his view of sexual selection, more recent work helps refine the theoretical bases to sex differences and life history allocations to mating effort. Second, I consider central models attempting to specify the phylogenetic details regarding how hominin sexuality might have changed, with most of those models honing in on transitions from a possible chimpanzee-like ancestor to the slightly polygynous and long-term bonded sociosexual partnerships observed among most recently studied hunter-gatherers. Third, I address recent genetic and physiological data contributing to a refined understanding of human sexuality. As examples, the availability of rapidly increasing genomic information aids comparative approaches to discern signals of selection in sexuality-related phenotypes, and neuroendocrine studies of human responses to sexual stimuli provide insight into homologous and derived mechanisms. Fourth, I consider some of the most recent, large, and rigorous studies of human sexuality. These provide insights into sexual behavior across other national samples and on the Internet. Fifth, I discuss the relevance of a life course perspective to understanding the evolution of human sexuality. Most research on the evolution of human sexuality focuses on young adults. Yet humans are sexual beings from gestation to death, albeit in different ways across the life course, and in ways that can be theoretically couched within life history theory. Copyright © 2013 Wiley Periodicals, Inc.

  3. Newborn neurons in the olfactory bulb selected for long-term survival through olfactory learning are prematurely suppressed when the olfactory memory is erased.

    Science.gov (United States)

    Sultan, Sébastien; Rey, Nolwen; Sacquet, Joelle; Mandairon, Nathalie; Didier, Anne

    2011-10-19

    A role for newborn neurons in olfactory memory has been proposed based on learning-dependent modulation of olfactory bulb neurogenesis in adults. We hypothesized that if newborn neurons support memory, then they should be suppressed by memory erasure. Using an ecological approach in mice, we showed that behaviorally breaking a previously learned odor-reward association prematurely suppressed newborn neurons selected to survive during initial learning. Furthermore, intrabulbar infusions of the caspase pan-inhibitor ZVAD (benzyloxycarbonyl-Val-Ala-Asp) during the behavioral odor-reward extinction prevented newborn neurons death and erasure of the odor-reward association. Newborn neurons thus contribute to the bulbar network plasticity underlying long-term memory.

  4. A Quality Assessment of Patient-Reported Outcome Measures for Sexual Function in Neurologic Patients Using the Consensus-based Standards for the Selection of Health Measurement Instruments Checklist: A Systematic Review.

    Science.gov (United States)

    't Hoen, Lisette A; Groen, Jan; Scheepe, Jeroen R; Reuvers, Sarah; Diaz, David Castro; Fernández, Bárbara Padilla; Del Popolo, Giulio; Musco, Stefania; Hamid, Rizwan; Ecclestone, Hazel; Karsenty, Gilles; Phé, Veronique; Boissier, Romain; Kessler, Thomas M; Gross, Tobias; Schneider, Marc P; Pannek, Jürgen; Blok, Bertil F M

    2016-06-23

    Impaired sexual function has a significant effect on quality of life. Various patient-reported outcome measures (PROMs) are available to evaluate sexual function. The quality of the PROMs to be used for neurologic patients remains unknown. To systematically review which validated PROMs are available to evaluate sexual function in neurologic patients and to critically assess the quality of the validation studies and measurement properties for each identified PROM. A systematic review was performed according to the Preferred Reporting Items for Systematic Review and Meta-analysis statement. The included publications were assessed according to the Consensus-Based Standards for the Selection of Health Measurement Instruments checklist. Twenty-one studies for PROMs regarding sexual function were identified for the following patient groups: spinal cord injury (11 studies), multiple sclerosis (MS; 6 studies), Parkinson's disease (2 studies), traumatic brain injury (1 study), and epilepsy (1 study). The evidence for the quality of PROMs was found to be variable, and overall evaluation of measurement properties was lacking in 71% of the studies. The measurement error and responsiveness were not studied in any of the publications. Several PROMs have been identified to evaluate sexual function in neurologic patients. Strong evidence was found only for the Multiple Sclerosis Intimacy and Sexuality Questionnaire-15 and Multiple Sclerosis Intimacy and Sexuality Questionnaire-19 for patients with MS, although evidence was lacking for certain measurement properties as well. Future research should focus on identifying relevant PROMs and establishing adequate quality for all measurement properties in studies with high methodological quality. A quality assessment of patient-reported outcome measures (PROMs) for sexual function in neurologic patients was made. The evidence found for good PROMs was limited. Studies with high methodological quality are needed to improve the quality of

  5. Analyses adjusting for selective crossover show improved overall survival with adjuvant letrozole compared with tamoxifen in the BIG 1-98 study.

    Science.gov (United States)

    Colleoni, Marco; Giobbie-Hurder, Anita; Regan, Meredith M; Thürlimann, Beat; Mouridsen, Henning; Mauriac, Louis; Forbes, John F; Paridaens, Robert; Láng, István; Smith, Ian; Chirgwin, Jacquie; Pienkowski, Tadeusz; Wardley, Andrew; Price, Karen N; Gelber, Richard D; Coates, Alan S; Goldhirsch, Aron

    2011-03-20

    Among postmenopausal women with endocrine-responsive breast cancer, the aromatase inhibitor letrozole, when compared with tamoxifen, has been shown to significantly improve disease-free survival (DFS) and time to distant recurrence (TDR). We investigated whether letrozole monotherapy prolonged overall survival (OS) compared with tamoxifen monotherapy. Of 8,010 postmenopausal women with hormone receptor-positive, early breast cancer enrolled on the Breast International Group (BIG) 1-98 study, 4,922 were randomly assigned to 5 years of continuous adjuvant therapy with either letrozole or tamoxifen. Of 2,459 patients enrolled in the tamoxifen treatment arm, 619 (25.2%) selectively crossed over to either adjuvant or extended letrozole after initial trial results were presented in January 2005. To gain better estimates of relative treatment effects in the presence of selective crossover, we used inverse probability of censoring weighted (IPCW) modeling. Weighted Cox models, by using IPCW, estimated a statistically significant, 18% reduction in the hazard of an OS event with letrozole treatment (hazard ratio [HR], 0.82; 95% CI, 0.70 to 0.95). Estimates of 5-year OS on the basis of IPCW were 91.8% and 90.4% for letrozole and tamoxifen, respectively. The HRs of DFS and TDR events by using IPCW modeling were 0.83 (95% CI, 0.74 to 0.94) and 0.80 (95% CI, 0.67 to 0.94), respectively (P < .05 for DFS, OS, and TDR). Median follow-up was 74 months. Adjuvant treatment with letrozole, compared with tamoxifen, significantly reduces the risk of death, the risk of recurrent disease, and the risk of recurrence at distant sites in postmenopausal women with hormone receptor-positive breast cancer.

  6. Sexual Health

    Science.gov (United States)

    ... health By Mayo Clinic Staff Sexual health basics Sexuality is part of being human. Love, affection and ... infections. Talking to kids about sex Kids and sexuality — those words strike fear into the hearts of ...

  7. Short-term threats for the sustained survival of freshwater Mollusca in the Olifants River and selected tributaries.

    Directory of Open Access Journals (Sweden)

    Kenné N. de Kock

    2013-02-01

    Full Text Available The conservation status of less than 2% of the more or less 7000 mollusk species known worldwide have been properly assessed. Consequently the general level of imperilment is poorly documented and almost certainly underestimated. Freshwater mollusks live permanently in water, have limited means of movement and are exposed to a variety of anthropogenic waste products due to the fact that waterbodies often act as sinks for a large array of harmful pollutants. The Olifants River is often described as one of the most polluted rivers in Southern Africa and is progressively subjected to extremely high pressure with regard to natural resources and associated rural transformation and pollution. Little is on record regarding the diversity of the Mollusca in the Olifants River; therefore, in the present study, four surveys of the molluscs were conducted in this river and selected tributaries during two consecutive years at three localities situated on the Highveld and four localities situated in the Lowveld respectively. The pH and electric conductivity of the water were determined during each survey at each one of the localities and values ranged from 6.93 to 9.50, and 110 µS to 1336 µS, for pH and conductivity respectively. A total of 25 mollusk species were collected during the four surveys which included the exotic invader species Lymnaea columella, Physa acuta, Aplexa marmorata and Tarebia granifera. The latter species yielded the highest number of specimens by far, mainly at a locality which could be described as largely transformed. The results of this investigation can serve as a point of departure for future surveys to evaluate the impact of anthropogenic disturbances on the mollusc diversity in the Olifants River and catchment.

  8. Genomic analysis of a sexually-selected character: EST sequencing and microarray analysis of eye-antennal imaginal discs in the stalk-eyed fly Teleopsis dalmanni (Diopsidae

    Directory of Open Access Journals (Sweden)

    Wang Xianhui

    2009-08-01

    Full Text Available Abstract Background Many species of stalk-eyed flies (Diopsidae possess highly-exaggerated, sexually dimorphic eye-stalks that play an important role in the mating system of these flies. Eye-stalks are increasingly being used as a model system for studying sexual selection, but little is known about the genetic mechanisms producing variation in these ornamental traits. Therefore, we constructed an EST database of genes expressed in the developing eye-antennal imaginal disc of the highly dimorphic species Teleopsis dalmanni. We used this set of genes to const