Sample records for disruptive sexual selection
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Environmental change disrupts communication and sexual selection in a stickleback population.
Candolin, Ulrika; Tukiainen, Iina; Bertell, Elina
2016-04-01
Environmental change that disrupts communication during mate choice and alters sexual selection could influence population dynamics. Yet little is known about such long-term effects. We investigated experimentally the consequences that disrupted visual communication during mate choice has for the quantity and viability of offspring produced in a threespine stickleback population (Gasterosteus aculeatus). We further related the results to long-term monitoring of population dynamics in the field to determine if changes are apparent under natural conditions. The results show that impaired visual communication because of algal blooms reduces reliability of male visual signals as indicators of offspring survival during their first weeks of life. This relaxes sexual selection but has no effect on the number of offspring hatching, as most males have a high hatching success in turbid water. Despite eutrophication and high turbidity levels that interfere with communication during mate choice, the population has grown during recent decades. Large numbers of offspring hatching, combined with high variation in juvenile fitness, has probably shifted selection to later life history stages and maintained a viable population. Together with reduced cost of sexual selection and ongoing ecosystem changes caused by human activities, this could have promoted population growth. These results point to the complexity of ecosystems and the necessity to consider all influencing factors when attempting to understand impacts of human activities on populations.
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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.
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The relationship between sexual selection and sexual conflict.
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.
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Sexual selection protects against extinction.
Lumley, Alyson J; Michalczyk, Łukasz; Kitson, James J N; Spurgin, Lewis G; Morrison, Catriona A; Godwin, Joanne L; Dickinson, Matthew E; Martin, Oliver Y; Emerson, Brent C; Chapman, Tracey; Gage, Matthew J G
2015-06-25
Reproduction through sex carries substantial costs, mainly because only half of sexual adults produce offspring. It has been theorized that these costs could be countered if sex allows sexual selection to clear the universal fitness constraint of mutation load. Under sexual selection, competition between (usually) males and mate choice by (usually) females create important intraspecific filters for reproductive success, so that only a subset of males gains paternity. If reproductive success under sexual selection is dependent on individual condition, which is contingent to mutation load, then sexually selected filtering through 'genic capture' could offset the costs of sex because it provides genetic benefits to populations. Here we test this theory experimentally by comparing whether populations with histories of strong versus weak sexual selection purge mutation load and resist extinction differently. After evolving replicate populations of the flour beetle Tribolium castaneum for 6 to 7 years under conditions that differed solely in the strengths of sexual selection, we revealed mutation load using inbreeding. Lineages from populations that had previously experienced strong sexual selection were resilient to extinction and maintained fitness under inbreeding, with some families continuing to survive after 20 generations of sib × sib mating. By contrast, lineages derived from populations that experienced weak or non-existent sexual selection showed rapid fitness declines under inbreeding, and all were extinct after generation 10. Multiple mutations across the genome with individually small effects can be difficult to clear, yet sum to a significant fitness load; our findings reveal that sexual selection reduces this load, improving population viability in the face of genetic stress.
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Sexual selection: Another Darwinian process.
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
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Signal trait sexual dimorphism and mutual sexual selection in Drosophila serrata.
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.
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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
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Parker, Geoff A
2014-08-21
After brief historic overviews of sexual selection and sexual conflict, I argue that pre-ejaculatory sexual selection (the form of sexual selection discussed by Darwin) arose at a late stage in an inevitable succession of transitions flowing from the early evolution of syngamy to the evolution of copulation and sex roles. If certain conditions were met, this "sexual cascade" progressed inevitably, if not, sexual strategy remained fixed at a given stage. Prolonged evolutionary history of intense sperm competition/selection under external fertilization preceded the rise of advanced mobility, which generated pre-ejaculatory sexual selection, followed on land by internal fertilization and reduced sperm competition in the form of postcopulatory sexual selection. I develop a prospective model of the early evolution of mobility, which, as Darwin realized, was the catalyst for pre-ejaculatory sexual selection. Stages in the cascade should be regarded as consequential rather than separate phenomena and, as such, invalidate much current opposition to Darwin-Bateman sex roles. Potential for sexual conflict occurs throughout, greatly increasing later in the cascade, reaching its peak under precopulatory sexual selection when sex roles become highly differentiated. Copyright © 2014 Cold Spring Harbor Laboratory Press; all rights reserved.
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Sexual selection protects against extinction
Lumley, Alyson; Michalczyk, Lukasz; Kitson, James; Spurgin, Lewis; Morrison, Catriona; Godwin, Joanne; Dickinson, Matthew; Martin, Oliver; Emerson, Brent; Chapman, Tracey; Gage, Matthew
2015-01-01
Reproduction through sex carries substantial costs, mainly because only half of sexual adults produce offspring. It has been theorised that these costs could be countered if sex allows sexual selection to clear the universal fitness constraint of mutation load. Under sexual selection, competition between (usually) males, and mate choice by (usually) females create important intraspecific filters for reproductive success, so that only a subset of males gains paternity. If reproductive success ...
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Sexual Selection and Adaptation to Novel Environments
Martinossi-Allibert, Ivain
2017-01-01
The work included in this thesis aims at exploring the environmental sensitivity of benefits and costs of sexual selection through a combined empirical and theoretical effort, to increase our understanding of the impact of environmental change on sexually reproducing populations.Can sexual selection promote adaptation to novel environments? Sexual selection for good genes should accelerate adaptation by granting higher reproductive success to individuals of high genetic quality. However, sexu...
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Sexual selection and hermaphroditic organisms: Testing theory
Directory of Open Access Journals (Sweden)
Janet L. LEONARD
2013-08-01
Full Text Available Sexual selection is widespread if not ubiquitous in hermaphroditic organisms. Although many phenomena that have been described as sexual selection in gonochores, (e.g. harem polygamy, multiple mating, elaborate courtship, even secondary sexual characters can be found in some hermaphrodites, what is more interesting is the ways in which sexual selection in hermaphrodites may differ from dioecious taxa. In hermaphrodites, an individual’s mating success includes its success from both sexual roles. Secondly, in many simultaneously hermaphroditic taxa there is strong evidence of sexual selection and yet the operational sex ratio is 1:1, by definition. Many simultaneous hermaphrodites have elaborate courtship and genital anatomy, suggesting sexual selection plays an important role in reproductive success. Sperm competition and cryptic female choice mean that the number of mates acquired is not necessarily a predictor of reproductive success. Even in simultaneous hermaphrodites with reciprocal mating, variance in reproductive success through the male role and through the female role may differ in a population. Moreover hermaphrodites may choose to emphasize one sexual role over the other. Data suggest that the preferred role varies in hermaphrodites, which creates an opportunity to test fundamental predictions and assumptions of sexual selection theory. Hermaphrodites may vary their emphasis on one sexual role over the other either developmentally or behaviorally in response to environmental or social parameters. How they use this capability in acquiring more or higher quality mates still requires study [Current Zoology 59 (4: 579–588, 2013].
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Crudgington, Helen S; Beckerman, Andrew P; Brüstle, Lena; Green, Kathleen; Snook, Rhonda R
2005-05-01
Sexual conflict over reproduction can occur between males and females. In several naturally promiscuous insect species, experimental evolution studies that have enforced monogamy found evidence for sexual conflict. Here, we subjected the naturally promiscuous, sperm-heteromorphic fruit fly Drosophila pseudoobscura to enforced monogamy, standard levels of promiscuity, and elevated opportunities for promiscuity in four replicate lines. We examined the effect of male and female selection history and the proximate effect of variation in male density on female fitness parameters. We found that male density rather than male selection history explained a greater degree of female fecundity, egg hatching success, and productivity. Additionally, females selected under elevated promiscuity had greater fecundity and hatching success than did enforced monogamy females. Selection line males do not differ in their capacity to coerce females to remate, suggesting no divergence in precopulatory manipulative ability. However, these males did vary in their ability to suppress female remating, suggesting postcopulatory manipulation. These results indicate that sexual conflict can be manifested through both the proximate effects of male density and the historical levels of sexual selection and that the sexes respond differentially to these factors and further stress the multifarious channels of sexual communication that contribute to fitness.
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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
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Darden, Safi K; James, Richard; Ramnarine, Indar W; Croft, Darren P
2009-07-22
Across sexually reproducing species, males and females are in conflict over the control of reproduction. At the heart of this conflict in a number of taxa is male harassment of females for mating opportunities and female strategies to avoid this harassment. One neglected consequence that may result from sexual harassment is the disruption of important social associations. Here, we experimentally manipulate the degree of sexual harassment that wild female guppies (Poecilia reticulata) experience by establishing replicated, semi-natural pools with different population sex ratios. We quantify the effects of sexual harassment on female social structure and the development of social recognition among females. When exposed to sexual harassment, we found that females had more disparate social networks with limited repeated interactions when compared to females that did not experience male harassment. Furthermore, females that did not experience harassment developed social recognition with familiar individuals over an 8-day period, whereas females that experienced harassment did not, an effect we suggest is due to disruption of association patterns. These results show that social network structure and social recognition can be affected by sexual harassment, an effect that will be relevant across taxonomic groups and that we predict will have fitness consequences for females.
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Sexually selected females in the monogamous Western Australian seahorse.
Kvarnemo, Charlotta; Moore, Glenn I; Jones, Adam G
2007-02-22
Studies of sexual selection in monogamous species have hitherto focused on sexual selection among males. Here, we provide empirical documentation that sexual selection can also act strongly on females in a natural population with a monogamous mating system. In our field-based genetic study of the monogamous Western Australian seahorse, Hippocampus subelongatus, sexual selection differentials and gradients show that females are under stronger sexual selection than males: mated females are larger than unmated ones, whereas mated and unmated males do not differ in size. In addition, the opportunity for sexual selection (variance in mating success divided by its mean squared) for females is almost three times that for males. These results, which seem to be generated by a combination of a male preference for larger females and a female-biased adult sex ratio, indicate that substantial sexual selection on females is a potentially important but under-appreciated evolutionary phenomenon in monogamous species.
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Why are sexually selected weapons almost absent in females?
Directory of Open Access Journals (Sweden)
Anders BERGLUND
2013-08-01
Full Text Available In sex role reversed species, predominantly females evolve sexually selected traits, such as ornaments and/or weapons. Female ornaments are common and their function well documented in many species, whether sex role reversed or not. However, sexually selected female weapons seem totally absent except for small wing spurs in three jacana species, present in both males and females. This poor female weaponry is in sharp contrast to the situation in species with conventional sex roles: males commonly have evolved sexually selected weapons as well as ornaments. At the same time, females in many taxa have naturally selected weapons, used in competition over resources or in predator defence. Why are sexually selected weapons then so rare, almost absent, in females? Here I briefly review weaponry in females and the function of these weapons, conclude that the near absence of sexually selected weapons begs an explanation, and suggest that costs of sexually selected weapons may exceed costs of ornaments. Females are more constrained when evolving sexually selected traits compared to males, at least compared to those males that do not provide direct benefits, as trait costs reduce a female’s fecundity. I suggest that this constraining trade-off between trait and fecundity restricts females to evolve ornaments but rarely weapons. The same may apply to paternally investing males. Whether sexually selected weapons actually are more costly than sexually selected ornaments remains to be investigated [Current Zoology 59 (4: 564–568, 2013].
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Endocrine-disrupting chemicals: prepubertal exposures and effects on sexual maturation and thyroid function in the male rat. A focus on the EDSTAC recommendations. Endocrine Disrupter Screening and Testing Advisory Committee.Stoker TE, Parks LG, Gray LE, Cooper RL.
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Border, Shana E
2018-01-01
Abstract Natural selection has been shown to drive population differentiation and speciation. The role of sexual selection in this process is controversial; however, most of the work has centered on mate choice while the role of male–male competition in speciation is relatively understudied. Here, we outline how male–male competition can be a source of diversifying selection on male competitive phenotypes, and how this can contribute to the evolution of reproductive isolation. We highlight how negative frequency-dependent selection (advantage of rare phenotype arising from stronger male–male competition between similar male phenotypes compared with dissimilar male phenotypes) and disruptive selection (advantage of extreme phenotypes) drives the evolution of diversity in competitive traits such as weapon size, nuptial coloration, or aggressiveness. We underscore that male–male competition interacts with other life-history functions and that variable male competitive phenotypes may represent alternative adaptive options. In addition to competition for mates, aggressive interference competition for ecological resources can exert selection on competitor signals. We call for a better integration of male–male competition with ecological interference competition since both can influence the process of speciation via comparable but distinct mechanisms. Altogether, we present a more comprehensive framework for studying the role of male–male competition in speciation, and emphasize the need for better integration of insights gained from other fields studying the evolutionary, behavioral, and physiological consequences of agonistic interactions. PMID:29492042
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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.
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Sexual dimorphism and directional sexual selection on aposematic signals in a poison frog
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
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Sexual Selection of Protamine 1 in Mammals.
Lüke, Lena; Tourmente, Maximiliano; Roldan, Eduardo R S
2016-01-01
Protamines have a crucial role in male fertility. They are involved in sperm chromatin packaging and influence the shape of the sperm head and, hence, are important for sperm performance. Protamine structure is basic with numerous arginine-rich DNA-binding domains. Postcopulatory sexual selection is thought to play an important role in protamine sequence evolution and expression. Here, we analyze patterns of evolution and sexual selection (in the form of sperm competition) acting on protamine 1 gene sequence in 237 mammalian species. We assessed common patterns as well as differences between the major mammalian subclasses (Eutheria, Metatheria) and clades. We found that a high arginine content in protamine 1 associates with a lower sperm head width, which may have an impact on sperm swimming velocity. Increase in arginine content in protamine 1 across mammals appears to take place in a way consistent with sexual selection. In metatherians, increase in sequence length correlates with sexual selection. Differences in selective pressures on sequences and codon sites were observed between mammalian clades. Our study revealed a complex evolutionary pattern of protamine 1, with different selective constraints, and effects of sexual selection, between mammalian groups. In contrast, the effect of arginine content on head shape, and the possible involvement of sperm competition, was identified across all mammals. © The Author 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
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Production control and supplier selection under demand disruptions
Directory of Open Access Journals (Sweden)
Xianzhe Chen
2010-12-01
Full Text Available This paper investigates the effects of demand disruptions on production control and supplier selection in a three-echelon supply chain system. The customer demand is modeled as a jump-diffusion process in a continuous-time setting. A two-number production-inventory policy is implemented in the production control model for the manufacturer. The objective is to minimize the long-term average total cost consisting of backlog cost, holding cost, switching cost, and ordering cost. The simulated annealing method is applied to search the optimal critical switching values. Furthermore, an improved analytical hierarchy process (AHP is proposed to select the best supplier, based on quantitative factors such as the optimal long-term total cost obtained through the simulated annealing method under demand disruptions and qualitative factors such as quality and service. Numerical studies are conducted to demonstrate the effects of demand disruptions in the face of various risk scenarios. Managerial insights from simulation results are provided as well. Our approaches can be implemented as the “stress test” for companies in front of various supply chain disruption scenarios.
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Homage to Bateman: sex roles predict sex differences in sexual selection.
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.
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Sexual and Natural Selection Both Influence Male Genital Evolution
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 ...
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Parental selection of children's sexual orientation.
Greenberg, A S; Bailey, J M
2001-08-01
As we learn more about the causes of sexual orientation, the likelihood increases that parents will one day be able to select the orientation of their children. This possibility (at least that of selecting for heterosexuality) has generated a great deal of concern among supporters of homosexual rights, with such selection being widely condemned as harmful and morally repugnant. Notwithstanding this widespread condemnation, and even assuming, as we do, that homosexuality is entirely acceptable morally, allowing parents, by means morally unproblematic in themselves, to select for heterosexuality would be morally acceptable. This is because allowing parents to select their children's sexual orientation would further parent's freedom to raise the sort of children they wish to raise and because selection for heterosexuality may benefit parents and children and is unlikely to cause significant harm.
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Sexual selection predicts species richness across the animal kingdom.
Janicke, Tim; Ritchie, Michael G; Morrow, Edward H; Marie-Orleach, Lucas
2018-05-16
Our improving knowledge of the animal tree of life consistently demonstrates that some taxa diversify more rapidly than others, but what contributes to this variation remains poorly understood. An influential hypothesis proposes that selection arising from competition for mating partners plays a key role in promoting speciation. However, empirical evidence showing a link between proxies of this sexual selection and species richness is equivocal. Here, we collected standardized metrics of sexual selection for a broad range of animal taxa, and found that taxonomic families characterized by stronger sexual selection on males show relatively higher species richness. Thus, our data support the hypothesis that sexual selection elevates species richness. This could occur either by promoting speciation and/or by protecting species against extinction. © 2018 The Author(s).
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The effect of sexual selection on adaptation and extinction under increasing temperatures.
Parrett, Jonathan M; Knell, Robert J
2018-04-25
Strong sexual selection has been reported to both enhance and hinder the adaptive capacity and persistence of populations when exposed to novel environments. Consequently, how sexual selection influences population adaption and persistence under stress remains widely debated. Here, we present two empirical investigations of the fitness consequences of sexual selection on populations of the Indian meal moth, Plodia interpunctella, exposed to stable or gradually increasing temperatures. When faced with increasing temperatures, strong sexual selection was associated with both increased fecundity and offspring survival compared with populations experiencing weak sexual selection, suggesting sexual selection acts to drive adaptive evolution by favouring beneficial alleles. Strong sexual selection did not, however, delay extinction when the temperature became excessively high. By manipulating individuals' mating opportunities during fitness assays, we were able to assess the effect of multiple mating independently from the effect of population-level sexual selection, and found that polyandry has a positive effect on both fecundity and offspring survival under increasing temperatures in those populations evolving with weak sexual selection. Within stable temperatures, there were some benefits from strong sexual selection but these were not consistent across the entire experiment, possibly reflecting changing costs and benefits of sexual selection under stabilizing and directional selection. These results indicate that sexual selection can provide a buffer against climate change and increase adaptation rates within a continuously changing environment. These positive effects of sexual selection may, however, be too small to protect populations and delay extinction when environmental changes are relatively rapid. © 2018 The Author(s).
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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...
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DEFF Research Database (Denmark)
Regenberg, Birgitte; Hansen, J.
2000-01-01
the GAP1 gene. This is caused by recombination between two Salmonella typuimurium hisG direct repeats embracing GAP1, and will result in a sub-population of gap1 cells. Such cells are selected on a medium containing D-histidine, and may subsequently be used for a second gene disruption. Hence, multiple...... flanked by short (60 bp) stretches of the gene in question. Through homologous recombination, the cassette will integrate into the target gene, which is thus replaced by GAP1, and mutants are selected for on minimal L-citrulline medium. When propagated under non-selective conditions, some cells will lose...... gene disruptions can be made fast, cheaply and easily in a gap1 strain, with two positive selection steps for each disruption. Copyright (C) 2000 John Wiley & Sons, Ltd....
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Darwin's explanation of races by means of sexual selection.
Millstein, Roberta L
2012-09-01
In Darwin's Sacred Cause, Adrian Desmond and James Moore contend that "Darwin would put his utmost into sexual selection because the subject intrigued him, no doubt, but also for a deeper reason: the theory vindicated his lifelong commitment to human brotherhood" (2009: p. 360). Without questioning Desmond and Moore's evidence, I will raise some puzzles for their view. I will show that attention to the structure of Darwin's arguments in the Descent of Man shows that they are far from straightforward. As Desmond and Moore note, Darwin seems to have intended sexual selection in non-human animals to serve as evidence for sexual selection in humans. However, Darwin's account of sexual selection in humans was different from the canonical cases that Darwin described at great length. If explaining the origin of human races was the main reason for introducing sexual selection, and if sexual selection was a key piece of Darwin's anti-slavery arguments, then it is puzzling why Darwin would have spent so much time discussing cases that did not really support his argument for the origin of human races, and it is also puzzling that his argument for the origin of human races would be so (atypically) poor. Copyright © 2012 Elsevier Ltd. All rights reserved.
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Prenatal undernutrition disrupted the sexual maturation, but not the sexual behavior, in male rats.
Matsuzaki, Toshiya; Munkhzaya, Munkhsaikhan; Tungalagsuvd, Altankhuu; Mayila, Yiliyasi; Iwasa, Takeshi; Yano, Kiyohito; Yanagihara, Rie; Tokui, Takako; Kato, Takeshi; Kuwahara, Akira; Matsui, Sumika; Irahara, Minoru
2017-10-01
Exposure to various stressors, including psychological, metabolic, and immune, in the perinatal period induces long-lasting effects in physiological function and increase the risk of metabolic disorders in later life. In the present study, sexual maturation and sexual behavior were assessed in prenatally undernourished mature male rats. All the pregnant rats were divided into the maternal normal nutrition (mNN) group and the maternal undernutrition (mUN) group. The mUN mothers received 50% of the amount of the daily food intake of the mNN mothers. Preputial separation and sexual behavior were observed in randomly selected pups of the mNN and mUN groups. The body weight of the mothers was significantly lighter in the mUN group than in the mNN group. Similarly, the pups in the mUN group showed a significantly lower body weight than those in the mNN group from postnatal day (PND) 1 to PND 15. The preputial separation day was significantly delayed in the mUN group, compared to the mNN group. Sexual behavior did not show any significant difference between the two groups. These findings indicated that prenatal undernutrition delayed sexual maturation, but did not suppress sexual behavior, in mature male rats.
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Maintenance of a genetic polymorphism with disruptive natural selection in stickleback.
Marchinko, Kerry B; Matthews, Blake; Arnegard, Matthew E; Rogers, Sean M; Schluter, Dolph
2014-06-02
The role of natural selection in the maintenance of genetic variation in wild populations remains a major problem in evolution. The influence of disruptive natural selection on genetic variation is especially interesting because it might lead to the evolution of assortative mating or dominance [1, 2]. In theory, variation can persist at a gene under disruptive natural selection, but the process is little studied and there are few examples [3, 4]. We report a stable polymorphism in the bony armor of threespine stickleback maintained with a deficit of heterozygotes at the major underlying gene, Ectodysplasin (Eda) [5]. The deficit vanishes at the embryo life stage only to re-emerge in adults, indicating that disruptive natural selection, rather than nonrandom mating, is the cause. The mechanism enabling long-term persistence of the polymorphism is unknown, but disruptive selection is predicted to be frequency dependent, favoring homozygous genotypes when they become rare. Further research on the ecological and evolutionary processes affecting individual genes will ultimately lead to a better understanding of the causes of genetic variation in populations. Copyright © 2014 Elsevier Ltd. All rights reserved.
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Positive allometry and the prehistory of sexual selection.
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.
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Mate choice and sexual selection: what have we learned since Darwin?
Jones, Adam G; Ratterman, Nicholas L
2009-06-16
Charles Darwin laid the foundation for all modern work on sexual selection in his seminal book The Descent of Man, and Selection in Relation to Sex. In this work, Darwin fleshed out the mechanism of sexual selection, a hypothesis that he had proposed in The Origin of Species. He went well beyond a simple description of the phenomenon by providing extensive evidence and considering the far-reaching implications of the idea. Here we consider the contributions of Darwin to sexual selection with a particular eye on how far we have progressed in the last 150 years. We focus on 2 key questions in sexual selection. First, why does mate choice evolve at all? And second, what factors determine the strength of mate choice (or intensity of sexual selection) in each sex? Darwin provided partial answers to these questions, and the progress that has been made on both of these topics since his time should be seen as one of the great triumphs of modern evolutionary biology. However, a review of the literature shows that key aspects of sexual selection are still plagued by confusion and disagreement. Many of these areas are complex and will require new theory and empirical data for complete resolution. Overall, Darwin's contributions are still surprisingly relevant to the modern study of sexual selection, so students of evolutionary biology would be well advised to revisit his works. Although we have made significant progress in some areas of sexual selection research, we still have much to accomplish.
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Sexual selection targets cetacean pelvic bones
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
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Female Remating, Sperm Competition and Sexual Selection in Drosophila
Singh, Dr. Shree Ram; Singh, Dr. B N; Hoenigsberg, Dr. H F
2002-01-01
Female remating is the fundamental to evolutionary biology as it determines the pattern of sexual selection and sexual conflict. Remating in females is an important component of Drosophila mating systems because it is associated with pattern of sperm usage and sexual selection. Remating is common in females of many species of Drosophila in both natural and laboratory populations. It is reported in many insect species and vertebrates also. Female remating is prerequisite for the ...
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Sexually selected traits: a fundamental framework for studies on behavioral epigenetics.
Jašarević, Eldin; Geary, David C; Rosenfeld, Cheryl S
2012-01-01
Emerging evidence suggests that epigenetic-based mechanisms contribute to various aspects of sex differences in brain and behavior. The major obstacle in establishing and fully understanding this linkage is identifying the traits that are most susceptible to epigenetic modification. We have proposed that sexual selection provides a conceptual framework for identifying such traits. These are traits involved in intrasexual competition for mates and intersexual choice of mating partners and generally entail a combination of male-male competition and female choice. These behaviors are programmed during early embryonic and postnatal development, particularly during the transition from the juvenile to adult periods, by exposure of the brain to steroid hormones, including estradiol and testosterone. We evaluate the evidence that endocrine-disrupting compounds, including bisphenol A, can interfere with the vital epigenetic and gene expression pathways and with the elaboration of sexually selected traits with epigenetic mechanisms presumably governing the expression of these traits. Finally, we review the evidence to suggest that these steroid hormones can induce a variety of epigenetic changes in the brain, including the extent of DNA methylation, histone protein alterations, and even alterations of noncoding RNA, and that many of the changes differ between males and females. Although much previous attention has focused on primary sex differences in reproductive behaviors, such as male mounting and female lordosis, we outline why secondary sex differences related to competition and mate choice might also trace their origins back to steroid-induced epigenetic programming in disparate regions of the brain.
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[Sexual offences--selected cases].
Łabecka, Marzena; Jarzabek-Bielecka, Grazyna; Lorkiewicz-Muszyńska, Dorota
2013-04-01
Expert testimony on violence victims also includes victims of sexual assault. The role of an expert is to classify the injuries by their severity as defined in art. 157 156 or 217 of the Criminal Code pertaining to crimes against health and life. Also, the role of an expert opinion is to determine whether the injuries identified during the exam occurred at the time and under the circumstances stated in medical history. The examination of sexual assault victims is conducted by two experts: a gynecologist and a forensic physician. Most examinations are performed at different times and various medical centers. The conclusions are presented in an official report. Regardless of victim age, all sexual crimes are investigated ex officio by the Police Department and the Prosecutor's Office. Further legal classification of criminal offenses is the task of an appropriate legal body and the offenses are codified in accordance with the provisions of chapter XXV of the Criminal Code, articles 197 - 205. In controversial cases, i.e. when two different expert opinions appear on the same case, or if, according to the law enforcement, a medical opinion is insufficient for some reason, an appropriate expert or team of experts is appointed to resolve the problem. To present selected cases of sexual violence victims treated at the Department of Gynecology and assessed at the Department of Forensic Medicine with reference to the challenges regarding qualification of the sustained injuries and clinical diagnoses. Research material included selected forensic opinions developed for law enforcement offices that involved victims of sexual violence. The expert opinions were prepared either on the basis of submitted evidence, or both, submitted evidence and examination of the victim at the Department of Forensic Medicine. Moreover the article presents a case of a patient examined and treated at the Department of Gynecology in Poznan. Based on the selected cases, the authors conclude that a
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Sexual selection and allometry: a critical reappraisal of the evidence and ideas.
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.
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Positive allometry and the prehistory of sexual selection
Tomkins, Joseph L.; LeBas, Natasha R.; Witton, Mark P.; Martill, David M.; Humphries, Stuart
2010-01-01
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 c...
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Procymidone (PRO) and dibutyl phthalate (DBP) alter male rat sexual differentiation by disrupting the androgen-signaling pathway via distinctly different cellular mechanisms of toxicity. DBP inhibits fetal Leydig cell androgen production whereas PRO binds AR and blocks androgen a...
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The role of ecology in speciation by sexual selection: a systematic empirical review.
Scordato, Elizabeth S C; Symes, Laurel B; Mendelson, Tamra C; Safran, Rebecca J
2014-01-01
Theoretical and empirical research indicates that sexual selection interacts with the ecological context in which mate choice occurs, suggesting that sexual and natural selection act together during the evolution of premating reproductive isolation. However, the relative importance of natural and sexual selection to speciation remains poorly understood. Here, we applied a recent conceptual framework for examining interactions between mate choice divergence and ecological context to a review of the empirical literature on speciation by sexual selection. This framework defines two types of interactions between mate choice and ecology: internal interactions, wherein natural and sexual selection jointly influence divergence in sexual signal traits and preferences, and external interactions, wherein sexual selection alone acts on traits and preferences but ecological context shapes the transmission efficacy of sexual signals. The objectives of this synthesis were 3-fold: to summarize the traits, ecological factors, taxa, and geographic contexts involved in studies of mate choice divergence; to analyze patterns of association between these variables; and to identify the most common types of interactions between mate choice and ecological factors. Our analysis revealed that certain traits are consistently associated with certain ecological factors. Moreover, among studies that examined a divergent sexually selected trait and an ecological factor, internal interactions were more common than external interactions. Trait-preference associations may thus frequently be subject to both sexual and natural selection in cases of divergent mate choice. Our results highlight the importance of interactions between sexual selection and ecology in mate choice divergence and suggest areas for future research. © The American Genetic Association. 2014. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
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Sexual selection and magic traits in speciation with gene flow
Directory of Open Access Journals (Sweden)
Maria R. SERVEDIO, Michael KOPP
2012-06-01
Full Text Available The extent to which sexual selection is involved in speciation with gene flow remains an open question and the subject of much research. Here, we propose that some insight can be gained from considering the concept of magic traits (i.e., traits involved in both reproductive isolation and ecological divergence. Both magic traits and other, “non-magic”, traits can contribute to speciation via a number of specific mechanisms. We argue that many of these mechanisms are likely to differ widely in the extent to which they involve sexual selection. Furthermore, in some cases where sexual selection is present, it may be prone to inhibit rather than drive speciation. Finally, there are a priori reasons to believe that certain categories of traits are much more effective than others in driving speciation. The combination of these points suggests a classification of traits that may shed light on the broader role of sexual selection in speciation with gene flow. In particular, we suggest that sexual selection can act as a driver of speciation in some scenarios, but may play a negligible role in potentially common categories of magic traits, and may be likely to inhibit speciation in common categories of non-magic traits [Current Zoology 58 (3: 507–513, 2012].
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The geography of sex-specific selection, local adaptation, and sexual dimorphism.
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.
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Trajković, Jelena; Miličić, Dragana; Savić, Tatjana; Pavković-Lučić, Sofija
2017-07-01
Evolution of reproductive isolation may be a consequence of a variety of signals used in courtship and mate preferences. Pheromones play an important role in both sexual selection and sexual isolation. The abundance of pheromones in Drosophila melanogaster may depend on different environmental factors, including diet. The aim of this study was to ascertain to which degree principal pheromones affect sexual selection in D. melanogaster. We used D. melanogaster strains reared for 14 years on four substrates: standard cornmeal substrate and those containing tomato, banana and carrot. We have previously determined that long-term maintaining of these dietary strains resulted in differences in their cuticular hydrocarbons profile (CHs). In this work, we have tested the level of sexual selection and sexual isolation between aforementioned strains. We found that the high levels of cis-vaccenyl acetate, 7-pentacosene and 7,11-nonacosadiene in the strain reared on a substrate containing carrot affected the individual attractiveness and influenced sexual isolation between flies of this strain and flies reared on a substrate containing banana. Based on these results, long-term different diets, may contribute, to sexual behaviour of D. melanogaster via the effects of principal pheromones. Copyright © 2017 Elsevier B.V. All rights reserved.
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Signal transducer and activator of transcription 5b (STAT5b) is a growth hormone (GH)-activated transcription factor and a master regulator of sexually dimorphic gene expression in the liver. Disruption ofthe GH hypothalamo-pituitary-liver axis controlling STAT5b activation can ...
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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.
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Do extra-group fertilizations increase the potential for sexual selection in male mammals?
Isvaran, Kavita; Sankaran, Sumithra
2017-10-01
Fertilizations by males outside the social breeding group (extra-group paternity, EGP) are widespread in birds and mammals. EGP is generally proposed to increase male reproductive skew and thereby increase the potential for sexual selection, but the generality of this relationship is unclear. We extracted data from 27 mammals in seven orders and used phylogenetic comparative methods to investigate the influence of EGP and social mating system on measures of inequality in male fertilization success, which are indices of the potential for sexual selection. We find that EGP and social mating system can predict the potential for sexual selection in mammalian populations, but only when considered jointly and not individually. EGP appears to increase the potential for sexual selection but only when the degree of social polygyny is relatively low. When social polygyny is high, EGP appears to result in a more uniform distribution of reproduction and a decrease in the potential for sexual selection. A possible explanation to be investigated is that the phenotype of extra-group fathers differs systematically across social mating systems. Our findings have implications for the use of EGP and social mating system as indices of sexual selection in comparative analyses of trait evolution under sexual selection. © 2017 The Author(s).
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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.
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Sexual selection affects local extinction and turnover in bird communities
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.
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Sexual Selection and the differences between the sexes in Mandrills (Mandrillus sphinx).
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.
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Sexual selection by male choice in monogamous and polygynous human populations.
Ihara, Y; Aoki, K
1999-02-01
The theoretical possibility of coevolution of a viability-reducing female physical trait and a male mating preference for that trait by Fisherian sexual selection in monogamous and polygynous populations is demonstrated using two-locus haploid models. It is assumed that there is dichotomous variation in male resources, resource-rich males have a wider choice among females than resource-poor males, and a female has greater reproductive success when mated with a resource-rich male than a resource-poor one. Under these assumptions, we find that sexual selection operates effectively when female reproductive success is strongly dependent on male resource, the proportion of females that mate with resource-rich males is neither small nor large, the degree of polygyny is low, and resources are inherited from father to son. We suggest that some human female physical traits may have evolved by sexual selection through male choice. The evolution of skin color by sexual selection is discussed as an example. Copyright 1999 Academic Press.
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Postcopulatory sexual selection is associated with reduced variation in sperm morphology.
Directory of Open Access Journals (Sweden)
Sara Calhim
2007-05-01
Full Text Available The evolutionary role of postcopulatory sexual selection in shaping male reproductive traits, including sperm morphology, is well documented in several taxa. However, previous studies have focused almost exclusively on the influence of sperm competition on variation among species. In this study we tested the hypothesis that intraspecific variation in sperm morphology is driven by the level of postcopulatory sexual selection in passerine birds.Using two proxy measures of sperm competition level, (i relative testes size and (ii extrapair paternity level, we found strong evidence that intermale variation in sperm morphology is negatively associated with the degree of postcopulatory sexual selection, independently of phylogeny.Our results show that the role of postcopulatory sexual selection in the evolution of sperm morphology extends to an intraspecific level, reducing the variation towards what might be a species-specific 'optimum' sperm phenotype. This finding suggests that while postcopulatory selection is generally directional (e.g., favouring longer sperm across avian species, it also acts as a stabilising evolutionary force within species under intense selection, resulting in reduced variation in sperm morphology traits. We discuss some potential evolutionary mechanisms for this pattern.
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Andersson, Malte
2004-01-01
Sexual selection in the form of sperm competition is a major explanation for small size of male gametes. Can sexual selection in polyandrous species with reversed sex roles also lead to reduced female gamete size? Comparative studies show that egg size in birds tends to decrease as a lineage evolves social polyandry. Here, a quantitative genetic model predicts that female scrambles over mates lead to evolution of reduced female gamete size. Increased female mating success drives the evolution of smaller eggs, which take less time to produce, until balanced by lowered offspring survival. Mean egg size is usually reduced and polyandry increased by increasing sex ratio (male bias) and maximum possible number of mates. Polyandry also increases with the asynchrony (variance) in female breeding start. Opportunity for sexual selection increases with the maximum number of mates but decreases with increasing sex ratio. It is well known that parental investment can affect sexual selection. The model suggests that the influence is mutual: owing to a coevolutionary feedback loop, sexual selection in females also shapes initial parental investment by reducing egg size. Feedback between sexual selection and parental investment may be common.
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Testing for a genetic response to sexual selection in a wild Drosophila population.
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.
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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
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Puniamoorthy, Nalini; Schäfer, Martin A; Blanckenhorn, Wolf U
2012-07-01
Sexual size dimorphism (SSD) varies widely across and within species. The differential equilibrium model of SSD explains dimorphism as the evolutionary outcome of consistent differences in natural and sexual selection between the sexes. Here, we comprehensively examine a unique cross-continental reversal in SSD in the dung fly, Sepsis punctum. Using common garden laboratory experiments, we establish that SSD is male-biased in Europe and female-biased in North America. When estimating sexual (pairing success) and fecundity selection (clutch size of female partner) on males under three operational sex ratios (OSRs), we find that the intensity of sexual selection is significantly stronger in European versus North American populations, increasing with male body size and OSR in the former only. Fecundity selection on female body size also increases strongly with egg number and weakly with egg volume, however, equally on both continents. Finally, viability selection on body size in terms of intrinsic (physiological) adult life span in the laboratory is overall nil and does not vary significantly across all seven populations. Although it is impossible to prove causality, our results confirm the differential equilibrium model of SSD in that differences in sexual selection intensity account for the reversal in SSD in European versus North American populations, presumably mediating the ongoing speciation process in S. punctum. © 2012 The Author(s).
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Sexual Selection Revisited ? Towards a Gender-Neutral Theory and Practice
2007-01-01
Abstract In a recent issue of this journal, Vandermassen suggested that feminists should include sexual selection theory and evolutionary psychology in a unifying theory of human nature. In response, this article aims to offer some insight into the development of sexual selection theory, to caution against Vandermassen's unreserved assimilation and to promote the opposite ongoing integration ? an inclusion of gender perspectives into evolutionary biology. In society today, opinions...
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Sexual Selection on male cuticular hydrocarbons via male-male competition and female choice.
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.
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Sex in murky waters: algal-induced turbidity increases sexual selection in pipefish.
Sundin, Josefin; Aronsen, Tonje; Rosenqvist, Gunilla; Berglund, Anders
2017-01-01
Algal-induced turbidity has been shown to alter several important aspects of reproduction and sexual selection. However, while turbidity has been shown to negatively affect reproduction and sexually selected traits in some species, it may instead enhance reproductive success in others, implying that the impact of eutrophication is far more complex than originally believed. In this study, we aimed to provide more insight into these inconsistent findings. We used molecular tools to investigate the impact of algal turbidity on reproductive success and sexual selection on males in controlled laboratory experiments, allowing mate choice, mating competition, and mate encounter rates to affect reproduction. As study species, we used the broad-nosed pipefish, Syngnathus typhle , a species practicing male pregnancy and where we have previously shown that male mate choice is impaired by turbidity. Here, turbidity instead enhanced sexual selection on male size and mating success as well as reproductive success. Effects from mating competition and mate encounter rates may thus override effects from mate choice based on visual cues, producing an overall stronger sexual selection in turbid waters. Hence, seemingly inconsistent effects of turbidity on sexual selection may depend on which mechanisms of sexual selection that have been under study. Algal blooms are becoming increasingly more common due to eutrophication of freshwater and marine environments. The high density of algae lowers water transparency and reduces the possibility for fish and other aquatic animals to perform behaviors dependent on vision. We have previously shown that pipefish are unable to select the best partner in mate choice trials when water transparency was reduced. However, fish might use other senses than vision to compensate for the reduction in water transparency. In this study, we found that when fish were allowed to freely interact, thereby allowing competition between partners and direct contact
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van Overveld, Mark; de Jong, Peter J.; Peters, Madelon L.; van Lankveld, Jacques; Melles, Reinhilde; ter Kuile, Moniek M.
Introduction. Disgust may be involved in sexual problems by disrupting sexual arousal and motivating avoidance of sexual intercourse. To test whether heightened disgust for sexual contaminants is related to sexual dysfunctions, the Sexual Disgust Questionnaire (SDQ) has recently been developed.
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Improved feature selection based on genetic algorithms for real time disruption prediction on JET
Energy Technology Data Exchange (ETDEWEB)
Ratta, G.A., E-mail: garatta@gateme.unsj.edu.ar [GATEME, Facultad de Ingenieria, Universidad Nacional de San Juan, Avda. San Martin 1109 (O), 5400 San Juan (Argentina); JET EFDA, Culham Science Centre, OX14 3DB Abingdon (United Kingdom); Vega, J. [Asociacion EURATOM/CIEMAT para Fusion, Avda. Complutense, 40, 28040 Madrid (Spain); JET EFDA, Culham Science Centre, OX14 3DB Abingdon (United Kingdom); Murari, A. [Associazione EURATOM-ENEA per la Fusione, Consorzio RFX, 4-35127 Padova (Italy); JET EFDA, Culham Science Centre, OX14 3DB Abingdon (United Kingdom)
2012-09-15
Highlights: Black-Right-Pointing-Pointer A new signal selection methodology to improve disruption prediction is reported. Black-Right-Pointing-Pointer The approach is based on Genetic Algorithms. Black-Right-Pointing-Pointer An advanced predictor has been created with the new set of signals. Black-Right-Pointing-Pointer The new system obtains considerably higher prediction rates. - Abstract: The early prediction of disruptions is an important aspect of the research in the field of Tokamak control. A very recent predictor, called 'Advanced Predictor Of Disruptions' (APODIS), developed for the 'Joint European Torus' (JET), implements the real time recognition of incoming disruptions with the best success rate achieved ever and an outstanding stability for long periods following training. In this article, a new methodology to select the set of the signals' parameters in order to maximize the performance of the predictor is reported. The approach is based on 'Genetic Algorithms' (GAs). With the feature selection derived from GAs, a new version of APODIS has been developed. The results are significantly better than the previous version not only in terms of success rates but also in extending the interval before the disruption in which reliable predictions are achieved. Correct disruption predictions with a success rate in excess of 90% have been achieved 200 ms before the time of the disruption. The predictor response is compared with that of JET's Protection System (JPS) and the ADODIS predictor is shown to be far superior. Both systems have been carefully tested with a wide number of discharges to understand their relative merits and the most profitable directions of further improvements.
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Synergistic Disruption of External Male Sex Organ Development by a Mixture of Four Antiandrogens
DEFF Research Database (Denmark)
Christiansen, Sofie; Scholze, Martin; Dalgaard, Majken
2009-01-01
: Strikingly, the effect of combined exposure to the selected chemicals on malformations of external sex organs was synergistic, and the observed responses were greater than would be predicted from the toxicities of the individual chemicals. In relation to other hallmarks of disrupted male sexual development......, and a pharmaceutical, finasteride, on landmarks of male sexual development in the rat, including changes in anogenital distance, retained nipples, sex organ weights and malformations of genitalia. These chemicals were chosen because they disrupt androgen action according to differing mechanisms of action. Results...... in male offspring. Conclusions: Since unhindered androgen action is essential for human male development in foetal life, these findings are highly relevant to human risk assessment. Evaluations that ignore the possibility of combination effects may lead to considerable underestimations of risks associated...
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Natural and sexual selection against hybrid flycatchers
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
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Renteria, Rafael; Baltz, Emily T; Gremel, Christina M
2018-01-15
Addiction involves a predominance of habitual control mediated through action selection processes in dorsal striatum. Research has largely focused on neural mechanisms mediating a proposed progression from ventral to dorsal lateral striatal control in addiction. However, over reliance on habit striatal processes may also arise from reduced cortical input to striatum, thereby disrupting executive control over action selection. Here, we identify novel mechanisms through which chronic intermittent ethanol exposure and withdrawal (CIE) disrupts top-down control over goal-directed action selection processes to produce habits. We find CIE results in decreased excitability of orbital frontal cortex (OFC) excitatory circuits supporting goal-directed control, and, strikingly, selectively reduces OFC output to the direct output pathway in dorsal medial striatum. Increasing the activity of OFC circuits restores goal-directed control in CIE-exposed mice. Our findings show habitual control in alcohol dependence can arise through disrupted communication between top-down, goal-directed processes onto basal ganglia pathways controlling action selection.
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Isoform-Selective Disruption of AKAP-Localized PKA Using Hydrocarbon Stapled Peptides
2015-01-01
A-kinase anchoring proteins (AKAPs) play an important role in the spatial and temporal regulation of protein kinase A (PKA) by scaffolding critical intracellular signaling complexes. Here we report the design of conformationally constrained peptides that disrupt interactions between PKA and AKAPs in an isoform-selective manner. Peptides derived from the A Kinase Binding (AKB) domain of several AKAPs were chemically modified to contain an all-hydrocarbon staple and target the docking/dimerization domain of PKA-R, thereby occluding AKAP interactions. The peptides are cell-permeable against diverse human cell lines, are highly isoform-selective for PKA-RII, and can effectively inhibit interactions between AKAPs and PKA-RII in intact cells. These peptides can be applied as useful reagents in cell-based studies to selectively disrupt AKAP-localized PKA-RII activity and block AKAP signaling complexes. In summary, the novel hydrocarbon-stapled peptides developed in this study represent a new class of AKAP disruptors to study compartmentalized RII-regulated PKA signaling in cells. PMID:24422448
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Can sexual selection drive female life histories? A comparative study on Galliform birds.
Kolm, N; Stein, R W; Mooers, A Ø; Verspoor, J J; Cunningham, E J A
2007-03-01
Sexual selection has been identified as a major evolutionary force shaping male life history traits but its impact on female life history evolution is less clear. Here we examine the impact of sexual selection on three key female traits (body size, egg size and clutch size) in Galliform birds. Using comparative independent contrast analyses and directional discrete analyses, based on published data and a new genera-level supertree phylogeny of Galliform birds, we investigated how sexual selection [quantified as sexual size dimorphism (SSD) and social mating system (MS)] affects these three important female traits. We found that female body mass was strongly and positively correlated with egg size but not with clutch size, and that clutch size decreased as egg size increased. We established that SSD was related to MS, and then used SSD as a proxy of the strength of sexual selection. We found both a positive relationship between SSD and female body mass and egg size and that increases in female body mass and egg size tend to occur following increases in SSD in this bird order. This pattern of female body mass increases lagging behind changes in SSD, established using our directional discrete analysis, suggests that female body mass increases as a response to increases in the level of sexual selection and not simply through a strong genetic relationship with male body mass. This suggests that sexual selection is linked to changes in female life history traits in Galliformes and we discuss how this link may shape patterns of life history variation among species.
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Evolution of male and female genitalia following release from sexual selection.
Cayetano, Luis; Maklakov, Alexei A; Brooks, Robert C; Bonduriansky, Russell
2011-08-01
Despite the key functions of the genitalia in sexual interactions and fertilization, the role of sexual selection and conflict in shaping genital traits remains poorly understood. Seed beetle (Callosobruchus maculatus) males possess spines on the intromittent organ, and females possess a thickened reproductive tract wall that also bears spines. We investigated the role of sexual selection and conflict by imposing monogamous mating on eight replicate populations of this naturally polygamous insect, while maintaining eight other populations under polygamy. To establish whether responses to mating system manipulation were robust to ecological context, we simultaneously manipulated life-history selection (early/late reproduction). Over 18-21 generations, male genital spines evolved relatively reduced length in large males (i.e., shallower static allometry) in monogamous populations. Two nonintromittent male genital appendages also evolved in response to the interaction of mating system and ecology. In contrast, no detectable evolution occurred in female genitalia, consistent with the expectation of a delayed response in defensive traits. Our results support a sexually antagonistic role for the male genital spines, and demonstrate the evolution of static allometry in response to variation in sexual selection opportunity. We argue that further advances in the study of genital coevolution will require a much more detailed understanding of the functions of male and female genital traits. © 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.
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Improved feature selection based on genetic algorithms for real time disruption prediction on JET
International Nuclear Information System (INIS)
Rattá, G.A.; Vega, J.; Murari, A.
2012-01-01
Highlights: ► A new signal selection methodology to improve disruption prediction is reported. ► The approach is based on Genetic Algorithms. ► An advanced predictor has been created with the new set of signals. ► The new system obtains considerably higher prediction rates. - Abstract: The early prediction of disruptions is an important aspect of the research in the field of Tokamak control. A very recent predictor, called “Advanced Predictor Of Disruptions” (APODIS), developed for the “Joint European Torus” (JET), implements the real time recognition of incoming disruptions with the best success rate achieved ever and an outstanding stability for long periods following training. In this article, a new methodology to select the set of the signals’ parameters in order to maximize the performance of the predictor is reported. The approach is based on “Genetic Algorithms” (GAs). With the feature selection derived from GAs, a new version of APODIS has been developed. The results are significantly better than the previous version not only in terms of success rates but also in extending the interval before the disruption in which reliable predictions are achieved. Correct disruption predictions with a success rate in excess of 90% have been achieved 200 ms before the time of the disruption. The predictor response is compared with that of JET's Protection System (JPS) and the ADODIS predictor is shown to be far superior. Both systems have been carefully tested with a wide number of discharges to understand their relative merits and the most profitable directions of further improvements.
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No Evidence for Pre-Copulatory Sexual Selection on Sperm Length in a Passerine Bird
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. PMID:22384277
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No evidence for pre-copulatory sexual selection on sperm length in a passerine bird.
Directory of Open Access Journals (Sweden)
Jan T Lifjeld
Full Text Available 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.
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Stephenson, Kyle R; Meston, Cindy M
2015-03-01
Recent research has highlighted a complex association between female sexual function and subjective distress regarding sexual activity. These findings are difficult to explain given limited knowledge as to the mechanisms through which impaired sexual function causes distress. The current study assessed whether a number of specific consequences of impaired sexual function, including decreased physical pleasure, disruption of sexual activity, and negative partner responses, mediated the association between sexual function and distress. Eighty-seven women in sexually active relationships reporting impairments in sexual function completed validated self-report measures and daily online assessments of sexual experiences. Participants completed the Sexual Satisfaction Scale for Women, the Female Sexual Function Index, and the Measure of Sexual Consequences. Results suggested that decreased physical pleasure and disruption of sexual activity, but not partner responses, statistically mediated the association between sexual function and distress. Sexual consequences represent potential maintaining factors of sexual dysfunction that are highly distressing to women. Results are discussed in the context of theoretical models of sexual dysfunction and related treatments. © 2014 International Society for Sexual Medicine.
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Antagonistic natural and sexual selection on wing shape in a scrambling damselfly.
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).
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Student-Initiated Sexual Health Selective as a Curricular Tool
Directory of Open Access Journals (Sweden)
Katie Johnson, BS
2015-06-01
Conclusions: The 1-week SHS was successfully implemented through the teamwork of a medical student and faculty champion. It resulted in more accurate knowledge and more open attitudes toward sexual health among participating medical students. Potential benefits to undergraduate medical educators are reviewed. Johnson K, Rullo J, and Faubion S. Student-initiated sexual health selective as a curricular tool. Sex Med 2015;3:118–127.
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Sexual selection studies: A NESCent catalyst meeting
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
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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
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Novel host plant leads to the loss of sexual dimorphism in a sexually selected male weapon.
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).
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Postcopulatory sexual selection influences baculum evolution in primates and carnivores.
Brindle, Matilda; Opie, Christopher
2016-12-14
The extreme morphological variability of the baculum across mammals is thought to be the result of sexual selection (particularly, high levels of postcopulatory selection). However, the evolutionary trajectory of the mammalian baculum is little studied and evidence for the adaptive function of the baculum has so far been elusive. Here, we use Markov chain Monte Carlo methods implemented in a Bayesian phylogenetic framework to reconstruct baculum evolution across the mammalian class and investigate the rate of baculum length evolution within the primate order. We then test the effects of testes mass (postcopulatory sexual selection), polygamy, seasonal breeding and intromission duration on the baculum in primates and carnivores. The ancestral mammal did not have a baculum, but both ancestral primates and carnivores did. No relationship was found between testes mass and baculum length in either primates or carnivores. Intromission duration correlated with baculum presence over the course of primate evolution, and prolonged intromission predicts significantly longer bacula in extant primates and carnivores. Both polygamous and seasonal breeding systems predict significantly longer bacula in primates. These results suggest the baculum plays an important role in facilitating reproductive strategies in populations with high levels of postcopulatory sexual selection. © 2016 The Authors.
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Nonsteroidal selective androgen receptor modulators enhance female sexual motivation.
Jones, Amanda; Hwang, Dong Jin; Duke, Charles B; He, Yali; Siddam, Anjaiah; Miller, Duane D; Dalton, James T
2010-08-01
Women experience a decline in estrogen and androgen levels after natural or surgically induced menopause, effects that are associated with a loss of sexual desire and bone mineral density. Studies in our laboratories have shown the beneficial effects of selective androgen receptor modulators (SARMs) in the treatment of osteoporosis and muscle wasting in animal models. A series of S-3-(phenoxy)-2-hydroxy-2-methyl-N-(4-cyano-3-trifluoromethyl-phenyl)-propionamide analogs was synthesized to evaluate the effects of B-ring substitutions on in vitro and in vivo pharmacologic activity, especially female sexual motivation. The androgen receptor (AR) relative binding affinities ranged from 0.1 to 26.5% (relative to dihydrotestosterone) and demonstrated a range of agonist activity at 100 nM. In vivo pharmacologic activity was first assessed by using male rats. Structural modifications to the B-ring significantly affected the selectivity of the SARMs, demonstrating that single-atom substitutions can dramatically and unexpectedly influence activity in androgenic (i.e., prostate) and anabolic (i.e., muscle) tissues. (S)-N-(4-cyano-3-trifluoromethyl-phenyl)-3-(3-fluoro,4-chlorophenoxy)-2-hydroxy-2-methyl-propanamide (S-23) displayed full agonist activity in androgenic and anabolic tissues; however, the remaining SARMs were more prostate-sparing, selectively maintaining the size of the levator ani muscle in castrated rats. The partner-preference paradigm was used to evaluate the effects of SARMs on female sexual motivation. With the exception of two four-halo substituted analogs, the SARMs increased sexual motivation in ovariectomized rats, with potency and efficacy comparable with testosterone propionate. These results indicate that the AR is important in regulating female libido given the nonaromatizable nature of SARMs and it could be a superior alternative to steroidal testosterone preparations in the treatment of hypoactive sexual desire disorder.
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Kin selection versus sexual selection: why the ends do not meet
DEFF Research Database (Denmark)
Boomsma, Jacobus J
2007-01-01
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......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...
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DEFF Research Database (Denmark)
Jacobsen, Pernille Rosenskjold; Christiansen, Sofie; Boberg, Julie
2010-01-01
Risk assessment is currently based on the no observed adverse effect levels (NOAELs) for single compounds. Humans are exposed to a mixture of chemicals and recent studies in our laboratory have shown that combined exposure to endocrine disrupters can cause adverse effects on male sexual development...... were gavaged during gestation and lactation with five doses of a mixture of the fungicides procymidone, mancozeb, epoxyconazole, tebuconazole and prochloraz. The mixture ratio was chosen according to the doses of each individual pesticide that produced no observable effects on pregnancy length and pup...... survival in our laboratory and the dose levels used ranged from 25 to 100% of this mixture. All dose levels caused increased gestation length and dose levels above 25% caused impaired parturition leading to markedly decreased number of live born offspring and high pup perinatal mortality. The sexual...
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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...
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Can sexual selection drive female life histories? A comparative study on Galliform birds
Kolm, N.; Stein, R. W.; Mooers, A. O.; Verspoor, J. J.; Cunningham, E. J. A.
2007-01-01
Sexual selection has been identified as a major evolutionary force shaping male life history traits but its impact on female life history evolution is less clear. Here we examine the impact of sexual selection on three key female traits (body size, egg size and clutch size) in Galliform birds. Using comparative independent contrast analyses and directional DISCRETE analyses, based on published data and a new genera-level supertree phylogeny of Galliform birds, we investigated how sexual selec...
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Sexual selection on receptor organ traits: younger females attract males with longer antennae
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.
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Since humans are exposed to more than one chemical at a time, concern has arisen about the effects of mixtures of chemicals on human reproduction and development. We are conducting studies to determine the 1) classes of chemicals that disrupt sexual differentiation via different ...
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How sexual selection can drive the evolution of costly sperm ornamentation
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.
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Selective Serotonin Reuptake Inhibitor-Induced Sexual Dysfunction in Adolescents: A Review.
Scharko, Alexander M.
2004-01-01
Objective: To review the existing literature on selective serotonin reuptake inhibitor (SSRI)-induced sexual dysfunction in adolescents. Method: A literature review of SSRI-induced adverse effects in adolescents focusing on sexual dysfunction was done. Nonsexual SSRI-induced adverse effects were compared in adult and pediatric populations.…
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Sexual selection is influenced by both developmental and adult environments.
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.
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Sexual differences in telomere selection in the wild.
Olsson, Mats; Pauliny, Angela; Wapstra, Erik; Uller, Tobias; Schwartz, Tonia; Miller, Emily; Blomqvist, Donald
2011-05-01
Telomere length is restored primarily through the action of the reverse transcriptase telomerase, which may contribute to a prolonged lifespan in some but not all species and may result in longer telomeres in one sex than the other. To what extent this is an effect of proximate mechanisms (e.g. higher stress in males, higher oestradiol/oestrogen levels in females), or is an evolved adaptation (stronger selection for telomere length in one sex), usually remains unknown. Sand lizard (Lacerta agilis) females have longer telomeres than males and better maintain telomere length through life than males do. We also show that telomere length more strongly contributes to life span and lifetime reproductive success in females than males and that telomere length is under sexually diversifying selection in the wild. Finally, we performed a selection analysis with number of recruited offspring into the adult population as a response variable with telomere length, life span and body size as predictor variables. This showed significant differences in selection pressures between the sexes with strong ongoing selection in females, with these three predictors explaining 63% of the variation in recruitment. Thus, the sexually dimorphic telomere dynamics with longer telomeres in females is a result of past and ongoing selection in sand lizards. Finally, we compared the results from our selection analyses based on Telometric-derived data to the results based on data generated by the software ImageJ. ImageJ resulted in shorter average telomere length, but this difference had virtually no qualitative effect on the patterns of ongoing selection. © 2011 Blackwell Publishing Ltd.
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The long-term evolution of multilocus traits under frequency-dependent disruptive selection
Van Doorn, G. Sander; Dieckmann, Ulf
Frequency-dependent disruptive selection is widely recognized as an important source of genetic variation. Its evolutionary consequences have been extensively studied using phenotypic evolutionary models, based on quantitative genetics, game theory, or adaptive dynamics. However, the genetic
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Short-term exposure to a synthetic estrogen disrupts mating dynamics in a pipefish.
Partridge, Charlyn; Boettcher, Anne; Jones, Adam G
2010-11-01
Sexual selection is responsible for the evolution of some of the most elaborate traits occurring in nature, many of which play a vital role in competition over access to mates and individual reproductive fitness. Because expression of these traits is typically regulated by sex-steroids there is a significant potential for their expression to be affected by the presence of certain pollutants, such as endocrine disrupting compounds. Endocrine disruptors have been shown to alter primary sexual traits and impact reproduction, but few studies have investigated how these compounds affect secondary sexual trait expression and how that may, in turn, impact mating dynamics. In this study we examine how short-term exposure to a synthetic estrogen impacts secondary sexual trait expression and mating dynamics in the Gulf pipefish, a species displaying sex-role reversal. Our results show that only 10days of exposure to 17α-ethinylestradiol results in adult male pipefish developing female-like secondary sexual traits. While these males are capable of reproduction, females discriminate against exposed males in mate choice trials. In natural populations, this type of discrimination would reduce male mating opportunities, thus potentially reducing their long-term reproductive success. Importantly, the effects of these compounds on mating dynamics and mating opportunity would not be observed using the current standard methods of assessing environmental contamination. However, disrupting these processes could have profound effects on the viability of exposed populations. Copyright © 2010 Elsevier Inc. All rights reserved.
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Sexual minorities and selection of a primary care physician in a midwestern U.S. city.
Labig, Chalmer E; Peterson, Tim O
2006-01-01
How and why sexual minorities select a primary care physician is critical to the development of methods for attracting these clients to a physician's practice. Data obtained from a sample of sexual minorities in a mid-size city in our nation's heartland would indicate that these patients are loyal when the primary care physician has a positive attitude toward their sexual orientation. The data also confirms that most sexual minorities select same sex physicians but not necessarily same sexual orientation physicians because of lack of knowledge of physicians' sexual orientation. Family practice physicians and other primary care physicians can reach out to this population by encouraging word of mouth advertising and by displaying literature on health issues for all sexual orientations in their offices.
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The evolution of sexes: A specific test of the disruptive selection theory.
da Silva, Jack
2018-01-01
The disruptive selection theory of the evolution of anisogamy posits that the evolution of a larger body or greater organismal complexity selects for a larger zygote, which in turn selects for larger gametes. This may provide the opportunity for one mating type to produce more numerous, small gametes, forcing the other mating type to produce fewer, large gametes. Predictions common to this and related theories have been partially upheld. Here, a prediction specific to the disruptive selection theory is derived from a previously published game-theoretic model that represents the most complete description of the theory. The prediction, that the ratio of macrogamete to microgamete size should be above three for anisogamous species, is supported for the volvocine algae. A fully population genetic implementation of the model, involving mutation, genetic drift, and selection, is used to verify the game-theoretic approach and accurately simulates the evolution of gamete sizes in anisogamous species. This model was extended to include a locus for gamete motility and shows that oogamy should evolve whenever there is costly motility. The classic twofold cost of sex may be derived from the fitness functions of these models, showing that this cost is ultimately due to genetic conflict.
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International Nuclear Information System (INIS)
Sciurano, R.; Rodriguero, M.; Gomez Cendra, P.; Vilardi, J.; Segura, D.; Cladera, J.L.; Allinghi, Armando
2007-01-01
Despite the interest in applying environmentally friendly control methods such as sterile insect technique (SIT) against Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae), information about its biology, taxonomy, and behavior is still insufficient. To increase this information, the present study aims to evaluate the performance of wild flies under field cage conditions through the study of sexual competitiveness among males (sexual selection). A wild population from Horco Molle, Tucuman, Argentina was sampled. Mature virgin males and females were released into outdoor field cages to compete for mating. Morphometric analyses were applied to determine the relationship between the multivariate phenotype and copulatory success. Successful and unsuccessful males were measured for 8 traits: head width (HW), face width (FW), eye length (EL), thorax length (THL), wing length (WL), wing width (WW), femur length (FL), and tibia length (TIL). Combinations of different multivariate statistical methods and graphical analyses were used to evaluate sexual selection on male phenotype. The results indicated that wing width and thorax length would be the most probable targets of sexual selection. They describe a non-linear association between expected fitness and each of these 2 traits. This non-linear relation suggests that observed selection could maintain the diversity related to body size. (author) [es
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Geography, assortative mating, and the effects of sexual selection on speciation with gene flow.
Servedio, Maria R
2016-01-01
Theoretical and empirical research on the evolution of reproductive isolation have both indicated that the effects of sexual selection on speciation with gene flow are quite complex. As part of this special issue on the contributions of women to basic and applied evolutionary biology, I discuss my work on this question in the context of a broader assessment of the patterns of sexual selection that lead to, versus inhibit, the speciation process, as derived from theoretical research. In particular, I focus on how two factors, the geographic context of speciation and the mechanism leading to assortative mating, interact to alter the effect that sexual selection through mate choice has on speciation. I concentrate on two geographic contexts: sympatry and secondary contact between two geographically separated populations that are exchanging migrants and two mechanisms of assortative mating: phenotype matching and separate preferences and traits. I show that both of these factors must be considered for the effects of sexual selection on speciation to be inferred.
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The Role of Sexual Selection in the Evolution of Chemical Signals in Insects
Directory of Open Access Journals (Sweden)
Sandra Steiger
2014-06-01
Full Text Available Chemical communication is the most ancient and widespread form of communication. Yet we are only beginning to grasp the complexity of chemical signals and the role they play in sexual selection. Focusing on insects, we review here the recent progress in the field of olfactory-based sexual selection. We will show that there is mounting empirical evidence that sexual selection affects the evolution of chemical traits, but form and strength of selection differ between species. Studies indicate that some chemical signals are expressed in relation to an individual’s condition and depend, for example, on age, immunocompetence, fertility, body size or degree of inbreeding. Males or females might benefit by choosing based on those traits, gaining resources or “good genes”. Other chemical traits appear to reliably reflect an individual’s underlying genotype and are suitable to choose a mating partner that matches best the own genotype.
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Ramm, Steven A; Khoo, Lin; Stockley, Paula
2010-01-01
The rapid divergence of genitalia is a pervasive trend in animal evolution, thought to be due to the action of sexual selection. To test predictions from the sexual selection hypothesis, we here report data on the allometry, variation, plasticity and condition dependence of baculum morphology in the house mouse (Mus musculus domesticus). We find that that baculum size: (a) exhibits no consistent pattern of allometric scaling (baculum size being in most cases unrelated to body size), (b) exhibits low to moderate levels of phenotypic variation, (c) does not exhibit phenotypic plasticity in response to differences in perceived levels of sexual competition and (d) exhibits limited evidence of condition dependence. These patterns provide only limited evidence in support of the sexual selection hypothesis, and no consistent support for any particular sexual selection mechanism; however, more direct measures of how genital morphology influences male fertilization success are required.
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Natural Aphrodisiacs-A Review of Selected Sexual Enhancers.
West, Elizabeth; Krychman, Michael
2015-10-01
The Food and Drug Administration defines an aphrodisiac drug product as "any product that bears labeling claims that it will arouse or increase sexual desire, or that it will improve sexual performance." Presently, there are no approved medications for the treatment of lowered desire for women, and many opt for "natural" products. The aim of this article was to review the most popular and currently used aphrodisiac products marketed in the United States. The safety and efficacy of animal- and plant-based aphrodisiacs, vitamins and minerals, and popular over-the-counter combination supplements have been reviewed. An English PubMed literature search was performed using the key words "sexuality," "sex," "aphrodisiac," and "sexual enhancer." Approximately 50 articles were reviewed by the authors. The authors used relevant case series, case-controlled, and randomized clinical trial data. Products were evaluated based on the quality of research, and their known efficacy and safety considerations. Products with low risk and potential benefit for sexual response based on prior research studies were highlighted. Research has demonstrated that the risks of yohimbine, Spanish fly, mad honey, and Bufo toad may outweigh any benefit, and these products should be avoided. Other products, such as Maca, Tribulus, Ginkgo, and ginseng, have limited but emerging data. Randomized clinical trial data are often lacking, but future research should be performed to further elucidate the efficacy and safety of these products. Future randomized clinical trials are warranted before health care practitioners can recommend most aphrodisiac products. There remain some medical concerns with drug interactions, purity, reliability, and safety. West E and Krychman M. Natural aphrodisiacs-A review of selected sexual enhancers.. Copyright © 2015 International Society for Sexual Medicine. Published by Elsevier Inc. All rights reserved.
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Sexual selection and physical attractiveness : Implications for mating dynamics.
Gangestad, S W
1993-09-01
Sexual selection processes have received much attention in recent years, attention reflected in interest in human mate preferences. Among these mate preferences are preferences for physical attractiveness. Preferences in and of themselves, however, do not fully explain the nature of the relationships that individuals attain. A tacit negotiation process underlies relationship formation and maintenance. The notion that preferences for physical attractiveness evolved under parasite-driven "good genes" sexual selection leads to predictions about the nature of trade-offs that individuals make between mates' physical attractiveness and investment potential. These predictions and relevant data are explored, with a primary emphasis on women's preferences for men's qualities. In addition, further implications of trade-offs are examined, most notably (a) the impact of environmental variations on the nature of mating and (b) some effects of trade-offs on infidelity and male attempts to control women.
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Rohner, Patrick T; Blanckenhorn, Wolf U; Puniamoorthy, Nalini
2016-06-01
Sexual size dimorphism (SSD) arises when the net effects of natural and sexual selection on body size differ between the sexes. Quantitative SSD variation between taxa is common, but directional intraspecific SSD reversals are rare. We combined micro- and macroevolutionary approaches to study geographic SSD variation in closely related black scavenger flies. Common garden experiments revealed stark intra- and interspecific variation: Sepsis biflexuosa is monomorphic across the Holarctic, while S. cynipsea (only in Europe) consistently exhibits female-biased SSD. Interestingly, S. neocynipsea displays contrasting SSD in Europe (females larger) and North America (males larger), a pattern opposite to the geographic reversal in SSD of S. punctum documented in a previous study. In accordance with the differential equilibrium model for the evolution of SSD, the intensity of sexual selection on male size varied between continents (weaker in Europe), whereas fecundity selection on female body size did not. Subsequent comparative analyses of 49 taxa documented at least six independent origins of male-biased SSD in Sepsidae, which is likely caused by sexual selection on male size and mediated by bimaturism. Therefore, reversals in SSD and the associated changes in larval development might be much more common and rapid and less constrained than currently assumed. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.
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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.
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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. PMID:22761675
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Chemical communication, sexual selection, and introgression in wall lizards.
MacGregor, Hannah E A; Lewandowsky, Rachel A M; d'Ettorre, Patrizia; Leroy, Chloé; Davies, Noel W; While, Geoffrey M; Uller, Tobias
2017-10-01
Divergence in communication systems should influence the likelihood that individuals from different lineages interbreed, and consequently shape the direction and rate of hybridization. Here, we studied the role of chemical communication in hybridization, and its contribution to asymmetric and sexually selected introgression between two lineages of the common wall lizard (Podarcis muralis). Males of the two lineages differed in the chemical composition of their femoral secretions. Chemical profiles provided information regarding male secondary sexual characters, but the associations were variable and inconsistent between lineages. In experimental contact zones, chemical composition was weakly associated with male reproductive success, and did not predict the likelihood of hybridization. Consistent with these results, introgression of chemical profiles in a natural hybrid zone resembled that of neutral nuclear genetic markers overall, but one compound in particular (tocopherol methyl ether) matched closely the introgression of visual sexual characters. These results imply that associations among male chemical profiles, sexual characters, and reproductive success largely reflect transient and environmentally driven effects, and that genetic divergence in chemical composition is largely neutral. We therefore suggest that femoral secretions in wall lizards primarily provide information about residency and individual identity rather than function as sexual signals. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.
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Diploidy and the selective advantage for sexual reproduction in unicellular organisms.
Kleiman, Maya; Tannenbaum, Emmanuel
2009-11-01
This article develops mathematical models describing the evolutionary dynamics of both asexually and sexually reproducing populations of diploid unicellular organisms. The asexual and sexual life cycles are based on the asexual and sexual life cycles in Saccharomyces cerevisiae, Baker's yeast, which normally reproduces by asexual budding, but switches to sexual reproduction when stressed. The mathematical models consider three reproduction pathways: (1) Asexual reproduction, (2) self-fertilization, and (3) sexual reproduction. We also consider two forms of genome organization. In the first case, we assume that the genome consists of two multi-gene chromosomes, whereas in the second case, we consider the opposite extreme and assume that each gene defines a separate chromosome, which we call the multi-chromosome genome. These two cases are considered to explore the role that recombination has on the mutation-selection balance and the selective advantage of the various reproduction strategies. We assume that the purpose of diploidy is to provide redundancy, so that damage to a gene may be repaired using the other, presumably undamaged copy (a process known as homologous recombination repair). As a result, we assume that the fitness of the organism only depends on the number of homologous gene pairs that contain at least one functional copy of a given gene. If the organism has at least one functional copy of every gene in the genome, we assume a fitness of 1. In general, if the organism has l homologous pairs that lack a functional copy of the given gene, then the fitness of the organism is kappa(l). The kappa(l) are assumed to be monotonically decreasing, so that kappa(0) = 1 > kappa(1) > kappa(2) > cdots, three dots, centered > kappa(infinity) = 0. For nearly all of the reproduction strategies we consider, we find, in the limit of large N, that the mean fitness at mutation-selection balance is max{2e(-mu) - 1,0} where N is the number of genes in the haploid set of
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Bos, M.; Scharloo, W.
1974-01-01
A genetic analysis was made of two lines which when subjected to disruptive selection with compulsary mating of opposite extremes (D−) showed a different response viz. one, D−-1, showing predominantly an increase of environmental variance and possibly interaction variance, the other, D−-2, showing
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From Freud to Feminism: Gendered Constructions of Blame Across Theories of Child Sexual Abuse.
Azzopardi, Corry; Alaggia, Ramona; Fallon, Barbara
2018-04-01
Most theories of child sexual abuse are, to some degree, gendered, with nonoffending mothers bearing the burden of blame, ideologically and legally, for the transgressions of predominantly male offenders. This article explores the social construction of blame for child sexual abuse via critical analyses of evolving theoretical perspectives on maternal culpability for the inception and maintenance of abuse dynamics. Drawing on selected conceptual and research knowledge that supports and refutes anecdotal claims, this synthesis of the literature culminates in the proposal of an evidence-informed, feminist-grounded, multitheoretical child sexual abuse framework that disrupts dominant mother-blaming discourse and guides socially just and ethically responsive policy, practice, and research.
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van Overveld, Mark; de Jong, Peter J; Peters, Madelon L; van Lankveld, Jacques; Melles, Reinhilde; ter Kuile, Moniek M
2013-02-01
Disgust may be involved in sexual problems by disrupting sexual arousal and motivating avoidance of sexual intercourse. To test whether heightened disgust for sexual contaminants is related to sexual dysfunctions, the Sexual Disgust Questionnaire (SDQ) has recently been developed. Previous research showed that particularly women with vaginismus display a generally heightened dispositional disgust propensity and heightened disgust toward stimuli depicting sexual intercourse. To determine the psychometric properties of the SDQ and test whether heightened disgust toward sexual stimuli is specific to vaginismus or can be observed in other sexual dysfunctions as well. First, a large sample of undergraduates and university employees completed the SDQ (N = 762) and several trait disgust indices. Next, women with vaginismus (N = 39), dyspareunia (N = 45), and men with erectile disorder (N = 28) completed the SDQ and were compared to participants without sexual problems (N = 70). SDQ to index sexual disgust. The SDQ proved a valid and reliable index to establish disgust propensity for sexual stimuli. Supporting construct validity of the SDQ, sexual disgust correlated with established trait indices. Furthermore, sexual disgust and willingness to handle sexually contaminated stimuli were associated with sexual functioning in women, but not in men. Specifically women with vaginismus displayed heightened sexual disgust compared to women without sexual problems, while men with erectile disorders demonstrated a lower willingness to handle sexually contaminated stimuli compared to men without sexual problems. The SDQ appears a valid and reliable measure of sexual disgust. The pattern of SDQ-scores across males and females with and without sexual dysfunctions corroborates earlier research suggesting that disgust appraisals are involved especially in vaginismus and supports the view that the difficulty with vaginal penetration experienced by women in vaginismus may partly be due to
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Labonne, Jacques; Hendry, Andrew P
2010-07-01
The standard predictions of ecological speciation might be nuanced by the interaction between natural and sexual selection. We investigated this hypothesis with an individual-based model tailored to the biology of guppies (Poecilia reticulata). We specifically modeled the situation where a high-predation population below a waterfall colonizes a low-predation population above a waterfall. Focusing on the evolution of male color, we confirm that divergent selection causes the appreciable evolution of male color within 20 generations. The rate and magnitude of this divergence were reduced when dispersal rates were high and when female choice did not differ between environments. Adaptive divergence was always coupled to the evolution of two reproductive barriers: viability selection against immigrants and hybrids. Different types of sexual selection, however, led to contrasting results for another potential reproductive barrier: mating success of immigrants. In some cases, the effects of natural and sexual selection offset each other, leading to no overall reproductive isolation despite strong adaptive divergence. Sexual selection acting through female choice can thus strongly modify the effects of divergent natural selection and thereby alter the standard predictions of ecological speciation. We also found that under no circumstances did divergent selection cause appreciable divergence in neutral genetic markers.
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Sex-ratio control erodes sexual selection, revealing evolutionary feedback from adaptive plasticity
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
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Estrogens can disrupt amphibian mating behavior.
Directory of Open Access Journals (Sweden)
Frauke Hoffmann
Full Text Available The main component of classical contraceptives, 17α-ethinylestradiol (EE2, has high estrogenic activity even at environmentally relevant concentrations. Although estrogenic endocrine disrupting compounds are assumed to contribute to the worldwide decline of amphibian populations by adverse effects on sexual differentiation, evidence for EE2 affecting amphibian mating behaviour is lacking. In this study, we demonstrate that EE2 exposure at five different concentrations (0.296 ng/L, 2.96 ng/L, 29.64 ng/L, 2.96 µg/L and 296.4 µg/L can disrupt the mating behavior of adult male Xenopus laevis. EE2 exposure at all concentrations lowered male sexual arousal, indicated by decreased proportions of advertisement calls and increased proportions of the call type rasping, which characterizes a sexually unaroused state of a male. Additionally, EE2 at all tested concentrations affected temporal and spectral parameters of the advertisement calls, respectively. The classical and highly sensitive biomarker vitellogenin, on the other hand, was only induced at concentrations equal or higher than 2.96 µg/L. If kept under control conditions after a 96 h EE2 exposure (2.96 µg/L, alterations of male advertisement calls vanish gradually within 6 weeks and result in a lower sexual attractiveness of EE2 exposed males toward females as demonstrated by female choice experiments. These findings indicate that exposure to environmentally relevant EE2 concentrations can directly disrupt male mate calling behavior of X. laevis and can indirectly affect the mating behavior of females. The results suggest the possibility that EE2 exposure could reduce the reproductive success of EE2 exposed animals and these effects might contribute to the global problem of amphibian decline.
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Meiotic drive influences the outcome of sexually antagonistic selection at a linked locus.
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.
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Pesticides Provoke Endocrine Disruption A Review
International Nuclear Information System (INIS)
Aly, M.A.S.
2006-01-01
Increasing numbers of environmental chemicals,including pesticides, have the ability to produce endocrine disruption by various mechanisms. such substances may affect hormone secretion from an endocrine gland and may alter the rate of hormone elimination from the body. environmental chemicals may also disrupt regulatory feedback mechanisms that exist between two endocrine organs; or may interact with a hormone receptor either by mimicking or antagonizing the actions of the natural hormone. these chemicals are referred to endocrine disruptive chemicals (EDC's). EDC's act to alter the blood hormone levels or the subsequent action of hormones . the use of radioimmunoassay(RIA) constitutes a superior and unrivalled tool for the determination and quantification of hormones.the endocrine system participates in virtually all important functions of an organism, such as sexual differentiation before birth, sexual maturation during puberty, reproduction in adulthood, growth, metabolism, digestion, cardiovascular function and excretion. hormones are also implicated in the etiology of certain cancers of hormone- dependent tissues, such as those of the breast, uterus, and prostate gland. therefore, endocrine disruption can potentially produce widespread effects. scientists should not stick to the past belief which presumes that pesticides have limited effect on some hormones. A paradigm shift in which a wider vision of understanding of the wholesome complex effects of pesticides on the whole body rather than a narrow limited understanding should take place
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Directory of Open Access Journals (Sweden)
Martha Lucía Baena
Full Text Available 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.
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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.
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Prenatal PCBs disrupt early neuroendocrine development of the rat hypothalamus
International Nuclear Information System (INIS)
Dickerson, Sarah M.; Cunningham, Stephanie L.; Gore, Andrea C.
2011-01-01
Neonatal exposure to endocrine disrupting chemicals (EDCs) such as polychlorinated biphenyls (PCBs) can interfere with hormone-sensitive developmental processes, including brain sexual differentiation. We hypothesized that disruption of these processes by gestational PCB exposure would be detectable as early as the day after birth (postnatal day (P) 1) through alterations in hypothalamic gene and protein expression. Pregnant Sprague-Dawley rats were injected twice, once each on gestational days 16 and 18, with one of the following: DMSO vehicle; the industrial PCB mixture Aroclor 1221 (A1221); a reconstituted mixture of the three most prevalent congeners found in humans, PCB138, PCB153, and PCB180; or estradiol benzoate (EB). On P1, litter composition, anogenital distance (AGD), and body weight were assessed. Pups were euthanized for immunohistochemistry of estrogen receptor α (ERα) or TUNEL labeling of apoptotic cells or quantitative PCR of 48 selected genes in the preoptic area (POA). We found that treatment with EB or A1221 had a sex-specific effect on developmental apoptosis in the neonatal anteroventral periventricular nucleus (AVPV), a sexually dimorphic hypothalamic region involved in the regulation of reproductive neuroendocrine function. In this region, exposed females had increased numbers of apoptotic nuclei, whereas there was no effect of treatment in males. For ERα, EB treatment increased immunoreactive cell numbers and density in the medial preoptic nucleus (MPN) of both males and females, while A1221 and the PCB mixture had no effect. PCR analysis of gene expression in the POA identified nine genes that were significantly altered by prenatal EDC exposure, in a manner that varied by sex and treatment. These genes included brain-derived neurotrophic factor, GABA B receptors-1 and -2, IGF-1, kisspeptin receptor, NMDA receptor subunits NR2b and NR2c, prodynorphin, and TGFα. Collectively, these results suggest that the disrupted sexual differentiation
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Young, Erica J; Aceti, Massimiliano; Griggs, Erica M; Fuchs, Rita A; Zigmond, Zachary; Rumbaugh, Gavin; Miller, Courtney A
2014-01-15
Memories associated with drugs of abuse, such as methamphetamine (METH), increase relapse vulnerability to substance use disorder. There is a growing consensus that memory is supported by structural and functional plasticity driven by F-actin polymerization in postsynaptic dendritic spines at excitatory synapses. However, the mechanisms responsible for the long-term maintenance of memories, after consolidation has occurred, are largely unknown. Conditioned place preference (n = 112) and context-induced reinstatement of self-administration (n = 19) were used to assess the role of F-actin polymerization and myosin II, a molecular motor that drives memory-promoting dendritic spine actin polymerization, in the maintenance of METH-associated memories and related structural plasticity. Memories formed through association with METH but not associations with foot shock or food reward were disrupted by a highly-specific actin cycling inhibitor when infused into the amygdala during the postconsolidation maintenance phase. This selective effect of depolymerization on METH-associated memory was immediate, persistent, and did not depend upon retrieval or strength of the association. Inhibition of non-muscle myosin II also resulted in a disruption of METH-associated memory. Thus, drug-associated memories seem to be actively maintained by a unique form of cycling F-actin driven by myosin II. This finding provides a potential therapeutic approach for the selective treatment of unwanted memories associated with psychiatric disorders that is both selective and does not rely on retrieval of the memory. The results further suggest that memory maintenance depends upon the preservation of polymerized actin. Copyright © 2014 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.
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The sight of the peacock's tail makes me sick: the early arguments on sexual selection.
Hiraiwa-Hasegawa, M
2000-03-01
Why does a peacock have a beautiful train, while a peahen is sober without such flamboyance? Darwin proposed the theory of sexual selection to explain the differences between the sexes of the same species. Recently the study of sexual selection has been one of the most flourishing areas in evolutionary biology. However, the theory met with great resistance from biologists since the publication of the idea and the history of the theory included a lot of misunderstanding and confusion. There are several reasons for this. First, classical Darwinism failed to recognize social competition as an important selective force. Second, the good-for-the-species argument, which persisted in the days after Darwin, made the sexual selection argument more difficult to under-stand. Compared to the discussions on animals, Darwin's argument on human sex differences is not satisfactory. The reason probably lies in the debate over human racial differences which prevailed in the 19th century.
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Seasonal change in the opportunity for sexual selection
Czech Academy of Sciences Publication Activity Database
Reichard, Martin; Smith, C.; Bryja, Josef
2008-01-01
Roč. 17, č. 2 (2008), s. 642-651 ISSN 0962-1083 R&D Projects: GA AV ČR KJB600930501 Grant - others:British Ecological Society(GB) ECPG 551/617 Institutional research plan: CEZ:AV0Z60930519 Keywords : bitterling * body size * sexual selection * mating success * reproductive skew Subject RIV: EH - Ecology, Behaviour Impact factor: 5.325, year: 2008 http://www.blackwell-synergy.com/doi/pdf/10.1111/j.1365-294X.2007.03602.x
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The evolution of autistic-like and schizotypal traits: A sexual selection hypothesis
Directory of Open Access Journals (Sweden)
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.
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Historical and Experimental Evidence of Sexual Selection for War Heroism
Rusch, H.; Leunissen, J.L.M.; van Vugt, M.
2015-01-01
We report three studies which test a sexual selection hypothesis for male war heroism. Based on evolutionary theories of mate choice we hypothesize that men signal their fitness through displaying heroism in combat. First, we report the results of an archival study on US-American soldiers who fought
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Directory of Open Access Journals (Sweden)
Cecilia P. Calabuig
2013-08-01
Full Text Available The Coscoroba Swan, Coscoroba coscoroba (Molina, 1782, is a poorly known aberrant Anserine endemic to South America. We captured adult birds (189 male, 157 female from the largest population in Brazil at the Taim Ecological Reserve, State of Rio Grande do Sul, Brazil. Different patterns between sexes can reflect differences in selection, and positive allometry may indicate that a character is sexually selected. We used body weight and 10 morphological measurements to examine allometric differences between males and females of C. coscoroba. Males were consistently larger than females. Analysis of scaling relationships against body mass showed that nostril, tail, wing and bill height were positively allometric (i.e., heavier birds had relatively larger character lengths, but there were no sexual differences in allometric slopes. However, for a given mass, mature females had longer tails, longer wings (up to metacarpophalangeal articulation and shorter heads than males. In the light of current debate in the literature, we discuss whether such positively allometric traits and sexual differences in scaling may be indicative of sexual selection. Although Coscoroba Swan is a monogamous species, increasing the size of some attributes may confer some advantage for mate selection or male-male competition and, contrary to other studies, we suggest that positively allometric slopes alone should not be considered as evidence for sexual selection of the considered traits.
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van der Molen, Elsa; Blokland, Arjan A. J.; Hipwell, Alison E.; Vermeiren, Robert R.J.M.; Doreleijers, Theo A.H.; Loeber, Rolf
2014-01-01
Background It is widely recognized that early onset of disruptive behavior is linked to a variety of detrimental outcomes in males later in life. In contrast, little is known about the association between girls’ childhood trajectories of disruptive behavior and adjustment problems in early adolescence. Methods The current study used 9 waves of data from the ongoing Pittsburgh Girls Study. A semi-parametric group based model was used to identify trajectories of disruptive behavior in 1,513 girls from age 6 to 12 years. Adjustment problems were characterized by depression, self-harm, PTSD, substance use, interpersonal aggression, sexual behavior, affiliation with delinquent peers, and academic achievement at ages 13 and 14. Results Three trajectories of childhood disruptive behavior were identified: low, medium, and high. Girls in the high group were at increased risk for depression, self-harm, PTSD, illegal substance use, interpersonal aggression, early and risky sexual behavior, and lower academic achievement. The likelihood of multiple adjustment problems increased with trajectories reflecting higher levels of disruptive behavior. Conclusion Girls following the high childhood trajectory of disruptive behavior require early intervention programs to prevent multiple, adverse outcomes in adolescence and further escalation in adulthood. PMID:25302849
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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.
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Furuya, Tetsuya; Mu, Jianbing; Hayton, Karen; Liu, Anna; Duan, Junhui; Nkrumah, Louis; Joy, Deirdre A; Fidock, David A; Fujioka, Hisashi; Vaidya, Akhil B; Wellems, Thomas E; Su, Xin-zhuan
2005-11-15
A male gametocyte defect in the Plasmodium falciparum Dd2 parasite was previously discovered through the observation that all progeny clones in a Dd2 x HB3 genetic cross were the result of fertilization events between Dd2 female and HB3 male gametes. A determinant linked to the defect in Dd2 was subsequently mapped to an 800-kb segment on chromosome 12. Here, we report further mapping of the determinant to an 82-kb region and the identification of a candidate gene, P. falciparum male development gene 1 (pfmdv-1), that is expressed at a lower level in Dd2 compared with the wild-type normal male gametocyte-producing ancestor W2. Pfmdv-1 protein is sexual-stage specific and is located on the gametocyte plasma membrane, parasitophorous vacuole membrane, and the membranes of cleft-like structures within the erythrocyte. Disruption of pfmdv-1 results in a dramatic reduction in mature gametocytes, especially functional male gametocytes, with the majority of sexually committed parasites developmentally arrested at stage I. The pfmdv-1-knockout parasites show disturbed membrane structures, particularly multimembrane vesicles/tubes that likely derive from deformed cleft-like structures. Mosquito infectivity of the knockout parasites was also greatly reduced but not completely lost. The results suggest that pfmdv-1 plays a key role in gametocyte membrane formation and integrity.
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Coevolution of parental investment and sexually selected traits drives sex-role divergence.
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.
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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.
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Bateman gradients in hermaphrodites: An extended approach to quantify sexual selection.
Anthes, N.; David, P.; Auld, J.R.; Hoffer, J.N.A.; Jarne, P.; Koene, J.M.; Kokko, H.; Lorenzi, M.C.; Pélissié, B.; Sprenger, D.; Staikou, A.; Schärer, L.
2011-01-01
Sexual selection is often quantified using Bateman gradients, which represent sex-specific regression slopes of reproductive success on mating success and thus describe the expected fitness returns from mating more often. Although the analytical framework for Bateman gradients aimed at covering all
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Sex differences in parental care: Gametic investment, sexual selection, and social environment.
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.
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Kleene, Kenneth C
2005-01-01
This review proposes that the peculiar patterns of gene expression in spermatogenic cells are the consequence of powerful evolutionary forces known as sexual selection. Sexual selection is generally characterized by intense competition of males for females, an enormous variety of the strategies to maximize male reproductive success, exaggerated male traits at all levels of biological organization, co-evolution of sexual traits in males and females, and conflict between the sexual advantage of the male trait and the reproductive fitness of females and the individual fitness of both sexes. In addition, spermatogenesis is afflicted by selfish genes that promote their transmission to progeny while causing deleterious effects. Sexual selection, selfish genes, and genetic conflict provide compelling explanations for many atypical features of gene expression in spermatogenic cells including the gross overexpression of certain mRNAs, transcripts encoding truncated proteins that cannot carry out basic functions of the proteins encoded by the same genes in somatic cells, the large number of gene families containing paralogous genes encoding spermatogenic cell-specific isoforms, the large number of testis-cancer-associated genes that are expressed only in spermatogenic cells and malignant cells, and the overbearing role of Sertoli cells in regulating the number and quality of spermatozoa.
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Okada, Takeshi; Kawakita, Fumihiro; Nishikawa, Hirofumi; Nakano, Fumi; Liu, Lei; Suzuki, Hidenori
2018-05-31
There are no direct evidences showing the linkage between Toll-like receptor 4 (TLR4) and blood-brain barrier (BBB) disruption after subarachnoid hemorrhage (SAH). The purpose of this study was to examine if selective blockage of TLR4 prevents BBB disruption after SAH in mice and if the TLR4 signaling involves mitogen-activated protein kinases (MAPKs). One hundred and fifty-one C57BL/6 male mice underwent sham or endovascular perforation SAH operation, randomly followed by an intracerebroventricular infusion of vehicle or two dosages (117 or 585 ng) of a selective TLR4 antagonist IAXO-102 at 30 min post-operation. The effects were evaluated by survival rates, neurological scores, and brain water content at 24-72 h and immunoglobulin G immunostaining and Western blotting at 24 h post-SAH. IAXO-102 significantly prevented post-SAH neurological impairments, brain edema, and BBB disruption, resulting in improved survival rates. IAXO-102 also significantly suppressed post-SAH activation of a major isoform of MAPK p46 c-Jun N-terminal kinase (JNK) and matrix metalloproteinase-9 as well as periostin induction and preserved tight junction protein zona occludens-1. Another selective TLR4 antagonist TAK-242, which has a different binding site from IAXO-102, also showed similar effects to IAXO-102. This study first provided the evidence that TLR4 signaling is involved in post-SAH acute BBB disruption and that the signaling is mediated at least partly by JNK activation. TLR4-targeted therapy may be promising to reduce post-SAH morbidities and mortalities.
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Sexual selection and the evolution of brain size in primates.
Schillaci, Michael A
2006-12-20
Reproductive competition among males has long been considered a powerful force in the evolution of primates. The evolution of brain size and complexity in the Order Primates has been widely regarded as the hallmark of primate evolutionary history. Despite their importance to our understanding of primate evolution, the relationship between sexual selection and the evolutionary development of brain size is not well studied. The present research examines the evolutionary relationship between brain size and two components of primate sexual selection, sperm competition and male competition for mates. Results indicate that there is not a significant relationship between relative brain size and sperm competition as measured by relative testis size in primates, suggesting sperm competition has not played an important role in the evolution of brain size in the primate order. There is, however, a significant negative evolutionary relationship between relative brain size and the level of male competition for mates. The present study shows that the largest relative brain sizes among primate species are associated with monogamous mating systems, suggesting primate monogamy may require greater social acuity and abilities of deception.
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Liang, Liqin; Li, Jianqiang; Cheng, Lin; Ling, Jian; Luo, Zhongqin; Bai, Miao; Xie, Bingyan
2014-11-01
The Fusarium oxysporum species complex consists of fungal pathogens that cause serial vascular wilt disease on more than 100 cultivated species throughout the world. Gene function analysis is rapidly becoming more and more important as the whole-genome sequences of various F. oxysporum strains are being completed. Gene-disruption techniques are a common molecular tool for studying gene function, yet are often a limiting step in gene function identification. In this study we have developed a F. oxysporum high-efficiency gene-disruption strategy based on split-marker homologous recombination cassettes with dual selection and electroporation transformation. The method was efficiently used to delete three RNA-dependent RNA polymerase (RdRP) genes. The gene-disruption cassettes of three genes can be constructed simultaneously within a short time using this technique. The optimal condition for electroporation is 10μF capacitance, 300Ω resistance, 4kV/cm field strength, with 1μg of DNA (gene-disruption cassettes). Under these optimal conditions, we were able to obtain 95 transformants per μg DNA. And after positive-negative selection, the transformants were efficiently screened by PCR, screening efficiency averaged 85%: 90% (RdRP1), 85% (RdRP2) and 77% (RdRP3). This gene-disruption strategy should pave the way for high throughout genetic analysis in F. oxysporum. Copyright © 2014 Elsevier GmbH. All rights reserved.
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Proximity of signallers can maintain sexual signal variation under stabilizing selection
van Wijk, M.; Heath, J.; Lievers, R.; Schal, C.; Groot, A.T.
2017-01-01
How sexual communication systems can evolve under stabilizing selection is still a paradox in evolutionary biology. In moths, females emit a species-specific sex pheromone, consisting of a blend of biochemically related components, to which males are attracted. Although males appear to exert strong
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Coria-Avila, Genaro Alfonso; Paredes-Ramos, Pedro; Galán, Ricardo; Herrera-Covarrubias, Deissy; López-Meraz, Maria-Leonor
2014-05-01
Female sexual behavior is sensitive to stress and diseases. Some studies have shown that status epilepticus (SE) can affect sexual proceptivity and receptivity in female rats and also increases reject responses towards males. However, epidemiologic studies indicate that SE is more frequent in young individuals. Herein, we assessed the effects of SE in infant females on their sexual behavior during adulthood. Thirteen-day-old (P13) rat pups received intraperitoneal injections of lithium chloride (3 mEq/kg). Twenty hours later, at P14, SE was induced by subcutaneous injection of pilocarpine hydrochloride (100 mg/kg s.c.). Control animals were given an equal volume of saline subcutaneously. The animals were weaned at P21 and, later in adulthood, were ovariectomized and hormone-primed with estradiol+progesterone, and their sexual behavior assessed during 4 separate trials of 30 min each with a stud male. Our results indicate that proceptive behaviors (solicitations and hops and darts) were impaired during the first trial, but no alterations were observed for receptivity and attractivity. By trial 3, all SE females displayed normal proceptivity. These results indicate that SE in infancy readily affects proceptivity in a reversible manner. We discuss the role of sexual experience in recovery. Copyright © 2014 Elsevier Inc. All rights reserved.
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Sexual selection and the adaptive evolution of PKDREJ protein in primates and rodents.
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.
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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.
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Sexual selection and the evolution of brain size in primates.
Directory of Open Access Journals (Sweden)
Michael A Schillaci
Full Text Available Reproductive competition among males has long been considered a powerful force in the evolution of primates. The evolution of brain size and complexity in the Order Primates has been widely regarded as the hallmark of primate evolutionary history. Despite their importance to our understanding of primate evolution, the relationship between sexual selection and the evolutionary development of brain size is not well studied. The present research examines the evolutionary relationship between brain size and two components of primate sexual selection, sperm competition and male competition for mates. Results indicate that there is not a significant relationship between relative brain size and sperm competition as measured by relative testis size in primates, suggesting sperm competition has not played an important role in the evolution of brain size in the primate order. There is, however, a significant negative evolutionary relationship between relative brain size and the level of male competition for mates. The present study shows that the largest relative brain sizes among primate species are associated with monogamous mating systems, suggesting primate monogamy may require greater social acuity and abilities of deception.
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Czech Academy of Sciences Publication Activity Database
Wilkins, M. R.; Karaardic, H.; Vortman, Y.; Parchman, T. L.; Albrecht, Tomáš; Petrželková, Adéla; Özkan, L.; Pap, P. L.; Hubbard, J. K.; Hund, A. K.; Safran, R. J.
2016-01-01
Roč. 29, č. 12 (2016), s. 2410-2421 ISSN 1010-061X R&D Projects: GA MŠk(CZ) LH14045 Institutional support: RVO:68081766 Keywords : birds * natural selection * population genetics * sexual selection & conflicts * speciation Subject RIV: EG - Zoology Impact factor: 2.792, year: 2016
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Archer, C R; Zajitschek, F; Sakaluk, S K; Royle, N J; Hunt, J
2012-10-01
Recent work suggests that sexual selection can influence the evolution of ageing and lifespan by shaping the optimal timing and relative costliness of reproductive effort in the sexes. We used inbred lines of the decorated cricket, Gryllodes sigillatus, to estimate the genetic (co)variance between age-dependent reproductive effort, lifespan, and ageing within and between the sexes. Sexual selection theory predicts that males should die sooner and age more rapidly than females. However, a reversal of this pattern may be favored if reproductive effort increases with age in males but not in females. We found that male calling effort increased with age, whereas female fecundity decreased, and that males lived longer and aged more slowly than females. These divergent life-history strategies were underpinned by a positive genetic correlation between early-life reproductive effort and ageing rate in both sexes, although this relationship was stronger in females. Despite these sex differences in life-history schedules, age-dependent reproductive effort, lifespan, and ageing exhibited strong positive intersexual genetic correlations. This should, in theory, constrain the independent evolution of these traits in the sexes and may promote intralocus sexual conflict. Our study highlights the importance of sexual selection to the evolution of sex differences in ageing and lifespan in G. sigillatus. © 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.
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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
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Directory of Open Access Journals (Sweden)
Francisco Garcia-Gonzalez
2011-01-01
Full Text Available Whether species exhibit significant heritable variation in fitness is central for sexual selection. According to good genes models there must be genetic variation in males leading to variation in offspring fitness if females are to obtain genetic benefits from exercising mate preferences, or by mating multiply. However, sexual selection based on genetic benefits is controversial, and there is limited unambiguous support for the notion that choosy or polyandrous females can increase the chances of producing offspring with high viability. Here we examine the levels of additive genetic variance in two fitness components in the dung beetle Onthophagus taurus. We found significant sire effects on egg-to-adult viability and on son, but not daughter, survival to sexual maturity, as well as moderate coefficients of additive variance in these traits. Moreover, we do not find evidence for sexual antagonism influencing genetic variation for fitness. Our results are consistent with good genes sexual selection, and suggest that both pre- and postcopulatory mate choice, and male competition could provide indirect benefits to females.
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Vaginal microbiota and viral sexually transmitted diseases.
Nardis, C; Mosca, L; Mastromarino, P
2013-01-01
Healthy vaginal microbiota is an important biological barrier to pathogenic microorganisms. When this predominantly Lactobacillus community is disrupted, decreased in abundance and replaced by different anaerobes, bacterial vaginosis (BV) may occur. BV is associated with prevalence and incidence of several sexually transmitted infections. This review provides background on BV, discusses the epidemiologic data to support a role of altered vaginal microbiota for acquisition of sexually transmitted diseases and analyzes mechanisms by which lactobacilli could counteract sexually transmitted viral infections.
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Gupta, Jhumka; Willie, Tiara C; Harris, Courtney; Campos, Paola Abril; Falb, Kathryn L; Garcia Moreno, Claudia; Diaz Olavarrieta, Claudia; Okechukwu, Cassandra A
2018-03-07
Disrupting women's employment is a strategy that abusive partners could use to prevent women from maintaining economic independence and stability. Yet, few studies have investigated disruptions in employment among victims of intimate partner violence (IPV) in low-income and middle-income countries. Moreover, even fewer have sought to identify which female victims of IPV are most vulnerable to such disruptions. Using baseline data from 947 women in Mexico City enrolled in a randomised controlled trial, multilevel latent class analysis (LCA) was used to classify women based on their reported IPV experiences. Furthermore, multilevel logistic regression analyses were performed on a subsample of women reporting current work (n=572) to investigate associations between LCA membership and IPV-related employment disruptions. Overall, 40.6% of women who were working at the time of the survey reported some form of work-related disruption due to IPV. LCA identified four distinct classes of IPV experiences: Low Physical and Sexual Violence (39.1%); High Sexual and Low Physical Violence class (9.6%); High Physical and Low Sexual Violence and Injuries (36.5%); High Physical and Sexual Violence and Injuries (14.8%). Compared with women in the Low Physical and Sexual Violence class, women in the High Physical and Sexual Violence and Injuries class and women in the High Physical and Low Sexual Violence and Injuries class were at greater risk of work disruption (adjusted relative risk (ARR) 2.44, 95% CI 1.80 to 3.29; ARR 2.05, 95% CI 1.56 to 2.70, respectively). No other statistically significant associations emerged. IPV, and specific patterns of IPV experiences, must be considered both in work settings and, more broadly, by economic development programmes. NCT01661504. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.
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Etiology and Management of Sexual Dysfunction
Directory of Open Access Journals (Sweden)
Narendra Kumar Muthugaduru Shivarudrappa
2009-09-01
Full Text Available Sexual dysfunction is the impairment or disruption of any of the three phases of normal sexual functioning, including loss of libido, impairment of physiological arousal and loss, delay or alteration of orgasm. Each one of these can be affected by an orchestra of factors like senility, medical and surgical illnesses, medications and drugs of abuse. Non-pharmacological therapy is the main stay in the treatment of sexual dysfunction and drugs are used as adjuncts for a quicker and better result. Management in many of the cases depends on the primary cause. Here is a review of the major etiological factors of sexual dysfunction and its management
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Loehr, Annalise; Doan, Long; Miller, Lisa R
2015-11-01
Empirical research has documented that contact with lesbians and gays is associated with more positive feelings toward and greater support for legal rights for them, but we know less about whether these effects extend to informal aspects of same-sex relationships, such as reactions to public displays of affection. Furthermore, many studies have assumed that contact influences levels of sexual prejudice; however, the possibility of selection effects, in which less sexually prejudiced people have contact, and more sexually prejudiced people do not, raises some doubts about this assumption. We used original data from a nationally representative sample of heterosexuals to determine whether those reporting contact with a lesbian, gay, bisexual, or transgender friend or relative exhibited less sexual prejudice toward lesbian and gay couples than those without contact. This study examined the effect of contact on attitudes toward formal rights and a relatively unexplored dimension, informal privileges. We estimated the effect of having contact using traditional (ordinary least squares regression) methods before accounting for selection effects using propensity score matching. After accounting for selection effects, we found no significant differences between the attitudes of those who had contact and those who did not, for either formal or informal measures. Thus, selection effects appeared to play a pivotal role in confounding the link between contact and sexual prejudice, and future studies should exercise caution in interpreting results that do not account for such selection effects.
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Emotion disrupts neural activity during selective attention in psychopathy.
Sadeh, Naomi; Spielberg, Jeffrey M; Heller, Wendy; Herrington, John D; Engels, Anna S; Warren, Stacie L; Crocker, Laura D; Sutton, Bradley P; Miller, Gregory A
2013-03-01
Dimensions of psychopathy are theorized to be associated with distinct cognitive and emotional abnormalities that may represent unique neurobiological risk factors for the disorder. This hypothesis was investigated by examining whether the psychopathic personality dimensions of fearless-dominance and impulsive-antisociality moderated neural activity and behavioral responses associated with selective attention and emotional processing during an emotion-word Stroop task in 49 adults. As predicted, the dimensions evidenced divergent selective-attention deficits and sensitivity to emotional distraction. Fearless-dominance was associated with disrupted attentional control to positive words, and activation in right superior frontal gyrus mediated the relationship between fearless-dominance and errors to positive words. In contrast, impulsive-antisociality evidenced increased behavioral interference to both positive and negative words and correlated positively with recruitment of regions associated with motivational salience (amygdala, orbitofrontal cortex, insula), emotion regulation (temporal cortex, superior frontal gyrus) and attentional control (dorsal anterior cingulate cortex). Individuals high on both dimensions had increased recruitment of regions related to attentional control (temporal cortex, rostral anterior cingulate cortex), response preparation (pre-/post-central gyri) and motivational value (orbitofrontal cortex) in response to negative words. These findings provide evidence that the psychopathy dimensions represent dual sets of risk factors characterized by divergent dysfunction in cognitive and affective processes.
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Holman, Luke; Bro-Jørgensen, Jakob
2016-08-01
Raia et al. propose that the evolution of the shape and complexity of animal ornaments (e.g., deer antlers) can be explained by interspecific variation in body size and is not influenced by sexual selection. They claim to show that ornament complexity is related to body size by an 0.25-power law and argue that this finding precludes a role for sexual selection in the evolution of ornament complexity. However, their study does not test alternative hypotheses and mismeasures antler shape allometry by omitting much of the published data. We show that an index of sexual selection (sexual size dimorphism) is positively correlated with size-corrected antler complexity and that the allometric slope of complexity is substantially greater than 0.25, contra Raia et al. We conclude that sexual selection and physical constraints both affect the evolution of antler shape.
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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.
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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.
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Sexual Self-Concept and Sexual Risk-Taking.
Breakwell, Glynis M.; Millward, Lynne J.
1997-01-01
Presents data from a survey of randomly selected adolescents (N=474) which examined differences between male and female sexual identities. Results indicate two main dimensions in male sexual self-concept: socioemotional and the relational. Female sexual self-concept revolved around concerns with assertiveness, such as controlling when sex occurs.…
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Biometric evidence that sexual selection has shaped the hominin face.
Directory of Open Access Journals (Sweden)
Eleanor M Weston
2007-08-01
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.
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Disruptive event analysis: volcanism and igneous intrusion
International Nuclear Information System (INIS)
Crowe, B.M.
1979-01-01
Three basic topics are addressed for the disruptive event analysis: first, the range of disruptive consequences of a radioactive waste repository by volcanic activity; second, the possible reduction of the risk of disruption by volcanic activity through selective siting of a repository; and third, the quantification of the probability of repository disruption by volcanic activity
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A mechanism of extreme growth and reliable signaling in sexually selected ornaments and weapons.
Emlen, Douglas J; Warren, Ian A; Johns, Annika; Dworkin, Ian; Lavine, Laura Corley
2012-08-17
Many male animals wield ornaments or weapons of exaggerated proportions. We propose that increased cellular sensitivity to signaling through the insulin/insulin-like growth factor (IGF) pathway may be responsible for the extreme growth of these structures. We document how rhinoceros beetle horns, a sexually selected weapon, are more sensitive to nutrition and more responsive to perturbation of the insulin/IGF pathway than other body structures. We then illustrate how enhanced sensitivity to insulin/IGF signaling in a growing ornament or weapon would cause heightened condition sensitivity and increased variability in expression among individuals--critical properties of reliable signals of male quality. The possibility that reliable signaling arises as a by-product of the growth mechanism may explain why trait exaggeration has evolved so many different times in the context of sexual selection.
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Sexual lubricants in South Africa may potentially disrupt mucosal ...
African Journals Online (AJOL)
more likely to result in HIV transmission than unprotected vaginal intercourse due to ... Distribution of condoms and water-based sexual lubricants forms a cornerstone of .... Organisations such as the US Centers for Disease. Control and the ...
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Sexual practices in Malaysia: determinants of sexual intercourse among unmarried youths.
Zulkifli, S N; Low, W Y
2000-10-01
This paper describes findings on selected determinants of sexual intercourse among 468 unmarried adolescents from a survey in Malaysia. Data on respondents' background, sexual experience, contraceptive use, and sexual attitudes are provided. Based on multiple logistic regressions, factors significantly predictive of sexual experience are gender, employment, and sexual attitudes.
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Briscoe Runquist, Ryan D; Geber, Monica A; Pickett-Leonard, Michael; Moeller, David A
2017-05-01
Selection on floral traits in hermaphroditic plants is determined by both male and female reproductive success. However, predictions regarding floral trait and mating system evolution are often based solely on female fitness. Selection via male fitness has the potential to affect the outcomes of floral evolution. In this study, we used paternity analysis to assess individual selfing rates and selection on floral traits via male and female fitness in an experimental population of Clarkia xantiana where pollen limitation of seed set was strong. We detected selection through both female and male fitness with reinforcing or noninterfering patterns of selection through the two sex functions. For female fitness, selection favored reduced herkogamy and protandry, traits that promote increased autonomous selfing. For male fitness, selection on petal area was disruptive, with higher trait values conferring greater pollinator attraction and outcross siring success and smaller trait values leading to higher selfed siring success. Combining both female and male fitness, selection on petal area and protandry was disruptive because intermediate phenotypes were less successful as both males and females. Finally, functional relationships among male and female fertility components indicated that selfing resulted in seed discounting and pollen discounting. Under these functional relationships, the evolutionarily stable selfing rate can be intermediate or predominantly selfing or outcrossing, depending on the segregating load of deleterious mutations.
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International Nuclear Information System (INIS)
Reiman, A.; Taylor, P.; Kellman, A.; LaHaye, R.
1996-01-01
We report on the results of a statistical analysis of the DIII-D disruption data base, and on an examination of a selected subset of the shots to determine the likely causes of disruptions. The statistical analysis focuses on the dependence of the disruption rate on key dimensionless parameters. We find that the disruption frequency is high at modest values of the parameters, and that it can be relatively low at operational limits. For example, the disruption frequency in an ITER relevant regime (β N /l i ∼ 2, 3 G > 0.6, where n G is the Greenwald limit) is approximately 23%. For this range of q, the disruption frequency rises only modestly to about 35% at the β limit, consistent with previous observations of a soft β limit for this q regime. For the range 6 95 G G < .9) in all q regimes we have studied. The location of the minimum moves to higher density with increasing q
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Jones, A G; Avise, J C
2001-01-01
In pipefishes and seahorses (family Syngnathidae), the males provide all postzygotic care of offspring by brooding embryos on their ventral surfaces. In some species, this phenomenon of male "pregnancy" results in a reversal of the usual direction of sexual selection, such that females compete more than males for access to mates, and secondary sexual characteristics evolve in females. Thus the syngnathids can provide critical tests of theories related to the evolution of sex differences and sexual selection. Microsatellite-based studies of the genetic mating systems of several species of pipefishes and seahorses have provided insights into important aspects of the natural history and evolution of these fishes. First, males of species with completely enclosed pouches have complete confidence of paternity, as might be predicted from parental investment theory for species in which males invest so heavily in offspring. Second, a wide range of genetic mating systems have been documented in nature, including genetic monogamy in a seahorse, polygynandry in two species of pipefish, and polyandry in a third pipefish species. The genetic mating systems appear to be causally related to the intensity of sexual selection, with secondary sex characters evolving most often in females of the more polyandrous species. Third, genetic studies of captive-breeding pipefish suggest that the sexual selection gradient (or Bateman gradient) may be a substantially better method for characterizing the mating system than previously available techniques. Finally, these genetic studies of syngnathid mating systems have led to some general insights into the occurrence of clustered mutations at microsatellite loci, the utility of linked loci in studies of parentage, and the use of parentage data for direct estimation of adult population size.
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Twinley, Rebecca
2017-01-01
Woman-to-woman rape and sexual assault globally remains largely unknown and unaddressed. Expectedly, victim/survivors often cope alone, or with limited support, in the traumatic aftermath of their sexual victimisation. Work is one occupation that is impacted upon at this time. The study explored the perceived impacts of woman-to-woman rape and sexual assault, the subsequent experience of disclosure, reaction, and support, and the consequences for victim/survivors' subjective experience of occupation. The study combined a sociological auto/biographical approach with an occupational science perspective. A web-based survey generated initial data, and was also used as a sampling tool; subsequently, 10 respondents were interviewed face-to-face, in various UK locations. An eleventh respondent shared her story through correspondence. Four key themes emerged: 1) Identity; 2) Emotion; 3) Survival; and 4) Occupation. The latter, occupation, incorporated study and work. For these victim/survivors, work or education can be experienced as either: disrupted (triggering) or as preservative (maintenance). Their life roles as worker or student were impacted by feelings that they could have performed better and achieved more. Occupational therapists and other relevant service providers could work with sexually victimised people in order to participate more satisfactorily and healthily in the occupation of work.
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Jones, Adam G.; Walker, DeEtte; Kvarnemo, Charlotta; Lindström, Kai; Avise, John C.
2001-01-01
Alternative mating strategies are common in nature and are generally thought to increase the intensity of sexual selection. However, cuckoldry can theoretically decrease the opportunity for sexual selection, particularly in highly polygamous species. We address here the influence of sneaking (fertilization thievery) on the opportunity for sexual selection in the sand goby Pomatoschistus minutus, a marine fish species in which males build and defend nests. Our microsatellite-based analysis of the mating system in a natural sand goby population shows high rates of sneaking and multiple mating by males. Sneaker males had fertilized eggs in ≈50% of the assayed nests, and multiple sneakers sometimes fertilized eggs from a single female. Successful males had received eggs from 2 to 6 females per nest (mean = 3.4). We developed a simple mathematical model showing that sneaking in this polygynous sand goby population almost certainly decreases the opportunity for sexual selection, an outcome that contrasts with the usual effects of cuckoldry in socially monogamous animals. These results highlight a more complex and interesting relationship between cuckoldry rates and the intensity of sexual selection than previously assumed in much of the literature on animal mating systems. PMID:11481481
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When Disruptive Approaches Meet Disruptive Technologies: Learning at a Distance.
Gibson, Chere Campbell
2000-01-01
Reviews research on constructivism in learning and selection of learning strategies. Suggests linking constructivism with instructional technologies for continuing medical education in order to "disrupt" reactive, habitual ways of learning and encourage active engagement. (SK)
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Crouch, Daniel J M
2017-10-27
The prevalence of sexual reproduction remains mysterious, as it poses clear evolutionary drawbacks compared to reproducing asexually. Several possible explanations exist, with one of the most likely being that finite population size causes linkage disequilibria to randomly generate and impede the progress of natural selection, and that these are eroded by recombination via sexual reproduction. Previous investigations have either analysed this phenomenon in detail for small numbers of loci, or performed population simulations for many loci. Here we present a quantitative genetic model for fitness, based on the Price Equation, in order to examine the theoretical consequences of randomly generated linkage disequilibria when there are many loci. In addition, most previous work has been concerned with the long-term consequences of deleterious linkage disequilibria for population fitness. The expected change in mean fitness between consecutive generations, a measure of short-term evolutionary success, is shown under random environmental influences to be related to the autocovariance in mean fitness between the generations, capturing the effects of stochastic forces such as genetic drift. Interaction between genetic drift and natural selection, due to randomly generated linkage disequilibria, is demonstrated to be one possible source of mean fitness autocovariance. This suggests a possible role for sexual reproduction in reducing the negative effects of genetic drift, thereby improving the short-term efficacy of natural selection. Copyright © 2017 Elsevier Ltd. All rights reserved.
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DEFF Research Database (Denmark)
Faurby, Søren; Nielsen, Kasper Sauer Kollerup; Bussarawit, Somchai
2011-01-01
. 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......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...
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Urfer, Matthias; Bogdanovic, Jasmina; Lo Monte, Fabio; Moehle, Kerstin; Zerbe, Katja; Omasits, Ulrich; Ahrens, Christian H; Pessi, Gabriella; Eberl, Leo; Robinson, John A
2016-01-22
Increasing antibacterial resistance presents a major challenge in antibiotic discovery. One attractive target in Gram-negative bacteria is the unique asymmetric outer membrane (OM), which acts as a permeability barrier that protects the cell from external stresses, such as the presence of antibiotics. We describe a novel β-hairpin macrocyclic peptide JB-95 with potent antimicrobial activity against Escherichia coli. This peptide exhibits no cellular lytic activity, but electron microscopy and fluorescence studies reveal an ability to selectively disrupt the OM but not the inner membrane of E. coli. The selective targeting of the OM probably occurs through interactions of JB-95 with selected β-barrel OM proteins, including BamA and LptD as shown by photolabeling experiments. Membrane proteomic studies reveal rapid depletion of many β-barrel OM proteins from JB-95-treated E. coli, consistent with induction of a membrane stress response and/or direct inhibition of the Bam folding machine. The results suggest that lethal disruption of the OM by JB-95 occurs through a novel mechanism of action at key interaction sites within clusters of β-barrel proteins in the OM. These findings open new avenues for developing antibiotics that specifically target β-barrel proteins and the integrity of the Gram-negative OM. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.
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Polygyny and extra-pair paternity enhance the opportunity for sexual selection in blue tits
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
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International Nuclear Information System (INIS)
Arditsoglou, Anastasia; Voutsa, Dimitra
2008-01-01
Two types of polar organic chemical integrative samplers (pharmaceutical POCIS and pesticide POCIS) were examined for their sampling efficiency of selected endocrine disrupting compounds (EDCs). Laboratory-based calibration of POCISs was conducted by exposing them at high and low concentrations of 14 EDCs (4-alkyl-phenols, their ethoxylate oligomers, bisphenol A, selected estrogens and synthetic steroids) for different time periods. The kinetic studies showed an integrative uptake up to 28 days. The sampling rates for the individual compounds were obtained. The use of POCISs could result in an integrative approach to the quality status of the aquatic systems especially in the case of high variation of water concentrations of EDCs. The sampling efficiency of POCISs under various field conditions was assessed after their deployment in different aquatic environments. - Calibration and field performance of polar organic integrative samplers for monitoring EDCs in aquatic environments
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Males that drop a sexually selected weapon grow larger testes.
Joseph, Paul N; Emberts, Zachary; Sasson, Daniel A; Miller, Christine W
2018-01-01
Costly sexually selected weapons are predicted to trade off with postcopulatory traits, such as testes. Although weapons can be important for achieving access to females, individuals of some species can permanently drop (i.e. autotomize) their weapons, without regeneration, to escape danger. We capitalized on this natural behavior to experimentally address whether the loss of a sexually selected weapon leads to increased testes investment in the leaf-footed cactus bug, Narnia femorata Stål (Hemiptera: Coreidae). In a second experiment, we measured offspring production for males that lost a weapon during development. As predicted, males that dropped a hind limb during development grew significantly larger testes than the control treatments. Hind-limb autotomy did not result in the enlargement of other nearby traits. Our results are the first to experimentally demonstrate that males compensate for natural weapon loss by investing more in testes. In a second experiment we found that females paired with males that lost a hind limb had 40% lower egg hatching success than females paired with intact males, perhaps because of lower mating receptivity to males with a lost limb. Importantly, in those cases where viable offspring were produced, males missing a hind limb produced 42% more offspring than males with intact limbs. These results suggest that the loss of a hind-limb weapon can, in some cases, lead to greater fertilization success. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.
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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 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 lesser
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International Nuclear Information System (INIS)
Westhuizen, Liana van der; Gelderblom, Wentzel C.A.; Shephard, Gordon S.; Swanevelder, Sonja
2004-01-01
In order to investigate the role of sphingolipid disruption in the cancer promoting potential of fumonisin B 1 (FB 1 ) in the development of hepatocyte nodules, male Fischer 344 rats were subjected to cancer initiation (FB 1 containing diet or diethylnitrosamine (DEN) by i.p. injection) and promotion (2-acetylaminofluorene with partial hepatectomy, 2-AAF/PH) treatments followed by a secondary FB 1 dietary regimen. Sphinganine (Sa) and sphingosine (So) levels were measured by high performance liquid chromatography in control, surrounding and nodular liver tissues of the rats. The disruption of sphingolipid biosynthesis by the secondary FB 1 treatment in the control rats was significantly (P 1 initiation and 2-AAF/PH promotion. When comparing the groups subjected to the secondary FB 1 treatment, the initiation effected by FB 1 was less (P 1 initiation was marginally increased in the nodules compared to the surrounding liver after 2-AAF/PH promotion and significantly (P 1 treatment. Although, the FB 1 -induced hepatocyte nodules were not resistant to the disruption of sphingolipid biosynthesis, the nodular So levels were increased and might provide a selective growth stimulus possibly induced by bio-active sphingoid intermediates such as sphingosine 1-phosphate (S1P)
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Higbee, Bradley S; Burks, Charles S
2008-10-01
Two experiments in 2003 examined the effects of different ways of dispensing the principal sex pheromone component on sexual communication among and crop damage by the navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae) in Nonpareil almonds and pistachios. A third experiment in 2004 compared the effect on navel orangeworm damage to several almond varieties using one of these dispensing systems by itself or with phosmet, phosmet alone, and an untreated control. Additional data are presented estimating release rates from timed aerosol release devices (PuffersNOW, Suterra LLC, Bend, OR) and hand-applied membrane dispensers. In 2003, puffers placed peripherally around 16-ha blocks, evenly spaced Puffers, and hand-applied dispensers reduced males captured in virgin-baited traps by > or = 95% and mating in sentinel females by > or = 69%, with evenly placed Puffers showing greater reduction of males captured and females mated compared with the other dispensing systems. Mating disruption with gridded Puffers or hand-applied devices in almonds resulted in an approximately 37% reduction of navel orangeworm damage (not significant), whereas peripheral Puffers resulted in a 16% reduction of navel orangeworm damage to almonds. In pistachios neither peripheral nor gridded Puffers reduced navel orangeworm damage, whereas insecticide reduced damage by 56%. In 2004, Puffers alone, insecticide alone, and both in combination significantly reduced navel orangeworm damage in Nonpareil almonds. In other, later harvested varieties, the insecticide treatments reduced damage, whereas the mating disruption treatment alone did not. We discuss application of these findings to management of navel orangeworm in these two crops.
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A change in competitive context reverses sexual selection on male size.
Kasumovic, M M; Andrade, M C B
2009-02-01
In studies of sexual selection, larger size is often argued to increase male fitness, and relatively smaller males are explained by genetic and/or environmental variation. We demonstrate that a size-development life-history trade-off could underlie the maintenance of a broad, unimodal distribution of size in male redback spiders (Latrodectus hasselti). Larger males are superior in direct competition, but redback males mature rapidly at small size in the presence of females. In field enclosures, we simulated two competitive contexts favouring development of divergent male sizes. Relatively smaller males lost when competing directly, but had 10 times higher fitness than relatively larger males when given the temporal advantage of rapid development. Linear selection gradients confirmed the reversal of selection on size, showing that it is critical to consider life-history decisions underlying the development of traits related to fitness.
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Heckert, Jessica
2016-11-01
This study examines the links between migration and sexual and reproductive health among rural-to-urban migrant youth in Haiti. It evaluates behavioural, knowledge and attitudinal components from the perspective of three competing explanations for migrants' behaviours: adaptation, disruption and selection. Discrete-time event history analysis is employed to compare these hypotheses using Haiti Demographic and Health Survey data (N=1215 adolescent girls, N=829 adolescent boys). Multi-level models are used to compare changes in knowledge and attitudes in individuals using data from the Haiti Youth Transitions Study (N=223). The findings reveal that disruption is the most plausible explanation for the timing of migration and first sex among girls. However, contrary to the assumption that migrant youth risk experiencing first sex earlier, girls are less likely to experience first sex near the time they migrate, and rural-to-urban migrant boys may experience first sex at later ages. The high aspirations of migrant youth provide a likely explanation for these findings. Furthermore, male migrants accumulate less protective knowledge, which is consistent with the disruption hypothesis, and migrants endorse premarital sex similarly to non-migrants. Sexual and reproductive health curricula should be adapted to the unique needs of migrant youth, and youth should be targeted before they migrate.
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Sexual selection on land snail shell ornamentation: a hypothesis that may explain shell diversity
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
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Alleles versus genotypes: Genetic interactions and the dynamics of selection in sexual populations
Neher, Richard
2010-03-01
Physical interactions between amino-acids are essential for protein structure and activity, while protein-protein interactions and regulatory interactions are central to cellular function. As a consequence of these interactions, the combined effect of two mutations can differ from the sum of the individual effects of the mutations. This phenomenon of genetic interaction is known as epistasis. However, the importance of epistasis and its effects on evolutionary dynamics are poorly understood, especially in sexual populations where recombination breaks up existing combinations of alleles to produce new ones. Here, we present a computational model of selection dynamics involving many epistatic loci in a recombining population. We demonstrate that a large number of polymorphic interacting loci can, despite frequent recombination, exhibit cooperative behavior that locks alleles into favorable genotypes leading to a population consisting of a set of competing clones. As the recombination rate exceeds a certain critical value this ``genotype selection'' phase disappears in an abrupt transition giving way to ``allele selection'' - the phase where different loci are only weakly correlated as expected in sexually reproducing populations. Clustering of interacting sets of genes on a chromosome leads to the emergence of an intermediate regime, where localized blocks of cooperating alleles lock into genetic modules. Large populations attain highest fitness at a recombination rate just below critical, suggesting that natural selection might tune recombination rates to balance the beneficial aspect of exploration of genotype space with the breaking up of synergistic allele combinations.
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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 ...
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Rasier, G; Toppari, J; Parent, A-S; Bourguignon, J-P
2006-07-25
Natural hormones and some synthetic chemicals spread into our surrounding environment share the capacity to interact with hormone action and metabolism. Exposure to such compounds can cause a variety of developmental and reproductive detrimental abnormalities in wildlife species and, potentially, in human. Many experimental and epidemiological data have reported that exposure of the developing fetus or neonate to environmentally relevant concentrations of some among these endocrine disrupters induces morphological, biochemical and/or physiological disorders in brain and reproductive organs, by interfering with the hormone actions. The impact of such exposures on the hypothalamic-pituitary-gonadal axis and subsequent sexual maturation is the subject of the present review. We will highlight epidemiological human studies and the effects of early exposure during gestational, perinatal or postnatal life in female rodents.
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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.
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Meston, Cindy M; Lorenz, Tierney A
2013-07-01
Physiological responses to sexual stimuli may contribute to the increased rate of sexual problems seen in women with childhood sexual abuse (CSA) histories. We compared two physiological stress responses as predictors of sexual function and satisfaction, sympathetic nervous system (SNS) activation and cortisol in women with (CSA, N = 136) and without CSA histories (NSA, N = 102). In CSA survivors, cortisol response to sexual stimuli did not significantly predict sexual functioning; however, in NSA women, cortisol increases were associated with poorer sexual functioning, and decreases with higher functioning. For women with CSA histories, lower SNS activity was associated with poorer sexual functioning. For CSA survivors with low lifetime trauma, lower SNS activity was associated with higher sexual satisfaction; for women with high lifetime trauma, the reverse was true. Decreased SNS activity during sexual stimuli predicted higher sexual functioning in NSA women with low lifetime exposure to traumatic events, but lower sexual functioning in those with high exposure. Differences between women with and without CSA histories in the association between cortisol and SNS response and sexual functioning and satisfaction suggests that CSA causes disruptions in both short and long-term stress responses to sexual stimuli that perpetuate into adulthood.
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Barreto, Felipe S.; Avise, John C.
2010-01-01
Taxa in which males alone invest in postzygotic care of offspring are often considered good models for investigating the proffered relationships between sexual selection and mating systems. In the pycnogonid sea spider Pycnogonum stearnsi, males carry large egg masses on their bodies for several weeks, so this species is a plausible candidate for sex-role reversal (greater intensity of sexual selection on females than on males). Here, we couple a microsatellite-based assessment of the mating ...
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Barreto, Felipe S; Avise, John C
2010-10-07
Taxa in which males alone invest in postzygotic care of offspring are often considered good models for investigating the proffered relationships between sexual selection and mating systems. In the pycnogonid sea spider Pycnogonum stearnsi, males carry large egg masses on their bodies for several weeks, so this species is a plausible candidate for sex-role reversal (greater intensity of sexual selection on females than on males). Here, we couple a microsatellite-based assessment of the mating system in a natural population with formal quantitative measures of genetic fitness to investigate the direction of sexual selection in P. stearnsi. Both sexes proved to be highly polygamous and showed similar standardized variances in reproductive and mating successes. Moreover, the fertility (number of progeny) of males and females appeared to be equally and highly dependent on mate access, as shown by similar Bateman gradients for the two sexes. The absence of sex-role reversal in this population of P. stearnsi is probably attributable to the fact that males are not limited by brooding space but have evolved an ability to carry large numbers of progeny. Body length was not a good predictor of male mating or reproductive success, so the aim of future studies should be to determine what traits are the targets of sexual selection in this species.
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THE ECONOMIC AND CAREER EFFECTS OF SEXUAL HARASSMENT ON WORKING WOMEN
MCLAUGHLIN, HEATHER; UGGEN, CHRISTOPHER; BLACKSTONE, AMY
2017-01-01
Many working women will experience sexual harassment at some point in their careers. While some report this harassment, many leave their jobs to escape the harassing environment. This mixed-methods study examines whether sexual harassment and subsequent career disruption affect women’s careers. Using in-depth interviews and longitudinal survey data from the Youth Development Study, we examine the effect of sexual harassment for women in the early career. We find that sexual harassment increases financial stress, largely by precipitating job change, and can significantly alter women’s career attainment. PMID:29056822
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THE ECONOMIC AND CAREER EFFECTS OF SEXUAL HARASSMENT ON WORKING WOMEN.
McLaughlin, Heather; Uggen, Christopher; Blackstone, Amy
2017-06-01
Many working women will experience sexual harassment at some point in their careers. While some report this harassment, many leave their jobs to escape the harassing environment. This mixed-methods study examines whether sexual harassment and subsequent career disruption affect women's careers. Using in-depth interviews and longitudinal survey data from the Youth Development Study, we examine the effect of sexual harassment for women in the early career. We find that sexual harassment increases financial stress, largely by precipitating job change, and can significantly alter women's career attainment.
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Directory of Open Access Journals (Sweden)
Maria João Fernandes Martins
Full Text Available Assessing the long-term macroevolutionary consequences of sexual selection has been hampered by the difficulty of studying this process in the fossil record. Cytheroid ostracodes offer an excellent system to explore sexual selection in the fossil record because their readily fossilized carapaces are sexually dimorphic. Specifically, males are relatively more elongate than females in this superfamily. This sexual shape difference is thought to arise so that males carapaces can accommodate their very large copulatory apparatus, which can account for up to one-third of body volume. Here we test this widely held explanation for sexual dimorphism in cytheroid ostracodes by correlating investment in male genitalia, a trait in which sexual selection is seen as the main evolutionary driver, with sexual dimorphism of carapace in the genus Cyprideis. We analyzed specimens collected in the field (C. salebrosa, USA; C. torosa, UK and from collections of the National Museum of Natural History, Washington, DC (C. mexicana. We digitized valve outlines in lateral view to obtain measures of size (valve area and shape (elongation, measured as length to height ratio, and obtained several dimensions from two components of the hemipenis: the muscular basal capsule, which functions as a sperm pump, and the section that includes the intromittent organ (terminal extension. In addition to the assessment of this primary sexual trait, we also quantified two dimensions of the male secondary sexual trait-where the transformed right walking leg functions as a clasping organ during mating. We also measured linear dimensions from four limbs as indicators of overall (soft-part body size, and assessed allometry of the soft anatomy. We observed significant correlations in males between valve size, but not elongation, and distinct structural parts of the hemipenis, even after accounting for their shared correlation with overall body size. We also found weak but significant
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Neural-net disruption predictor in JT-60U
International Nuclear Information System (INIS)
Yoshino, R.
2003-01-01
The prediction of major disruptions caused by the density limit, the plasma current ramp-down with high internal inductance l i , the low density locked mode and the β-limit has been investigated in JT-60U. The concept of 'stability level', newly proposed in this paper to predict the occurrence of a major disruption, is calculated from nine input parameters every 2 ms by the neural network and the start of a major disruption is predicted when the stability level decreases to a certain level, the 'alarm level'. The neural network is trained in two steps. It is first trained with 12 disruptive and six non-disruptive shots (total of 8011 data points). Second, the target output data for 12 disruptive shots are modified and the network is trained again with additional data points generated by the operator. The 'neural-net disruption predictor' obtained has been tested for 300 disruptive shots (128 945 data points) and 1008 non-disruptive shots (982 800 data points) selected from nine years of operation (1991-1999) of JT-60U. Major disruptions except for those caused by the -limit have been predicted with a prediction success rate of 97-98% at 10 ms prior to the disruption and higher than 90% at 30 ms prior to the disruption while the false alarm rate is 2.1% for non-disruptive shots. This prediction performance has been confirmed for 120 disruptive shots (56 163 data points), caused by the density limit, as well as 1032 non-disruptive shots (1004 611 data points) in the last four years of operation (1999-2002) of JT-60U. A careful selection of the input parameters supplied to the network and the newly developed two-step training of the network have reduced the false alarm rate resulting in a considerable improvement of the prediction success rate. (author)
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Female responses to experimental removal of sexual selection components in Drosophila melanogaster
Innocenti, Paolo; Flis, Ilona; Morrow, Edward H.
2014-01-01
Background Despite the common assumption that multiple mating should in general be favored in males, but not in females, to date there is no consensus on the general impact of multiple mating on female fitness. Notably, very little is known about the genetic and physiological features underlying the female response to sexual selection pressures. By combining an experimental evolution approach with genomic techniques, we investigated the effects of single and multiple matings on female fecundi...
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Sztepanacz, Jacqueline L; Rundle, Howard D
2012-10-01
Directional selection is prevalent in nature, yet phenotypes tend to remain relatively constant, suggesting a limit to trait evolution. However, the genetic basis of this limit is unresolved. Given widespread pleiotropy, opposing selection on a trait may arise from the effects of the underlying alleles on other traits under selection, generating net stabilizing selection on trait genetic variance. These pleiotropic costs of trait exaggeration may arise through any number of other traits, making them hard to detect in phenotypic analyses. Stabilizing selection can be inferred, however, if genetic variance is greater among low- compared to high-fitness individuals. We extend a recently suggested approach to provide a direct test of a difference in genetic variance for a suite of cuticular hydrocarbons (CHCs) in Drosophila serrata. Despite strong directional sexual selection on these traits, genetic variance differed between high- and low-fitness individuals and was greater among the low-fitness males for seven of eight CHCs, significantly more than expected by chance. Univariate tests of a difference in genetic variance were nonsignificant but likely have low power. Our results suggest that further CHC exaggeration in D. serrata in response to sexual selection is limited by pleiotropic costs mediated through other traits. © 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.
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Balasundaram, B; Harrison, S T L
2006-06-05
Intracellular products, not secreted from the microbial cell, are released by breaking the cell envelope consisting of cytoplasmic membrane and an outer cell wall. Hydrodynamic cavitation has been reported to cause microbial cell disruption. By manipulating the operating variables involved, a wide range of intensity of cavitation can be achieved resulting in a varying extent of disruption. The effect of the process variables including cavitation number, initial cell concentration of the suspension and the number of passes across the cavitation zone on the release of enzymes from various locations of the Brewers' yeast was studied. The release profile of the enzymes studied include alpha-glucosidase (periplasmic), invertase (cell wall bound), alcohol dehydrogenase (ADH; cytoplasmic) and glucose-6-phosphate dehydrogenase (G6PDH; cytoplasmic). An optimum cavitation number Cv of 0.13 for maximum disruption was observed across the range Cv 0.09-0.99. The optimum cell concentration was found to be 0.5% (w/v, wet wt) when varying over the range 0.1%-5%. The sustained effect of cavitation on the yeast cell wall when re-circulating the suspension across the cavitation zone was found to release the cell wall bound enzyme invertase (86%) to a greater extent than the enzymes from other locations of the cell (e.g. periplasmic alpha-glucosidase at 17%). Localised damage to the cell wall could be observed using transmission electron microscopy (TEM) of cells subjected to less intense cavitation conditions. Absence of the release of cytoplasmic enzymes to a significant extent, absence of micronisation as observed by TEM and presence of a lower number of proteins bands in the culture supernatant on SDS-PAGE analysis following hydrodynamic cavitation compared to disruption by high-pressure homogenisation confirmed the selective release offered by hydrodynamic cavitation. Copyright 2006 Wiley Periodicals, Inc.
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An introduction to genetic quality in the context of sexual selection.
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.
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Directory of Open Access Journals (Sweden)
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.
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Svensson, O; Kvarnemo, C
2003-09-01
Both natural selection and sexual selection may act on nest-building. We tested experimentally how different regimes of egg-predation and male-male competition influence nest-building before mating, using the marine fish sand goby, Pomatoschistus minutus. Males with sneaker males present built the smallest nest-openings, smaller than males held alone or with Pomatoschistus microps males (which may predate eggs and compete over nest-sites but not compete over fertilizations). Males with visual access to other nest-building males tended also to build smaller openings than males held alone or with P. microps. Males with egg-predators present built nests with openings not differing significantly from any other treatment. Our results indicate that the small nest-openings found in the sneaker male treatment are sexually selected through protection against sneaking or by female choice. Across treatments, time span before a male started to build his nest also explained variation in nest-opening width; males starting late built larger nest-openings.
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DEFF Research Database (Denmark)
Hansen, Pernille Reimer; Christiansen, Sofie; Boberg, Julie
from gestational day 7 to postnatal day (PND)13 with either vehicle (control) or a mixture of the five pesticides at 25%, 50%, 75% or 100% of their individual NOAELs for causing major effects on pregnancy length and pup survival in our earlier studies. The pregnancy length was dose....... Although laboratory animal studies have shown that some endocrine disrupting pesticides can affect reproduction and sexual differentiation, individual pesticides may appear to be present in human tissues at too low levels to cause concern for adverse reproductive effects. However, recent studies in our...... laboratory have shown that combined exposure to endocrine disrupters can cause adverse effects on male sexual development, even though the doses of the single compounds are below their individual NOAELs for anti-androgenic effects. Here, we present results from range finding studies with combined exposure...
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The Relationship between Childhood Sexual Abuse and Sexual Dysfunction in Jamaican Adults
Swaby, Antoneal N.; Morgan, Kai A. D.
2009-01-01
This study examined the associations between early traumatic sexualization and later sexual dysfunction in a sample of 100 Jamaican adults while identifying the linkages between age, frequency of abuse, and gender on sexual functioning. Participants were selected via purposive and convenience sampling and divided equally into comparison and…
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Network Formation under the Threat of Disruption
Hoyer, B.
2013-01-01
The studies in this thesis are focused on the impact the presence of a network disruptor has on network formation models. In particular, we build two theoretical models to study the effect of network disruption on network formation and test the effect network disruption has on equilibrium selection
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Genomic Signatures of Sexual Conflict.
Kasimatis, Katja R; Nelson, Thomas C; Phillips, Patrick C
2017-10-30
Sexual conflict is a specific class of intergenomic conflict that describes the reciprocal sex-specific fitness costs generated by antagonistic reproductive interactions. The potential for sexual conflict is an inherent property of having a shared genome between the sexes and, therefore, is an extreme form of an environment-dependent fitness effect. In this way, many of the predictions from environment-dependent selection can be used to formulate expected patterns of genome evolution under sexual conflict. However, the pleiotropic and transmission constraints inherent to having alleles move across sex-specific backgrounds from generation to generation further modulate the anticipated signatures of selection. We outline methods for detecting candidate sexual conflict loci both across and within populations. Additionally, we consider the ability of genome scans to identify sexually antagonistic loci by modeling allele frequency changes within males and females due to a single generation of selection. In particular, we highlight the need to integrate genotype, phenotype, and functional information to truly distinguish sexual conflict from other forms of sexual differentiation. © The American Genetic Association 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
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The Significance of Sexuality and Intimacy in the Lives of Older African Americans With HIV/AIDS
Nevedal, Andrea; Sankar, Andrea
2016-01-01
Purpose of the Study: Aging and HIV/AIDS research focuses primarily on standardized clinical, social, and behavioral measures, leaving unanswered questions about how this chronic and stigmatizing condition affects life course expectations and the meaning of aging with the disease. Utilizing Gaylene Becker’s (1997) life course disruption theory, we explored older African Americans’ experiences of living with HIV/AIDS. Design and Methods: A purposive sample (N = 43) of seropositive African Americans aged 50 and older was selected from a parent study. Thirteen participants completed one semi-structured in-depth interview on life course expectations and experiences of living with HIV/AIDS. Interview transcripts were analyzed using standard qualitative coding and thematic analysis. Results: Responding to broad, open-ended questions about the impact of HIV on life course expectations, participants emphasized how HIV limited their ability to experience sexuality and intimacy. Two major themes emerged, damaged sexuality and constrained intimacy. Implications: Older African Americans’ discussions of living with HIV focused on the importance of and the challenges to sexuality and intimacy. Researchers and clinicians should be attentive to significant and ongoing HIV-related challenges to sexuality and intimacy facing older African Americans living with HIV/AIDS. PMID:26035889
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Sexual Selection of Human Cooperative Behaviour: An Experimental Study in Rural Senegal
Tognetti, Arnaud; Berticat, Claire; Raymond, Michel; Faurie, Charlotte
2012-01-01
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 do...
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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
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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.
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2013-01-01
Background The cloning of gene sequences forms the basis for many molecular biological studies. One important step in the cloning process is the isolation of bacterial transformants carrying vector DNA. This involves a vector-encoded selectable marker gene, which in most cases, confers resistance to an antibiotic. However, there are a number of circumstances in which a different selectable marker is required or may be preferable. Such situations can include restrictions to host strain choice, two phase cloning experiments and mutagenesis experiments, issues that result in additional unnecessary cloning steps, in which the DNA needs to be subcloned into a vector with a suitable selectable marker. Results We have used restriction enzyme mediated gene disruption to modify the selectable marker gene of a given vector by cloning a different selectable marker gene into the original marker present in that vector. Cloning a new selectable marker into a pre-existing marker was found to change the selection phenotype conferred by that vector, which we were able to demonstrate using multiple commonly used vectors and multiple resistance markers. This methodology was also successfully applied not only to cloning vectors, but also to expression vectors while keeping the expression characteristics of the vector unaltered. Conclusions Changing the selectable marker of a given vector has a number of advantages and applications. This rapid and efficient method could be used for co-expression of recombinant proteins, optimisation of two phase cloning procedures, as well as multiple genetic manipulations within the same host strain without the need to remove a pre-existing selectable marker in a previously genetically modified strain. PMID:23497512
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Quantitative genetic models of sexual selection by male choice.
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.
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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.
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Tian, Hua; Wu, Peng; Wang, Wei; Ru, Shaoguo
2015-05-01
Although bioaccumulation of tributyltin (TBT) in fish has been confirmed, information on possible effects of TBT on reproductive system of fish is still relatively scarce, particularly at environmentally relevant levels. To evaluate the adverse effects and intrinsic toxicological properties of TBT in male fish, we studied aromatase gene expression in the brain, sex steroid contents, primary and secondary sexual characteristics, and reproductive behavior in male guppies (Poecilia reticulata) exposed to tributyltin chloride at the nominal concentrations of 5, 50, and 500 ng/L for 28 days in a semi-static exposure system. Radioimmunoassay demonstrated that treatment with 50 ng/L TBT caused an increase in systemic levels of testosterone of male guppies. Gonopodial index, which showed a positive correlation with testosterone levels, was elevated in the 5 ng/L and 50 ng/L TBT treated groups. Real-time PCR revealed that TBT exposure had inhibiting effects on expression of two isoforms of guppy aromatase in the brain, and these changes at the molecular levels were associated with a disturbance of reproductive behavior of the individuals, as measured by decreases in frequencies of posturing, sigmoid display, and chase activities when males were paired with females. This study provides the first evidence that TBT can cause abnormalities of secondary sexual characteristics in teleosts and that suppression of reproductive behavior in teleosts by TBT is due to its endocrine-disrupting action as an aromatase inhibitor targeting the nervous system. Copyright © 2015 Elsevier B.V. All rights reserved.
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Schielzeth, Holger; Streitner, Corinna; Lampe, Ulrike; Franzke, Alexandra; Reinhold, Klaus
2014-12-01
Genome size is largely uncorrelated to organismal complexity and adaptive scenarios. Genetic drift as well as intragenomic conflict have been put forward to explain this observation. We here study the impact of genome size on sexual attractiveness in the bow-winged grasshopper Chorthippus biguttulus. Grasshoppers show particularly large variation in genome size due to the high prevalence of supernumerary chromosomes that are considered (mildly) selfish, as evidenced by non-Mendelian inheritance and fitness costs if present in high numbers. We ranked male grasshoppers by song characteristics that are known to affect female preferences in this species and scored genome sizes of attractive and unattractive individuals from the extremes of this distribution. We find that attractive singers have significantly smaller genomes, demonstrating that genome size is reflected in male courtship songs and that females prefer songs of males with small genomes. Such a genome size dependent mate preference effectively selects against selfish genetic elements that tend to increase genome size. The data therefore provide a novel example of how sexual selection can reinforce natural selection and can act as an agent in an intragenomic arms race. Furthermore, our findings indicate an underappreciated route of how choosy females could gain indirect benefits. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.
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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
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Chesson, Harrell W
2012-03-01
The purpose of this review is to highlight selected studies in the economics literature that address sexually transmitted disease (STD)-related topics that are typically not examined in the STD literature. Two databases (EconLit and Web of Science) were searched to locate STD-related articles in the economics journals. Relevant articles were also identified in other ways, such as informal discussions with colleagues familiar with the literature. To maintain a focus on unique STD-related topics, studies with topics common in the STD literature (e.g., cost-effectiveness, transmission modeling) were excluded. Selected STD-related studies in the economics literature were grouped into the following 8 topics: impact of abortion laws and policies on sexual health outcomes; same-sex marriage and syphilis rates; alcohol policy and STD rates; welfare laws and STD rates; discounting the future; HIV disclosure laws; the impact of tolerance for gays on HIV incidence; and economic versus epidemiologic models of HIV dynamics. A general theme of STD-related studies in the economics literature is that laws and policies that increased the "cost" of risky sex tended to reduce the demand for risky sex, and therefore reduce the incidence of STDs. Economic research can contribute in novel ways to our understanding of influences on risky sexual behavior at the individual level and STD incidence at the population level. Economists and STD experts could mutually benefit from increased collaboration.
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Analyzing the concept of disruptive behavior in healthcare work: an integrative review*
Directory of Open Access Journals (Sweden)
Roberta Meneses Oliveira
Full Text Available Abstract OBJECTIVE To analyze the concept of disruptive behavior in healthcare work. METHOD An integrative review carried out in the theoretical phase of a qualitative research substantiated by the theoretical framework of the Hybrid Model of Concept Development. The search for articles was conducted in the CINAHL, LILACS, PsycINFO, PubMed and SciVerse Scopus databases in 2013. RESULTS 70 scientific articles answered the guiding question and lead to attributes of disruptive behavior, being: incivility, psychological violence and physical/sexual violence; with their main antecedents (intrapersonal, interpersonal and organizational being: personality characteristics, stress and work overload; and consequences of: workers' moral/mental distress, compromised patient safety, labor loss, and disruption of communication, collaboration and teamwork. CONCLUSION Analysis of the disruptive behavior concept in healthcare work showed a construct in its theoretical stage that encompasses different disrespectful conduct adopted by health workers in the hospital context, which deserve the attention of leadership for better recognition and proper handling of cases and their consequences.
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[Medical students' sexuality--development and fulfilment of sexual needs].
Müldner-Nieckowski, Łukasz; Klasa, Katarzyna; Sobański, Jerzy A; Rutkowski, Krzysztof; Dembińska, Edyta
2012-01-01
Education in human sexual physiology and pathology, as well as own sexual health of medical doctors determines in a large proportion the ability to talk with patients about their sexual disorders. Therefore the authors considered important to collect and assess data regarding sexual health and development of Medical Faculty students. Analysis of selected aspects of psychosexual development and sex life of IVth grade medical students. We applied the self-report Questionnaire of Satisfaction with Sexual Life (KSS2), an instrument created to assess sexual problems in patients treated with group psychotherapy. Medical students filled the questionnaire when attending the courses of Psychopathology of neurotic disorders or Psychotherapy. Analysis of the collected data revealed a relatively high differentiation of the studied group in regard of satisfaction and experiences with sexual life, attitudes towards masturbation, relationships and sexual activity. Regarding some aspects, significant differences between women and men occurred. A set of factors were identified, some of them may negatively influence medical doctor's competencies in the domain of sexual health. These are not having sexual debut or even lack of any erotic experiences and lack of sexual satisfaction. The results indicate a significant prevalence of factors, which may impede students education as well as taking into consideration the sexual issues during the medical interview. Assessment of influence of students' and doctors' own sexuality on their competencies in diagnostics and treatment requires further studies.
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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.
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Kingma, Sjouke A.; Szentirmai, Istvan; Szekely, Tamas; Bokony, Veronika; Bleeker, Maarten; Liker, Andras; Komdeur, Jan; McGraw, K.
Melanin-based ornaments are often involved in signaling aggression and dominance, and their role in sexual selection is increasingly recognized. We investigated the functions of a melanin-based plumage ornament (facial 'mask') in male Eurasian penduline tits Remiz pendulinus in the contexts of
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Consequences of family disruption on children's educational outcomes in Norway.
Steele, Fiona; Sigle-Rushton, Wendy; Kravdal, Øystein
2009-08-01
Using high-quality data from Norwegian population registers, we examine the relationship between family disruption and children's educational outcomes. We distinguish between disruptions caused by parental divorce and paternal death and, using a simultaneous equation model, pay particular attention to selection bias in the effect of divorce. We also allow for the possibility that disruption may have different effects at different stages of a child's educational career. Our results suggest that selection on time-invariant maternal characteristics is important and works to overstate the effects of divorce on a child's chances of continuing in education. Nevertheless, the experience of marital breakdown during childhood is associated with lower levels of education, and the effect weakens with the child's age at disruption. The effects of divorce are most pronounced for the transitions during or just beyond the high school level. In models that do not allow for selection, children who experienced a father's death appear less disadvantaged than children whose parents divorced. After we control for selection, however differences in the educational qualifications of children from divorced and bereaved families narrow substantially and, at mean ages of divorce, are almost non-existent.
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A lover or a fighter? Opposing sexual selection pressures on men?s vocal pitch and facial hair
Saxton, Tamsin K.; Mackey, Lauren L.; 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 ...
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Wagman, Jennifer A; Charvat, Blake; Thoma, Marie E; Ndyanabo, Anthony; Nalugoda, Fred; Ssekasanvu, Joseph; Kigozi, Grace; Serwadda, David; Kagaayi, Joseph; Wawer, Maria J; Gray, Ronald H
2016-11-01
We assessed the association between intimate partner violence (IPV) and union disruption (divorce or separation) in the rural Ugandan setting of Rakai District. We analyzed longitudinal data collected from April 1999 to June 2006, from 6834 women (15-49 years) living in 50 communities in Rakai. Participants were either officially married, traditionally married or in a consensual union during one or more surveys and completed at least one follow-up survey. The primary outcome was union disruption through divorce or separation from the primary sexual partner. Past year IPV ranged from 6.49 % (severe physical abuse) to 31.99 % (emotional abuse). Severe physical IPV was significantly associated with divorce/separation, after adjusting for other covariates (aOR = 1.80, 95 % CI 1.01-3.22). Another predictor of union disruption was a woman having two or more sexual partners in the past year (aOR = 8.42, 95 % CI 5.97-11.89). Factors protecting against divorce/separation included an increasing number of co-resident biological children and longer duration of union. IPV, particularly severe physical abuse, is an important risk factor for union disruption. Marital counseling, health education and interventions should address the role of IPV on the wellbeing of women and the stability of couples in Uganda.
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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.
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The Significance of Sexuality and Intimacy in the Lives of Older African Americans With HIV/AIDS.
Nevedal, Andrea; Sankar, Andrea
2016-08-01
Aging and HIV/AIDS research focuses primarily on standardized clinical, social, and behavioral measures, leaving unanswered questions about how this chronic and stigmatizing condition affects life course expectations and the meaning of aging with the disease. Utilizing Gaylene Becker's (1997) life course disruption theory, we explored older African Americans' experiences of living with HIV/AIDS. A purposive sample (N = 43) of seropositive African Americans aged 50 and older was selected from a parent study. Thirteen participants completed one semi-structured in-depth interview on life course expectations and experiences of living with HIV/AIDS. Interview transcripts were analyzed using standard qualitative coding and thematic analysis. Responding to broad, open-ended questions about the impact of HIV on life course expectations, participants emphasized how HIV limited their ability to experience sexuality and intimacy. Two major themes emerged, damaged sexuality and constrained intimacy. Older African Americans' discussions of living with HIV focused on the importance of and the challenges to sexuality and intimacy. Researchers and clinicians should be attentive to significant and ongoing HIV-related challenges to sexuality and intimacy facing older African Americans living with HIV/AIDS. © The Author 2015. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
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Sexual and social competition: broadening perspectives by defining female roles.
Rubenstein, Dustin R
2012-08-19
Males figured more prominently than females in Darwin's view of sexual selection. He considered female choice of secondary importance to male-male competition as a mechanism to explain the evolution of male ornaments and armaments. Fisher later demonstrated the importance of female choice in driving male trait evolution, but his ideas were largely ignored for decades. As sexual selection came to embrace the notions of parent-offspring and sexual conflict, and experimental tests of female choice showed promise, females began to feature more prominently in the framework of sexual selection theory. Recent debate over this theory has centred around the role of females, not only over the question of choice, but also over female-female competition. Whereas some have called for expanding the sexual selection framework to encompass all forms of female-female competition, others have called for subsuming sexual selection within a broader framework of social selection, or replacing it altogether. Still others have argued for linking sexual selection more clearly to other evolutionary theories such as kin selection. Rather than simply debating terminology, we must take a broader view of the general processes that lead to trait evolution in both sexes by clearly defining the roles that females play in the process, and by focusing on intra- and inter-sexual interactions in males and females.
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Guadarrama-Bazante, Irma L; Canseco-Alba, Ana; Rodríguez-Manzo, Gabriela
2014-10-01
Dopamine (DA) plays a central role in the expression of male sexual behavior. The effects of DA-enhancing drugs on copulation seem to vary depending on the dose of the agonist used, the type of DA receptor activated, and the sexual condition of the animals. The aim of the present study was to carry out a systematic analysis of the effects of dopaminergic agonists on the expression of male sexual behavior by sexually competent rats in different sexual motivational states, that is when sexually active (sexually experienced) and when temporarily inhibited (sexually exhausted). To this end, the same doses of the nonselective DA receptor agonist apomorphine, the selective D2-like DA receptor agonist quinpirole, and the selective D1-like DA receptor agonist SKF38393 were injected intraperitoneally to sexually experienced or sexually exhausted male rats and their sexual behavior was recorded. Low apomorphine doses induced expression of sexual behavior in sexually satiated rats, but only reduced the intromission latency of sexually experienced rats. SKF38393 facilitated the expression of sexual behavior by sexually exhausted rats, but not that of sexually experienced males and quinpirole did not exert an effect in both types of animal. In line with these results, the apomorphine-induced reversal of sexual exhaustion was blocked by the D1-like receptor antagonist SCH23390. The data suggest that DA receptors play distinct roles in the expression of sexual behavior by male rats depending on their motivational state and that activation of D1-like receptors promotes the expression of sexual behavior in satiated rats.
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Communication Training as a Prevention to Sexual Harassment.
Berryman-Fink, Cynthia
Although illegal, sexual harassment is frequent in the American workplace and extremely disruptive and costly to employees and employers alike. Most organizational responses to the problem have been hard line, short term, after-the-fact measures that inform, threaten, or discipline employees. What is needed, however, is a training program with an…
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[Neurobiological foundations underlying normal and disturbed sexuality].
Krüger, T H C; Kneer, J
2017-05-01
Sexual functions are regulated by hormonal and neurochemical factors as well as neuronal networks. An understanding of these basic principles is necessary for the diagnostics, counselling and treatment of sexual problems. Description of essential mechanisms of sexual function on a neurochemical and neuronal level. Literature search, selection and discussion of relevant studies. Analogous to the dual control model there are primary inhibitory (e. g. serotonin) and excitatory neurotransmitter systems (e.g. sex steroids and dopamine). Moreover, neuronal structures have been identified that are responsible for processing sexual stimuli. These networks are altered in subjects with sexual disorders or by pharmacological treatment, e. g. antiandrogens and selective serotonin reuptake inhibitors (SSRI) CONCLUSION: Knowledge of the neurobiology of sexuality forms the foundations for the treatment of sexual dysfunctions in psychiatry and other disciplines.
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Endocrine Disruption of Vasopressin Systems and Related Behaviors
Directory of Open Access Journals (Sweden)
Heather B. Patisaul
2017-06-01
Full Text Available Endocrine disrupting chemicals (EDCs are chemicals that interfere with the organizational or activational effects of hormones. Although the vast majority of the EDC literature focuses on steroid hormone signaling related impacts, growing evidence from a myriad of species reveals that the nonapeptide hormones vasopressin (AVP and oxytocin (OT may also be EDC targets. EDCs shown to alter pathways and behaviors coordinated by AVP and/or OT include the plastics component bisphenol A (BPA, the soy phytoestrogen genistein (GEN, and various flame retardants. Many effects are sex specific and likely involve action at nuclear estrogen receptors. Effects include the elimination or reversal of well-characterized sexually dimorphic aspects of the AVP system, including innervation of the lateral septum and other brain regions critical for social and other non-reproductive behaviors. Disruption of magnocellular AVP function has also been reported in rats, suggesting possible effects on hemodynamics and cardiovascular function.
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Conversion of homothallic yeast to heterothallism trough HO gene disruption
CSIR Research Space (South Africa)
Van Zyl, WH
1993-04-01
Full Text Available A simple method was developed for the conversion of homothallic Saccharomyces cerevisiae yeaststrains to heterothallism through HO gene disruption. An integrative ho:: neo disrupted allele was constructed by cloning a dominant selectable marker...
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Information processing of sexual abuse in elders.
Burgess, Ann W; Clements, Paul T
2006-01-01
Sexual abuse is considered to be a pandemic contemporary public health issue, with significant physical and psychosocial consequences for its victims. However, the incidence of elder sexual assault is difficult to estimate with any degree of confidence. A convenience sample of 284 case records were reviewed for Post-Traumatic Stress Disorder (PTSD) symptoms. The purpose of this paper is to present the limited data noted on record review on four PTSD symptoms of startle, physiological upset, anger, and numbness. A treatment model for information processing of intrapsychic trauma is presented to describe domain disruption within a nursing diagnosis of rape trauma syndrome and provide guidance for sensitive assessment and intervention.
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Guppy sexual behavior as an effect biomarker of estrogen mimics
DEFF Research Database (Denmark)
Bayley, M; Nielsen, J R; Baatrup, E
1999-01-01
There is widespread concern that some environmental chemicals can reduce the reproductive capability of humans and wildlife by mimicking natural estrogens and disrupting endocrine function. This potential threat to animal populations posed by xenoestrogens has, hardly surprisingly, been met...... strongly on the ability to perform the appropriate sexual behavior. The sexual display of the male guppy is strongly linked to reproductive success and is readily quantified under laboratory conditions. This preliminary study demonstrates that exposure of adult male guppies to water weakly contaminated...... with either natural estrogen (17beta-estradiol) or the xenoestrogen (4-tert-octylphenol) causes a dramatic decrease in the rate and intensity of sexual display. It is concluded that quantitative analysis of the sexual display of male guppies holds great promise as a biomarker at the organismal level...
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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
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Friendship, sexual intimacy and young people's negotiations of sexual health.
Byron, Paul
2017-04-01
This paper examines how young people's friendships influence safer sexual practices. Through a thematic discourse analysis, interviews with Sydney-based young people (aged 18-25 years) and Australian-based sexual health websites for young people are considered. Interview data illustrate how friendships can support young people's sexual experiences, concerns and safeties beyond the practice of 'safe sex' (condom use). This is evident in friends' practices of sex and relationship advice, open dialogue, trust and sharing experiential knowledge, as well as friend-based sex. Meanwhile, friendship discourse from selected Australian sexual health websites fails to engage with the support offered by friendship, or its value to a sexual health agenda. Foucault's account of friendship as a space of self-invention is considered in light of these data, along with his argument that friendship poses a threat to formal systems of knowing and regulating sex. Whether sexual or not, many close friendships are sexually intimate given the knowledge, support and influence these offer to one's sexual practices and relations. This paper argues that greater attention to friendship among sexual health promoters and researchers would improve professional engagements with young people's contemporary sexual cultures, and better inform their attempts to engage young people through social media.
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Generalized structural equations improve sexual-selection analyses.
Directory of Open Access Journals (Sweden)
Sonia Lombardi
Full Text Available Sexual selection is an intense evolutionary force, which operates through competition for the access to breeding resources. There are many cases where male copulatory success is highly asymmetric, and few males are able to sire most females. Two main hypotheses were proposed to explain this asymmetry: "female choice" and "male dominance". The literature reports contrasting results. This variability may reflect actual differences among studied populations, but it may also be generated by methodological differences and statistical shortcomings in data analysis. A review of the statistical methods used so far in lek studies, shows a prevalence of Linear Models (LM and Generalized Linear Models (GLM which may be affected by problems in inferring cause-effect relationships; multi-collinearity among explanatory variables and erroneous handling of non-normal and non-continuous distributions of the response variable. In lek breeding, selective pressure is maximal, because large numbers of males and females congregate in small arenas. We used a dataset on lekking fallow deer (Dama dama, to contrast the methods and procedures employed so far, and we propose a novel approach based on Generalized Structural Equations Models (GSEMs. GSEMs combine the power and flexibility of both SEM and GLM in a unified modeling framework. We showed that LMs fail to identify several important predictors of male copulatory success and yields very imprecise parameter estimates. Minor variations in data transformation yield wide changes in results and the method appears unreliable. GLMs improved the analysis, but GSEMs provided better results, because the use of latent variables decreases the impact of measurement errors. Using GSEMs, we were able to test contrasting hypotheses and calculate both direct and indirect effects, and we reached a high precision of the estimates, which implies a high predictive ability. In synthesis, we recommend the use of GSEMs in studies on
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Skeletal injuries associated with sexual abuse
Energy Technology Data Exchange (ETDEWEB)
Johnson, Karl; Chapman, Stephen [Department of Radiology, Birmingham Children' s Hospital, Steelhouse Lane, B4 6NH, Birmingham (United Kingdom); Hall, Christine M. [Department of Radiology, Great Ormond Street Hospital for Children, London (United Kingdom)
2004-08-01
Background: Sexual abuse is often associated with physical abuse, the most common injuries being bruising and other soft-tissue injuries, but fractures occur in 5% of sexually abused children. The fractures described to date have formed part of the spectrum of injuries in these children and have not been specifically related to the abusive act. Objective: To describe concurrent sexual abuse and fractures. Materials and methods: Three children with pelvic or femoral shaft injuries in association with sexual abuse. Results: A 3-year-old girl with extensive soft-tissue injuries to the arms, legs and perineum also sustained fractures of both pubic rami and the sacral side of the right sacro-iliac joint. A 5-month-old girl with an introital tear was shown to have an undisplaced left femoral shaft fracture. A 5-year-old girl presented with an acute abdomen and pneumoperitoneum due to a ruptured rectum following sexual abuse. She had old healed fractures of both pubic rami with disruption of the symphysis pubis. Conclusions: Although the finding of a perineal injury in a young child may be significant enough for the diagnosis of abuse, additional skeletal injuries revealed by radiography will assist in confirmation of that diagnosis and may be more common than hitherto suspected. (orig.)
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Skeletal injuries associated with sexual abuse
International Nuclear Information System (INIS)
Johnson, Karl; Chapman, Stephen; Hall, Christine M.
2004-01-01
Background: Sexual abuse is often associated with physical abuse, the most common injuries being bruising and other soft-tissue injuries, but fractures occur in 5% of sexually abused children. The fractures described to date have formed part of the spectrum of injuries in these children and have not been specifically related to the abusive act. Objective: To describe concurrent sexual abuse and fractures. Materials and methods: Three children with pelvic or femoral shaft injuries in association with sexual abuse. Results: A 3-year-old girl with extensive soft-tissue injuries to the arms, legs and perineum also sustained fractures of both pubic rami and the sacral side of the right sacro-iliac joint. A 5-month-old girl with an introital tear was shown to have an undisplaced left femoral shaft fracture. A 5-year-old girl presented with an acute abdomen and pneumoperitoneum due to a ruptured rectum following sexual abuse. She had old healed fractures of both pubic rami with disruption of the symphysis pubis. Conclusions: Although the finding of a perineal injury in a young child may be significant enough for the diagnosis of abuse, additional skeletal injuries revealed by radiography will assist in confirmation of that diagnosis and may be more common than hitherto suspected. (orig.)
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Directory of Open Access Journals (Sweden)
Paola Laiolo
Full Text Available Multilevel selection has rarely been studied in the ecological context of animal populations, in which neighbourhood effects range from competition among territorial neighbours to source-sink effects among local populations. By studying a Dupont's lark Chersophilus duponti metapopulation, we analyze neighbourhood effects mediated by song repertoires on fitness components at the individual level (life-span and population level (growth rate. As a sexual/aggressive signal with strong effects on fitness, birdsong creates an opportunity for group selection via neighbour interactions, but may also have population-wide effects by conveying information on habitat suitability to dispersing individuals. Within populations, we found a disruptive pattern of selection at the individual level and an opposite, stabilizing pattern at the group level. Males singing the most complex songs had the longest life-span, but individuals with the poorest repertoires lived longer than 'average' males, a finding that likely reflects two male strategies with respect to fitness and sexual trait expression. Individuals from groups with intermediate repertoires had the longest life-span, likely benefitting from conspecific signalling to attract females up to the detrimental spread of competitive interactions in groups with superior vocal skills. Within the metapopulation selection was directional but again followed opposite patterns at the two levels: Populations had the highest growth rate when inhabiting local patches with complex repertoires surrounded by patches with simple repertoires. Here the song may impact metapopulation dynamics by guiding prospecting individuals towards populations advertising habitat quality. Two fitness components linked to viability were therefore influenced by the properties of the group, and birdsong was the target of selection, contributing to linking social/sexual processes at the local scale with regional population dynamics.
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Simulating Impacts of Disruptions to Liquid Fuels Infrastructure
Energy Technology Data Exchange (ETDEWEB)
Wilson, Michael [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Resilience and Regulatory Effects; Corbet, Thomas F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Policy and Decision Analytics; Baker, Arnold B. [ABB Consulting, Albuquerque, NM (United States); O' Rourke, Julia M. [Univ. of Texas, Austin, TX (United States). Dept. of Mechanical Engineering
2015-04-01
This report presents a methodology for estimating the impacts of events that damage or disrupt liquid fuels infrastructure. The impact of a disruption depends on which components of the infrastructure are damaged, the time required for repairs, and the position of the disrupted components in the fuels supply network. Impacts are estimated for seven stressing events in regions of the United States, which were selected to represent a range of disruption types. For most of these events the analysis is carried out using the National Transportation Fuels Model (NTFM) to simulate the system-level liquid fuels sector response. Results are presented for each event, and a brief cross comparison of event simulation results is provided.
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Disruptive event analysis: volcanism and igneous intrusion
International Nuclear Information System (INIS)
Crowe, B.M.
1980-08-01
An evaluation is made of the disruptive effects of volcanic activity with respect to long term isolation of radioactive waste through deep geologic storage. Three major questions are considered. First, what is the range of disruption effects of a radioactive waste repository by volcanic activity. Second, is it possible, by selective siting of a repository, to reduce the risk of disruption by future volcanic activity. And third, can the probability of repository disruption by volcanic activity be quantified. The main variables involved in the evaluation of the consequences of repository disruption by volcanic activity are the geometry of the magma-repository intersection (partly controlled by depth of burial) and the nature of volcanism. Potential radionuclide dispersal by volcanic transport within the biosphere ranges in distance from several kilometers to global. Risk from the most catastrophic types of eruptions can be reduced by careful site selection to maximize lag time prior to the onset of activity. Certain areas or volcanic provinces within the western United States have been sites of significant volcanism and should be avoided as potential sites for a radioactive waste repository. Examples of projection of future sites of active volcanism are discussed for three areas of the western United States. Probability calculations require two types of data: a numerical rate or frequency of volcanic activity and a numerical evaluation of the areal extent of volcanic disruption for a designated region. The former is clearly beyond the current state of art in volcanology. The latter can be approximated with a reasonable degree of satisfaction. In this report, simplified probability calculations are attempted for areas of past volcanic activity
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Townsend, J M; Levy, G D
1990-04-01
Male (n = 170) and female (n = 212) college students viewed photographs, which had been prerated for physical attractiveness, of three opposite-sex individuals. These photographs were paired with three levels of occupational status and income. Subjects indicated their willingness to engage in relationships of varying levels of sexual intimacy and marital potential with the portrayed individuals. Analyses of variance, correlations, and trend analyses supported the hypotheses. Compared to men, women are more likely to prefer or insist that sexual intercourse occur in relationships that involve affection and marital potential, and women place more emphasis than men do on partners' SES in such relationships. Consequently, men's SES and their willingness and ability to invest affection and resources in relationships may often outweigh the effects of their physical attractiveness in women's actual selection of partners. These results and the literature reviewed are more consistent with parental investment theory than with the view that these sex differences are solely the result of differential access to resources and differential socialization.
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Energy Technology Data Exchange (ETDEWEB)
Westhuizen, Liana van der; Gelderblom, Wentzel C.A.; Shephard, Gordon S; Swanevelder, Sonja
2004-07-15
In order to investigate the role of sphingolipid disruption in the cancer promoting potential of fumonisin B{sub 1} (FB{sub 1}) in the development of hepatocyte nodules, male Fischer 344 rats were subjected to cancer initiation (FB{sub 1} containing diet or diethylnitrosamine (DEN) by i.p. injection) and promotion (2-acetylaminofluorene with partial hepatectomy, 2-AAF/PH) treatments followed by a secondary FB{sub 1} dietary regimen. Sphinganine (Sa) and sphingosine (So) levels were measured by high performance liquid chromatography in control, surrounding and nodular liver tissues of the rats. The disruption of sphingolipid biosynthesis by the secondary FB{sub 1} treatment in the control rats was significantly (P<0.05) enhanced by the 2-AAF/PH cancer promotion treatment. The nodular and surrounding Sa levels returned to baseline following FB{sub 1} initiation and 2-AAF/PH promotion. When comparing the groups subjected to the secondary FB{sub 1} treatment, the initiation effected by FB{sub 1} was less (P<0.01) sensitive to the accumulation of Sa in the nodular and surrounding tissues than DEN initiation and the 2-AAF/PH control treatment. In contrast, the So level of FB{sub 1} initiation was marginally increased in the nodules compared to the surrounding liver after 2-AAF/PH promotion and significantly (P<0.05) higher with the secondary FB{sub 1} treatment. Although, the FB{sub 1}-induced hepatocyte nodules were not resistant to the disruption of sphingolipid biosynthesis, the nodular So levels were increased and might provide a selective growth stimulus possibly induced by bio-active sphingoid intermediates such as sphingosine 1-phosphate (S1P)
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Structural adaptations to diverse fighting styles in sexually selected weapons.
McCullough, Erin L; Tobalske, Bret W; Emlen, Douglas J
2014-10-07
The shapes of sexually selected weapons differ widely among species, but the drivers of this diversity remain poorly understood. Existing explanations suggest weapon shapes reflect structural adaptations to different fighting styles, yet explicit tests of this hypothesis are lacking. We constructed finite element models of the horns of different rhinoceros beetle species to test whether functional specializations for increased performance under species-specific fighting styles could have contributed to the diversification of weapon form. We find that horns are both stronger and stiffer in response to species-typical fighting loads and that they perform more poorly under atypical fighting loads, which suggests weapons are structurally adapted to meet the functional demands of fighting. Our research establishes a critical link between weapon form and function, revealing one way male-male competition can drive the diversification of animal weapons.
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Allan, George F; Tannenbaum, Pamela; Sbriscia, Tifanie; Linton, Olivia; Lai, Muh-Tsann; Haynes-Johnson, Donna; Bhattacharjee, Sheela; Zhang, Xuqing; Sui, Zhihua; Lundeen, Scott G
2007-08-01
Androgen receptor (AR) ligands with tissue selectivity (selective androgen receptor modulators, or SARMs) have potential for treating muscle wasting, hypogonadism of aging, osteoporosis, female sexual dysfunction, and other indications. JNJ-28330835 is a nonsteroidal AR ligand with mixed agonist and antagonist activity in androgen-responsive cell-based assays. It is an orally active SARM with muscle selectivity in orchidectomized rat models. It stimulated growth of the levator ani muscle, stimulating maximal growth at a dose of 10 mg/kg. At the same time, JNJ-28330835 reduced prostate weight in intact rats by a mean of 30% at 10 mg/kg, while having no inhibitory effect on muscle. Using magnetic resonance imaging (MRI) to monitor body composition, it prevented half of the loss of lean body mass associated with orchidectomy, and restored about 30% of lost lean mass to aged orchidectomized rats. It had agonist effects on markers of both osteoclast and osteoblast activity, suggesting that it reduces bone turnover. In a model of sexual behavior, JNJ-28330835 enhanced the preference of ovariectomized female rats for sexually intact male rats over nonsexual orchidectomized males. JNJ-28330835 is a prostate-sparing SARM with the potential for clinically beneficial effects in muscle-wasting diseases and sexual function disorders.
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Directory of Open Access Journals (Sweden)
Małgorzata Pilot
2016-08-01
Full Text Available Domesticated species are often composed of distinct populations differing in the character and strength of artificial and natural selection pressures, providing a valuable model to study adaptation. In contrast to pure-breed dogs that constitute artificially maintained inbred lines, free-ranging dogs are typically free-breeding, i.e., unrestrained in mate choice. Many traits in free-breeding dogs (FBDs may be under similar natural and sexual selection conditions to wild canids, while relaxation of sexual selection is expected in pure-breed dogs. We used a Bayesian approach with strict false-positive control criteria to identify FST-outlier SNPs between FBDs and either European or East Asian breeds, based on 167,989 autosomal SNPs. By identifying outlier SNPs located within coding genes, we found four candidate genes under diversifying selection shared by these two comparisons. Three of them are associated with the Hedgehog (HH signaling pathway regulating vertebrate morphogenesis. A comparison between FBDs and East Asian breeds also revealed diversifying selection on the BBS6 gene, which was earlier shown to cause snout shortening and dental crowding via disrupted HH signaling. Our results suggest that relaxation of natural and sexual selection in pure-breed dogs as opposed to FBDs could have led to mild changes in regulation of the HH signaling pathway. HH inhibits adhesion and the migration of neural crest cells from the neural tube, and minor deficits of these cells during embryonic development have been proposed as the underlying cause of “domestication syndrome.” This suggests that the process of breed formation involved the same genetic and developmental pathways as the process of domestication.
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Verweij, K.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
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Genetic constraints and sexual dimorphism in immune defense
DEFF Research Database (Denmark)
Rolff, Jens; Armitage, Sophie Alice Octavia; Coltman, David W.
2005-01-01
The absence of continued evolutionary change despite the presence of genetic variation and directional selection is very common. Genetic correlations between traits can reduce the evolvability of traits. One intriguing example might be found in a sexual conflict over sexually dimorphic traits......: a common genetic architecture constrains the response to selection on a trait subjected to sexually asymmetric selection pressures. Here we show that males and females of the mealworm beetle Tenebrio molitor differ in the quantitative genetic architecture of four traits related to immune defense...
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Gender Differences In Premarital Sexual Permissiveness Among ...
African Journals Online (AJOL)
This paper examined the concept of premariatal sexual permissiveness among selected University undergraduates in a state owned university in Nigeria, believing that the policy of non-residential status of the University will facilitate premarital sexual activity among the students. Using a total of 400 purposively selected ...
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Planche, Vincent; Panatier, Aude; Hiba, Bassem; Ducourneau, Eva-Gunnel; Raffard, Gerard; Dubourdieu, Nadège; Maitre, Marlène; Lesté-Lasserre, Thierry; Brochet, Bruno; Dousset, Vincent; Desmedt, Aline; Oliet, Stéphane H; Tourdias, Thomas
2017-02-01
Memory impairment is an early and disabling manifestation of multiple sclerosis whose anatomical and biological substrates are still poorly understood. We thus investigated whether memory impairment encountered at the early stage of the disease could be explained by a differential vulnerability of particular hippocampal subfields. By using experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis, we identified that early memory impairment was associated with selective alteration of the dentate gyrus as pinpointed in vivo with diffusion-tensor-imaging (DTI). Neuromorphometric analyses and electrophysiological recordings confirmed dendritic degeneration, alteration in glutamatergic synaptic transmission and impaired long-term synaptic potentiation selectively in the dentate gyrus, but not in CA1, together with a more severe pattern of microglial activation in this subfield. Systemic injections of the microglial inhibitor minocycline prevented DTI, morphological, electrophysiological and behavioral impairments in EAE-mice. Furthermore, daily infusions of minocycline specifically within the dentate gyrus were sufficient to prevent memory impairment in EAE-mice while infusions of minocycline within CA1 were inefficient. We conclude that early memory impairment in EAE is due to a selective disruption of the dentate gyrus associated with microglia activation. These results open new pathophysiological, imaging, and therapeutic perspectives for memory impairment in multiple sclerosis. Copyright © 2016 Elsevier Inc. All rights reserved.
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Bower-Phipps, Laura
2017-01-01
Significant progress has been made in equal rights for lesbian, gay, bisexual, transgender, queer, intersex, and asexual (LGBTQIA) individuals, yet schools remain institutions where sexual and gender diversity are marginalized and/or silenced. Queer theory, a non-linear theory that disrupts dominant beliefs about gender and sexuality and what…
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Connallon, Tim; Clark, Andrew G
2010-12-01
Sex-biased genes--genes that are differentially expressed within males and females--are nonrandomly distributed across animal genomes, with sex chromosomes and autosomes often carrying markedly different concentrations of male- and female-biased genes. These linkage patterns are often gene- and lineage-dependent, differing between functional genetic categories and between species. Although sex-specific selection is often hypothesized to shape the evolution of sex-linked and autosomal gene content, population genetics theory has yet to account for many of the gene- and lineage-specific idiosyncrasies emerging from the empirical literature. With the goal of improving the connection between evolutionary theory and a rapidly growing body of genome-wide empirical studies, we extend previous population genetics theory of sex-specific selection by developing and analyzing a biologically informed model that incorporates sex linkage, pleiotropy, recombination, and epistasis, factors that are likely to vary between genes and between species. Our results demonstrate that sex-specific selection and sex-specific recombination rates can generate, and are compatible with, the gene- and species-specific linkage patterns reported in the genomics literature. The theory suggests that sexual selection may strongly influence the architectures of animal genomes, as well as the chromosomal distribution of fixed substitutions underlying sexually dimorphic traits. © 2010 The Author(s). Evolution© 2010 The Society for the Study of Evolution.
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Sexual imprinting on ecologically divergent traits leads to sexual isolation in sticklebacks.
Kozak, Genevieve M; Head, Megan L; Boughman, Janette W
2011-09-07
During sexual imprinting, offspring learn parental phenotypes and then select mates who are similar to their parents. Imprinting has been thought to contribute to the process of speciation in only a few rare cases; this is despite imprinting's potential to generate assortative mating and solve the problem of recombination in ecological speciation. If offspring imprint on parental traits under divergent selection, these traits will then be involved in both adaptation and mate preference. Such 'magic traits' easily generate sexual isolation and facilitate speciation. In this study, we show that imprinting occurs in two ecologically divergent stickleback species (benthics and limnetics: Gasterosteus spp.). Cross-fostered females preferred mates of their foster father's species. Furthermore, imprinting is essential for sexual isolation between species; isolation was reduced when females were raised without fathers. Daughters imprinted on father odour and colour during a critical period early in development. These traits have diverged between the species owing to differences in ecology. Therefore, we provide the first evidence that imprinting links ecological adaptation to sexual isolation between species. Our results suggest that imprinting may facilitate the evolution of sexual isolation during ecological speciation, may be especially important in cases of rapid diversification, and thus play an integral role in the generation of biodiversity.
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Jandegian, Caitlin M.; Deem, Sharon L.; Bhandari, Ramji K.; Holliday, Casey M.; Nicks, Diane; Rosenfeld, Cheryl S.; Selcer, Kyle; Tillitt, Donald E.; vom Saal, Fredrick S.; Velez, Vanessa; Yang, Ying; Holliday, Dawn K.
2015-01-01
Environmental chemicals can disrupt endocrine signaling and adversely impact sexual differentiation in wildlife. Bisphenol A (BPA) is an estrogenic chemical commonly found in a variety of habitats. In this study, we used painted turtles (Chrysemys picta), which have temperature-dependent sex determination (TSD), as an animal model for ontogenetic endocrine disruption by BPA. We hypothesized that BPA would override TSD and disrupt sexual development. We incubated farm-raised turtle eggs at the male-producing temperature (26 °C), randomly assigned individuals to treatment groups: control, vehicle control, 17β-estradiol (E2, 20 ng/g-egg) or 0.01, 1.0, 100 μg BPA/g-egg and harvested tissues at hatch. Typical female gonads were present in 89% of the E2-treated “males”, but in none of the control males (n = 35). Gonads of BPA-exposed turtles had varying amounts of ovarian-like cortical (OLC) tissue and disorganized testicular tubules in the medulla. Although the percentage of males with OLCs increased with BPA dose (BPA-low = 30%, BPA-medium = 33%, BPA-high = 39%), this difference was not significant (p = 0.85). In all three BPA treatments, SOX9 patterns revealed disorganized medullary testicular tubules and β-catenin expression in a thickened cortex. Liver vitellogenin, a female-specific liver protein commonly used as an exposure biomarker, was not induced by any of the treatments. Notably, these results suggest that developmental exposure to BPA disrupts sexual differentiation in painted turtles. Further examination is necessary to determine the underlying mechanisms of sex reversal in reptiles and how these translate to EDC exposure in wild populations.
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Tomkins, Patrick; Saaristo, Minna; Bertram, Michael G; Tomkins, Raymond B; Allinson, Mayumi; Wong, Bob B M
2017-11-01
Despite a growing literature highlighting the potential impact of human-induced environmental change on mechanisms of sexual selection, relatively little is known about the effects of chemical pollutants on male-male competition. One class of environmental pollutant likely to impact male competitive interactions is the endocrine-disrupting chemicals (EDCs), a large and heterogeneous group of chemical contaminants with the potential to influence morphology, physiology and behaviour at minute concentrations. One EDC of increasing concern is the synthetic, androgenic steroid 17β-trenbolone, which is used globally to promote growth in beef cattle. Although 17β-trenbolone has been found to cause severe morphological and behavioural abnormalities in fish, its potential impact on male-male competition has yet to be investigated. To address this, we exposed wild male guppies (Poecilia reticulata) to an environmentally realistic concentration of 17β-trenbolone (average measured concentration: 8 ng/L) for 21 days using a flow-through system. We found that, in the presence of a competitor, 17β-trenbolone-exposed males carried out more frequent aggressive behaviours towards rival males than did unexposed males, as well as performing less courting behaviour and more sneak (i.e., coercive) mating attempts towards females. Considering that, by influencing mating outcomes, male-male competition has important consequences for population dynamics and broader evolutionary processes, this study highlights the need for greater understanding of the potential impact of EDCs on the mechanisms of sexual selection. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.
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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.
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SEXUAL SELECTION. Irrationality in mate choice revealed by túngara frogs.
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.
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Queen Specific Exocrine Glands in Legionary Ants and Their Possible Function in Sexual Selection.
Hölldobler, Bert
2016-01-01
The colonies of army ants and some other legionary ant species have single, permanently wingless queens with massive post petioles and large gasters. Such highly modified queens are called dichthadiigynes. This paper presents the unusually rich exocrine gland endowment of dichthadiigynes, which is not found in queens of other ant species. It has been suggested these kinds of glands produce secretions that attract and maintain worker retinues around queens, especially during migration. However, large worker retinues also occur in non-legionary species whose queens do not have such an exuberance of exocrine glands. We argue and present evidence in support of our previously proposed hypothesis that the enormous outfit of exocrine glands found in dichthadiigynes is due to sexual selection mediated by workers as the main selecting agents.
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Queen Specific Exocrine Glands in Legionary Ants and Their Possible Function in Sexual Selection.
Directory of Open Access Journals (Sweden)
Bert Hölldobler
Full Text Available The colonies of army ants and some other legionary ant species have single, permanently wingless queens with massive post petioles and large gasters. Such highly modified queens are called dichthadiigynes. This paper presents the unusually rich exocrine gland endowment of dichthadiigynes, which is not found in queens of other ant species. It has been suggested these kinds of glands produce secretions that attract and maintain worker retinues around queens, especially during migration. However, large worker retinues also occur in non-legionary species whose queens do not have such an exuberance of exocrine glands. We argue and present evidence in support of our previously proposed hypothesis that the enormous outfit of exocrine glands found in dichthadiigynes is due to sexual selection mediated by workers as the main selecting agents.
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Endocrine Disrupting Chemicals and Disease Susceptibility
Schug, Thaddeus T.; Janesick, Amanda; Blumberg, Bruce; Heindel, Jerrold J.
2011-01-01
Environmental chemicals have significant impacts on biological systems. Chemical exposures during early stages of development can disrupt normal patterns of development and thus dramatically alter disease susceptibility later in life. Endocrine disrupting chemicals (EDCs) interfere with the body's endocrine system and produce adverse developmental, reproductive, neurological, cardiovascular, metabolic and immune effects in humans. A wide range of substances, both natural and man-made, are thought to cause endocrine disruption, including pharmaceuticals, dioxin and dioxin-like compounds, polychlorinated biphenyls, DDT and other pesticides, and components of plastics such as bisphenol A (BPA) and phthalates. EDCs are found in many everyday products– including plastic bottles, metal food cans, detergents, flame retardants, food additives, toys, cosmetics, and pesticides. EDCs interfere with the synthesis, secretion, transport, activity, or elimination of natural hormones. This interference can block or mimic hormone action, causing a wide range of effects. This review focuses on the mechanisms and modes of action by which EDCs alter hormone signaling. It also includes brief overviews of select disease endpoints associated with endocrine disruption. PMID:21899826
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Women's Sexual Health and Reproductive Function After SCI.
Courtois, Frédérique; Alexander, Marcalee; McLain, Amie B Jackson
2017-01-01
Sexual function and to a lesser extent reproduction are often disrupted in women with spinal cord injuries (SCI), who must be educated to better understand their sexual and reproductive health. Women with SCI are sexually active; they can use psychogenic or reflexogenic stimulation to obtain sexual pleasure and orgasm. Treatment should consider a holistic approach using autonomic standards to describe remaining sexual function and to assess both genital function and psychosocial factors. Assessment of genital function should include thoracolumbar dermatomes, vulvar sensitivity (touch, pressure, vibration), and sacral reflexes. Self-exploration should include not only clitoral stimulation, but also stimulation of the vagina (G spot), cervix, and nipples conveyed by different innervation sources. Treatments may consider PDE5 inhibitors and flibanserin on an individual basis, and secondary consequences of SCI should address concerns with spasticity, pain, incontinence, and side effects of medications. Psychosocial issues must be addressed as possible contributors to sexual dysfunctions (eg, lower self-esteem, past sexual history, depression, dating habits). Pregnancy is possible for women with SCI; younger age at the time of injury and at the time of pregnancy being significant predictors of successful pregnancy, along with marital status, motor score, mobility, and occupational scores. Pregnancy may decrease the level of functioning (eg, self-care, ambulation, upper-extremity tasks), may involve complications (eg, decubitus ulcers, weight gain, urological complications), and must be monitored for postural hypotension and autonomic dysreflexia. Taking into consideration the physical and psychosocial determinants of sexuality and childbearing allows women with SCI to achieve positive sexual and reproductive health.
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Woolf-King, Sarah E.; Maisto, Stephen; Carey, Michael; Vanable, Peter
2013-01-01
Experimental research on sexual decision making is limited, despite the public health importance of such work. We describe formative work conducted in advance of an experimental study designed to evaluate the effects of alcohol intoxication and sexual arousal on risky sexual decision making among men who have sex with men. In Study 1, we describe the procedures for selecting and validating erotic film clips (to be used for the experimental manipulation of arousal). In Study 2, we describe the tailoring of two interactive role-play videos to be used to measure risk perception and communication skills in an analog risky sex situation. Together, these studies illustrate a method for creating experimental stimuli to investigate sexual decision making in a laboratory setting. Research using this approach will support experimental research that affords a stronger basis for drawing causal inferences regarding sexual decision making. PMID:19760530
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Energy flow during disruptions in JET
International Nuclear Information System (INIS)
Paley, J.I.; Andrew, P.; Cowley, S.C.; Fundamenski, W.; Huber, A.
2005-01-01
Disruptions place severe limitations on the materials selected for plasma facing components in fusion devices. In a disruption, the plasma stored thermal and magnetic energy is dissipated leading to predicted power loadings in the current quench of up to 10 MW m -2 in JET. In the thermal quench very high power loads of up to 10 G Wm -2 would be expected if all the power flowed to the steady state strike points, however this is not observed. In this paper the energy balance associated with both events is investigated. The magnetic energy is found to balance well with radiated energy. Circumstantial evidence for limiter interaction during the thermal quench of plasmas in divertor configuration is presented and a possible mechanism for limiter interaction in disruptions resulting from the collapse of an internal transport barrier is discussed
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Zhang, Ji-Liang; Liu, Min; Zhang, Chun-Nuan; Li, Er-Chao; Fan, Ming-Zhen; Huang, Mao-Xian
2018-07-30
The brain of fish displays sexual dimorphisms and exhibits remarkable sexual plasticity throughout their life span. Although reproductive toxicity of tributyltin (TBT) in fish is well documented in fish, it remains unknown whether TBT interrupts sexual dimorphisms of fish brains. In this work, brain transcriptomic profiles of rare minnow (Gobiocypris rarus) was characterized and sex-biased genes were identified using RNA sequencing. Functional annotation and enrichment analysis were performed to reveal differences of gene products and pathways between the brains of male and female fish. Furthermore, transcriptomic responses of male and female brains to TBT at 10 ng/L were also investigated to understand effects of TBT on brain sexual dimorphisms. Only 345 male-biased and 273 female-biased genes were found in the brains. However, significant female-biased pathways of circadian rhythm and phototransduction were identified in the brains by enrichment analysis. Interestingly, following TBT exposure in the female fish, the circadian rhythm pathway was significantly disrupted based on enrichment analysis, while in the male fish, the phototransduction pathway was significantly disrupted. In the female fish, expression of genes (Per, Cry, Rev-Erb α, Ror, Dec and CK1δ/ε) in the circadian rhythm pathway was down-regulated after TBT exposure; while in the male fish, expression of genes (Rec, GNAT1_2, GNGT1, Rh/opsin, PDE and Arr) in the phototransduction pathway was up-regulated after TBT exposure. Overall, our results not only provide key data on the molecular basis of brain sexual dimorphisms in fish, but also offer valuable resources for investigating molecular mechanisms by which environmental chemicals might influence brain sexual plasticity. Copyright © 2018 Elsevier Inc. All rights reserved.
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Directory of Open Access Journals (Sweden)
Manuel F. G. Weinkauf
2014-10-01
Full Text Available Extinction is a remarkably difficult phenomenon to study under natural conditions. This is because the outcome of stress exposure and associated fitness reduction is not known until the extinction occurs and it remains unclear whether there is any phenotypic reaction of the exposed population that can be used to predict its fate. Here we take advantage of the fossil record, where the ecological outcome of stress exposure is known. Specifically, we analyze shell morphology of planktonic Foraminifera in sediment samples from the Mediterranean, during an interval preceding local extinctions. In two species representing different plankton habitats, we observe shifts in trait state and decrease in variance in association with non-terminal stress, indicating stabilizing selection. At terminal stress levels, immediately before extinction, we observe increased growth asymmetry and trait variance, indicating disruptive selection and bet-hedging. The pre-extinction populations of both species show a combination of trait states and trait variance distinct from all populations exposed to non-terminal levels of stress. This finding indicates that the phenotypic history of a population may allow the detection of threshold levels of stress, likely to lead to extinction. It is thus an alternative to population dynamics in studying and monitoring natural population ecology.
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Limmer, Mark
2016-03-01
Understanding and addressing the sexual risk taking of young men remains a key research, policy, and practice concern in attempts to improve the emotional and physical sexual health of young men and their sexual partners. This article explores one of the ways in which young men attempt to mitigate sexual risk through the assigning of labels to particular young women and using these as a basis for their decisions in relation to sexual activity, contraception, and condom use. The article uses the lens of hegemonic masculinities theory to increase understanding of the role played by the construction and performance of marginalized masculinities and how these in turn are influenced by social exclusionary processes. The article draws on focus group and interview data from 46 young men aged 15 to 17 years living in the northwest of England, purposively selected on the basis of the prevailing policy definitions of social inclusion and exclusion. The article describes a form of marginalized masculinity pertaining to socially excluded young men, which as a result of limited access to other tenets of hegemonic masculinity, is disproportionately reliant on sexual expertise and voracity alongside overt demonstrations of their superiority over women. It is in this context that young women are assigned the labels of "dirty" or "clean" on the basis of a selection of arbitrary judgments relating to dress, demeanor, area of residence, and perceived sexual activities. The motivations of the young men, the impact on young women, and the policy and practice implications are all discussed. © The Author(s) 2014.
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Artocarpus heterophyllus seeds inhibits sexual competence but not fertility of male rats.
Ratnasooriya, W D; Jayakody, J R A C
2002-03-01
According to Ayurvedic literature of Sri Lanka, roasted seeds of Artocarpus heterophyllus Lam. (Family: Moraceae) has aphrodisiac activity. However, some reproductively active young men in rural areas of Sri Lanka claim that consumption of these seeds few hours prior to coitus disrupts sexual function. Because of these two conflicting claims, it was thought useful to scientifically investigate the effects of A. heterophyllus seeds on male sexual function and fertility. This was done using a seed suspension in 1% methylcellulose (SS) in rats. In a sexual behaviour study using receptive female rats, an oral administration of 500 mg/kg dose of SS markedly inhibited libido, sexual arousal, sexual vigour and sexual performance within 2 hr. Further, the treatment induced a mild erectile dysfunction. These antimasculine effects on sexual function was not evident 6 hr post treatment indicating rapid onset and offset of action. Further, these actions on the sexual behaviour was not due to general toxicity, liver toxicity, stress or reduction in blood testosterone level but due to marked sedative activity. In a mating study, SS failed to alter ejaculating competence and fertility. These results suggest that A. heterophyllous seeds do not have aphrodisiac action, at least, in rats.
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Taylor, Tonya N; Munoz-Plaza, Corrine E; Goparaju, Lakshmi; Martinez, Omar; Holman, Susan; Minkoff, Howard L; Karpiak, Stephen E; Gandhi, Monica; Cohen, Mardge H; Golub, Elizabeth T; Levine, Alexandra M; Adedimeji, Adebola A; Gonsalves, Rebecca; Bryan, Tiffany; Connors, Nina; Schechter, Gabrielle; Wilson, Tracey E
2017-05-01
There is limited research examining the sexual health and well-being of older women living with HIV (OWLH). Most studies focus on sexual dysfunction, leaving aside the richer context of sexuality and sexual health, including the effect of age-related psychosocial and interpersonal changes on sexual health behaviors. Guided by the integrative biopsychosocial model and the sexual health model, this study explored the importance of sex and sexuality among OWLH to identify their sexual health and HIV prevention needs for program planning. A purposive sample (n = 50) of OWLH was selected from a parent study (n = 2052). We conducted 8 focus groups and 41 in-depth interviews with 50 African American and Latina OWLH aged 50-69 years old in three U.S. cities. The triangulation approach was used to synthesize the data. Six salient themes emerged: sexual pleasure changes due to age, sexual freedom as women age, the role of relationships in sexual pleasure, changes in sexual ability and sexual health needs, sexual risk behaviors, and ageist assumptions about older women's sexuality. We found that sexual pleasure and the need for intimacy continue to be important for OWLH, but that changing sexual abilities and sexual health needs, such as the reduction of sexual desire, as well as increased painful intercourse due to menopause-associated vaginal drying, were persistent barriers to sexual fulfillment and satisfaction. Particular interpersonal dynamics, including low perceptions of the risk of HIV transmission as related to gender, viral suppression, and habitual condomless sex with long-term partners without HIV transmission have resulted in abandoning safer sex practices with serodiscordant partners. These findings suggest that HIV prevention for OWLH should focus on how sexual function and satisfaction intersect with sexual risk. HIV prevention for OWLH should promote ways to maintain satisfying and safe sex lives among aging women.
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A cost of sexual attractiveness to high-fitness females.
Directory of Open Access Journals (Sweden)
Tristan A F Long
2009-12-01
Full Text Available Adaptive mate choice by females is an important component of sexual selection in many species. The evolutionary consequences of male mate preferences, however, have received relatively little study, especially in the context of sexual conflict, where males often harm their mates. Here, we describe a new and counterintuitive cost of sexual selection in species with both male mate preference and sexual conflict via antagonistic male persistence: male mate choice for high-fecundity females leads to a diminished rate of adaptive evolution by reducing the advantage to females of expressing beneficial genetic variation. We then use a Drosophila melanogaster model system to experimentally test the key prediction of this theoretical cost: that antagonistic male persistence is directed toward, and harms, intrinsically higher-fitness females more than it does intrinsically lower-fitness females. This asymmetry in male persistence causes the tails of the population's fitness distribution to regress towards the mean, thereby reducing the efficacy of natural selection. We conclude that adaptive male mate choice can lead to an important, yet unappreciated, cost of sex and sexual selection.
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Modeling Sexual Selection in Túngara Frog and Rationality of Mate Choice.
Vargas Bernal, Esteban; Sanabria Malagon, Camilo
2017-12-01
The males of the species of frogs Engystomops pustulosus produce simple and complex calls to lure females, as a way of intersexual selection. Complex calls lead males to a greater reproductive success than what simple calls do. However, the complex calls are also more attractive to their main predator, the bat Trachops cirrhosus. Therefore, as M. Ryan suggests in (The túngara frog: a study in sexual selection and communication. University of Chicago Press, Chicago, 1985), the complexity of the calls lets the frogs keep a trade-off between reproductive success and predation. In this paper, we verify this trade-off from the perspective of game theory. We first model the proportion of simple calls as a symmetric game of two strategies. We also model the effect of adding a third strategy, males that keep quiet and intercept females, which would play a role of intrasexual selection. Under the assumption that the decision of the males takes into account this trade-off between reproductive success and predation, our model reproduces the observed behavior reported in the literature with minimal assumption on the parameters. From the model with three strategies, we verify that the quiet strategy could only coexists with the simple and complex strategies if the rate at which quiet males intercept females is high, which explains the rarity of the quiet strategy. We conclude that the reproductive strategy of the male frog E. pustulosus is rational.
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A role for sexual conflict in the evolution of reproductive traits in Nasonia wasps?
Geuverink, Elzemiek; Gerritsma, Sylvia; Pannebakker, Bart A.; Beukeboom, Leo W.
2009-01-01
Sexual conflict theory predicts that female and male reproductive traits coevolve resulting in disruption of reproductive behaviour upon mating of individuals from diverged populations. We used interfertile species of haplodiploid Nasonia wasps to compare re-mating frequency, longevity, oviposition
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Influences of dopamine and glutamate in the medial preoptic area on male sexual behavior.
Will, Ryan G; Hull, Elaine M; Dominguez, Juan M
2014-06-01
Several brain nuclei interact to orchestrate the appetitive and consummatory aspects of male sexual behavior. Of these structures, the medial preoptic area (mPOA) of the hypothalamus is of particular interest, as it receives input from all sensory modalities, and damage to this region disrupts copulation in a wide variety of taxa. Furthermore, the mPOA is both responsive to gonadal hormones and involved in endocrine regulation. Neurochemical studies have demonstrated that both dopamine and glutamate levels rise in the mPOA in response to sexual activity, while antagonism of these neurotransmitters impairs male sexual response. Here we review how dopamine and glutamate act in the mPOA to modulate male sexual behavior. Copyright © 2014 Elsevier Inc. All rights reserved.
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Potential exposure to endocrine disrupting chemicals and selected adverse pregnancy outcomes
DEFF Research Database (Denmark)
Bengtsson, Jessica; Thygesen, Pernille Søgaard; Kaerlev, Linda
2017-01-01
potential occupational exposure to endocrine disrupting chemicals (EDC) of the mother during pregnancy is associated with preterm birth and low birth weight. Methods: Pregnant women referred to an Occupational Health Clinic (OHC) in two Danish regions (Copenhagen or Aarhus) between 1984 and 2010, suspected...
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Choularia, Zoe; Hutchison, Craig; Karatzias, Thanos
2009-01-01
Primary objective: The authors sought to summarise and evaluate evidence regarding vicarious traumatisation (VT) in practitioners working with adult survivors of sexual violence and/or child sexual abuse (CSA). Methods and selection criteria: Relevant publications were identified from systematic literature searches of PubMed and PsycINFO. Studies were selected for inclusion if they examined vicarious traumatisation resulting from sexual violence and/or CSA work and were published in English b...
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Young, Michael; Palacios, Rebecca; Penhollow, Tina M.
2012-01-01
To improve the quality of research and commentary concerning adolescent sexuality and evaluation of both comprehensive sexuality education and abstinence education programs, this article aims to help readers (1) select appropriate measures to study adolescent sexual behavior, (2) develop appropriate study designs to evaluate adolescent sexual…
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Freshman Sexual Attitudes and Behavior.
Nutt, Roberta L.; Sedlacek, William E.
At the University of Maryland, 758 randomly selected incoming freshman students were administered an anonymous poll regarding their sexual attitudes and behavior. Results showed that the Maryland freshman generally resembled other U.S. college students in their sexual experience. Approximately half (52% of males, 46% of females) reported that they…
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DEFF Research Database (Denmark)
Hansen, Pernille Reimer; Taxvig, Camilla; Christiansen, Sofie
2009-01-01
/l. At GD21, fetuses were examined for anogenital distance, plasma thyroxine levels, testicular and plasma levels of testosterone and progesterone, and testicular testosterone production and histopathology. In addition, endocrine disrupting activity of nitrate and nitrite were studied in two in vitro assays......Animal studies have shown that nitrate acts as an endocrine disrupter affecting the androgen production in adult males. This raises a concern for more severe endocrine disrupting effects after exposure during the sensitive period of prenatal male sexual development. As there are no existing studies...... of effects of nitrate on male sexual development, the aim of the study was to examine how in utero exposure to nitrate would affect male rat fetuses. Pregnant dams were dosed with nitrate in the drinking water from gestational day (GD) 7 to GD21 at the following dose levels 17.5, 50, 150, 450, and 900 mg...
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Taylor, Tonya N.; Munoz-Plaza, Corrine E.; Goparaju, Lakshmi; Martinez, Omar; Holman, Susan; Minkoff, Howard L.; Karpiak, Stephen E.; Gandhi, Monica; Cohen, Mardge H.; Golub, Elizabeth T.; Levine, Alexandra M.; Adedimeji, Adebola A.; Gonsalves, Rebecca; Bryan, Tiffany; Connors, Nina; Schechter, Gabrielle; Wilson, Tracey E.
2016-01-01
There is limited research examining the sexual health and wellbeing of older women living with HIV (OWLH). Most studies focus on sexual dysfunction, leaving aside the richer context of sexuality and sexual health, including the effect of age-related psychosocial and interpersonal changes on sexual health behaviors. Guided by the integrative biopsychosocial model and the sexual health model, this study explored the importance of sex and sexuality among OWLH to identify their sexual health and HIV prevention needs for program planning. A purposive sample (n=50) of OWLH was selected from a parent study (n=2,052). We conducted 8 focus groups and 41 in-depth interviews with 50 African American and Latina OWLH aged 50–69 years old in three U.S. cities. The triangulation approach was used to synthesize the data. Six salient themes emerged: sexual pleasure changes due to age, sexual freedom as women age, the role of relationships in sexual pleasure, changes in sexual ability and sexual health needs, sexual risk behaviors, and ageist assumptions about older women’s sexuality. We found that sexual pleasure and the need for intimacy continue to be important for OWLH, but that changing sexual abilities and sexual health needs, such as the reduction of sexual desire, as well as increased painful intercourse due to menopause-associated vaginal drying, were persistent barriers to sexual fulfillment and satisfaction. Particular interpersonal dynamics, including low perceptions of the risk of HIV transmission as related to gender, viral suppression and habitual condomless sex with long term partners without HIV transmission have resulted in abandoning safer sex practices with serodiscordant partners. These findings suggest that HIV prevention for OWLH should focus on how sexual function and satisfaction intersect with sexual risk. HIV prevention for OWLH should promote ways to maintain satisfying and safe sex lives among aging women. PMID:27220311
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Directory of Open Access Journals (Sweden)
Amiteye Samuel
2011-08-01
Full Text Available Abstract Background Apomixis, a natural form of asexual seed production in plants, is considered to have great biotechnological potential for agriculture. It has been hypothesised that de-regulation of the sexual developmental pathway could trigger apomictic reproduction. The genus Boechera represents an interesting model system for understanding apomixis, having both sexual and apomictic genotypes at the diploid level. Quantitative qRT-PCR is the most extensively used method for validating genome-wide gene expression analyses, but in order to obtain reliable results, suitable reference genes are necessary. In this work we have evaluated six potential reference genes isolated from a 454 (FLX derived cDNA library of Boechera. RNA from live microdissected ovules and anthers at different developmental stages, as well as vegetative tissues of apomictic and sexual Boechera, were used to validate the candidates. Results Based on homologies with Arabidopsis, six genes were selected from a 454 cDNA library of Boechera: RPS18 (Ribosomal sub protein 18, Efalpha1 (Elongation factor 1 alpha, ACT 2 (Actin2, UBQ (polyubiquitin, PEX4 (Peroxisomal ubiquitin conjugating enzyme and At1g09770.1 (Arabidopsis thaliana cell division cycle 5. Total RNA was extracted from 17 different tissues, qRT-PCRs were performed, and raw Ct values were analyzed for primer efficiencies and gene ratios. The geNorm and normFinder applications were used for selecting the most stable genes among all tissues and specific tissue groups (ovule, anthers and vegetative tissues in both apomictic and sexual plants separately. Our results show that BoechRPS18, BoechEfα1, BoechACT2 and BoechUBQ were the most stable genes. Based on geNorm, the combinations of BoechRPS18 and BoechEfα1 or BoechUBQ and BoechEfα1 were the most stable in the apomictic plant, while BoechRPS18 and BoechACT2 or BoechUBQ and BoechACT2 performed best in the sexual plant. When subgroups of tissue samples were analyzed
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Directory of Open Access Journals (Sweden)
Manivasagam Sindhu
2011-04-01
Full Text Available Abstract Background Cytochrome P450 monooxygenases form a large superfamily of enzymes that catalyze diverse reactions. The P450SU1 gene from the soil bacteria Streptomyces griseolus encodes CYP105A1 which acts on various substrates including sulfonylurea herbicides, vitamin D, coumarins, and based on the work presented here, brassinosteroids. P450SU1 is used as a negative-selection marker in plants because CYP105A1 converts the relatively benign sulfonyl urea pro-herbicide R7402 into a highly phytotoxic product. Consistent with its use for negative selection, transgenic Arabidopsis plants were generated with P450SU1 situated between recognition sequences for FLP recombinase from yeast to select for recombinase-mediated excision. However, unexpected and prominent developmental aberrations resembling those described for mutants defective in brassinosteroid signaling were observed in many of the lines. Results The phenotypes of the most affected lines included severe stunting, leaf curling, darkened leaves characteristic of anthocyanin accumulation, delayed transition to flowering, low pollen and seed yields, and delayed senescence. Phenotype severity correlated with P450SU1 transcript abundance, but not with transcript abundance of other experimental genes, strongly implicating CYP105A1 as responsible for the defects. Germination and seedling growth of transgenic and control lines in the presence and absence of 24-epibrassinolide indicated that CYP105A1 disrupts brassinosteroid signaling, most likely by inactivating brassinosteroids. Conclusions Despite prior use of this gene as a genetic tool, deleterious growth in the absence of R7402 has not been elaborated. We show that this gene can cause aberrant growth by disrupting brassinosteroid signaling and affecting homeostasis.
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Phase Transitions in Sexual Populations Subject to Stabilizing Selection
Rogers, A.
2003-04-01
We show that a simple model of an evolving sexual population, which dates back to some of the earliest work in theoretical population genetics, exhibits an unexpected and previously unobserved phase transition between ordered and disordered states. This behavior is not present in populations evolving asexually without recombination and is thus important in any comparison of sexual and asexual populations. In order to calculate the details of the phase transition, we use techniques from statistical physics. We introduce the correlation of the population as the order parameter of the system and use maximum entropy inference to find the state of the population at any time.
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Influence of the menopause in the sexual standard: opinion of women
Directory of Open Access Journals (Sweden)
Rosália Teixeira de Araújo
2007-01-01
Full Text Available In this study we objectify: to inquire the physiological modifications of the menopause that influence the sexual standard of the woman; to know if the frequency of the sexual activity changed the menopause after and to investigate the factors aggravations or extenuating circumstances in the sexual life during this phase. One is about a study of quanti-qualitative nature, had as scene the Center of Health Almerinda Lomanto, having as informing 16 women. The data had been collected using the form. The data had been submitted to the Technique of Analysis of Content of Bardin, of where categories and subcategorias had emerged: Changes observed in the sexual relationship after the menopause (Reduction of the libido, Incompreensão of the friend, did not have alteration, positive Change; Reasons that had favored the changes (physiological Alterations in the sexual act, menorragia Chronic headache nauseas fogacho/, Lack or psychological reduction of the pleasure, Alterations. We conclude that during the climatério and after the menopause, can occur physiological modifications that influence the standard of the sexual act, fits professional we while of health, to search to promote attitudes and behaviors that aim at the disruption of myths and taboos and the promotion of the sexual health.
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Lessells, C.M.
2012-01-01
Parental care includes a wide variety of traits that enhance offspring development and survival. It is taxonomically widespread and is central to the maintenance of biodiversity through its close association with other phenomena such as sexual selection, life-history evolution, sex allocation,
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Women's Construction of Embodiment and the Abject Sexual Body After Cancer.
Parton, Chloe M; Ussher, Jane M; Perz, Janette
2016-03-01
Cancer and cancer treatments can cause significant changes to women's sexual well-being. We explored how women construct a sense of their bodies and sexual "selves" in the context of cancer. Sixteen women, across a range of ages (20-71 years), cancer types, and cancer stages, took part in in-depth semistructured interviews. We conducted a thematic discourse analysis, drawing on feminist poststructuralist theory, identifying "the abject body" as a dominant theme. Participants constructed abject bodies as being "beyond abnormality," "outside idealized discourses of embodied femininity," and "out of control." The women's accounts varied in management and resistance of the abject body discourse, through bodily practices of concealment, resisting discourses of feminine beauty, and repositioning the body as a site of personal transformation. The corporeality of the cancerous body can be seen to disrupt hegemonic discourses of femininity and sexuality, with implications for how women practice and make meaning of embodied sexual subjectivity. © The Author(s) 2015.
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DEFF Research Database (Denmark)
Lundgaard, Stine Schmieg; Rosenstand, Claus Andreas Foss
This book shares knowledge collected from 2015 and onward within the Consortium for Digital Disruption anchored at Aalborg University (www.dd.aau.dk). Evidenced by this publication, the field of disruptive innovation research has gone through several stages of operationalizing the theory. In recent...... years, researchers are increasingly looking back towards the origins of the theory in attempts to cure it from its most obvious flaws. This is especially true for the use of the theory in making predictions about future disruptions. In order to continue to develop a valuable theory of disruption, we...... find it useful to first review what the theory of disruptive innovation initially was, how it has developed, and where we are now. A cross section of disruptive innovation literature has been reviewed in order to form a general foundation from which we might better understand the changing world...
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Cryptic sexual size dimorphism in Malagasy plovers Charadrius spp ...
African Journals Online (AJOL)
Taken together, our work reports SSD in small African plovers that exhibit monomorphic plumage, and we propose that SSD may be more common than currently acknowledged; we term this 'cryptic sexual size dimorphism'. Our results also suggest sexual selection and/or natural selection exert different pressures on body ...
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Sexual safety and sexual security among young Black women who have sex with women and men.
Alexander, Kamila Anise; Fannin, Ehriel F
2014-01-01
To examine sexuality narratives of Black women who have sex with women and men and explore factors that influence their sexual safety and sexual security. Secondary qualitative content analysis. We recruited young self-identified Black women from beauty salons and community-based organizations. Our sample included a subset of five sexually active, Black women age 19 to 25 who reported engaging in sexual relationships with women and men. Participants were selected from a larger parent study that included sexuality narratives from 25 women. We analyzed interview transcripts in which participants described sexual relationships. We used constant comparative techniques and conventional content analysis methodology. We uncovered three themes illustrating influences on sexual safety and sexual security: institutional expectations, emotional connectedness, and sexual behaviors. From this analysis, we derive valuable insights into decision-making processes within sexual relationships from the perspectives of young Black women who have sex with women and men. Clinicians and investigators can use these findings to inform programs designed to improve the sexual health of this often invisible group of women. Nurses are uniquely positioned to support young women as they navigate societal institutions and emotional experiences that inform future sexual decisions and behaviors. © 2014 AWHONN, the Association of Women's Health, Obstetric and Neonatal Nurses.
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Athletes with inguinal disruption benefit from endoscopic totally extraperitoneal (TEP) repair.
Roos, M M; Bakker, W J; Goedhart, E A; Verleisdonk, E J M M; Clevers, G J; Voorbrood, C E H; Sanders, F B M; Naafs, D B; Burgmans, J P J
2018-06-01
Inguinal disruption, a common condition in athletes, is a diagnostic and therapeutic challenge. The aim of this study was to evaluate the effect of endoscopic totally extraperitoneal (TEP) repair in athletes with inguinal disruption, selected through a multidisciplinary, systematic work-up. An observational, prospective cohort study was conducted in 32 athletes with inguinal disruption. Athletes were assessed by a sports medicine physician, radiologist and hernia surgeon and underwent subsequent endoscopic TEP repair with placement of polypropylene mesh. The primary outcome was pain reduction during exercise on the numeric rating scale (NRS) 3 months postoperatively. Secondary outcomes were sports resumption, physical functioning and long-term pain intensity. Patients were assessed preoperatively, 3 months postoperatively and after a median follow-up of 19 months. Follow-up was completed in 30 patients (94%). The median pain score decreased from 8 [interquartile range (IQR) 7-8] preoperatively to 2 (IQR 0-5) 3 months postoperatively (p disruption, selected through a multidisciplinary, systematic work-up, benefit from TEP repair.
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A prediction tool for real-time application in the disruption protection system at JET
International Nuclear Information System (INIS)
Cannas, B.; Fanni, A.; Sonato, P.; Zedda, M.K.
2007-01-01
A disruption prediction system, based on neural networks, is presented in this paper. The system is ideally suitable for on-line application in the disruption avoidance and/or mitigation scheme at the JET tokamak. A multi-layer perceptron (MLP) predictor module has been trained on nine plasma diagnostic signals extracted from 86 disruptive pulses, selected from four years of JET experiments in the pulse range 47830-57346 (from 1999 to 2002). The disruption class of the disruptive pulses is available. In particular, the selected pulses belong to four classes (density limit/high radiated power, internal transport barrier, mode lock and h-mode/l-mode). A self-organizing map has been used to select the samples of the pulses to train the MLP predictor module and to determine its target, increasing the prediction capability of the system. The prediction performance has been tested over 86 disruptive and 102 non-disruptive pulses. The test has been performed presenting to the network all the samples of each pulse sampled every 20 ms. The missed alarm rate and the false alarm rate of the predictor, up to 100 ms prior to the disruption time, are 23% and 1%, respectively. Recent plasma configurations might present features different from those observed in the experiments used in the training set. This 'novelty' can lead to incorrect behaviour of the predictor. To improve the robustness and reliability of the system, a novelty detection module has been integrated in the prediction system, increasing the system performance and resulting in a missed alarm rate reduced to 7% and a false alarm rate reduced to 0%
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Senior Adult Sexuality in Age Segregated and Age Integrated Communities.
Weinstein, Stellye; Rosen, Efrem
1988-01-01
Middle-income older adults (N=314) responded to senior adult sexuality scale. Results showed that respondents who selected to reside in age-segregated leisure-type retirement communities exhibited significantly more sexual interest, sexual activities, and liberal sexual attitudes than did respondents residing in age-integrated mainstream…
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Trilobite spines and beetle horns: sexual selection in the Palaeozoic?
Knell, Robert J; Fortey, Richard A
2005-06-22
Raphiophorid trilobites commonly bore median cephalic protuberances such as spines or bulbs, showing a remarkable variety of form. It is unlikely that their primary function was for protection or in hydrodynamics. A case is made that they were secondary sexual features, by comparison with similar morphological structures developed on rhinoceros beetles and other arthropods. This interpretation is supported by four lines of evidence: their ontogeny, their diversity, the existence of plausible examples of sexual dimorphs in some cases and the fact that they show positive allometry.
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Exposure to sexualized media content and selective attention for sexual cues: An experimental study
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
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Evidence for strong intralocus sexual conflict in the Indian meal moth, Plodia interpunctella.
Lewis, Zenobia; Wedell, Nina; Hunt, John
2011-07-01
Males and females share a genome and express many shared phenotypic traits, which are often selected in opposite directions. This generates intralocus sexual conflict that may constrain trait evolution by preventing the sexes from reaching their optimal phenotype. Furthermore, if present across multiple loci, intralocus sexual conflict can result in a gender load that may diminish the benefits of sexual selection and help maintain genetic variation for fitness. Despite the importance of intralocus sexual conflict, surprisingly few empirical studies conclusively demonstrate its operation. We show that the pattern of multivariate selection acting on three sexually dimorphic life-history traits (development time, body size, and longevity) in the Indian meal moth, Plodia interpunctella, is opposing for the sexes. Moreover, we combined our estimates of selection with the additive genetic variance-covariance matrix (G) to predict the evolutionary response of the life-history traits in the sexes and showed that the angle between the vector of responses and the vector of sexually antagonistic selection was almost orthogonal at 84.70°. Thus, G biases the predicted response of life-history traits in the sexes away from the direction of sexually antagonistic selection, confirming the presence of strong intralocus sexual conflict in this species. Despite this, sexual dimorphism has evolved in all of the life-history traits examined suggesting that mechanism(s) have evolved to resolve this conflict and allow the sexes to reach their life-history optima. We argue that intralocus sexual conflict is likely to play an important role in the evolution of divergent life-history strategies between the sexes in this species. © 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.
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Crothers, Laura R; Cummings, Molly E
2013-05-01
Though theory predicts consistency of warning signals in aposematic species to facilitate predator learning, variation in these signals often occurs in nature. The strawberry poison frog Dendrobates pumilio is an exceptionally polytypic (populations are phenotypically distinct) aposematic frog exhibiting variation in warning color and brightness. In the Solarte population, males and females both respond differentially to male brightness variation. Here, we demonstrate through spectrophotometry and visual modeling that aposematic brightness variation within this population is likely visible to two putative predators (crabs, snakes) and conspecifics but not to the presumed major predator (birds). This study thus suggests that signal brightness within D. pumilio populations can be shaped by sexual selection, with limited opportunity for natural selection to influence this trait due to predator sensory constraints. Because signal brightness changes can ultimately lead to changes in hue, our findings at the within-population level can provide insights into understanding this polytypism at across-population scales.
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DEFF Research Database (Denmark)
Rosenstand, Claus Andreas Foss
det digitale domæne ud over det niveau, der kendetegner den nuværende debat, så præsenteres der ny viden om digital disruption. Som noget nyt udlægges Clayton Christens teori om disruptiv innovation med et særligt fokus på små organisationers mulighed for eksponentiel vækst. Specielt udfoldes...... forholdet mellem disruption og den stadig accelererende digitale udvikling i konturerne til ny teoridannelse om digital disruption. Bogens undertitel ”faretruende og fascinerende forandringer” peger på, at der er behov for en nuanceret debat om digital disruption i modsætning til den tone, der er slået an i...... videre kalder et ”disruption-råd”. Faktisk er rådet skrevet ind i 2016 regeringsgrundlaget for VLK-regeringen. Disruption af organisationer er ikke et nyt fænomen; men hastigheden, hvormed det sker, er stadig accelererende. Årsagen er den globale mega-trend: Digitalisering. Og derfor er specielt digital...
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Higbee, Bradley S; Burks, Charles S; Cardé, Ring T
2017-10-01
The navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae), is a key pest of almonds and pistachios and is sometimes controlled using mating disruption as part of a program of integrated management. The formulation used has a single, nonattractive compound [(11Z,13Z)-hexadecadienal] as the active ingredient that is emitted from timed aerosol dispensers. This study compared this nonattractive, single-compound formulation with two aerosol formulations also containing two additional compounds [(11Z,13Z)-hexadecadien-1-ol and (3Z,6Z,9Z,12Z,15Z)-tricosapentaene] that are found in the pheromone glands, and that in combination with the aldehyde are attractive in wind-tunnel and field-attraction trials. An experiment in pistachios found 97% to 99% suppression of males captured in female-baited traps and 82-93% suppression of mating in sentinel females. Both assays revealed a trend to greater suppression by the more complete pheromone formulations. In almonds, where the abundance of navel orangeworm was lower, all three formulations suppressed males captured in traps and mating in sentinel females by >99%. Each of the formulations significantly reduced damage to Nonpareil almonds. In almonds, there were no significant differences among the formulations in disruption of sexual communication or in damage. These findings suggest that it may be possible to make mating disruption more cost-effective and to achieve higher levels of mating disruption by using attractive aerosol formulations to reduce the number of dispenser per ha. Such a formulation, however, would be more expensive to register in the United States than pheromones meeting the definition of straight-chain lepidopteran pheromone, including the currently used aldehyde-only formulation. Published by Oxford University Press on behalf of Entomological Society of America 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.
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Sexual orientation data collection and progress toward Healthy People 2010.
Sell, R L; Becker, J B
2001-06-01
Without scientifically obtained data and published reports, it is difficult to raise awareness and acquire adequate resources to address the health concerns of lesbian, gay, and bisexual Americans. The Department of Health and Human Services must recognize gaps in its information systems regarding sexual orientation data and take immediate steps to monitor and eliminate health disparities as delineated in Healthy People 2010. A paper supported by funding from the Office of the Assistant Secretary for Planning and Evaluation explores these concerns and suggests that the department (1) create work groups to examine the collection of sexual orientation data; (2) create a set of guiding principles to govern the process of selecting standard definitions and measures; (3) recognize that racial/ethnic, immigrant-status, age, socioeconomic, and geographic differences must be taken into account when standard measures of sexual orientation are selected; (4) select a minimum set of standard sexual orientation measures; and (5) develop a long-range strategic plan for the collection of sexual orientation data.
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High male sexual investment as a driver of extinction in fossil ostracods.
Martins, Maria João Fernandes; Puckett, T Markham; Lockwood, Rowan; Swaddle, John P; Hunt, Gene
2018-04-01
Sexual selection favours traits that confer advantages in the competition for mates. In many cases, such traits are costly to produce and maintain, because the costs help to enforce the honesty of these signals and cues 1 . Some evolutionary models predict that sexual selection also produces costs at the population level, which could limit the ability of populations to adapt to changing conditions and thus increase the risk of extinction 2-4 . Other models, however, suggest that sexual selection should increase rates of adaptation and enhance the removal of deleterious mutations, thus protecting populations against extinction 3, 5, 6 . Resolving the conflict between these models is not only important for explaining the history of biodiversity, but also relevant to understanding the mechanisms of the current biodiversity crisis. Previous attempts to test the conflicting predictions produced by these models have been limited to extant species and have thus relied on indirect proxies for species extinction. Here we use the informative fossil record of cytheroid ostracods-small, bivalved crustaceans with sexually dimorphic carapaces-to test how sexual selection relates to actual species extinction. We show that species with more pronounced sexual dimorphism, indicating the highest levels of male investment in reproduction, had estimated extinction rates that were ten times higher than those of the species with the lowest investment. These results indicate that sexual selection can be a substantial risk factor for extinction.
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DEFF Research Database (Denmark)
2016-01-01
This is a short video on the theme disruption and entrepreneurship. It takes the form of an interview with John Murray......This is a short video on the theme disruption and entrepreneurship. It takes the form of an interview with John Murray...
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Kawatsu, Kazutaka
2013-02-01
The assumption of a twofold cost of sex not only complicates the maintenance of sex but also sets conditions for sexual conflict: in organisms with the twofold cost, males often sexually harass females. Sexual harassment is detrimental to female fitness and thus might help maintain sexual populations if male harassment inflicts a harsher cost on parthenogens than on sexual females (asymmetric harassment cost). However, the generality of this concept is now considered doubtful because selective harassment of parthenogens results in loss of mating opportunities for males. Using three mathematical models, I show here that sexual harassment still can impose the asymmetric cost on parthenogens. First, I apply the Lotka-Volterra model to show the degree of asymmetric harassment cost that permits sex to be maintained stably in the population. Second, using adaptive dynamics, I examine whether sexually antagonistic coevolution for sexual harassment, which occurs only in sexual populations, can promote the asymmetric harassment cost. Finally, an individual-based model, which assumes a spatial structure unlike that in the other two, demonstrates that the asymmetric evolution of harassment cost prevents further invasions of parthenogens from different patches into sexual lineages; these mechanisms may account for allopatric distributions of sexual and parthenogenetic lineages as well as the maintenance of sex.
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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.
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Edwards, Nora; Kriegsfeld, Lance; Crews, David
2004-12-10
The preoptic area-anterior hypothalamus (POAH) continuum is critical for the integration of environmental, physiological, and behavioral cues associated with reproduction in vertebrates. In the present study, radiofrequency lesions in the POAH abolished sexual behavior in the leopard gecko (Eublepharis macularius). Furthermore, results suggest a differential effect of POAH lesions on those behaviors regarded as appetitive (tail vibration and grip) and those regarded as consummatory (mounting and copulation), with consummatory behaviors being affected to a greater extent. E. macularius is an ectothermic vertebrate that modulates body temperature behaviorally relative to ambient temperature. In vertebrates, the POAH is also an important integrator of thermoregulation. Thus, the present study investigated whether lesions that disrupt reproductive behavior also disrupt body temperature regulation. While virtually all males displayed diurnal rhythms in thermoregulatory behavior prior to surgery, this pattern was abolished in a small proportion of animals bearing POAH lesions. Lesions that abolished thermoregulatory rhythms involved the suprachiasmatic nucleus (SCN), whereas lesions confined to the POAH, while dramatically influencing sexual behavior, did not affect thermoregulatory rhythms or temperature set point. Together, these findings identify the POAH as an important neural locus regulating sexual behavior but not thermoregulation and suggest that the SCN acts as a pacemaker controlling daily behavioral temperature regulation in this species.
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Sexual dimorphism in bite performance drives morphological variation in chameleons.
da Silva, Jessica M; Herrel, Anthony; Measey, G John; Tolley, Krystal A
2014-01-01
Phenotypic performance in different environments is central to understanding the evolutionary and ecological processes that drive adaptive divergence and, ultimately, speciation. Because habitat structure can affect an animal's foraging behaviour, anti-predator defences, and communication behaviour, it can influence both natural and sexual selection pressures. These selective pressures, in turn, act upon morphological traits to maximize an animal's performance. For performance traits involved in both social and ecological activities, such as bite force, natural and sexual selection often interact in complex ways, providing an opportunity to understand the adaptive significance of morphological variation with respect to habitat. Dwarf chameleons within the Bradypodion melanocephalum-Bradypodion thamnobates species complex have multiple phenotypic forms, each with a specific head morphology that could reflect its use of either open- or closed-canopy habitats. To determine whether these morphological differences represent adaptations to their habitats, we tested for differences in both absolute and relative bite performance. Only absolute differences were found between forms, with the closed-canopy forms biting harder than their open-canopy counterparts. In contrast, sexual dimorphism was found for both absolute and relative bite force, but the relative differences were limited to the closed-canopy forms. These results indicate that both natural and sexual selection are acting within both habitat types, but to varying degrees. Sexual selection seems to be the predominant force within the closed-canopy habitats, which are more protected from aerial predators, enabling chameleons to invest more in ornamentation for communication. In contrast, natural selection is likely to be the predominant force in the open-canopy habitats, inhibiting the development of conspicuous secondary sexual characteristics and, ultimately, enforcing their overall diminutive body size and
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Is it useful to view the brain as a secondary sexual characteristic?
Ball, Gregory F; Balthazart, Jacques; McCarthy, Margaret M
2014-10-01
Many sex differences in brain and behavior related to reproduction are thought to have evolved based on sexual selection involving direct competition for mates during male-male competition and female choice. Therefore, certain aspects of brain circuitry can be viewed as secondary sexual characteristics. The study of proximate causes reveals that sex differences in the brain of mammals and birds reflect organizational and activational effects of sex steroids as articulated by Young and collaborators. However, sex differences in brain and behavior have been identified in the cognitive domain with no obvious link to reproduction. Recent views of sexual selection advocate for a broader view of how intra-sexual selection might occur including such examples as competition within female populations for resources that facilitate access to mates rather than mating competition per se. Sex differences can also come about for other reasons than sexual selection and recent work on neuroendocrine mechanisms has identified a plethora of ways that the brain can develop in a sex specific manner. Identifying the brain as sexually selected requires careful hypothesis testing so that one can link a sex-biased aspect of a neural trait to a behavior that provides an advantage in a competitive mating situation. Copyright © 2014 Elsevier Ltd. All rights reserved.
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Olver, Mark E; Mundt, James C; Thornton, David; Beggs Christofferson, Sarah M; Kingston, Drew A; Sowden, Justina N; Nicholaichuk, Terry P; Gordon, Audrey; Wong, Stephen C P
2018-04-30
The present study sought to develop updated risk categories and recidivism estimates for the Violence Risk Scale-Sexual Offense version (VRS-SO; Wong, Olver, Nicholaichuk, & Gordon, 2003-2017), a sexual offender risk assessment and treatment planning tool. The overarching purpose was to increase the clarity and accuracy of communicating risk assessment information that includes a systematic incorporation of new information (i.e., change) to modify risk estimates. Four treated samples of sexual offenders with VRS-SO pretreatment, posttreatment, and Static-99R ratings were combined with a minimum follow-up period of 10-years postrelease (N = 913). Logistic regression was used to model 5- and 10-year sexual and violent (including sexual) recidivism estimates across 6 different regression models employing specific risk and change score information from the VRS-SO and/or Static-99R. A rationale is presented for clinical applications of select models and the necessity of controlling for baseline risk when utilizing change information across repeated assessments. Information concerning relative risk (percentiles) and absolute risk (recidivism estimates) is integrated with common risk assessment language guidelines to generate new risk categories for the VRS-SO. Guidelines for model selection and forensic clinical application of the risk estimates are discussed. (PsycINFO Database Record (c) 2018 APA, all rights reserved).
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Effectiveness of the Sexual Attitude Restructuring Curriculum amongst Taiwanese Graduate Students
Lin, Yi-Li; Lin, Yen-Chin
2018-01-01
This article discusses the effectiveness of the Sexual Attitude Restructuring (SAR) curriculum in developing positive sexual attitudes amongst Taiwanese graduate students in human sexuality. Through purposive sampling, 32 graduate students in human sexuality were selected to participate in the study. Before and after providing participants with a…
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The psychosexual profile of sexual assistants: an internet-based explorative study.
Directory of Open Access Journals (Sweden)
Erika Limoncin
Full Text Available Sexual assistance may have some aspects that resemble prostitution and others that might lead one to think of sexual assistants as similar to a group of subjects whose sexual object is disability (devotees. In this study, we investigate whether a rigorous selection and training process on the part of specialised organisations may reduce the risk of training subjects with an atypical sexual interest and behaviours resembling prostitution.The study population consisted of 152 subjects defining themselves as sexual assistants. Subjects were initially contacted on websites specifically dedicated to sexual assistants and prostitutes. One hundred and twenty subjects were selected, by propensity score analysis, and studied by means of a modified version of a semi-structured questionnaire previously developed to investigate a population of subjects attracted by disability.The study group was composed of 80 trained and 40 untrained sexual assistants, with mean ages of 41.5 (SD +/-12.58 and 44.5 (SD +/-11.62, respectively. A significant number of untrained subjects affirmed that their motivation in carrying out sexual assistance was of a remunerative nature, while this number was lower among the trained assistants (p = 0.001. Nearly all untrained subjects claimed to do one or more of the following activities during sexual assistance: sexual intercourse, oral sex, and masturbation. Among the trained subjects, however, only 47.5% claimed to do one or more of these activities, which means that there is a significant gap between trained and untrained assistants (p<0.0001. The existence of an atypical sexual interest was more evident between untrained rather than between trained subjects (p<0.0001.Sexual assistance represents a way through which people affected by disabilities may attain the right to explore their sexuality in a safe setting. This can be guaranteed only if sexual assistants are trained and carefully selected by specialised organisations.
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Li, Chunyan; Cheng, Zixi; Wu, Taiwen; Liang, Xiao; Gaoshan, Junjian; Li, Lihe; Hong, Ping; Tang, Kun
2017-08-25
A growing prevalence of unexpected pregnancies and younger age of sexual debut is observed among Chinese young people, while they lack formal sexuality education from schools and parents. It is necessary to measure their knowledge level of sexual and reproductive health, and how such knowledge associates with their sexual behaviors and reproductive health outcomes, which would shed light on the effectiveness of sexuality education in China. An Internet-based questionnaire survey was conducted from January to August, 2015. 130 colleges were selected from eastern, central, and western parts China with a good balance of geographic distributions. The survey link was subsequently delivered to the focal points in each college for voluntary participation, targeting on undergraduates aged 18 ~ 25. Information on demographics, experience of school-based sexuality education (defined as any course introducing information on sexual and reproductive health) and SRH knowledge quiz was collected. Multivariate linear regression and logistic regression were applied to explore the relationship between students' SRH knowledge, sexual behaviors and reproductive health outcomes, such as sexual intercourse (penetrative sex by vaginal or anal), unprotected sex, pregnancy and abortion, etc. A total sample of 17,966 Chinese college students (mean age = 20.2, 60.4% female) eventually entered the analysis. Only 55.6% of the respondents self-reported having received sexuality education before, and they scored significantly higher (2.33/4.00) in the SRH knowledge quiz than those who had not (1.75/4.00). Among the sexually experienced students (n = 3639, 20.2%), both males and females with higher SRH knowledge were less likely to report having experience of (partner's) pregnancy or abortion (OR sexually experienced males, those with higher SRH knowledge had a slightly later age of sexual debut (coefficient = 0.28, p sexual intercourses (OR = 0.82, 95%C.I.: 0.69 ~ 0.96). Students
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Correlated evolution of migration and sexual dichromatism in the New World orioles (icterus).
Friedman, Nicholas R; Hofmann, Christopher M; Kondo, Beatrice; Omland, Kevin E
2009-12-01
The evolution of sexual dimorphism has long been attributed to sexual selection, specifically as it would drive repeated gains of elaborate male traits. In contrast to this pattern, New World oriole species all exhibit elaborate male plumage, and the repeated gains of sexual dichromatism observed in the genus are due to losses of female elaboration. Interestingly, most sexually dichromatic orioles belong to migratory or temperate-breeding clades. Using character scoring and ancestral state reconstructions from two recent studies in Icterus, we tested a hypothesis of correlated evolution between migration and sexual dichromatism. We employed two discrete phylogenetic comparative approaches: the concentrated changes test and Pagel's discrete likelihood test. Our results show that the evolution of these traits is significantly correlated (CCT: uncorrected P model of character evolution suggests that gains of sexual dichromatism are 23 times more likely to occur in migratory taxa. This study demonstrates that a life-history trait with no direct relationship with sexual selection has a strong influence on the evolution of sexual dichromatism. We recommend that researchers further investigate the role of selection on elaborate female traits in the evolution of sexual dimorphism.
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Energy Technology Data Exchange (ETDEWEB)
Pereira, Augusto, E-mail: augusto.pereira@ciemat.es [Laboratorio Nacional de Fusión, CIEMAT, Madrid (Spain); Vega, Jesús; Moreno, Raúl [Laboratorio Nacional de Fusión, CIEMAT, Madrid (Spain); Dormido-Canto, Sebastián [Dpto. Informática y Automática – UNED, Madrid (Spain); Rattá, Giuseppe A. [Laboratorio Nacional de Fusión, CIEMAT, Madrid (Spain); Pavón, Fernando [Dpto. Informática y Automática – UNED, Madrid (Spain)
2015-10-15
Recently, a probabilistic classifier has been developed at JET to be used as predictor from scratch. It has been applied to a database of 1237 JET ITER-like wall (ILW) discharges (of which 201 disrupted) with good results: success rate of 94% and false alarm rate of 4.21%. A combinatorial analysis between 14 features to ensure the selection of the best ones to achieve good enough results in terms of success rate and false alarm rate was performed. All possible combinations with a number of features between 2 and 7 were tested and 9893 different predictors were analyzed. An important drawback in this analysis was the time required to compute the results that can be estimated in 1731 h (∼2.4 months). Genetic algorithms (GA) are searching algorithms that simulate the process of natural selection. In this article, the GA and the Venn predictors are combined with the objective not only of finding good enough features within the 14 available ones but also of reducing the computational time requirements. Five different performance metrics as measures of the GA fitness function have been evaluated. The best metric was the measurement called Informedness, with just 6 generations (168 predictors at 29.4 h).
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International Nuclear Information System (INIS)
Pereira, Augusto; Vega, Jesús; Moreno, Raúl; Dormido-Canto, Sebastián; Rattá, Giuseppe A.; Pavón, Fernando
2015-01-01
Recently, a probabilistic classifier has been developed at JET to be used as predictor from scratch. It has been applied to a database of 1237 JET ITER-like wall (ILW) discharges (of which 201 disrupted) with good results: success rate of 94% and false alarm rate of 4.21%. A combinatorial analysis between 14 features to ensure the selection of the best ones to achieve good enough results in terms of success rate and false alarm rate was performed. All possible combinations with a number of features between 2 and 7 were tested and 9893 different predictors were analyzed. An important drawback in this analysis was the time required to compute the results that can be estimated in 1731 h (∼2.4 months). Genetic algorithms (GA) are searching algorithms that simulate the process of natural selection. In this article, the GA and the Venn predictors are combined with the objective not only of finding good enough features within the 14 available ones but also of reducing the computational time requirements. Five different performance metrics as measures of the GA fitness function have been evaluated. The best metric was the measurement called Informedness, with just 6 generations (168 predictors at 29.4 h).
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Treatment of childhood sexual abuse: an updated review.
Cummings, Marissa; Berkowitz, Steven J; Scribano, Philip V
2012-12-01
Childhood sexual abuse (CSA) involves multiple complex factors that make the evaluation of therapeutic interventions especially complicated. PTSD prevalence rates of CSA are approximately 37 % -53 %. Several other psychiatric sequelae of CSA exist. CSA appears to disrupt brain and body physiology. One co-located service delivery model reported a 52 % linkage rate of CSA survivors with mental health treatment. This article reviews current literature on the treatment of CSA, including psychosocial interventions, pharmacotherapy, and early preventative interventions. It also provides an update on the short- and long-term sequelae of CSA and implications for future research directions. A literature search of papers published in the last 3 years was conducted using the keywords treatment, sexual abuse, childhood, epigenetics, resilience and review, and searching the following databases: PsycInfo, PubMed, Substance Abuse and Mental Health Services Administration, and Centers for Disease Control.
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Diet selection and seasonal dietary switch of a large sexually dimorphic herbivore
Shannon, Graeme; Mackey, Robin L.; Slotow, Rob
2013-01-01
Although diet selection and the physiological adaptations of grazers and browsers have been widely studied, much less is known about mixed-feeders that target both grass and woody species. The ability to switch diet allows the individual to respond to spatial and temporal changes in forage abundance and quality, providing a key mechanism for large herbivores to exploit heterogeneous environments. We compare diet selection and timing of the seasonal dietary switch for a large-bodied, sexually dimorphic mixed-feeder, the African elephant. The study was carried out on a small population of elephants (n = 48) in the Pongola Game Reserve (PGR), South Africa. Sex-specific dietary composition evaluated from feeding behaviour correlated with composition in dung samples from individuals of known sex. Grass was strongly preferred during the wet season and browse in the winter dry season. However, adult male elephants switched from browse to grass earlier, and consumed a greater overall proportion of grass in their diet, compared with adult females and their associated family groups. Male elephants also spent more time in grassland habitats, and expanded their ranges to a greater extent than females following the end of the dry season. Our results suggest that smaller adult body size, high nutritional demands of offspring, and the constraints of sociality have contributed to female elephants in PGR resolving their diet selection strategies to target higher quality foraging opportunities, whilst males appear to be adopting a rate maximizing approach. The behavioural differences between the sexes are pronounced, which has implications for elephant management approaches that are typically focussed at the population level.
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Gershman, Susan N.; Mitchell, Christopher; Sakaluk, Scott K.; Hunt, John
2012-01-01
Nuptial food gifts function to enhance male fertilization success, but their consumption is not always beneficial to females. In decorated crickets, the spermatophore transferred at mating includes a gelatinous mass, the spermatophylax, which is consumed by females after mating. However, females often discard spermatophylaxes shortly after mating, whereupon they terminate sperm transfer. We hypothesized that females discard gifts based on their assessment of the gift itself, and specifically the composition of free amino acids. We tested this hypothesis by comparing spermatophylaxes discarded by females after mating with those that were destined to be fully consumed, and employed multivariate selection analysis to quantify the strength and form of multivariate sexual selection operating on the free amino acid composition of gifts. The analysis yielded a saddle-shaped fitness surface with two local peaks. Different amino acid profiles appear to elicit continued feeding on the spermatophylax either because they offer the same level of gustatory appeal, or because they differentially affect both the gustatory appeal and texture of the spermatophylax. We conclude that the gustatory response of females to males' nuptial food gifts represents an important avenue of post-copulatory mate choice, imposing significant sexual selection on the free amino acid composition of the spermatophylax. PMID:22357263
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Sexual harassment against nurses in Turkey.
Celik, Yusuf; Celik, Sevilay Senol
2007-01-01
To identify the prevalence and sources of sexual harassment against nurses in Turkey, its consequences, and factors affecting harassment experiences. Descriptive survey. Participants (N=622) were selected from nurses working in eight Ministry of Health hospitals in Turkey. Participants were surveyed with a Sexual Harassment Questionnaire, consisting of the sociodemographic characteristics of participants, types of sexual harassment, sources, feelings, ramifications, and ways to cope with sexual harassment behaviors. Frequency and percentage distributions, chi-square, and logistic regression were used for data analysis. The results showed 37.1% of participants had been harassed sexually. Physicians were identified as the primary instigators of sexual harassment. The most common reactions against harassers were anger and fear; frequently reported negative effects of sexual harassment were disturbed mental health function, decline in job performance, and headache. "Did nothing" was the coping method used most commonly by the nurses. About 80% of sexually harassed nurses did not report the incident of sexual harassment to hospital administration. The lower working status and power of nurses in the workplace, poor working conditions in healthcare settings, and insufficient administrative mechanisms, including the present law and regulations against sexual harassers, were identified as important factors in the work environment in Turkey.
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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.
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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
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Sexual Dimorphism in Bite Performance Drives Morphological Variation in Chameleons
da Silva, Jessica M.; Herrel, Anthony; Measey, G. John; Tolley, Krystal A.
2014-01-01
Phenotypic performance in different environments is central to understanding the evolutionary and ecological processes that drive adaptive divergence and, ultimately, speciation. Because habitat structure can affect an animal’s foraging behaviour, anti-predator defences, and communication behaviour, it can influence both natural and sexual selection pressures. These selective pressures, in turn, act upon morphological traits to maximize an animal’s performance. For performance traits involved in both social and ecological activities, such as bite force, natural and sexual selection often interact in complex ways, providing an opportunity to understand the adaptive significance of morphological variation with respect to habitat. Dwarf chameleons within the Bradypodion melanocephalum-Bradypodion thamnobates species complex have multiple phenotypic forms, each with a specific head morphology that could reflect its use of either open- or closed-canopy habitats. To determine whether these morphological differences represent adaptations to their habitats, we tested for differences in both absolute and relative bite performance. Only absolute differences were found between forms, with the closed-canopy forms biting harder than their open-canopy counterparts. In contrast, sexual dimorphism was found for both absolute and relative bite force, but the relative differences were limited to the closed-canopy forms. These results indicate that both natural and sexual selection are acting within both habitat types, but to varying degrees. Sexual selection seems to be the predominant force within the closed-canopy habitats, which are more protected from aerial predators, enabling chameleons to invest more in ornamentation for communication. In contrast, natural selection is likely to be the predominant force in the open-canopy habitats, inhibiting the development of conspicuous secondary sexual characteristics and, ultimately, enforcing their overall diminutive body size and
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Sexual dimorphism in bite performance drives morphological variation in chameleons.
Directory of Open Access Journals (Sweden)
Jessica M da Silva
Full Text Available Phenotypic performance in different environments is central to understanding the evolutionary and ecological processes that drive adaptive divergence and, ultimately, speciation. Because habitat structure can affect an animal's foraging behaviour, anti-predator defences, and communication behaviour, it can influence both natural and sexual selection pressures. These selective pressures, in turn, act upon morphological traits to maximize an animal's performance. For performance traits involved in both social and ecological activities, such as bite force, natural and sexual selection often interact in complex ways, providing an opportunity to understand the adaptive significance of morphological variation with respect to habitat. Dwarf chameleons within the Bradypodion melanocephalum-Bradypodion thamnobates species complex have multiple phenotypic forms, each with a specific head morphology that could reflect its use of either open- or closed-canopy habitats. To determine whether these morphological differences represent adaptations to their habitats, we tested for differences in both absolute and relative bite performance. Only absolute differences were found between forms, with the closed-canopy forms biting harder than their open-canopy counterparts. In contrast, sexual dimorphism was found for both absolute and relative bite force, but the relative differences were limited to the closed-canopy forms. These results indicate that both natural and sexual selection are acting within both habitat types, but to varying degrees. Sexual selection seems to be the predominant force within the closed-canopy habitats, which are more protected from aerial predators, enabling chameleons to invest more in ornamentation for communication. In contrast, natural selection is likely to be the predominant force in the open-canopy habitats, inhibiting the development of conspicuous secondary sexual characteristics and, ultimately, enforcing their overall diminutive
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Altwegg, Res; De Klerk, Helen M; Midgley, Guy F
2015-02-01
Crown fire is a key selective pressure in Mediterranean-type plant communities. Adaptive responses to fire regimes involve trade-offs between investment for persistence (fire survival and resprouting) and reproduction (fire mortality, fast growth to reproductive maturity, and reseeding) as investments that enhance adult survival lower growth and reproductive rates. Southern hemisphere Mediterranean-type ecosystems are dominated by species with either endogenous regeneration from adult resprouting or fire-triggered seedling recruitment. Specifically, on nutrient-poor soils, these are either resprouting or reseeding life histories, with few intermediate forms, despite the fact that the transition between strategies is evolutionarily labile. How did this strong dichotomy evolve? We address this question by developing a stochastic demographic model to assess determinants of relative fitness of reseeders, resprouters and hypothetical intermediate forms. The model was parameterised using published demographic data from South African protea species and run over various relevant fire regime parameters facets. At intermediate fire return intervals, trade-offs between investment in growth versus fire resilience can cause fitness to peak at either of the extremes of the reseeder-resprouter continuum, especially when assuming realistic non-linear shapes for these trade-offs. Under these circumstances, the fitness landscape exhibits a saddle which could lead to disruptive selection. The fitness gradient between the peaks was shallow, which may explain why this life-history trait is phylogenetically labile. Resprouters had maximum fitness at shorter fire-return intervals than reseeders. The model suggests that a strong dichotomy in fire survival strategy depends on a non-linear trade-off between growth and fire persistence traits.
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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.
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Rationally Irrational: The Case of Sexual Burglary.
Pedneault, Amelie; Beauregard, Eric; Harris, Danielle A; Knight, Raymond A
2015-08-01
The present study investigated rationality in sexually motivated burglaries. Specifically, we analyzed the situational cues identified by sexual burglars in their target selection. The research project investigated 224 individual incidents of residential burglary with apparent sexual motivations. Situational characteristics of the incidents were recorded and analyzed using forward sequential regressions. Results indicated that most sexually motivated burglaries occurred in occupied residences with deficient physical guardianship, when the victim was alone. Violence, theft, penetration, and fetishism were found to be committed in circumstances that increased the benefits and lowered the risks. Results showed that sexual burglary is rational in nature-sexual burglars chose residences that were easy to break into. We found little support for the premise that such opportunities arose while carrying out regular burglaries. Instead, the data indicated that sexual burglars acted opportunistically on situational cues that are markedly dissimilar to those of regular burglars. © The Author(s) 2014.
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International Nuclear Information System (INIS)
Wesson, J.A.; Gill, R.D.; Hugon, M.
1989-01-01
In JET, both high density and low-q operation are limited by disruptions. The density limit disruptions are caused initially by impurity radiation. This causes a contraction of the plasma temperature profile and leads to an MHD unstable configuration. There is evidence of magnetic island formation resulting in minor disruptions. After several minor disruptions, a major disruption with a rapid energy quench occurs. This event takes place in two stages. In the first stage there is a loss of energy from the central region. In the second stage there is a more rapid drop to a very low temperature, apparently due to a dramatic increase in impurity radiation. The final current decay takes place in the resulting cold plasma. During the growth of the MHD instability the initially rotating mode is brought to rest. This mode locking is believed to be due to an electromagnetic interaction with the vacuum vessel and external magnetic field asymmetries. The low-q disruptions are remarkable for the precision with which they occur at q ψ = 2. These disruptions do not have extended precursors or minor disruptions. The instability grows and locks rapidly. The energy quench and current decay are generally similar to those of the density limit. (author). 43 refs, 35 figs, 3 tabs
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Family Structure, Maternal Dating, and Sexual Debut: Extending the Conceptualization of Instability.
Zito, Rena Cornell; De Coster, Stacy
2016-05-01
Family structure influences the risk of early onset of sexual intercourse. This study proposes that the family structures associated with risk-single-mother, step-parent, and cohabiting-influence early sexual debut due to family instability, including shifts in family structure and maternal dating, which can undermine parental control and transmit messages about the acceptability of nonmarital sex. Previous research has not considered maternal dating as a component of family instability, assuming single mothers who date and those who do not date experience comparable levels of family disruption and transmit similar messages about the acceptability of nonmarital sex. Hypotheses are assessed using logistic regression models predicting the odds of early onset of sexual intercourse among 9959 respondents (53 % female, 47 % male) from the National Longitudinal Study of Adolescent to Adult Health. Respondents were ages 12-17 at the first wave of data collection and 18-26 at the third wave, when respondents reported the age at which they first had sexual intercourse. Results show that maternal dating is a source of family instability with repercussions for early sexual debut. Parental control and permissive attitudes towards teenage sex and pregnancy link at-risk family structures and maternal dating to early sexual initiation among females, though these variables do not fully explain family structure and maternal dating effects. Among males, the influence of maternal dating on early sexual debut is fully explained by the learning of permissive sexual attitudes.
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"Children are sexually innocent": Iranian parents' understanding of children's sexuality.
Merghati-Khoei, Effat; Abolghasemi, Naria; Smith, Thomas G
2014-04-01
Sexuality education (SE) is hotly contested in the West and there is much abstinence-only education; however, it remains controversial in a variety of contexts, including in Iran. The lack of consensus about children's SE in Muslim societies obliges us to explore different aspects of this topic systematically. The qualitative research presented here was about how Iranian parents perceived children's sexuality. Data from parents of 26 children were collected during four focus group sessions. Informants were selected from Area 5 in West Tehran. This area included 72 primary schools for girls and 82 for boys. The sessions were facilitated by using a semi-structured focus group guide. Content analysis was adopted using combined free and analytical coding to reduce data, to extract meanings, and to categorize domains. One of the three main domains identified, family management of child sexuality, is comprised of the following: (1) understanding of child sexuality, (2) family rules, (3) parent-child interactions, and (4) opposite sex interactions. Parental misinformation, accumulated myths, and ignorance about children's sexual development were evident. Strict family rules and a lack of consistent policy and instruction for SE were also identified. Parents said they were neither well-prepared nor competent to educate their children about sexuality. In fact, a majority of mothers raised "incompetence" as an important determinant in their own parent-child interactions. Societal changes as well as children's socialization patterns have forced parents to accept their children's opposite sex friendships as a reality. Results suggest a community need for developing comprehensive and culturally sensitive SE for schools and parental use.
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Digital disruption ?syndromes.
Sullivan, Clair; Staib, Andrew
2017-05-18
The digital transformation of hospitals in Australia is occurring rapidly in order to facilitate innovation and improve efficiency. Rapid transformation can cause temporary disruption of hospital workflows and staff as processes are adapted to the new digital workflows. The aim of this paper is to outline various types of digital disruption and some strategies for effective management. A large tertiary university hospital recently underwent a rapid, successful roll-out of an integrated electronic medical record (EMR). We observed this transformation and propose several digital disruption "syndromes" to assist with understanding and management during digital transformation: digital deceleration, digital transparency, digital hypervigilance, data discordance, digital churn and post-digital 'depression'. These 'syndromes' are defined and discussed in detail. Successful management of this temporary digital disruption is important to ensure a successful transition to a digital platform. What is known about this topic? Digital disruption is defined as the changes facilitated by digital technologies that occur at a pace and magnitude that disrupt established ways of value creation, social interactions, doing business and more generally our thinking. Increasing numbers of Australian hospitals are implementing digital solutions to replace traditional paper-based systems for patient care in order to create opportunities for improved care and efficiencies. Such large scale change has the potential to create transient disruption to workflows and staff. Managing this temporary disruption effectively is an important factor in the successful implementation of an EMR. What does this paper add? A large tertiary university hospital recently underwent a successful rapid roll-out of an integrated electronic medical record (EMR) to become Australia's largest digital hospital over a 3-week period. We observed and assisted with the management of several cultural, behavioural and
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Mating Disruption for the 21st Century: Matching Technology With Mechanism.
Miller, James R; Gut, Larry J
2015-06-01
Progress toward proof of the principal cause of insect mating disruption under a particular set of conditions has been hindered by a lack of logical rigor and clean falsifications of possible explanations. Here we make the case that understanding of mating disruption and optimization of particular formulations can be significantly advanced by rigorous application of the principles of strong inference. To that end, we offer a dichotomous key for eight distinct categories of mating disruption and detail criteria and methodologies for differentiating among them. Mechanisms of mating disruption closely align with those established for enzyme inhibition, falling into two major categories-competitive and noncompetitive. Under competitive disruption, no impairments are experienced by males, females, or the signal of females. Therefore, males can respond to females and traps. Competitive disruption is entirely a numbers game where the ratio of dispensers to females and traps is highly consequential and renders the control pest-density-dependent. Under noncompetitive disruption, males, females, or the signal from females are already impaired when sexual activity commences. The control achieved noncompetitively offers the notable advantage of being pest-density-independent. Dosage-response curves are the best way to distinguish competitive from noncompetitive disruption. Purely competitive disruption produces: a smoothly concave curve when untransformed capture data are plotted on the y-axis against density of dispensers on the x-axis; a straight line with positive slope when the inverse of catch is plotted against density of pheromone dispensers; and, a straight line with negative slope when catch is plotted against density of pheromone dispensers × catch. Disruption operating only noncompetitively produces: a straight line with negative slope when untransformed capture data are plotted on the y-axis against density of dispensers on the x-axis; an upturning curve when the
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The Psychosexual Profile of Sexual Assistants: An Internet-Based Explorative Study
Limoncin, Erika; Galli, Debora; Ciocca, Giacomo; Gravina, Giovanni Luca; Carosa, Eleonora; Mollaioli, Daniele; Lenzi, Andrea; Jannini, Emmanuele A.
2014-01-01
Introduction Sexual assistance may have some aspects that resemble prostitution and others that might lead one to think of sexual assistants as similar to a group of subjects whose sexual object is disability (devotees). In this study, we investigate whether a rigorous selection and training process on the part of specialised organisations may reduce the risk of training subjects with an atypical sexual interest and behaviours resembling prostitution. Materials and Methods The study population consisted of 152 subjects defining themselves as sexual assistants. Subjects were initially contacted on websites specifically dedicated to sexual assistants and prostitutes. One hundred and twenty subjects were selected, by propensity score analysis, and studied by means of a modified version of a semi-structured questionnaire previously developed to investigate a population of subjects attracted by disability. Results The study group was composed of 80 trained and 40 untrained sexual assistants, with mean ages of 41.5 (SD +/−12.58) and 44.5 (SD +/−11.62), respectively. A significant number of untrained subjects affirmed that their motivation in carrying out sexual assistance was of a remunerative nature, while this number was lower among the trained assistants (p = 0.001). Nearly all untrained subjects claimed to do one or more of the following activities during sexual assistance: sexual intercourse, oral sex, and masturbation. Among the trained subjects, however, only 47.5% claimed to do one or more of these activities, which means that there is a significant gap between trained and untrained assistants (p<0.0001). The existence of an atypical sexual interest was more evident between untrained rather than between trained subjects (p<0.0001). Conclusions Sexual assistance represents a way through which people affected by disabilities may attain the right to explore their sexuality in a safe setting. This can be guaranteed only if sexual assistants are trained and
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Sexual Pain Disorders in Spanish Women Drug Users.
Del Río, Francisco Javier; Cabello-Santamaría, Francisco; Cabello-García, Marina A; Aragón-Vela, Jerónimo
2017-01-28
The impact of pain in sexuality, couple relationships and the quality of life is very well known. The relationship between substance abuse and the presence of sexual pain disorder is assessed, together with anxiety and sexual attitudes . Two samples were selected. One sample for women with a history of substance abuse (n = 129), and another one of women nonconsumers (n = 129). The Golombok Rust Inventory of Sexual Satisfaction (GRISS), the Sexual Opinion Survey (SOS) and the State Trait Anxiety Inventory (STAI) questionnaires were used. The results indicate that women consumers obtained a higher mean scores in sexual pain disorder (4.88 > 2.89, that is 65.12%), plus higher mean scores on state anxiety (23.82 > 14.56) and trait anxiety (30.93 > 16.95), and lower average figure in erotophilia (84.93 < 95.81). It was also verified that the period of abstinence does not improve sexual response. Substance consumption affects sexual response in women negatively. Sexual response does not improve with abstinence period.
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Ybarra, Michele L.; Mitchell, Kimberly J.
2014-01-01
Objective To examine the relation between “sexting,” (sending and sharing sexual photos online via text messaging and in-person) with sexual risk behaviors and psychosocial challenge in adolescence. Methods Data were collected online between 2010 and 2011 with 3,715 randomly selected 13- to 18-year-old youth across the United States. Results Seven percent of youth reported sending or showing someone sexual pictures of themselves, where they were nude or nearly nude, online, via text messaging, or in-person, during the past year. Although females and older youth were more likely to share sexual photos than males and younger youth, the profile of psychosocial challenge and sexual behavior was similar for all youth. After adjusting for demographic characteristics, sharing sexual photos was associated with all types of sexual behaviors assessed (e.g., oral sex, vaginal sex) as well as some of the risky sexual behaviors examined—particularly having concurrent sexual partners and having more past-year sexual partners. Adolescents who shared sexual photos also were more likely to use substances and less likely to have high self-esteem than their demographically similar peers. Conclusions While the media has portrayed “sexting” as a problem caused by new technology, health professionals may be more effective by approaching it as an aspect of adolescent sexual development and exploration and, in some cases, risk-taking and psychosocial challenge. PMID:25266148
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Ybarra, Michele L; Mitchell, Kimberly J
2014-12-01
To examine the relation between "sexting" (sending and sharing sexual photos online, via text messaging, and in person) with sexual risk behaviors and psychosocial challenge in adolescence. Data were collected online between 2010 and 2011 with 3,715 randomly selected 13- to 18-year-old youth across the United States. Seven percent of youth reported sending or showing someone sexual pictures of themselves, in which they were nude or nearly nude, online, via text messaging, or in person, during the past year. Although females and older youth were more likely to share sexual photos than males and younger youth, the profile of psychosocial challenge and sexual behavior was similar for all youth. After adjusting for demographic characteristics, sharing sexual photos was associated with all types of sexual behaviors assessed (e.g., oral sex, vaginal sex) as well as some of the risky sexual behaviors examined-particularly having concurrent sexual partners and having more past-year sexual partners. Adolescents who shared sexual photos also were more likely to use substances and less likely to have high self-esteem than their demographically similar peers. Although the media has portrayed sexting as a problem caused by new technology, health professionals may be more effective by approaching it as an aspect of adolescent sexual development and exploration and, in some cases, risk-taking and psychosocial challenge. Copyright © 2014 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.
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Veeramachaneni, D N R; Palmer, J S; Amann, R P; Pau, K-Y F
2007-01-01
Rabbit does (7-9 per group) were treated daily per orum from gestation day 15 through post-natal week 4 to provide per kg body wt 25 micaromol (low) or 250 micromol (high) p,p'-DDT or a mixture of DDT and vinclozolin (12.5 and 125 micromol each). Developmental as well as post-pubertal reproductive sequelae of male progeny were studied. Testicular descent in some pups was impaired by DDT. Serum LH or testosterone was not affected. FSH was lower in mixture- but not in DDT-exposed rabbits. Lack of sexual interest, penile erection and ejaculation were observed in some mixture rabbits. Sperm counts were unaffected, but morphologically normal spermatozoa were fewer; nuclear and acrosomal morphogenesis was disrupted. Atypical germ cells resembling carcinoma in situ were found. Also considering data for vinclozolin [Veeramachaneni DNR, Palmer JS, Amann RP, Kane CM, Higuchi TT, Pau K-YF. Disruption of sexual function, FSH secretion, and spermiogenesis in rabbits following developmental exposure to vinclozolin, a fungicide. Reproduction 2006;131:805-16], we concluded that DDT causes cryptorchidism and germ cell atypia, vinclozolin permanently disrupts FSH secretion and sexual function, and the mixture causes the full spectrum of dysgenesis.
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[Influence of cumulated sexual trauma on sexual life and relationship of a patient].
Sobański, Jerzy A; Klasa, Katarzyna; Cyranka, Katarzyna; Müldner-Nieckowski, Lukasz; Dembińska, Edyta; Rutkowski, Krzysztof; Smiatek-Mazgaj, Bogna; Mielimaka, Michal
2014-01-01
The assessment of links of accumulated traumatic events of a sexual nature, recollected from the past, with the current functioning of the patients in the area of sexual life and relationship. Comorbidity of memories of traumatic sexual events from childhood and puberty in patients with the features of their current partner relationships and sexual life were analyzed on the basis of Live Inventory completed by 2,582 women and 1,347 men, before treatment in day hospital (years 1980-2002). The accumulation was evaluated for a combination of two or three selected events. The presence of relatively numerous traumatic events in the field of sexuality early initiation or enforced initiation, incest or its attempt, sub-optimal sexual education and punishment for masturbation was indicated. In some patients, these events occurred simultaneously. Especially in women, the presence in the same person of two or three aggravating circumstances of life was associated with a higher risk of among others fleeting, casual sexual contacts, marriage under the influence of environment pressures, reluctance to partner. Increased accumulation - the presence in the same patient of more than one adverse circumstances associated with sexual development - leads to a higher incidence of interference in relationship with a partner including the elements of sexual dysfunction. The obtained results are generally consistent with clinical observations and literature despite different, simplified methodology of the study based on the analysis of single variables from questionnaire interviews. Finding fewer links in the group of men can be explained by their much lower number in the study group and less frequent burdening with certain traumatic events or different experiencing.
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Frentiu, Francesca D; Adamski, Marcin; McGraw, Elizabeth A; Blows, Mark W; Chenoweth, Stephen F
2009-01-01
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 thi...
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From Evolutionary Allometry to Sexual Display: (A Reply to Holman and Bro-Jørgensen).
Raia, Pasquale; Passaro, Federico; Carotenuto, Francesco; Meiri, Shai; Piras, Paolo
2016-08-01
Conventional wisdom holds that the complex shapes of deer antlers are produced under the sole influence of sexual selection. We questioned this view by demonstrating that trends for increased body size evolution passively yield more-complex ornaments, even in organisms where no effect of sexual selection is possible, with similar allometric slopes. Recent investigations suggest that sexual selection on antlers of larger deer species is stronger than that in smaller species; hence, the use of conspicuous antlers for display in large male deer is a secondary function driven by especially intense sexual selection on these large-bodied species. Since ancestral deer were small and had very simple antlers, such an intense selection on antlers shape was probably absent in early deer. Therefore, the evolution of complex ornaments is coupled with body size evolution, even in deer.
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Togawa, Yoichiro; Nunoshiba, Tatsuo; Hiratsu, Keiichiro
2018-02-01
Markerless gene-disruption technology is particularly useful for effective genetic analyses of Thermus thermophilus (T. thermophilus), which have a limited number of selectable markers. In an attempt to develop a novel system for the markerless disruption of genes in T. thermophilus, we applied a Cre/lox system to construct a triple gene disruptant. To achieve this, we constructed two genetic tools, a loxP-htk-loxP cassette and cre-expressing plasmid, pSH-Cre, for gene disruption and removal of the selectable marker by Cre-mediated recombination. We found that the Cre/lox system was compatible with the proliferation of the T. thermophilus HB27 strain at the lowest growth temperature (50 °C), and thus succeeded in establishing a triple gene disruptant, the (∆TTC1454::loxP, ∆TTC1535KpnI::loxP, ∆TTC1576::loxP) strain, without leaving behind a selectable marker. During the process of the sequential disruption of multiple genes, we observed the undesired deletion and inversion of the chromosomal region between multiple loxP sites that were induced by Cre-mediated recombination. Therefore, we examined the effects of a lox66-htk-lox71 cassette by exploiting the mutant lox sites, lox66 and lox71, instead of native loxP sites. We successfully constructed a (∆TTC1535::lox72, ∆TTC1537::lox72) double gene disruptant without inducing the undesired deletion of the 0.7-kbp region between the two directly oriented lox72 sites created by the Cre-mediated recombination of the lox66-htk-lox71 cassette. This is the first demonstration of a Cre/lox system being applicable to extreme thermophiles in a genetic manipulation. Our results indicate that this system is a powerful tool for multiple markerless gene disruption in T. thermophilus.
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Sexual orientation in males and the evolution of anisogamy.
Reed, Lawrence Ian
2010-02-01
How might homosexual orientation have evolved and been maintained? Several adaptationist explanations have been examined in attempt to reconcile the presence of same-sex sexual behaviors with traditional selection-based theory, showing little empirical support. The current paper presents a novel adaptationist explanation for the evolution and maintenance of same-sex sexual behaviors in males, both between- and within-species, related to the evolution of anisogamy. Under conditions of isogamy, sexual reproduction occurs between individuals with gametes of similar morphology. With the evolution of anisogamy came greater specificity on the types of individuals that would produce offspring when mated with (i.e. those with opposing gamete sizes). It is suggested that with this evolutionary change, a specified psychological adaptation orienting individuals primarily towards mating partners with newly opposing gamete sizes was then selected for. It is thus hypothesized that sexual orientation will vary along the anisogamy-isogamy continuum, with homosexual orientation being associated with closer approximations towards isogamy. This hypothesis leads to two specific predictions. First, in comparisons between species, the presence of same-sex sexual behaviors will be more likely to occur as sperm to egg ratios approach 1:1. Second, in comparisons within species, those individuals with greater sperm lengths will be more likely to exhibit same-sex sexual behaviors than those with lesser sperm lengths. Examination of the present hypothesis stands to greatly increase our knowledge of the selective forces shaping both biological and psychological evolution.
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Sexual Violence Infrastructures (SVIs): Hotels and Cyberspace as ...
African Journals Online (AJOL)
The study draws from a prominent criminology theory – routine activities theory to analyse the necessary conditions under which sexual predators select potential targets or victims. These conditions include the availability of three essential factors: existence of a motivated offender (sexual predator), an attractive target, and ...
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Sexual Assault against Female Nigerian Students | Kullima | African ...
African Journals Online (AJOL)
Sexual assault is a common social disorder among students in our tertiary institutions. This study ascertains the extent and effect of sexual assault among Nigerian students. Two hundred and Sixty Eight structured questionnaires were distributed to randomly selected students in 4 tertiary institutions, information on socio ...
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Satisfação sexual na demência Sexual satisfaction in dementia
Directory of Open Access Journals (Sweden)
Marcela Moreira Lima Nogueira
2013-01-01
Full Text Available CONTEXTO: A demência pode resultar em comprometimento da intimidade e sexualidade de casais idosos. OBJETIVOS: Avaliar alterações na atividade sexual, bem como os fatores de satisfação e/ou insatisfação sexual de casais nos quais um dos parceiros possua demência. MÉTODO: Busca nas bases de dados ISI, PubMed/Medline e SciELO de artigos sobre sexualidade na demência, entre janeiro de 1990 e março de 2012, utilizando as palavras-chave: "demência", "satisfação sexual", "intimidade" e "sexualidade". RESULTADOS: Foram encontrados 12 artigos. A sobrecarga de cuidados e a alteração de papéis na relação conjugal foram consideradas as principais causas para o declínio da atividade sexual. A disfunção erétil em pacientes e cônjuges, a capacidade decisória para o consentimento da relação sexual por parte do paciente demenciado e os problemas referentes à idade e à saúde (física e emocional do cônjuge e/ou paciente foram os fatores associados à insatisfação sexual. CONCLUSÃO: A intimidade e a atividade sexual dos casais em que um dos parceiros é portador de demência são influenciadas negativamente pela relação de cuidados decorrente da doença e pela sobrecarga dos cônjuges. Por outro lado, a atividade sexual pode ser positivamente substituída por demonstrações de carinho e empatia entre os cônjuges.BACKGROUND: Dementia may result on impairment in intimacy and sexuality of elderly couples. OBJECTIVES: Evaluate changes in sexual activity, as well as the factors which cause sexual satisfaction and/or dissatisfaction in couples in which one of the partners has dementia. METHOD: A search at ISI, PubMed/Medline and SciELO was made for articles about sexuality in dementia, from January 1990 to March 2012, using the keywords: "dementia", "sexual satisfaction", "intimacy" and "sexuality". RESULTS: Twelve articles were selected. The burden of care and the change of roles in couples' relationship were the main reasons for
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Sexuality in older adults: Clinical and psychosocial dilemmas
Isha Dhingra; Avinash De Sousa; Sushma Sonavane
2016-01-01
The present review aims to throw some light on the various aspects of sexuality in older adults and the challenges faced by medical professionals working in this area. Keyword searches using the terms "sexuality," "sexual dysfunction," "geriatric," "old age," and others in combination were carried out on PubMed, Google Scholar, and the Cochrane Database of Systematic Reviews. Relevant clinical trials, case studies, and review papers were selected. This was further supplemented with the clinic...
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Primate brain architecture and selection in relation to sex.
Lindenfors, Patrik; Nunn, Charles L; Barton, Robert A
2007-05-10
Social and competitive demands often differ between the sexes in mammals. These differing demands should be expected to produce variation in the relative sizes of various brain structures. Sexual selection on males can be predicted to influence brain components handling sensory-motor skills that are important for physical competition or neural pathways involving aggression. Conversely, because female fitness is more closely linked to ecological factors and social interactions that enable better acquisition of resources, social selection on females should select for brain components important for navigating social networks. Sexual and social selection acting on one sex could produce sexual dimorphism in brain structures, which would result in larger species averages for those same brain structures. Alternatively, sex-specific selection pressures could produce correlated effects in the other sex, resulting in larger brain structures for both males and females of a species. Data are presently unavailable for the sex-specific sizes of brain structures for anthropoid primates, but under either scenario, the effects of sexual and social selection should leave a detectable signal in average sizes of brain structures for different species. The degree of male intra-sexual selection was positively correlated with several structures involved in autonomic functions and sensory-motor skills, and in pathways relating to aggression and aggression control. The degree of male intra-sexual selection was not correlated with relative neocortex size, which instead was significantly positively correlated with female social group size, but negatively correlated with male group size. Sexual selection on males and social selection on females have exerted different effects on primate brain architecture. Species with a higher degree of male intra-sexual selection carry a neural signature of an evolutionary history centered on physical conflicts, but no traces of increased demands on
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Primate brain architecture and selection in relation to sex
Directory of Open Access Journals (Sweden)
Nunn Charles L
2007-05-01
Full Text Available Abstract Background Social and competitive demands often differ between the sexes in mammals. These differing demands should be expected to produce variation in the relative sizes of various brain structures. Sexual selection on males can be predicted to influence brain components handling sensory-motor skills that are important for physical competition or neural pathways involving aggression. Conversely, because female fitness is more closely linked to ecological factors and social interactions that enable better acquisition of resources, social selection on females should select for brain components important for navigating social networks. Sexual and social selection acting on one sex could produce sexual dimorphism in brain structures, which would result in larger species averages for those same brain structures. Alternatively, sex-specific selection pressures could produce correlated effects in the other sex, resulting in larger brain structures for both males and females of a species. Data are presently unavailable for the sex-specific sizes of brain structures for anthropoid primates, but under either scenario, the effects of sexual and social selection should leave a detectable signal in average sizes of brain structures for different species. Results The degree of male intra-sexual selection was positively correlated with several structures involved in autonomic functions and sensory-motor skills, and in pathways relating to aggression and aggression control. The degree of male intra-sexual selection was not correlated with relative neocortex size, which instead was significantly positively correlated with female social group size, but negatively correlated with male group size. Conclusion Sexual selection on males and social selection on females have exerted different effects on primate brain architecture. Species with a higher degree of male intra-sexual selection carry a neural signature of an evolutionary history centered on
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Garcia, Justin R; MacKillop, James; Aller, Edward L; Merriwether, Ann M; Wilson, David Sloan; Lum, J Koji
2010-11-30
Human sexual behavior is highly variable both within and between populations. While sex-related characteristics and sexual behavior are central to evolutionary theory (sexual selection), little is known about the genetic bases of individual variation in sexual behavior. The variable number tandem repeats (VNTR) polymorphism in exon III of the human dopamine D4 receptor gene (DRD4) has been correlated with an array of behavioral phenotypes and may be predicatively responsible for variation in motivating some sexual behaviors, particularly promiscuity and infidelity. We administered an anonymous survey on personal history of sexual behavior and intimate relationships to 181 young adults. We also collected buccal wash samples and genotyped the DRD4 VNTR. Here we show that individuals with at least one 7-repeat allele (7R+) report a greater categorical rate of promiscuous sexual behavior (i.e., having ever had a "one-night stand") and report a more than 50% increase in instances of sexual infidelity. DRD4 VNTR genotype varies considerably within and among populations and has been subject to relatively recent, local selective pressures. Individual differences in sexual behavior are likely partially mediated by individual genetic variation in genes coding for motivation and reward in the brain. Conceptualizing these findings in terms of r/K selection theory suggests a mechanism for selective pressure for and against the 7R+ genotype that may explain the considerable global allelic variation for this polymorphism.
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Associations between Dopamine D4 Receptor Gene Variation with Both Infidelity and Sexual Promiscuity
Garcia, Justin R.; MacKillop, James; Aller, Edward L.; Merriwether, Ann M.; Wilson, David Sloan; Lum, J. Koji
2010-01-01
Background Human sexual behavior is highly variable both within and between populations. While sex-related characteristics and sexual behavior are central to evolutionary theory (sexual selection), little is known about the genetic bases of individual variation in sexual behavior. The variable number tandem repeats (VNTR) polymorphism in exon III of the human dopamine D4 receptor gene (DRD4) has been correlated with an array of behavioral phenotypes and may be predicatively responsible for variation in motivating some sexual behaviors, particularly promiscuity and infidelity. Methodology/Principal Findings We administered an anonymous survey on personal history of sexual behavior and intimate relationships to 181 young adults. We also collected buccal wash samples and genotyped the DRD4 VNTR. Here we show that individuals with at least one 7-repeat allele (7R+) report a greater categorical rate of promiscuous sexual behavior (i.e., having ever had a “one-night stand”) and report a more than 50% increase in instances of sexual infidelity. Conclusions/Significance DRD4 VNTR genotype varies considerably within and among populations and has been subject to relatively recent, local selective pressures. Individual differences in sexual behavior are likely partially mediated by individual genetic variation in genes coding for motivation and reward in the brain. Conceptualizing these findings in terms of r/K selection theory suggests a mechanism for selective pressure for and against the 7R+ genotype that may explain the considerable global allelic variation for this polymorphism. PMID:21152404
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Directory of Open Access Journals (Sweden)
Justin R Garcia
2010-11-01
Full Text Available Human sexual behavior is highly variable both within and between populations. While sex-related characteristics and sexual behavior are central to evolutionary theory (sexual selection, little is known about the genetic bases of individual variation in sexual behavior. The variable number tandem repeats (VNTR polymorphism in exon III of the human dopamine D4 receptor gene (DRD4 has been correlated with an array of behavioral phenotypes and may be predicatively responsible for variation in motivating some sexual behaviors, particularly promiscuity and infidelity.We administered an anonymous survey on personal history of sexual behavior and intimate relationships to 181 young adults. We also collected buccal wash samples and genotyped the DRD4 VNTR. Here we show that individuals with at least one 7-repeat allele (7R+ report a greater categorical rate of promiscuous sexual behavior (i.e., having ever had a "one-night stand" and report a more than 50% increase in instances of sexual infidelity.DRD4 VNTR genotype varies considerably within and among populations and has been subject to relatively recent, local selective pressures. Individual differences in sexual behavior are likely partially mediated by individual genetic variation in genes coding for motivation and reward in the brain. Conceptualizing these findings in terms of r/K selection theory suggests a mechanism for selective pressure for and against the 7R+ genotype that may explain the considerable global allelic variation for this polymorphism.
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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 ...
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Suckling, D M; Dymock, J J; Park, K C; Wakelin, R H; Jamieson, L E
2013-09-01
The guava moth, Coscinoptycha improbana, an Australian species that infests fruit crops in commercial and home orchards, was first detected in New Zealand in 1997. A four-component pheromone blend was identified but is not yet commercially available. Using single sensillum recordings from male antennae, we established that the same olfactory receptor neurons responded to two guava moth sex pheromone components, (Z)-11-octadecen-8-one and (Z)-12-nonadecen-9-one, and to a chain length analog, (Z)-13-eicosen-10-one, the sex pheromone of the related peach fruit moth, Carposina sasakii. We then field tested whether this non-specificity of the olfactory neurons might enable disruption of sexual communication by the commercially available analog, using male catch to synthetic lures in traps in single-tree, nine-tree and 2-ha plots. A disruptive pheromone analog, based on chain length, is reported for the first time. Trap catches for guava moth were disrupted by three polyethylene tubing dispensers releasing the analog in single-tree plots (86% disruption of control catches) and in a plots of nine trees (99% disruption). Where peach fruit moth pheromone dispensers were deployed at a density of 1000/ha in two 2-ha areas, pheromone traps for guava moth were completely disrupted for an extended period (up to 470 days in peri-urban gardens in Mangonui and 422 days in macadamia nut orchards in Kerikeri). In contrast, traps in untreated areas over 100 m away caught 302.8 ± 128.1 moths/trap in Mangonui and 327.5 ± 78.5 moths/ trap in Kerikeri. The longer chain length in the pheromone analog has greater longevity than the natural pheromone due to its lower volatility. Chain length analogs may warrant further investigation for mating disruption in Lepidoptera, and screening using single-sensillum recording is recommended.
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[Technological convergence will quickly generate disruptive innovations in oncology].
Coucke, Ph A
2016-06-01
Convergence between information and communication technology and recent developments in medical care will totally change the health care sector. The way we perform diagnosis, treatment and follow-up will undergo disruptive changes in a very near future. We intend to highlight this statement by a limited selection of examples of radical innovations, especially in the field of oncology. To be totally disruptive and to illustrate the concept of "lateral power" - especially cognitive distribution - the list of references is only made up of internet links. Anyone - patients included - can easily and instantly access to this information everywhere.
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Sexual dysfunction and cardiovascular diseases: a systematic review of prevalence
Directory of Open Access Journals (Sweden)
Elisabete Rodrigues Nascimento
2013-11-01
Full Text Available The aim of this study was to conduct a systematic review of the literature regarding the prevalence of sexual dysfunction in patients with cardiovascular diseases. An article search of the ISI Web of Science and PubMed databases using the search terms "sexual dysfunction”, “cardiovascular diseases”, “coronary artery disease", “myocardial infarct" and “prevalence” was performed. In total, 893 references were found. Non-English-language and repeated references were excluded. After an abstract analysis, 91 references were included for full-text reading, and 24 articles that evaluated sexual function using validated instruments were selected for this review. This research was conducted in October 2012, and no time restrictions were placed on any of the database searches. Reviews and theoretical articles were excluded; only clinical trials and epidemiological studies were selected for this review. The studies were mostly cross-sectional, observational and case-control in nature; other studies used prospective cohort or randomized clinical designs. In women, all domains of sexual function (desire, arousal, vaginal lubrication, orgasm, sexual dissatisfaction and pain were affected. The domains prevalent in men included erectile dysfunction and premature ejaculation and orgasm. Sexual dysfunction was related to the severity of cardiovascular disease. When they resumed sexual activity, patients with heart disease reported significant difficulty, including a lack of interest in sex, sexual dissatisfaction and a decrease in the frequency of sexual activity.
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Evolution and maintenance of sexual size dimorphism: Aligning phylogenetic and experimental evidence
Directory of Open Access Journals (Sweden)
Matjaz eKuntner
2014-06-01
Full Text Available Integrating the insights derived from both phylogenetic and experimental approaches offers a more complete understanding of evolutionary patterns and processes, yet it is rarely a feature of investigations of the evolutionary significance of trait variation. We combine these approaches to reinterpret the patterns and processes in the evolution of female biased sexual size dimorphism in Nephilidae, a spider lineage characterized by the most extreme sexual size dimorphism among terrestrial animals. We use a molecular phylogeny to reconstruct the size evolution for each sex and reveal a case of sexually dimorphic gigantism: both sexes steadily outgrow their ancestral sizes, but the female and male slopes differ, and hence sexual size dimorphism steadily increases. A review of the experimental evidence reveals a predominant net selection for large size in both sexes, consistent with the phylogenetic pattern for females but not for males. Thus, while sexual size dimorphism in spiders most likely originates and is maintained by fecundity selection on females, it is unclear what selection pressures prevent males from becoming as large as females. This integrated approach highlights the dangers of inferring evolutionary significance from experimental studies that isolate the effects of single selection pressures.
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Vannier, Sarah A; Rosen, Natalie O
2017-03-01
Sexual problems are common during pregnancy, but the proportion of pregnant women who experience sexual distress is unknown. In non-pregnant samples, sexual distress is associated with lower sexual and relationship satisfaction. To identify the proportion of women experiencing sexual distress during pregnancy and to compare the sexual and relationship satisfaction of women who report sexual distress during pregnancy with that of women without distress. Two-hundred sixty-one pregnant women completed a cross-sectional online survey. Women completed validated measurements of sexual functioning (Female Sexual Function Index; score sexual problem), sexual distress (Female Sexual Distress Scale; score ≥ 15 indicates clinically significant distress), sexual satisfaction (Global Measure of Sexual Satisfaction), and relationship satisfaction (Couples Satisfaction Index). Overall, 42% of women met the clinical cutoff for sexual distress. Of sexually active women (n = 230), 26% reported concurrent sexual problems and distress and 14% reported sexual distress in the absence of sexual problems. Sexual distress and/or problems in sexual functioning were linked to lower sexual and relationship satisfaction compared with pregnant women with lower sexual distress and fewer sexual problems. Sexual distress is common during pregnancy and associated with lower sexual and relationship satisfaction. Health care providers should ask pregnant women about feelings of sexual distress. Identifying pregnant women who experience sexual distress and referring them to appropriate resources could help minimize sexual and relationship problems during pregnancy. Vannier SA, Rosen NO. Sexual Distress and Sexual Problems During Pregnancy: Associations With Sexual and Relationship Satisfaction. J Sex Med 2017;14:387-395. Copyright © 2017 International Society for Sexual Medicine. Published by Elsevier Inc. All rights reserved.
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Pateau, Victoire; Razafimandimby, Bienvenue; Vandeputte, Patrick; Thornton, Christopher R; Guillemette, Thomas; Bouchara, Jean-Philippe; Giraud, Sandrine
2018-02-01
Scedosporium species are opportunistic pathogens responsible for a large variety of infections in humans. An increasing occurrence was observed in patients with underlying conditions such as immunosuppression or cystic fibrosis. Indeed, the genus Scedosporium ranks the second among the filamentous fungi colonizing the respiratory tracts of the CF patients. To date, there is very scarce information on the pathogenic mechanisms, at least in part because of the limited genetic tools available. In the present study, we successfully developed an efficient transformation and targeted gene disruption approach on the species Scedosporium aurantiacum. The disruption cassette was constructed using double-joint PCR procedure, and resistance to hygromycin B as the selection marker. This proof of concept was performed on the functional gene SODC encoding the Cu,Zn-superoxide dismutase. Disruption of the SODC gene improved susceptibility of the fungus to oxidative stress. This technical advance should open new research areas and help to better understand the biology of Scedosporium species.
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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.
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Cross-sex genetic correlation does not extend to sexual size dimorphism in spiders
Turk, Eva; Kuntner, Matjaž; Kralj-Fišer, Simona
2018-02-01
Males and females are often subjected to different selection pressures for homologous traits, resulting in sex-specific optima. Because organismal attributes usually share their genetic architectures, sex-specific selection may lead to intralocus sexual conflict. Evolution of sexual dimorphism may resolve this conflict, depending on the degree of cross-sex genetic correlation ( r MF) and the strength of sex-specific selection. In theory, high r MF implies that sexes largely share the genetic base for a given trait and are consequently sexually monomorphic, while low r MF indicates a sex-specific genetic base and sexual dimorphism. Here, we broadly test this hypothesis on three spider species with varying degrees of female-biased sexual size dimorphism, Larinioides sclopetarius (sexual dimorphism index, SDI = 0.85), Nuctenea umbratica (SDI = 0.60), and Zygiella x-notata (SDI = 0.46). We assess r MF via same-sex and opposite-sex heritability estimates. We find moderate body mass heritability but no obvious patterns in sex-specific heritability. Against the prediction, the degree of sexual size dimorphism is unrelated to the relative strength of same-sex versus opposite-sex heritability. Our results do not support the hypothesis that sexual size dimorphism is negatively associated with r MF. We conclude that sex-specific genetic architecture may not be necessary for the evolution of a sexually dimorphic trait.
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International Nuclear Information System (INIS)
Bondeson, A.
1987-01-01
This paper discusses major and minor disruptions in Tokamaks. A number of models and numerical simulations of disruptions based on resistive MHD are reviewed. A discussion is given of how disruptive current profiles are correlated with the experimentally known operational limits in density and current. It is argued that the q a =2 limit is connected with stabilization of the m=2/n=1 tearing mode for a approx.< 2.7 by resistive walls and mode rotation. Experimental and theoretical observations indicate that major disruptions usually occur in at least two phases, first a 'predisruption', or loss of confinement in the region 1 < q < 2, leaving the q approx.= 1 region almost unaffected, followed by a final disruption of the central part, interpreted here as a toroidal n = 1 external kink mode. (author)
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The effect of music on repetitive disruptive vocalizations of persons with dementia.
Casby, J A; Holm, M B
1994-10-01
This study examined the effect of classical music and favorite music on the repetitive disruptive vocalizations of long-term-care facility (LTCF) residents with dementia of the Alzheimer's type (DAT). Three subjects diagnosed with DAT who had a history of repetitive disruptive vocalizations were selected for the study. Three single-subject withdrawal designs (ABA, ACA, and ABCA) were used to assess subjects' repetitive disruptive vocalizations during each phase: no intervention (A); relaxing, classical music (B); and favorite music (C). Classical music and favorite music significantly decreased the number of vocalizations in two of the three subjects (p < .05). These findings support a method that was effective in decreasing the disruptive vocalization pattern common in those with DAT in the least restrictive manner, as mandated by the Omnibus Budget Reconciliation Act of 1987.
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Visiting Entertainment Venues and Sexual Health in China
Li, Li; Wu, Zunyou; Rotheram-Borus, Mary Jane; Guan, Jihui; Yin, Yueping; Detels, Roger; Wu, Sheng; Lee, Sung-Jae; Cao, Haijun; Lin, Chunqing; Rou, Keming; Liu, Zhendong
2008-01-01
Entertainment venues in China are associated with risky sexual behavior. Most previous studies related to entertainment venues in China have focused on sex workers and commercial sex, but this study addressed sexual health in a sample of the general urban population. A randomly selected sample of market vendors (n = 4,510) from an eastern city was recruited and assessed to examine relationships between entertainment venue visits and sexual risk. Both behavioral (self-reports of unprotected se...
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Menstrual cycle phase alters women's sexual preferences for composers of more complex music.
Charlton, Benjamin D
2014-06-07
Over 140 years ago Charles Darwin first argued that birdsong and human music, having no clear survival benefit, were obvious candidates for sexual selection. Whereas the first contention is now universally accepted, his theory that music is a product of sexual selection through mate choice has largely been neglected. Here, I provide the first, to my knowledge, empirical support for the sexual selection hypothesis of music evolution by showing that women have sexual preferences during peak conception times for men that are able to create more complex music. Two-alternative forced-choice experiments revealed that woman only preferred composers of more complex music as short-term sexual partners when conception risk was highest. No preferences were displayed when women chose which composer they would prefer as a long-term partner in a committed relationship, and control experiments failed to reveal an effect of conception risk on women's preferences for visual artists. These results suggest that women may acquire genetic benefits for offspring by selecting musicians able to create more complex music as sexual partners, and provide compelling support for Darwin's assertion 'that musical notes and rhythm were first acquired by the male or female progenitors of mankind for the sake of charming the opposite sex'.
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Maniglio, Roberto
2015-07-01
To elucidate the significance, nature, and direction of the potential relationship between child sexual abuse and conduct disorder, all the pertinent studies were reviewed. Ten databases were searched. Blind assessments of study eligibility and quality were performed by two independent researchers. Thirty-six studies including 185,358 participants and meeting minimum quality criteria that were enough to ensure objectivity and to not invalidate results were analyzed. Across the majority of studies, conduct disorder was significantly and directly related to child sexual abuse, especially repeated sexual molestation and abuse involving penetration, even after controlling for various sociodemographic, family, and clinical variables. The association between child sexual abuse and conduct disorder was not confounded by other risk factors, such as gender, socioeconomic status, school achievement, substance problems, physical abuse, parental antisocial behavior or substance problems, parent-child relationships, and family disruption, conflict, or violence. Evidence for a significant interactive effect between child sexual abuse and monoamine oxidase A gene on conduct disorder was scant. Early sexual abuse might predispose to the subsequent onset of conduct disorder which, in turn, may lead to further sexual victimization through association with sexually abusive peers or involvement in dangerous situations or sexual survival strategies. © The Author(s) 2014.
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Sexual Orientation and Spatial Position Effects on Selective Forms of Object Location Memory
Rahman, Qazi; Newland, Cherie; Smyth, Beatrice Mary
2011-01-01
Prior research has demonstrated robust sex and sexual orientation-related differences in object location memory in humans. Here we show that this sexual variation may depend on the spatial position of target objects and the task-specific nature of the spatial array. We tested the recovery of object locations in three object arrays (object…
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The Rectal Cancer Female Sexuality Score
DEFF Research Database (Denmark)
Thyø, Anne; Emmertsen, Katrine J; Laurberg, Søren
2018-01-01
BACKGROUND: Sexual dysfunction and impaired quality of life is a potential side effect to rectal cancer treatment. OBJECTIVE: The objective of this study was to develop and validate a simple scoring system intended to evaluate sexual function in women treated for rectal cancer. DESIGN......: This is a population-based cross-sectional study. SETTINGS: Female patients diagnosed with rectal cancer between 2001 and 2014 were identified by using the Danish Colorectal Cancer Group's database. Participants filled in the validated Sexual Function Vaginal Changes questionnaire. Women declared to be sexually active...... in the validation group. PATIENTS: Female patients with rectal cancer above the age of 18 who underwent abdominoperineal resection, Hartmann procedure, or total/partial mesorectal excision were selected. MAIN OUTCOME MEASURES: The primary outcome measured was the quality of life that was negatively affected because...
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Degendering (sexual) violence in intimate relationships
DEFF Research Database (Denmark)
Bertelsen, Eva; Østerby Sørensen, William; Jensen, Mathilde Worch
2018-01-01
Even though Denmark in many respects shows some of the most gender equality rates in the world, the rates of physical and/or sexual violence against women in Denmark are among the highest in Europe. In this article we seek to describe state responses to these figures. We do so by investigating...... the symbolic representations of sexual violence in intimate relationships, framing contemporary political/societal developments of the Danish field of welfare work addressing violence in intimate relationships as well as the dominating knowledge production substantiating these. Theoretically, Slavoj Zizek...... and his concept objective violence inform the paper, in order to analyze authoritative representations of ‘sexual violence in intimate relationships’ in three areas: Danish legislation and legal practices, Danish research on sexual violence, and policy-papers. Thus the Danish Criminal Code, selected...
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Effects of combined exposure to anti-androgens on development and sexual dimorphic behaviour in rats
DEFF Research Database (Denmark)
Christiansen, Sofie
Summary Background: Androgens are key regulators of male sexual differentiation during the in utero and early postnatal development. Exposure to endocrine disrupting chemicals (EDCs) that counteract androgen action at some stage in these periods can permanently demasculinise male foetuses and lead......? Is sexually dimorphic behaviour in rats affected at lower dose levels of anti-androgens and thereby a more sensitive endpoint than morphological effects on the male external reproductive organs? The thesis is based on the results of in vivo studies where mated female Wistar rats were exposed to anti......-androgens either alone or in mixtures during pregnancy and lactation. The endpoints examined for anti-androgenic effects in the offspring were: Anogenital distance (AGD), nipple retention (NR), and external (morphological) malformations in pups and sexually mature male rats. Furthermore, the effects of the anti...
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Efficient gene replacements in ku70 disruption strain of Aspergillus chevalieri var. intermedius
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Qingqing Huang
2017-01-01
Full Text Available Aspergillus chevalieri var. intermedius is a dominant filamentous fungal species in Fuzhuan tea and is associated with the quality and health benefits of this tea. The sexual or asexual reproduction of this fungus depends on the osmotic pressure of the tea. Efforts to enhance the beneficial effects of A. chevalieri var. intermedius are hampered by difficulties in disrupting its genes. To address this issue, we identified the A. chevalieri var. intermedius homolog (Acku70 of human Ku70 and generated an Acku70 disruption strain (ΔAcku70, aiming to improve the gene replacement efficiency. ΔAcku70 grew at a slightly lower rate in vitro than the wild-type strain; however, the two strains exhibited similar sensitivity to temperature, osmotic pressure and the effects of ethyl methane sulphonate and H2O2. The replacement efficiency of veA and flbA dramatically increased in ΔAcku70 compared to that in the wild type. The efficiency of flbA replacement increased from 2.6% to 80%, whereas the frequency of veA disruption increased from 15.2% to 83.9% and from 30.8% to 86.8%. Thus, ΔAcku70 is suitable for use as a type strain for large-scale functional genomic analysis of A. chevalieri var. intermedius.
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Developmental toxicity of endocrine disrupters bisphenol A and vinclozolin in a terrestrial isopod.
Lemos, M F L; van Gestel, C A M; Soares, A M V M
2010-08-01
Studies of the effects of endocrine-disrupting compounds (EDCs) on invertebrates are still largely underrepresented. This work aims to fill this gap by assessing the effects of bisphenol A (BPA) and vinclozolin (Vz) on the terrestrial isopod Porcellio scaber (common rough woodlouse). Male adult and sexually undifferentiated juvenile woodlice were exposed to the toxicants. Effects on molting regime and growth were investigated independently for males and female woodlice after sexual differentiation. Both chemicals elicited developmental toxicity to P. scaber by causing overall decreased growth. Nevertheless, BPA induced molting, whereas Vz delayed it. Although the LC50 values for juvenile and adult survival were fairly similar, juvenile woodlice showed an increased chronic sensitivity to both chemicals, and female woodlice were most the sensitive to BPA. We recommend the use of adults, juveniles, female, and male woodlice, as well as a large range of toxicant concentrations, to provide valuable information regarding differential dose responses, effects, and threshold values for EDCs.
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Sexual conflict predicts morphology and behavior in two species of penduline tits
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Komdeur Jan
2010-04-01
Full Text Available Abstract Background The evolutionary interests of males and females rarely coincide (sexual conflict, and these conflicting interests influence morphology, behavior and speciation in various organisms. We examined consequences of variation in sexual conflict in two closely-related passerine birds with contrasting breeding systems: the Eurasian penduline tit Remiz pendulinus (EPT exhibiting a highly polygamous breeding system with sexually antagonistic interests over parental care, and the socially monogamous Cape penduline tit Anthoscopus minutus (CPT. We derived four a priori predictions from sexual conflict theory and tested these using data collected in Central Europe (EPT and South Africa (CPT. Firstly, we predicted that EPTs exhibit more sexually dimorphic plumage than CPTs due to more intense sexual selection. Secondly, we expected brighter EPT males to provide less care than duller males. Thirdly, since song is a sexually selected trait in many birds, male EPTs were expected to exhibit more complex songs than CPT males. Finally, intense sexual conflict in EPT was expected to lead to low nest attendance as an indication of sexually antagonistic interests, whereas we expected more cooperation between parents in CPT consistent with their socially monogamous breeding system. Results Consistent with our predictions EPTs exhibited greater sexual dimorphism in plumage and more complex song than CPTs, and brighter EPT males provided less care than duller ones. EPT parents attended the nest less frequently and less simultaneously than CPT parents. Conclusions These results are consistent with sexual conflict theory: species in which sexual conflict is more manifested (EPT exhibited a stronger sexual dimorphism and more elaborated sexually selected traits than species with less intense sexual conflict (CPT. Our results are also consistent with the notion that EPTs attempt to force their partner to work harder as expected under sexual conflict: each
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Sexual conflict predicts morphology and behavior in two species of penduline tits.
van Dijk, René E; Pogány, Akos; Komdeur, Jan; Lloyd, Penn; Székely, Tamás
2010-04-23
The evolutionary interests of males and females rarely coincide (sexual conflict), and these conflicting interests influence morphology, behavior and speciation in various organisms. We examined consequences of variation in sexual conflict in two closely-related passerine birds with contrasting breeding systems: the Eurasian penduline tit Remiz pendulinus (EPT) exhibiting a highly polygamous breeding system with sexually antagonistic interests over parental care, and the socially monogamous Cape penduline tit Anthoscopus minutus (CPT). We derived four a priori predictions from sexual conflict theory and tested these using data collected in Central Europe (EPT) and South Africa (CPT). Firstly, we predicted that EPTs exhibit more sexually dimorphic plumage than CPTs due to more intense sexual selection. Secondly, we expected brighter EPT males to provide less care than duller males. Thirdly, since song is a sexually selected trait in many birds, male EPTs were expected to exhibit more complex songs than CPT males. Finally, intense sexual conflict in EPT was expected to lead to low nest attendance as an indication of sexually antagonistic interests, whereas we expected more cooperation between parents in CPT consistent with their socially monogamous breeding system. Consistent with our predictions EPTs exhibited greater sexual dimorphism in plumage and more complex song than CPTs, and brighter EPT males provided less care than duller ones. EPT parents attended the nest less frequently and less simultaneously than CPT parents. These results are consistent with sexual conflict theory: species in which sexual conflict is more manifested (EPT) exhibited a stronger sexual dimorphism and more elaborated sexually selected traits than species with less intense sexual conflict (CPT). Our results are also consistent with the notion that EPTs attempt to force their partner to work harder as expected under sexual conflict: each member of the breeding pair attempts to shift the
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Selection gradients, the opportunity for selection, and the coefficient of determination.
Moorad, Jacob A; Wade, Michael J
2013-03-01
Abstract We derive the relationship between R(2) (the coefficient of determination), selection gradients, and the opportunity for selection for univariate and multivariate cases. Our main result is to show that the portion of the opportunity for selection that is caused by variation for any trait is equal to the product of its selection gradient and its selection differential. This relationship is a corollary of the first and second fundamental theorems of natural selection, and it permits one to investigate the portions of the total opportunity for selection that are involved in directional selection, stabilizing (and diversifying) selection, and correlational selection, which is important to morphological integration. It also allows one to determine the fraction of fitness variation not explained by variation in measured phenotypes and therefore attributable to random (or, at least, unknown) influences. We apply our methods to a human data set to show how sex-specific mating success as a component of fitness variance can be decoupled from that owing to prereproductive mortality. By quantifying linear sources of sexual selection and quadratic sources of sexual selection, we illustrate that the former is stronger in males, while the latter is stronger in females.
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Fitzpatrick, John L; Simmons, Leigh W; Evans, Jonathan P
2012-08-01
Assessing how selection operates on several, potentially interacting, components of the ejaculate is a challenging endeavor. Ejaculates can be subject to natural and/or sexual selection, which can impose both linear (directional) and nonlinear (stabilizing, disruptive, and correlational) selection on different ejaculate components. Most previous studies have examined linear selection of ejaculate components and, consequently, we know very little about patterns of nonlinear selection on the ejaculate. Even less is known about how selection acts on the ejaculate as a functionally integrated unit, despite evidence of covariance among ejaculate components. Here, we assess how selection acts on multiple ejaculate components simultaneously in the broadcast spawning sessile invertebrate Mytilus galloprovincialis using the statistical tools of multivariate selection analyses. Our analyses of relative fertilization rates revealed complex patterns of selection on sperm velocity, motility, and morphology. Interestingly, the most successful ejaculates were made up of slower swimming sperm with relatively low percentages of motile cells, and sperm with smaller head volumes that swam in highly pronounced curved swimming trajectories. These results are consistent with an emerging body of literature on fertilization kinetics in broadcast spawners, and shed light on the fundamental nature of selection acting on the ejaculate as a functionally integrated unit. © 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.
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There has been increasing concern that low-dose exposure to hormonally active chemicals disrupts sexual differentiation of the brain and peripheral nervous system. There also has been active drug development research on the therapeutic potential of hormone therapy on behaviors. T...
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Original article Sexual self-esteem and sexual needs of young adults with cerebral palsy
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Klaudia Czapla
2014-10-01
Full Text Available Background Sexuality is an important part of human existence, irrespective of race, religion or level of physical fitness. It can, however, be treated and exhibited by individuals in very different ways. The place of sexuality in a person’s life, and in the way it is materialised, is determined by a number of biopsychosocial factors. For some, the presence of these factors and their influence is not a matter of choice. They may arise as a consequence of the psychophysical condition of their organism. People with motor disabilities undoubtedly belong to this group. Participants and procedure The study was carried out in Poland on a group of 61 people with roughly equal proportions of men and women. Subject selection was non-random; every subject was diagnosed with cerebral palsy (CP and was aged between 15 and 25. All of the subjects had normal levels of intelligence. Two methods were used in the study: Sexual Self-esteem Scale and Sexual Needs Scale. Results The results in terms of sexual self-esteem and sexual needs allowed two different subgroups of subjects to be distinguished (H – with high scores; L – with low scores. The analysis of significance levels of the differences in terms of sexual self-esteem and sexual needs between subgroups H and L confirmed the clear distinction between each of the subgroups’ clinical pictures (p < .001 in 20 out of 21 of the analysed aspects. Falling in love was the only matter that did not differentiate the subgroups. Conclusions There is a clear polarization of the results. Only 1/3 of the respondents had high sexual self-esteem and sexual needs. The remaining 2/3 reported having a rather low sexual self-esteem and low levels of needs with regards to their own sexuality. It needs to be stressed that CP-affected youth, similarly to their peers, may need support in discovering their sexuality and satisfying their sexual needs (2/3 of the respondents. The specifics of the range of support should
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Male sexual harassment alters female social behaviour towards other females.
Darden, Safi K; Watts, Lauren
2012-04-23
Male harassment of females to gain mating opportunities is a consequence of an evolutionary conflict of interest between the sexes over reproduction and is common among sexually reproducing species. Male Trinidadian guppies Poecilia reticulata spend a large proportion of their time harassing females for copulations and their presence in female social groups has been shown to disrupt female-female social networks and the propensity for females to develop social recognition based on familiarity. In this study, we investigate the behavioural mechanisms that may lead to this disruption of female sociality. Using two experiments, we test the hypothesis that male presence will directly affect social behaviours expressed by females towards other females in the population. In experiment one, we tested for an effect of male presence on female shoaling behaviour and found that, in the presence of a free-swimming male guppy, females spent shorter amounts of time with other females than when in the presence of a free-swimming female guppy. In experiment two, we tested for an effect of male presence on the incidence of aggressive behaviour among female guppies. When males were present in a shoal, females exhibited increased levels of overall aggression towards other females compared with female only shoals. Our work provides direct evidence that the presence of sexually harassing males alters female-female social behaviour, an effect that we expect will be recurrent across taxonomic groups.
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Adeniyi, W. O.; Okewole, J. O.
2014-01-01
The study examined the influence of knowledge and awareness of sexually transmitted diseases on change in sexual behaviour of fresh undergraduates with a view to providing useful suggestions for positive sexual behaviour of adolescents. The study adopted the descriptive survey design. A sample of 600 fresh undergraduates was selected from the…
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Sá, Susana I; Teixeira, Natércia; Fonseca, Bruno M
2018-01-01
Tamoxifen (TAM) is a selective estrogen receptor modulator, widely used in the treatment and prevention of estrogen-dependent breast cancer. Although with great clinical results, women on TAM therapy still report several side effects, such as sexual dysfunction, which impairs quality of life. The anatomo-functional substrates of the human sexual behavior are still unknown; however, these same substrates are very well characterized in the rodent female sexual behavior, which has advantage of being a very simple reflexive response, dependent on the activation of estrogen receptors (ERs) in the ventrolateral division of the hypothalamic ventromedial nucleus (VMNvl). In fact, in the female rodent, the sexual behavior is triggered by increasing circulation levels of estradiol that changes the nucleus neurochemistry and modulates its intricate neuronal network. Therefore, we considered of notice the examination of the possible neurochemical alterations and the synaptic plasticity impairment in VMNvl neurons of estradiol-primed female rats treated with TAM that may be in the basis of this neurological disorder. Accordingly, we used stereological and biochemical methods to study the action of TAM in axospinous and axodendritic synaptic plasticity and on ER expression. The administration of TAM changed the VMNvl neurochemistry by reducing ERα mRNA and increasing ERβ mRNA expression. Furthermore, present results show that TAM induced neuronal atrophy and reduced synaptic connectivity, favoring electrical inactivity. These data suggest that these cellular and molecular changes may be a possible neuronal mechanism of TAM action in the disruption of the VMNvl network, leading to the development of behavioral disorders. Copyright © 2017 Elsevier Inc. All rights reserved.
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Soler, J J; Moreno, J
2012-08-01
Wallace proposed in 1868 that natural rather than sexual selection could explain the striking differences in avian plumage dichromatism. Thus, he predicted that nesting habits, through their association with nest predation, could drive changes in sexual dichromatism by enabling females in cavity nesters to become as conspicuous as males, whereas Darwin (1871, The Descent of Man and Selection in Relation to Sex, John Murray, London) argued that sexual selection was the sole explanation for dichromatism. Sexual dichromatism is currently used as indicating the strength of sexual selection, and therefore testing Wallace's claim with modern phylogentically controlled methodologies is of prime interest for comparing the roles of natural and sexual selection in affecting the evolution of avian coloration. Here, we have related information on nest attendance, sexual dichromatism and nesting habits (open and cavity nesting) to male and female plumage conspicuousness in European passerines. Nest incubation attendance does not explain male or female plumage conspicuousness but nest type does. Moreover, although females of monochromatic and cavity nesting species are more conspicuous than females of other species, males of monochromatic and open nesting species are those with more cryptic plumage. Finally, analyses of character evolution suggest that changes in nesting habits influence the probability of changes in both dichromatism and plumage conspicuousness of males but do not significantly affect those in females. These results strongly suggest a role of nesting habits in the evolution of plumage conspicuousness of males, and a role for sexual selection also in females, both factors affecting the evolution of sexual dichromatism. We discuss our findings in relation to the debate that Darwin and Wallace maintained more than one century ago on the importance of natural and sexual selection in driving the evolution of plumage conspicuousness and sexual dichromatism in birds
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Adolescent Sexual Decision-Making: An Integrative Review.
Hulton, Linda J.
2001-10-03
PURPOSE: The purpose of this integrative review was to summarize the present literature to identify factors associated with adolescent sexual decision-making. Thirty-eight salient research studies were selected as a basis of this review from the databases of Medline, CINAHL, and Psychinfo using the Cooper methodology. CONCLUSIONS: Two categories of decision-making were identified: 1) The research on factors related to the decisions that adolescents make to become sexually active or to abstain from sexual activity; 2) The research on factors related to contraceptive decision-making. The most consistent findings were that the factors of gender differences, cognitive development, perception of benefits, parental influences, social influences, and sexual knowledge were important variables in the decision-making processes of adolescents. IMPLICATIONS: Practice implications for nursing suggest that clinicians should assess adolescent sexual decision-making in greater detail and address the social and psychological context in which sexual experiences occur. Nurses must be aware of the differences between adolescent and adult decision-making processes and incorporate knowledge of growth and development into intervention strategies. Moreover, to the degree that adolescent sexual decision-making proves to be less than rational, interventions designed to improve competent sexual decision-making are needed.
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Persistent sexual dysfunction after early exposure to SSRIs
DEFF Research Database (Denmark)
Simonsen, Anders Lykkemark; Danborg, Pia Brandt; Gøtzsche, Peter Christian
2016-01-01
BACKGROUND: Sexual dysfunction is a common adverse effect of selective serotonin reuptake inhibitors (SSRIs) and there is a concern that the sexual harms might persist after discontinuation of therapy. OBJECTIVE: To assess whether the use of SSRIs in animals can lead to persistent sexual...... dysfunction. METHODS: Systematic review of animal studies measuring sexual behaviour after end of treatment with SSRIs or serotonin norepinephrine reuptake inhibitors. DATA SOURCES: We searched PubMed and EMBASE. RESULTS: We included 14 studies. The general quality of the studies was poor. Only four studies.......74; 95% CI = 0.60-0.92) and no ejaculation behaviour (RR = 0.49, 95% CI = 0.24-1.00). CONCLUSION: Our results showed substantial and lasting effects on sexual behaviour in rats after exposure to an SSRI early in life on important sexual outcomes....
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The impact of mental illness on sexual dysfunction.
Zemishlany, Zvi; Weizman, Abraham
2008-01-01
Sexual dysfunction is prevalent among psychiatric patients and may be related to both the psychopathology and the pharmacotherapy. The negative symptoms of schizophrenia limit the capability for interpersonal and sexual relationships. The first-generation antipsychotics cause further deterioration in erectile and orgasmic function. Due to their weak antagonistic activity at D2 receptors, second-generation antipsychotics are associated with fewer sexual side effects, and thus may provide an option for schizophrenia patients with sexual dysfunction. Depression and anxiety are a cause for sexual dysfunction that may be aggravated by antidepressants, especially selective serotonin reuptake inhibitors (SSRIs). SSRI-induced sexual dysfunction may be overcome by lowering doses, switching to an antidepressant with low propensity to cause sexual dysfunction (bupropion, mirtazapine, nefazodone, reboxetine), addition of 5HT2 antagonists (mirtazapine, mianserin) or coadministration of 5-phosphodiesterase inhibitors. Eating disorders and personality disorders, mainly borderline personality disorder, are also associated with sexual dysfunction. Sexual dysfunction in these cases stems from impaired interpersonal relationships and may respond to adequate psychosexual therapy. It is mandatory to identify the specific sexual dysfunction and to treat the patients according to his/her individual psychopathology, current pharmacotherapy and interpersonal relationships.
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Regret Expression and Social Learning Increases Delay to Sexual Gratification.
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Amanda J Quisenberry
Full Text Available Modification and prevention of risky sexual behavior is important to individuals' health and public health policy. This study employed a novel sexual discounting task to elucidate the effects of social learning and regret expression on delay to sexual gratification in a behavioral task.Amazon Mechanical Turk Workers were assigned to hear one of three scenarios about a friend who engages in similar sexual behavior. The scenarios included a positive health consequence, a negative health consequence or a negative health consequence with the expression of regret. After reading one scenario, participants were asked to select from 60 images, those with whom they would have casual sex. Of the selected images, participants chose one image each for the person they most and least want to have sex with and person most and least likely to have a sexually transmitted infection. They then answered questions about engaging in unprotected sex now or waiting some delay for condom-protected sex in each partner condition.Results indicate that the negative health outcome scenario with regret expression resulted in delayed sexual gratification in the most attractive and least STI partner conditions, whereas in the least attractive and most STI partner conditions the negative health outcome with and without regret resulted in delayed sexual gratification.Results suggest that the sexual discounting task is a relevant laboratory measure and the framing of information to include regret expression may be relevant for prevention of risky sexual behavior.
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Sexual conflict arising from extrapair matings in birds.
Chaine, Alexis S; Montgomerie, Robert; Lyon, Bruce E
2015-01-20
The discovery that extrapair copulation (EPC) and extrapair paternity (EPP) are common in birds led to a paradigm shift in our understanding of the evolution of mating systems. The prevalence of extrapair matings in pair-bonded species sets the stage for sexual conflict, and a recent focus has been to consider how this conflict can shape variation in extrapair mating rates. Here, we invert the causal arrow and consider the consequences of extrapair matings for sexual conflict. Extrapair matings shift sexual conflict from a simple two-player (male vs. female) game to a game with three or more players, the nature of which we illustrate with simple diagrams that highlight the net costs and benefits of extrapair matings to each player. This approach helps identify the sorts of traits that might be under selection because of sexual conflict. Whether EPP is driven primarily by the extrapair male or the within-pair female profoundly influences which players are in conflict, but the overall pattern of conflict varies little among different mating systems. Different aspects of conflict are manifest at different stages of the breeding cycle and can be profitably considered as distinct episodes of selection caused by conflict. This perspective is illuminating both because conflict between specific players can change across episodes and because the traits that evolve to mediate conflict likely differ between episodes. Although EPP clearly leads to sexual conflict, we suggest that the link between sexual conflict and multiple paternity might be usefully understood by examining how deviations from lifetime sexual monogamy influence sexual conflict. Copyright © 2015 Cold Spring Harbor Laboratory Press; all rights reserved.
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Wound Disruption Following Colorectal Operations.
Moghadamyeghaneh, Zhobin; Hanna, Mark H; Carmichael, Joseph C; Mills, Steven; Pigazzi, Alessio; Nguyen, Ninh T; Stamos, Michael J
2015-12-01
Postoperative wound disruption is associated with high morbidity and mortality. We sought to identify the risk factors and outcomes of wound disruption following colorectal resection. The American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database was used to examine the clinical data of patients who underwent colorectal resection from 2005 to 2013. Multivariate regression analysis was performed to identify risk factors of wound disruption. We sampled a total of 164,297 patients who underwent colorectal resection. Of these, 2073 (1.3 %) had wound disruption. Patients with wound disruption had significantly higher mortality (5.1 vs. 1.9 %, AOR: 1.46, P = 0.01). The highest risk of wound disruption was seen in patients with wound infection (4.8 vs. 0.9 %, AOR: 4.11, P disruption such as chronic steroid use (AOR: 1.71, P disruption compared to open surgery (AOR: 0.61, P disruption occurs in 1.3 % of colorectal resections, and it correlates with mortality of patients. Wound infection is the strongest predictor of wound disruption. Chronic steroid use, obesity, severe COPD, prolonged operation, non-elective admission, and serum albumin level are strongly associated with wound disruption. Utilization of the laparoscopic approach may decrease the risk of wound disruption when possible.
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A preference for a sexual signal keeps females safe.
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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.
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Molina, R; Araa, S; Ibazeta, G; Jordan, P; Lagos, E
1987-01-01
A survey of knowledge, attitude, and practices regarding human reproduction and sexuality was undertaken in 2 groups of secondary school students in Chile to assess whether greater knowledge of reproduction and sexuality is associated with greater permissiveness and earlier initiation of sexual activity. Students in 2 public schools, 1 coeducational and 1 for female students only, were of lower middle class background, while students at the coeducational private school were of higher socioeconomic status. An anonymous, semiclosed questionnaire was administered to students in the 3 schools. The schools were selected because their directors agreed to permit the study. 14.8% of the 351 public school students were aged 14 or under and 77.8% were 15-18, while 99.5% of the 197 private school students were aged 15-18. The students' levels of knowledge of human reproduction and sexuality were measured through direct personal assessments by the students themselves and through 21 questions to confirm the assessments. At least 93% of students in all schools said their level of knowledge was medium or high, but the test indicated that only 64% of public school students and 75% of private school students actually had medium or high levels of knowledge. 45.9% of private and 27.9% of public school students felt the information they received from their schools about sexuality was adequate, while 41.9% of private and 60.9% of public school students felt it was insufficient. There were no significant differences in the opinions of the 2 groups of students concerning premarital sex, but the reasons given by the private school students to explain their attitudes expressed a greater sense of commitment to the partner, while those of the public school students tended to be more functional. Among public school students, 38.7% of males and 9.7% of females reported having had sexual relations, while among private school students, 17.7% of males and 4.4% of females reported having done so
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Timmerman, M. C.
2004-01-01
Objective: To explore the impact of the school climate on adolescents' reporting of sexual harassment. Design: A quantitative survey among students in their 4th year of secondary education. Setting: Questionnaires were completed in a class setting. Method: An a-select sampling strategy was used to select 2808 students in 22 schools. Results:…
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Garduño-Gutiérrez, René; León-Olea, Martha; Rodríguez-Manzo, Gabriela
2013-11-01
Male rats allowed to copulate until reaching sexual exhaustion exhibit a long-lasting sexual behavior inhibition (around 72 h) that can be reversed by systemic opioid receptor antagonist administration. Copulation activates the mesolimbic dopaminergic system (MLS) and promotes endogenous opioid release. In addition, endogenous opioids, acting at the ventral tegmental area (VTA), modulate the activity of the MLS. We hypothesized that endogenous opioids participate in the sexual exhaustion phenomenon by interacting with VTA opioid receptors and consequently, its reversal by opioid antagonists could be exerted at those receptors. In this study we determined the effects of intra-VTA infusion of different doses of the non-specific opioid receptor antagonist naltrexone (0.1-1.0 μg/rat) on the already established sexual behavior inhibition of sexually exhausted male rats. To elucidate the possible involvement of VTA δ-opioid receptors in the naltrexone-mediated reversal of sexual exhaustion, the effects of different doses of the selective δ-opioid receptor antagonist, naltrindole (0.03-1.0 μg/rat) were also tested. Results showed that intra-VTA injection of 0.3 μg naltrexone reversed the sexual inhibition of sexually exhausted rats, evidenced by an increased percentage of animals capable of showing two successive ejaculations. Intra-VTA infused naltrindole did not reverse sexual exhaustion at any dose. It is concluded that the MLS is involved in the reversal of sexual exhaustion induced by systemic naltrexone, and that μ-, but not δ-opioid receptors participate in this effect. Intra-VTA naltrexone infusion to sexually experienced male rats had an inhibitory effect on sexual activity. The opposite effects of intra-VTA naltrexone on male rat sexual behavior expression of sexually experienced and sexually exhausted rats is discussed. Copyright © 2013 Elsevier B.V. All rights reserved.
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The Shadow of Silence on the Sexual Rights of Married Iranian Women
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Roksana Janghorban
2015-01-01
Full Text Available There has been a recent shift in the field of sexual health, representing a move away from biomedical concerns to sexual rights frameworks. However, few studies on sexuality are based on a rights framework. The unspoken nature of sexuality in Iranian culture has led to a lack of national studies on the topic. The objective of this study was to explore the perceptions and experiences of married Iranian women on sexual rights in their sexual relationships. In this grounded theory study, 37 participants (25 married women, 5 husbands, and 7 midwives were selected. Data were collected through in-depth interviews and analyzed through open, axial, and selective coding using MAXQDA software version 2007. The analysis revealed the core category of “sexual interaction in the shadow of silence.” The interrelated categories subsumed under the core category included adopting a strategy of silence, trying to negotiate sex, seeking help, and sexual adjustment. The silence originating from women’s interactions with their families and society, from girlhood to womanhood, was identified as the core concept in Iranian women’s experiences of sexual rights. A focus on husbands’ roles seems salient because they can direct or alter some learned feminine roles, especially silence regarding sexual matters, which then affects the realization of women’s sexual rights.
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Breuer, Thomas; Robbins, Martha M; Boesch, Christophe
2007-11-01
Investigating sexual dimorphism is important for our understanding of its influence on reproductive strategies including male-male competition, mate choice, and sexual conflict. Measuring physical traits in wild animals can be logistically challenging and disruptive for the animals. Therefore body size and ornament variation in wild primates have rarely been quantified. Gorillas are amongst the most sexually dimorphic and dichromatic primates. Adult males (silverbacks) possess a prominent sagittal crest, a pad of fibrous and fatty tissue on top of the head, have red crest coloration, their saddle appears silver, and they possess a silverline along their stomach. Here we measure levels of sexual dimorphism and within-male variation of body length, head size, and sexual dichromatism in a population of wild western gorillas using photogrammetry. Digital photogrammetry is a useful and precise method to measure sexual dimorphism in physical traits yielding sexual dimorphism indices (ISD), similar to those derived from traditional measurements of skeletal remains. Silverbacks were on an average 1.23 times longer in body length than adult females. Sexual dimorphism of head size was highest in measures of crest size (max ISD: 60.4) compared with measures of facial height (max ISD: 24.7). The most sexually dimorphic head size measures also showed the highest within-sex variation. We found no clear sex differences in crest coloration but there was large sexual dichromatism with high within-male variation in saddle coloration and silverline size. Further studies should examine if these sexually dimorphic traits are honest signals of competitive ability and confer an advantage in reproductive success.
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Rajabizadeh, Ghodratolah; Yazdanpanah, Fatemeh; Ramezani, Mohammad Arash
2017-01-01
Background The present study was conducted with the aim of designing a causal model for the evaluation of sexual dysfunctions based on the variables of methadone dosage and sexual self-concept among individuals undergoing methadone maintenance treatment (MMT). Methods The study population of the present study consisted of married men of 20 to 45 years of age with sexual ýrelations and undergoing MMT for a minimum of 8 weeks referring to all MMT clinics of Kerman, Iran, in ýý2015-2016. ýThe subjects were selected through multi-stage cluster sampling (n = 250). Data were collected using the General Health Questionnaire (GHQ-28), Multi-Dimensional Sexual Self-concept Questionnaire (MSSQ), and Internal Index for Erectile Function (IIEF). Data were analyzed using path analysis method and Pearson correlation coefficient. The suggested model was evaluated using structural equation model (SEM), and indirect relationships were assessed using Bootstrap method. Findings The suggested model showed acceptable fitness with the data, and all routes, except methadone use route, to sexual function were significant. The result of the multiple ýindirect route showed that sexual function had a significant relationship with methadone use through ýsexual self-concept. In total, 60% of variance in sexual dysfunction was explained using the variables of the suggested model. Conclusion Further studies are suggested to be conducted regarding psychological factors effective on the sexual dysfunctions among individuals undergoing MMT, such as sexual self-concept. Moreover, more detailed evaluation of each subscale of positive and negative sexual self-concept is recommended to assess the psychological causes of sexual dysfunctions in these individuals and design psychological, behavioral, and cognitive-behavioral treatment interventions for them. PMID:29299211
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Rajabizadeh, Ghodratolah; Yazdanpanah, Fatemeh; Ramezani, Mohammad Arash
2017-04-01
The present study was conducted with the aim of designing a causal model for the evaluation of sexual dysfunctions based on the variables of methadone dosage and sexual self-concept among individuals undergoing methadone maintenance treatment (MMT). The study population of the present study consisted of married men of 20 to 45 years of age with sexual ýrelations and undergoing MMT for a minimum of 8 weeks referring to all MMT clinics of Kerman, Iran, in ýý2015-2016. ýThe subjects were selected through multi-stage cluster sampling (n = 250). Data were collected using the General Health Questionnaire (GHQ-28), Multi-Dimensional Sexual Self-concept Questionnaire (MSSQ), and Internal Index for Erectile Function (IIEF). Data were analyzed using path analysis method and Pearson correlation coefficient. The suggested model was evaluated using structural equation model (SEM), and indirect relationships were assessed using Bootstrap method. The suggested model showed acceptable fitness with the data, and all routes, except methadone use route, to sexual function were significant. The result of the multiple ýindirect route showed that sexual function had a significant relationship with methadone use through ýsexual self-concept. In total, 60% of variance in sexual dysfunction was explained using the variables of the suggested model. Further studies are suggested to be conducted regarding psychological factors effective on the sexual dysfunctions among individuals undergoing MMT, such as sexual self-concept. Moreover, more detailed evaluation of each subscale of positive and negative sexual self-concept is recommended to assess the psychological causes of sexual dysfunctions in these individuals and design psychological, behavioral, and cognitive-behavioral treatment interventions for them.
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Krantz, Megan; Goldstein, Tina; Rooks, Brian; Merranko, John; Liao, Fangzi; Gill, Mary Kay; Diler, Rasim; Hafeman, Danella; Ryan, Neal; Goldstein, Benjamin; Yen, Shirley; Hower, Heather; Hunt, Jeffrey; Keller, Martin; Strober, Michael; Axelson, David; Birmaher, Boris
2018-02-01
This study aims to document rates of sexual activity among youth with bipolar spectrum disorder (BD) and to examine demographic and clinical factors associated with first sexual activity and sexual risk behavior during follow-up. The sample was drawn from the Course and Outcome of Bipolar Youth (COBY) study of 413 youth 7 to 17 years at baseline who met criteria for bipolar spectrum disorder according to the Schedule for Affective Disorders and Schizophrenia for School-Aged Children. Psychiatric symptoms during follow-up were assessed using the Adolescent Longitudinal Interview Follow-Up Evaluation (ALIFE). Sexual behavior and level of sexual risk (e.g., unprotected sex, multiple partners, and/or partners with known sexually transmitted infections) were assessed by trained evaluators using the ALIFE Psychosocial Functioning Scale. Analyses were conducted in relation to first sexual behavior during follow-up and then to subsequent sexual behaviors (mean 9.7 years, standard deviation 3.2). Sexually active COBY youth (n = 292 of 413; 71%) were more likely females, using substances, and not living with both parents. Consistent with findings among healthy youth, earlier first sexual activity in the sample was significantly associated with low socioeconomic status, female sex, comorbid disruptive behavior disorder, and substance use. As with healthy youth, sexual risk behavior during follow-up was significantly associated with non-Caucasian race, low socioeconomic status, substance use, and history of sexual abuse. Of those COBY youth who were sexually active, 11% reported sexual assault or abuse, 36% reported becoming pregnant (or the significant other becoming pregnant), and 15% reported having at least 1 abortion (or the significant other having an abortion) during follow-up. Hypomanic symptoms during follow-up were temporally associated with the greatest risk for sexual risk behavior. Demographic and clinical factors could help identify youth with bipolar spectrum
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International Nuclear Information System (INIS)
Cannas, B.; Fanni, A.; Pautasso, G.; Sias, G.; Sonato, P.
2009-01-01
The present understanding of disruption physics has not gone so far as to provide a mathematical model describing the onset of this instability. A disruption prediction system, based on a statistical analysis of the diagnostic signals recorded during the experiments, would allow estimating the probability of a disruption to take place. A crucial point for a good design of such a prediction system is the appropriateness of the data set. This paper reports the details of the database built to train a disruption predictor based on neural networks for ASDEX Upgrade. The criteria of pulses selection, the analyses performed on plasma parameters and the implemented pre-processing algorithms, are described. As an example of application, a short description of the disruption predictor is reported.
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Rethinking our assumptions about the evolution of bird song and other sexually dimorphic signals
Directory of Open Access Journals (Sweden)
J. Jordan Price
2015-04-01
Full Text Available Bird song is often cited as a classic example of a sexually-selected ornament, in part because historically it has been considered a primarily male trait. Recent evidence that females also sing in many songbird species and that sexual dimorphism in song is often the result of losses in females rather than gains in males therefore appears to challenge our understanding of the evolution of bird song through sexual selection. Here I propose that these new findings do not necessarily contradict previous research, but rather they disagree with some of our assumptions about the evolution of sexual dimorphisms in general and female song in particular. These include misconceptions that current patterns of elaboration and diversity in each sex reflect past rates of change and that levels of sexual dimorphism necessarily reflect levels of sexual selection. Using New World blackbirds (Icteridae as an example, I critically evaluate these past assumptions in light of new phylogenetic evidence. Understanding the mechanisms underlying such sexually dimorphic traits requires a clear understanding of their evolutionary histories. Only then can we begin to ask the right questions.
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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.
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Hald, Gert Martin; Stulhofer, Aleksandar; Lange, Theis
2018-03-01
Investigations of patterns of sexual arousal to certain groups of sexually explicit media (SEM) in the general population in non-laboratory settings are rare. Such knowledge could be important to understand more about the relative specificity of sexual arousal in different SEM users. (i) To investigate whether sexual arousal to non-mainstream vs mainstream SEM contents could be categorized across gender and sexual orientation, (ii) to compare levels of SEM-induced sexual arousal, sexual satisfaction, and self-evaluated sexual interests and fantasies between non-mainstream and mainstream SEM groups, and (iii) to explore the validity and predictive accuracy of the Non-Mainstream Pornography Arousal Scale (NPAS). Online cross-sectional survey of 2,035 regular SEM users in Croatia. Patterns of sexual arousal to 27 different SEM themes, sexual satisfaction, and self-evaluations of sexual interests and sexual fantasies. Groups characterized by sexual arousal to non-mainstream SEM could be identified across gender and sexual orientation. These non-mainstream SEM groups reported more SEM use and higher average levels of sexual arousal across the 27 SEM themes assessed compared with mainstream SEM groups. Only few differences were found between non-mainstream and mainstream SEM groups in self-evaluative judgements of sexual interests, sexual fantasies, and sexual satisfaction. The internal validity and predictive accuracy of the NPAS was good across most user groups investigated. The findings suggest that in classified non-mainstream SEM groups, patterns of sexual arousal might be less fixated and category specific than previously assumed. Further, these groups are not more judgmental of their SEM-related sexual arousal patterns than groups characterized by patterns of sexual arousal to more mainstream SEM content. Moreover, accurate identification of non-mainstream SEM group membership is generally possible across gender and sexual orientation using the NPAS. Hald GM
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Energy Technology Data Exchange (ETDEWEB)
Lopez-Martinez, Giancarlo; Hahn, Daniel A [Department of Entomology and Nematology, University of Florida, Gainesville, FL (United States)
2013-01-15
Most organisms are repeatedly exposed to oxidative stress from multiple sources throughout their lifetimes, potentially affecting all aspects of organismal performance. Here we test whether exposure to a conditioning bout of anoxia early in adulthood induces a hormetic response that confers resistance to oxidative stress and enhances male sexual performance later in life in the Caribbean fruit fly, Anastrepha suspensa. Anoxic conditioning of adults prior to emergence led to an increase in antioxidant capacity driven by mitochondrial superoxide dismutase and glutathione peroxidase. When exposed to gamma irradiation, a strong oxidative stressor, males that received anoxic conditioning had lower lipid and protein oxidative damage at sexual maturity. Anoxia conditioning led to greater male sexual competitiveness compared with unconditioned males when both were irradiated, although there was no effect of anoxia conditioning on mating competitiveness in unirradiated males. Anoxia also led to higher adult emergence rates and greater flight ability in irradiation-stressed flies while preserving steriity. Thus, hormetic treatments that increased antioxidant enzyme activity also improved male performance after irradiation, suggesting that antioxidant enzymes play an important role in mediating the relationship between oxidative stress and sexual selection. Furthermore, our work has important applied implications for the sterile insect technique (SIT), an environmentally friendly method of insect pest control where males are sterilized by irradiation and deployed in the field to disrupt pest populations via mating. We suggest that hormetic treatments specifically designed to enhance antioxidant activity may produce more sexually competitive sterile males, thus improving the efficacy and economy of SIT programs. (author)
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Endocrine Disrupting Chemicals (EDCs)
... Center Pacientes y Cuidadores Hormones and Health The Endocrine System Hormones Endocrine Disrupting Chemicals (EDCs) Steroid and Hormone ... Hormones and Health › Endocrine Disrupting Chemicals (EDCs) The Endocrine System Hormones Endocrine Disrupting Chemicals (EDCs) EDCs Myth vs. ...
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Sexual Narcissism and the Perpetration of Sexual Aggression
McNulty, James K.
2014-01-01
Despite indirect evidence linking narcissism to sexual aggression, studies directly examining this relationship have yielded inconsistent results. Likely contributing to such inconsistencies, prior research has used global measures of narcissism not sensitive to whether the components of narcissism are activated in sexual versus non-sexual domains. The current research avoided such problems by using a measure of sexual narcissism to predict sexual aggression. In a sample of 299 men and women, Study 1 validated the Sexual Narcissism Scale, a new sexuality research instrument with four subscales—Sexual Exploitation, Sexual Entitlement, Low Sexual Empathy, and Sexual Skill. Then, in a sample of 378 men, Study 2 demonstrated that sexual narcissism was associated with reports of the frequency of sexual aggression, three specific types of sexual aggression (unwanted sexual contact, sexual coercion, and attempted/completed rape), and the likelihood of future sexual aggression. Notably, global narcissism was unrelated to all indices of sexual aggression when sexual narcissism was controlled. That sexual narcissism outperformed global assessments of narcissism to account for variance in sexual aggression suggests that future research may benefit by examining whether sexual narcissism and other sexual-situation-specific measurements of personality can similarly provide a more valid test of the association between personality and other sexual behaviors and outcomes (e.g., contraceptive use, infidelity, sexual satisfaction). PMID:19130204
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Sexual narcissism and the perpetration of sexual aggression.
Widman, Laura; McNulty, James K
2010-08-01
Despite indirect evidence linking narcissism to sexual aggression, studies directly examining this relationship have yielded inconsistent results. Likely contributing to such inconsistencies, prior research has used global measures of narcissism not sensitive to whether the components of narcissism are activated in sexual versus non-sexual domains. The current research avoided such problems by using a measure of sexual narcissism to predict sexual aggression. In a sample of 299 men and women, Study 1 validated the Sexual Narcissism Scale, a new sexuality research instrument with four subscales-Sexual Exploitation, Sexual Entitlement, Low Sexual Empathy, and Sexual Skill. Then, in a sample of 378 men, Study 2 demonstrated that sexual narcissism was associated with reports of the frequency of sexual aggression, three specific types of sexual aggression (unwanted sexual contact, sexual coercion, and attempted/completed rape), and the likelihood of future sexual aggression. Notably, global narcissism was unrelated to all indices of sexual aggression when sexual narcissism was controlled. That sexual narcissism outperformed global assessments of narcissism to account for variance in sexual aggression suggests that future research may benefit by examining whether sexual narcissism and other sexual-situation-specific measurements of personality can similarly provide a more valid test of the association between personality and other sexual behaviors and outcomes (e.g., contraceptive use, infidelity, sexual satisfaction).
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Disruptions in the TFTR tokamak
International Nuclear Information System (INIS)
Janos, A.; Fredrickson, E.D.; McGuire, K.; Batha, S.H.; Bell, M.G.; Bitter, M.; Budny, R.; Bush, C.E.; Efthimion, P.C.; Hawryluk, R.J.; Hill, K.W.; Hosea, J.; Jobes, F.C.; Johnson, D.W.; Levinton, F.; Mansfield, D.; Meade, D.; Medley, S.S.; Monticello, D.; Mueller, D.; Nagayama, Y.; Owens, D.K.; Park, H.; Park, W.; Post, D.E.; Schivell, J.; Strachan, J.D.; Taylor, G.; Ulrickson, M.; Goeler, S. von; Wilfrid, E.; Wong, K.L.; Yamada, M.; Young, K.M.; Zarnstorff, M.C.; Zweben, S.J.; Drake, J.F.; Kleva, R.G.; Fleischmann, H.H.
1993-03-01
For a successful reactor, it will be useful to predict the occurrence of disruptions and to understand disruption effects including how a plasma disrupts onto the wall and how reproducibly it does so. Studies of disruptions on TFTR at both high-β pol and high-density have shown that, in both types, a fast growing m/n=1/1 mode plays an important role. In highdensity disruptions, a newly observed fast m/n = 1/1 mode occurs early in the thermal decay phase. For the first time in TFTR q-profile measurements just prior to disruptions have been made. Experimental studies of heat deposition patterns on the first wall of TFTR due to disruptions have provided information on MHD phenomena prior to or during the disruption, how the energy is released to the wall, and the reproducibility of the heat loads from disruptions. This information is important in the design of future devices such as ITER. Several new processes of runaway electron generation are theoretically suggested and their application to TFTR and ITER is considered, together with a preliminary assessment of x-ray data from runaways generated during disruptions
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Niehaus, Ashley F; Jackson, Joan; Davies, Stephanie
2010-12-01
Childhood sexual trauma has been demonstrated to increase survivors' risk for engaging in unrestricted sexual behaviors and experiencing adolescent sexual assault. The current study used the sexual self-schema construct to examine cognitive representations of sexuality that might drive these behavioral patterns. In Study 1 (N = 774), we attempted to improve the content validity of the Sexual Self Schema Scale for child sexual abuse (CSA) survivors, introducing a fourth sexual self-schema factor titled the "immoral/irresponsible" factor. In Study 2 (N = 1150), the potential differences in sexual self-views, as assessed by the four sexual self-schema factors, between CSA survivors and non-victims were explored. In addition, Study 2 evaluated how these sexual self-schema differences may contribute to participation in unrestricted sexual behaviors and risk for sexual assault in adolescence. Results indicated that a history of CSA impacted the way women viewed themselves as a sexual person on each of the four factors. CSA survivors were found to view themselves as more open and possessing more immoral/irresponsible cognitions about sexuality as compared to women who did not have a CSA history. In addition, the CSA survivors endorsed less embarrassment and passionate/romantic views of their sexual selves. The interaction of CSA severity and the sexual self-schemas explained variance in adolescent sexual assault experiences above and beyond the severity of CSA history and participation in risky sexual behaviors. The findings suggest that sexual self-views may serve to moderate the relationship between CSA and adolescent sexual assault. Implications of these findings and directions for future research are discussed.
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Dopamine D5 receptor modulates male and female sexual behavior in mice.
Kudwa, A E; Dominguez-Salazar, E; Cabrera, D M; Sibley, D R; Rissman, E F
2005-07-01
Dopamine exerts its actions through at least five receptor (DAR) isoforms. In female rats, D5 DAR may be involved in expression of sexual behavior. We used a D5 knockout (D5KO) mouse to assess the role of D5 DAR in mouse sexual behavior. Both sexes of D5KO mice are fertile and exhibit only minor disruptions in exploratory locomotion, startle, and prepulse inhibition responses. This study was conducted to characterize the sexual behavior of male and female D5KO mice relative to their WT littermates. Female WT and D5KO littermates were ovariectomized and given a series of sexual behavior tests after treatment with estradiol benzoate (EB) and progesterone (P). Once sexual performance was optimal the dopamine agonist, apomorphine (APO), was substituted for P. Male mice were observed in pair- and trio- sexual behavior tests. To assess whether the D5 DAR is involved in rewarding aspects of sexual behavior, WT and D5KO male mice were tested for conditioned place preference. Both WT and D5KO females can display receptivity after treatment with EB and P, but APO was only able to facilitate receptivity in EB-primed WT, not in D5KO, mice. Male D5KO mice display normal masculine sexual behavior in mating tests. In conditioned preference tests, WT males formed a conditioned preference for context associated with either intromissions alone or ejaculation as the unconditioned stimulus. In contrast, D5KO males only showed a place preference when ejaculation was paired with the context. In females, the D5 DAR is essential for the actions of dopamine on receptivity. In males, D5 DAR influences rewarding aspects of intromissions. Taken together, the work suggests that the D5 receptor mediates dopamine's action on sexual behavior in both sexes, perhaps via a reward pathway.
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Sexual media exposure, sexual behavior, and sexual violence victimization in adolescence.
Ybarra, Michele L; Strasburger, Victor C; Mitchell, Kimberly J
2014-11-01
Emerging research suggests sexual media affects sexual behavior, but most studies are based on regional samples and few include measures of newer mediums. Furthermore, little is known about how sexual media relates to sexual violence victimization. Data are from 1058 youth 14 to 21 years of age in the national, online Growing up with Media study. Forty-seven percent reported that many or almost all/all of at least one type of media they consumed depicted sexual situations. Exposure to sexual media in television and movies, and music was greater than online and in games. All other things equal, more frequent exposure to sexual media was related to ever having had sex, coercive sex victimization, and attempted/completed rape but not risky sexual behavior. Longer standing mediums such as television and movies appear to be associated with greater amounts of sexual media consumption than newer ones, such as the Internet. A nuanced view of how sexual media content may and may not be affecting today's youth is needed. © The Author(s) 2014.
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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.
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BINARY DISRUPTION BY MASSIVE BLACK HOLES: HYPERVELOCITY STARS, S STARS, AND TIDAL DISRUPTION EVENTS
Energy Technology Data Exchange (ETDEWEB)
Bromley, Benjamin C. [Department of Physics and Astronomy, University of Utah, 115 S 1400 E, Rm 201, Salt Lake City, UT 84112 (United States); Kenyon, Scott J.; Geller, Margaret J.; Brown, Warren R., E-mail: bromley@physics.utah.edu, E-mail: skenyon@cfa.harvard.edu, E-mail: mgeller@cfa.harvard.edu, E-mail: wbrown@cfa.harvard.edu [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States)
2012-04-20
We examine whether disrupted binary stars can fuel black hole growth. In this mechanism, tidal disruption produces a single hypervelocity star (HVS) ejected at high velocity and a former companion star bound to the black hole. After a cluster of bound stars forms, orbital diffusion allows the black hole to accrete stars by tidal disruption at a rate comparable to the capture rate. In the Milky Way, HVSs and the S star cluster imply similar rates of 10{sup -5} to 10{sup -3} yr{sup -1} for binary disruption. These rates are consistent with estimates for the tidal disruption rate in nearby galaxies and imply significant black hole growth from disrupted binaries on 10 Gyr timescales.
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Brassard, Audrey; Dupuy, Emmanuelle; Bergeron, Sophie; Shaver, Phillip R
2015-01-01
We examined the potential role of three mediators--sexual self-esteem, sexual anxiety, and sexual assertiveness--of the association between romantic attachment insecurities (anxiety and avoidance) and two aspects of women's sexual functioning: sexual function and sexual satisfaction. A sample of 556 women aged 18 to 30 agreed to complete an online series of validated questionnaires assessing attachment insecurities and several aspects of sexual functioning. Lower sexual self-esteem and higher sexual anxiety mediated the associations between attachment anxiety and lower sexual function and satisfaction. Lower sexual self-esteem and higher sexual anxiety also partially mediated the links between attachment-related avoidance and the two sexual functioning variables. Sexual assertiveness, however, did not mediate these associations. A significant interaction between attachment anxiety and avoidance was also found to predict sexual satisfaction, with women high in avoidance and low in anxiety being the least satisfied. Results are discussed in terms of theoretical and clinical implications.
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Conceptual model of male military sexual trauma.
Elder, William B; Domino, Jessica L; Rentz, Timothy O; Mata-Galán, Emma L
2017-08-01
Male sexual trauma is understudied, leaving much to be known about the unique mental health needs of male survivors. This study examined veteran men's perceptions of the effects of military sexual trauma. Military sexual trauma was defined as physically forced, verbally coerced, or substance-incapacitated acts experienced during military service. Interviews were conducted with 21 male veterans who reported experiencing military sexual trauma. Data were drawn together using a grounded theory methodology. Three categories emerged from data analysis, including (a) types of military sexual trauma (being touched in a sexual way against their will [N = 18]; sexual remarks directed at them [N = 15]; being physically forced to have sex [N = 13]); (b) negative life effects (difficulty trusting others [N = 18]; fear of abandonment [N = 17]; substance use [N = 13]; fear of interpersonal violence [N = 12]; conduct and vocational problems [N = 11]; irritability/aggression [N = 8]; insecurity about sexual performance [N = 8]; difficulty managing anger [N = 8]); and (c) posttraumatic growth (N = 15). Results from this study suggest sexual trauma in the military context may affect systems of self-organization, specifically problems in affective, self-concept, and relational domains, similar to symptoms of those who have experienced prolonged traumatic stressors. This model can be used by clinicians to select treatments that specifically target these symptoms and promote posttraumatic growth. (PsycINFO Database Record (c) 2017 APA, all rights reserved).
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Statistical analysis of JET disruptions
International Nuclear Information System (INIS)
Tanga, A.; Johnson, M.F.
1991-07-01
In the operation of JET and of any tokamak many discharges are terminated by a major disruption. The disruptive termination of a discharge is usually an unwanted event which may cause damage to the structure of the vessel. In a reactor disruptions are potentially a very serious problem, hence the importance of studying them and devising methods to avoid disruptions. Statistical information has been collected about the disruptions which have occurred at JET over a long span of operations. The analysis is focused on the operational aspects of the disruptions rather than on the underlining physics. (Author)
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A lover or a fighter? Opposing sexual selection pressures on men's vocal pitch and facial hair.
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.
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International Nuclear Information System (INIS)
Murray, J.G.; Bronner, G.
1982-07-01
Calculations of disruption time and energy dissipation have been obtained by simulating the plasma as an electrical conducting loop that varies in resistivity, current density, major radius. The calculations provide results which are in good agreement with experimental observations. It is believed that this approach allows engineering designs for disruptions to be completed in large tokamaks such as INTOR or FED
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Alcohol consumption and high risk sexual behaviour among female ...
African Journals Online (AJOL)
Alcohol consumption has been associated with high risk sexual behaviour among key populations such as female sex workers. We explored the drivers of alcohol consumption and its relationship to high risk sexual behaviour. Participants were drawn from a cohort of 1 027 women selected from 'hot spots' in the suburbs of ...
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Nanotechnology and the Future of Condoms in the Prevention of Sexually Transmitted Infections
Yah, Clarence S.; Simate, Geoffrey S.; Hlangothi, Percy; Somai, Benesh M.
2018-01-01
Objective: The human immunodeficiency virus (HIV) is among the utmost destructive viruses humankind has ever faced in almost four decades. It carries with it profound socioeconomic and public health implications. Unfortunately, there is, currently, no effective cure for HIV infections. This review discusses the various types of condoms, microbicides, and the potential use of nanoparticle-coated condoms as a means of diminishing the risk of HIV transmission and sexually transmitted infections (STIs) during sexual intercourse. Methods: We identified 153 articles from 1989 to 2015 indexed in various journal platforms, reports, and magazines. Using the PRISMA guidelines as proxy in performing the research review process, only 53 articles were selected. Ideally, articles that failed to describe the nature and types of condoms, condom failures, nanoparticle-coated condoms, microbicides, and HIV prevention were excluded. Results and Discussion: In general, it has been shown that antiretroviral therapy (ART) currently available can only limit transmission and acquisition of HIV strains. Apart from ART treatment, the use of condoms has been identified globally as a cost-effective intervention for reducing the spread of HIV and other STIs. However, while condoms are supposed to be effective, reliable, and easy to use, research has shown that they are attributable to 20% failures including breakages. Nevertheless, other studies have shown that coating condoms with nanoparticles is an important and effective method for reducing condom breakage and HIV/STI transmission during sexual intercourse. Conclusions: A review of literature cited in this paper has shown that nanotechnology-based condom systems have the potential to prevent the spread of HIV and STIs. Furthermore, the antimicrobial nature of some nanoparticles could provide a safe and efficient way to disrupt and/or inactivate different STIs – including viral, bacterial, and fungal diseases. PMID:29536957
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Wanner, B; Vitaro, F; Tremblay, R E; Turecki, G
2012-11-01
Suicidal behavior is frequently associated with a history of childhood abuse yet it remains unclear precisely how early life adversity may increase suicide risk later in life. As such, our aim was to examine whether lifetime trajectories of disruptiveness and anxiousness trait dysregulation explain the association between childhood adversity and suicidal behavior; and moreover, to test the potential modifying effects of mental disorders on these associations. A sample of 1776 individuals from a prospective school-based cohort followed longitudinally for over 22 years was investigated. We tested the influence of disruptiveness and anxiousness trajectories from age 6 to 12 years on the association between childhood adversity (i.e. sexual and physical abuse) and history of suicide attempts (SA) using logistic regression models. Both adolescent externalizing and internalizing Axis I disorders and gender were tested as potential modifiers of these associations. Four distinct longitudinal trajectories were identified for both disruptiveness and anxiousness. The high disruptiveness trajectory accounted for the association between childhood adversity and SA, but only for females. The high anxiousness trajectory also explained the association between adversity and SA; however, in this case it was not sex but mental disorders that influenced the potency of the mediating effect. More specifically, anxiousness fully explained the effect of adversity on SA in the presence of externalizing disorders, whereas in the absence of these disorders, this effect was significantly attenuated. This study provides evidence that both disruptiveness and anxiousness play an important role in explaining the relationship between childhood adversity and SA.
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Internal disruption in tokamaks
International Nuclear Information System (INIS)
Kuvshinov, B.N.; Savrukhin, P.V.
1990-01-01
A review of results of experimental and theoretical investigations of internal disruption in tokamaks is given. Specific features of various types of saw-tooth oscillations are described and their classification is performed. Theoretical models of the process of development of internal disruption instability are discussed. Effect of internal disruption on parameters of plasma, confined in tokamak, is considered. Scalings of period and amplitude of saw-tooth oscillations, as well as version radius are presented. Different methods for stabilizing instability of internal disruption are described
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Internal disruptions in tokamaks
International Nuclear Information System (INIS)
Kuvshinov, B.N.; Savrukhin, P.V.
1990-01-01
Experimental and theoretical studies of the phenomenon of internal disruptions in tokamaks are reviewed. A classification scheme is introduced and the features of different types of sawtooth oscillations are described. A theoretical model for the development of the internal disruption instability is discussed. The effect of internal disruptions on the parameters of plasma confined in tokamaks is discussed. Scaling laws for the period and amplitude of sawtooth oscillations, as well as for the inversion radius, are presented. Different methods of stabilizing the internal disruption instability are described
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The biology of human sexuality: evolution, ecology and physiology
Directory of Open Access Journals (Sweden)
PW Bateman
2006-09-01
Full Text Available Many evolutionary biologists argue that human sexual behaviour can be studied in exactly the same way as that of other species. Many sociologists argue that social influences effectively obscure, and are more important than, a reductionist biological approach to human sexual behaviour. Here,we authors attempt to provide a broad introduction to human sexual behaviour from a biological standpoint and to indicate where the ambiguous areas are. We outline the evolutionary selective pressures that are likely to have influenced human behaviour and mate choice in the past and in the present; ecological features that influence such things as degree of parental care and polygamy; and the associated physiology of human sexuality. Then they end with a discussion of �abnormal� sexuality.
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Endocrinology of human female sexuality, mating, and reproductive behavior.
Motta-Mena, Natalie V; Puts, David A
2017-05-01
Hormones orchestrate and coordinate human female sexual development, sexuality, and reproduction in relation to three types of phenotypic changes: life history transitions such as puberty and childbirth, responses to contextual factors such as caloric intake and stress, and cyclical patterns such as the ovulatory cycle. Here, we review the endocrinology underlying women's reproductive phenotypes, including sexual orientation and gender identity, mate preferences, competition for mates, sex drive, and maternal behavior. We highlight distinctive aspects of women's sexuality such as the possession of sexual ornaments, relatively cryptic fertile windows, extended sexual behavior across the ovulatory cycle, and a period of midlife reproductive senescence-and we focus on how hormonal mechanisms were shaped by selection to produce adaptive outcomes. We conclude with suggestions for future research to elucidate how hormonal mechanisms subserve women's reproductive phenotypes. Copyright © 2016 Elsevier Inc. All rights reserved.
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Parkes, Alison; Wight, Daniel; Hunt, Kate; Henderson, Marion; Sargent, James
2013-01-01
Sexual content in teenagers' media diets is known to predict early sexual behaviour. Research on sexual content has not allowed for the social context of media use, which may affect selection and processing of content. This study investigated whether sexual media content and/or contextual factors (co-viewing, parental media restrictions) were associated with early sexual behaviour using 2251 14–15 year-olds from Scotland, UK. A third (n = 733) reported sexual intercourse. In multivariable analysis the likelihood of intercourse was lower with parental restriction of sexual media and same-sex peer co-viewing; but higher with mixed-sex peer co-viewing. Parental co-viewing, other parental restrictions on media and sexual film content exposure were not associated with intercourse. Findings suggest the context of media use may influence early sexual behaviour. Specific parental restrictions on sexual media may offer more protection against early sex than other restrictions or parental co-viewing. Further research is required to establish causal mechanisms. PMID:24215959
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Pelekanos, Michael; Stofman, Guy M; Niren, Neil
2016-12-13
The aim of this investigation was to determine, through two Investigational Review Board (IRB)-approved studies, if a new topical vasodilating cream (NTVC; Life Science Enhancement Corporation, Pittsburgh PA) could improve female sexual response. Study I subjectively evaluated sexual female response as accessed by a modification of the Female Intervention Efficacy Index (FIEI). FIEI was developed at the University of California as an immediate outcome measure of medical intervention to treat female sexual dysfunction.1 In Study II, 10 randomly selected positive responders from Study I were subsequently analyzed objectively with clitoral plethysmography in order to determine the effect of the NTVC and placebo on blood flow.2 RESULTS: In the subjective Study I (81 patients ranging in age from 18 to 63), a positive response trend for the NTVC was demonstrated compared to the placebo. In the objective Study II, 10 randomly selected patients who responded positive in Study I were objectively evaluated for response of increased blood flow in the clitoris after application of both the NTVC and placebo. The clitoral blood flow was shown to have increased with statistical significance for the NTVC in all 10 patients compared to the placebo, with the NTVC exhibiting an average 69% increase in clitoral blood flow. The female sexual response is complex. In the subjective Study I, the NTVC demonstrated positive trends for enhanced lubrication, genital sensation, intercourse, and overall sexual experience. In the objective Study II, 10 of the positive subjective responders from Study I were randomly selected to evaluate their response to the NTVC compared to the placebo. This was done via Doppler plethysmography (DP). All 10 patients demonstrated a statistically significant response rate for increase in clitoral blood flow using the NTVC compared to the placebo, with an average blood flow increase of 69%. This portion of the investigation demonstrates a significant positive end
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Assessing sexual conflict in the Drosophila melanogaster laboratory model system
Rice, William R; Stewart, Andrew D; Morrow, Edward H; Linder, Jodell E; Orteiza, Nicole; Byrne, Phillip G
2006-01-01
We describe a graphical model of interlocus coevolution used to distinguish between the interlocus sexual conflict that leads to sexually antagonistic coevolution, and the intrinsic conflict over mating rate that is an integral part of traditional models of sexual selection. We next distinguish the ‘laboratory island’ approach from the study of both inbred lines and laboratory populations that are newly derived from nature, discuss why we consider it to be one of the most fitting forms of laboratory analysis to study interlocus sexual conflict, and then describe four experiments using this approach with Drosophila melanogaster. The first experiment evaluates the efficacy of the laboratory model system to study interlocus sexual conflict by comparing remating rates of females when they are, or are not, provided with a spatial refuge from persistent male courtship. The second experiment tests for a lag-load in males that is due to adaptations that have accumulated in females, which diminish male-induced harm while simultaneously interfering with a male's ability to compete in the context of sexual selection. The third and fourth experiments test for a lag-load in females owing to direct costs from their interactions with males, and for the capacity for indirect benefits to compensate for these direct costs. PMID:16612888
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Estimation of post disruption plasma temperature for fast current quench Aditya plasma shots
International Nuclear Information System (INIS)
Purohit, S.; Chowdhuri, M.B.; Joisa, Y.S.; Raval, J.V.; Ghosh, J.; Jha, R.
2013-01-01
Characteristics of tokamak current quenches are an important issue for the determination of electromagnetic forces that act on the in-vessel components and vacuum vessel during major disruptions. It is observed that thermal quench is followed by a sharp current decay. Fast current quench disruptive plasma shots were investigated for ADITYA tokamak. The current decay time was determined for the selected shots, which were in the range of 0.8 msec to 2.5 msec. This current decay information was then applied to L/R model, frequently employed for the estimation of the current decay time in tokamak plasmas, considering plasma inductance and plasma resistivity. This methodology was adopted for the estimation of the post disruption plasma temperature using the experimentally observed current decay time for the fast current quench disruptive ADITYA plasma shots. The study reveals that for the identified shots there is a constant increase in the current decay time with the post disruption plasma temperature. The investigations also explore the behavior post disruption plasma temperature and the current decay time as a function of the edge safety factor, Q. Post disruption plasma temperature and the current decay time exhibits a decrease with the increase in the value Q. (author)
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Possible evolutionary origins of human female sexual fluidity.
Kanazawa, Satoshi
2017-08-01
I propose an evolutionary theory of human female sexual fluidity and argue that women may have been evolutionarily designed to be sexually fluid in order to allow them to have sex with their cowives in polygynous marriage and thus reduce conflict and tension inherent in such marriage. In addition to providing an extensive definition and operationalization of the concept of sexual fluidity and specifying its ultimate function for women, the proposed theory can potentially solve several theoretical and empirical puzzles in evolutionary psychology and sex research. Analyses of the National Longitudinal Study of Adolescent Health (Add Health) confirm the theory's predictions that: (i) women (but not men) who experience increased levels of sexual fluidity have a larger number of children (suggesting that female sexual fluidity, if heritable, may be evolutionarily selected); (ii) women (but not men) who experience marriage or parenthood early in adult life subsequently experience increased levels of sexual fluidity; and (iii) sexual fluidity is significantly positively correlated with known markers of unrestricted sexual orientation among women whereas it is significantly negatively correlated with such markers among men. © 2016 Cambridge Philosophical Society.
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A comparison of rapists and sexual murderers on demographic and selected psychometric measures.
Oliver, Caroline J; Beech, Anthony R; Fisher, Dawn; Beckett, Richard
2007-06-01
This study compared 58 sexual murderers and 112 rapists who were about to undergo treatment in prison for their sexual offending behavior. The two groups were compared on background, personality, offense, and victim characteristics. The sexual murderer group were less likely to have been involved in a relationship at the time of their index offense, generally attacked older victims, and had higher self-esteem. The rapist sample were found to have more violent previous convictions and scored higher on measures of historical deviance (nonsexual), paranoid suspicion, and resentment. No differences were found on the personality or clinical syndrome scales of the Millon Clinical Multiaxial Inventory-III. However, the rapist sample had significantly higher mean scores on the Paranoid Suspicion, Resentment, and Self-Esteem subscales of the Antisocial Personality Questionnaire. Future research should compare the two groups on dynamic or changeable factors to determine differential treatment needs.
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[Sex differences in sexual versus emotional jealousy: evolutionary approach and recent discussions].
Demirtaş Madran, H Andaç
2008-01-01
Sex differences in jealousy have been reported widely in the social psychological, clinical psychological, psychiatric, and anthropological literature. Many of the studies conducted on jealousy have focused on the sex differences in the level of reported jealousy. Most research has reported that there is no difference between men and women regarding the level of reported jealousy, but there are some sex differences between sexual and emotional jealousy. Evolutionary psychologists divide jealousy into 2 dimensions based on their observations and empirical research findings: Sexual jealousy and emotional jealousy. Sexual jealousy is knowing or suspecting that one's partners has had sexual relationship with a third person, whereas emotional jealousy is triggered by partner's emotional involvement with and/or love for another person. The parental investment model, which extended Darwin's explanations of sexual selection, provides a useful theoretical framework for studying sexual and emotional jealousy. According to this model sexual selection is driven by differential parental investment by men and women; men should experience more sexual jealousy than women and women should experience more emotional jealousy than men. Considerable research has focused on testing this hypothesis and, with a few exceptions, the results are generally consistent with the evolutionary account. In this study, firstly, a brief definition of the sexual and emotional jealousy will be given. Then, sex differences in sexual and emotional jealousy will be explained according to the evolutionary theory. Finally, the results of empirical studies and critiques of the evolutionary model will be given.
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Disruptive behavior scale for adolescents (DISBA): development and psychometric properties.
Karimy, Mahmood; Fakhri, Ahmad; Vali, Esmaeel; Vali, Farzaneh; Veiga, Feliciano H; Stein, L A R; Araban, Marzieh
2018-01-01
Growing evidence indicates that if disruptive behavior is left unidentified and untreated, a significant proportion of these problems will persist and may develop into problems linked with delinquency, substance abuse, and violence. Research is needed to develop valid and reliable measures of disruptive behavior to assist recognition and impact of treatments on disruptive behavior. The aim of this study was to develop and evaluate the psychometric properties of a scale for disruptive behavior in adolescents. Six hundred high school students (50% girls), ages ranged 15-18 years old, selected through multi stage random sampling. Psychometrics of the disruptive behavior scale for adolescents (DISBA) (Persian version) was assessed through content validity, explanatory factor analysis (EFA) using Varimax rotation and confirmatory factor analysis (CFA). The reliability of this scale was assessed via internal consistency and test-retest reliability. EFA revealed four factors accounting for 59% of observed variance. The final 29-item scale contained four factors: (1) aggressive school behavior, (2) classroom defiant behavior, (3) unimportance of school, and (4) defiance to school authorities. Furthermore, CFA produced a sufficient Goodness of Fit Index > 0.90. Test-retest and internal consistency reliabilities were acceptable at 0.85 and 0.89, respectively. The findings from this study suggest that the Iranian version of DISBA questionnaire has content validity. Further studies are needed to evaluate stronger psychometric properties for DISBA.
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Disruptive technologies in higher education
Directory of Open Access Journals (Sweden)
Michael Flavin
2012-08-01
Full Text Available This paper analyses the role of “disruptive” innovative technologies in higher education. In this country and elsewhere, Higher Education Institutions (HEIs have invested significant sums in learning technologies, with Virtual Learning Environments (VLEs being more or less universal, but these technologies have not been universally adopted and used by students and staff. Instead, other technologies not owned or controlled by HEIs are widely used to support learning and teaching. According to Christensen's theory of Disruptive Innovation, these disruptive technologies are not designed explicitly to support learning and teaching in higher education, but have educational potential. This study uses Activity Theory and Expansive Learning to analyse data regarding the impact of disruptive technologies. The data were obtained through a questionnaire survey about awareness and use of technologies, and through observation and interviews, exploring participants’ actual practice. The survey answers tended to endorse Disruptive Innovation theory, with participants establishing meanings for technologies through their use of them, rather than in keeping with a designer's intentions. Observation revealed that learners use a narrow range of technologies to support learning, but with a tendency to use resources other than those supplied by their HEIs. Interviews showed that participants use simple and convenient technologies to support their learning and teaching. This study identifies a contradiction between learning technologies made available by HEIs, and technologies used in practice. There is no evidence to suggest that a wide range of technologies is being used to support learning and teaching. Instead, a small range of technologies is being used for a wide range of tasks. Students and lecturers are not dependent on their HEIs to support learning and teaching. Instead, they self-select technologies, with use weighted towards established brands. The
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Patterns of Asexuality in China: Sexual Activity, Sexual and Romantic Attraction, and Sexual Desire.
Zheng, Lijun; Su, Yanchen
2018-05-01
This study examined patterns of asexuality in Chinese asexual people in terms of sexual activities, sexual/romantic attraction, and sexual desire. The sample included 227 (64 men and 163 women) asexual participants and 57 (26 men and 31 women) uncertain asexual participants recruited from social networks for asexual people. The control group included 217 (115 men and 102 women) heterosexual participants recruited from general social networks. Participants scoring 40 or higher on the Asexuality Identification Scale were classified as asexual. Asexual participants reported having less frequent masturbation, sexual intercourse experience, and sexual and romantic attraction compared to heterosexual participants. Lower sexual attraction among asexuals indicated that "people who experience little or no sexual attraction" would be a more appropriate definition of asexuality. The pattern of uncertain asexual participants' sexual/romantic attraction and sexual desire was intermediate between heterosexual and asexual participants. Asexual participants scored significantly lower on dyadic sexual desire and slightly lower on solitary sexual desire than heterosexual participants. There were significant differences in sexual activities and solitary sexual desire among romantic orientation categories. Homoromantic participants showed higher dyadic sexual desire and were more likely to engage in masturbation, indicating the heterogeneity among asexual people. The findings indicated that Chinese asexual people showed similar patterns of asexuality as in Western nations. Specifically, asexual people have little or no sexual attraction, non-partner-orientated sexual desire, and are heterogeneous in sexual activities and sexual desire. This implies similar mechanisms underlying the etiology of asexuality across cultures.
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Hasbi, Ahmed; Perreault, Melissa L.; Shen, Maurice Y. F.; Zhang, Lucia; To, Ryan; Fan, Theresa; Nguyen, Tuan; Ji, Xiaodong; O'Dowd, Brian F.; George, Susan R.
2014-01-01
Although the dopamine D1-D2 receptor heteromer has emerging physiological relevance and a postulated role in different neuropsychiatric disorders, such as drug addiction, depression, and schizophrenia, there is a need for pharmacological tools that selectively target such receptor complexes in order to analyze their biological and pathophysiological functions. Since no selective antagonists for the D1-D2 heteromer are available, serial deletions and point mutations were used to precisely identify the amino acids involved in an interaction interface between the receptors, residing within the carboxyl tail of the D1 receptor that interacted with the D2 receptor to form the D1-D2 receptor heteromer. It was determined that D1 receptor carboxyl tail residues 404Glu and 405Glu were critical in mediating the interaction with the D2 receptor. Isolated mutation of these residues in the D1 receptor resulted in the loss of agonist activation of the calcium signaling pathway mediated through the D1-D2 receptor heteromer. The physical interaction between the D1 and D2 receptor could be disrupted, as shown by coimmunoprecipitation and BRET analysis, by a small peptide generated from the D1 receptor sequence that contained these amino acids, leading to a switch in G-protein affinities and loss of calcium signaling, resulting in the inhibition of D1-D2 heteromer function. The use of the D1-D2 heteromer-disrupting peptide in vivo revealed a pathophysiological role for the D1-D2 heteromer in the modulation of behavioral despair. This peptide may represent a novel pharmacological tool with potential therapeutic benefits in depression treatment.—Hasbi, A., Perreault, M. L., Shen, M. Y. F., Zhang, L., To, R., Fan, T., Nguyen, T., Ji, X., O'Dowd, B. F., George, S. R. A peptide targeting an interaction interface disrupts the dopamine D1-D2 receptor heteromer to block signaling and function in vitro and in vivo: effective selective antagonism. PMID:25063849
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Symposium on disruptive instabilities at Garching
International Nuclear Information System (INIS)
Lackner, K.
1979-01-01
The phenomenon of disruptive instabilities was investigated with a special care at the IPP at Garching. After lectures and panel sessions it appears suitable, to subdivide the disruptive phenomena into four classes: 1. The internal disruption (the socalled saw-tooth oscillators). 2. the socalled reconnection disruptions. 3. The large disruptions. 4. The small disruptions. The four appearance forms of the phenomena are briefly explained. (GG) [de
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Howard, J R; O'Neill, S; Travers, C
2006-10-01
To investigate the sexual behavior, sexual relationships, sexual satisfaction, sexual dysfunction and sexual distress in a population of older urban Australian women. In 2004, 474 women participating in the Longitudinal Assessment of Ageing in Women (LAW) Study completed a series of questionnaires about sexuality. They included the Short Personal Experiences Questionnaire (SPEQ), Relationship Assessment Scale (RAS), Female Sexual Distress Scale (FSDS), questions concerning past sexual abuse based on the Sex in Australia Study, and questions comparing present and past sexual interest and activity. The percentage of women with partners ranged from 83.3% in the 40 - 49-year age group to 46.4% women in the 70 - 79-year age group. The sexual ability of partners diminished markedly with age, with only 4.8% of the partners using medication to enable erections. Only 2.5% of women reported low relationship satisfaction. The incidence of sexual distress was also low, being reported by only 5.7% of women. Younger women and women with partners had higher levels of distress than older women. Indifference to sexual frequency rose from 26.7% in women aged 40 - 49 years to 72.3% in the 70 - 79-year age group. Past sexual abuse was recalled by 22.7% of women and 11.6% recalled multiple episodes of abuse. Women who recalled abuse had lower scores for satisfaction with sexual frequency. It appears from this study that there is a wide range of sexual experience amongst aging women, from never having had a sexual partner, to having solitary sex, to having a relationship with or without sex into the seventh decade. As women age, they experience a decrease in sexual activity, interest in sex, and distress about sex. This may be associated with the loss of intimate relationships as part of separation, divorce or bereavement. Decreased sexual activity with aging may be interpreted as a biological phenomenon (part of the aging process) or as sexual dysfunction, or it may be the result of
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Sexual reproduction and the evolution of microbial pathogens.
Heitman, Joseph
2006-09-05
Three common systemic human fungal pathogens--Cryptococcus neoformans, Candida albicans and Aspergillus fumigatus--have retained all the machinery to engage in sexual reproduction, and yet their populations are often clonal with limited evidence for recombination. Striking parallels have emerged with four protozoan parasites that infect humans: Toxoplasma gondii, Trypanosoma brucei, Trypanosoma cruzi and Plasmodium falciparum. Limiting sexual reproduction appears to be a common virulence strategy, enabling generation of clonal populations well adapted to host and environmental niches, yet retaining the ability to engage in sexual or parasexual reproduction and respond to selective pressure. Continued investigation of the sexual nature of microbial pathogens should facilitate both laboratory investigation and an understanding of the complex interplay between pathogens, hosts, vectors, and their environments.
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Survey of disruption causes at JET
International Nuclear Information System (INIS)
De Vries, P.C.; Johnson, M.F.; Alper, B.; Hender, T.C.; Riccardo, V.; Buratti, P.; Koslowski, H.R.
2011-01-01
A survey has been carried out into the causes of all 2309 disruptions over the last decade of JET operations. The aim of this survey was to obtain a complete picture of all possible disruption causes, in order to devise better strategies to prevent or mitigate their impact. The analysis allows the effort to avoid or prevent JET disruptions to be more efficient and effective. As expected, a highly complex pattern of chain of events that led to disruptions emerged. It was found that the majority of disruptions had a technical root cause, for example due to control errors, or operator mistakes. These bring a random, non-physics, factor into the occurrence of disruptions and the disruption rate or disruptivity of a scenario may depend more on technical performance than on physics stability issues. The main root cause of JET disruptions was nevertheless due to neo-classical tearing modes that locked, closely followed in second place by disruptions due to human error. The development of more robust operational scenarios has reduced the JET disruption rate over the last decade from about 15% to below 4%. A fraction of all disruptions was caused by very fast, precursorless unpredictable events. The occurrence of these disruptions may set a lower limit of 0.4% to the disruption rate of JET. If one considers on top of that human error and all unforeseen failures of heating or control systems this lower limit may rise to 1.0% or 1.6%, respectively.
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Sexuality education in Malaysia: perceived issues and barriers by professionals.
Khalaf, Zahra Fazli; Low, Wah Yun; Merghati-Khoei, Effat; Ghorbani, Behzad
2014-07-01
This research explored the perspectives of Malaysian professionals on the issues and barriers affecting the implementation of sexuality education in Malaysia. This qualitative study involved in-depth interviews with 15 key professionals working in the field of sexuality and reproductive health in Malaysia. Thematic analysis was selected to analyze data. Barriers to sexuality education were perceived from 5 aspects: feasibility, acceptability, accountability, strategies, and community unawareness. Respondents believed that implementing national sexuality education is a time-consuming project. They regarded Malaysian multicultural society as a barrier to national sexuality education, and they believed that school-based sexuality education is not easily accomplished in Malaysia; also abstinence-only policy restricts the access of young people to accurate information. Lack of community involvement was perceived as a key concern to sexuality education. Campaigning to promote awareness of families, teachers, community leaders, and policy makers are recommended to help establishing national sexuality education in Malaysia. © 2014 APJPH.
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Directory of Open Access Journals (Sweden)
Gert Martin Hald, PhD
2018-03-01
Hald GM, Stulhofer A, Lange T, et al. Sexual Arousal and Sexually Explicit Media (SEM: Comparing Patterns of Sexual Arousal to SEM and Sexual Self-Evaluations and Satisfaction Across Gender and Sexual Orientation. Sex Med 2018;6:30–38.
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Dysregulated sexuality and high sexual desire: distinct constructs?
Winters, Jason; Christoff, Kalina; Gorzalka, Boris B
2010-10-01
The literature on dysregulated sexuality, whether theoretical, clinical or empirical, has failed to differentiate the construct from high sexual desire. In this study, we tested three hypotheses which addressed this issue. A sample of 6458 men and 7938 women, some of whom had sought treatment for sexual compulsivity, addiction or impulsivity, completed an online survey comprised of various sexuality measures. Men and women who reported having sought treatment scored significantly higher on measures of dysregulated sexuality and sexual desire. For men, women, and those who had sought treatment, dysregulated sexuality was associated with increased sexual desire. Confirmatory factor analysis supported a one-factor model, indicating that, in both male and female participants, dysregulated sexuality and sexual desire variables loaded onto a single underlying factor. The results of this study suggest that dysregulated sexuality, as currently conceptualized, labelled, and measured, may simply be a marker of high sexual desire and the distress associated with managing a high degree of sexual thoughts, feelings, and needs.
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Sexuality in older adults: Clinical and psychosocial dilemmas
Directory of Open Access Journals (Sweden)
Isha Dhingra
2016-01-01
Full Text Available The present review aims to throw some light on the various aspects of sexuality in older adults and the challenges faced by medical professionals working in this area. Keyword searches using the terms "sexuality," "sexual dysfunction," "geriatric," "old age," and others in combination were carried out on PubMed, Google Scholar, and the Cochrane Database of Systematic Reviews. Relevant clinical trials, case studies, and review papers were selected. This was further supplemented with the clinical experience of the authors, who work with older patients in a psychiatric outpatient setting with a dedicated sexual disorders clinic. Sexuality is a lifelong phenomenon and its expression a basic human right across all ages. However, the construct of normalcy for sex in aging is blurred, with agism playing a distinct role. Older adults face much stigma when expressing sexual desires or concerns, both from their own families and the health-care system. Sexual dysfunctions due to comorbid medical illnesses and medications are often treatable. Evidence-based treatments for sexual dysfunction in the elderly, lesbian, gay, bisexual, transgender, and queer, and other orientations are especially underrepresented in research; available research has several limitations. Sexuality in people with dementia and sexual rights in nursing homes are gray areas. Medical training, treatment guidelines, and health-care facilities all need to be stepped up in terms of awareness and quality of care provided to the elderly with concerns related to sexuality.
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Czerniawski, Jennifer; Miyashita, Teiko; Lewandowski, Gail; Guzowski, John F
2015-02-01
Neuroinflammation is implicated in impairments in neuronal function and cognition that arise with aging, trauma, and/or disease. Therefore, understanding the underlying basis of the effect of immune system activation on neural function could lead to therapies for treating cognitive decline. Although neuroinflammation is widely thought to preferentially impair hippocampus-dependent memory, data on the effects of cytokines on cognition are mixed. One possible explanation for these inconsistent results is that cytokines may disrupt specific neural processes underlying some forms of memory but not others. In an earlier study, we tested the effect of systemic administration of bacterial lipopolysaccharide (LPS) on retrieval of hippocampus-dependent context memory and neural circuit function in CA3 and CA1 (Czerniawski and Guzowski, 2014). Paralleling impairment in context discrimination memory, we observed changes in neural circuit function consistent with disrupted pattern separation function. In the current study we tested the hypothesis that acute neuroinflammation selectively disrupts memory retrieval in tasks requiring hippocampal pattern separation processes. Male Sprague-Dawley rats given LPS systemically prior to testing exhibited intact performance in tasks that do not require hippocampal pattern separation processes: novel object recognition and spatial memory in the water maze. By contrast, memory retrieval in a task thought to require hippocampal pattern separation, context-object discrimination, was strongly impaired in LPS-treated rats in the absence of any gross effects on exploratory activity or motivation. These data show that LPS administration does not impair memory retrieval in all hippocampus-dependent tasks, and support the hypothesis that acute neuroinflammation impairs context discrimination memory via disruption of pattern separation processes in hippocampus. Copyright © 2014 Elsevier Inc. All rights reserved.
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Sexual harassment of the physiotherapist in South Africa
Directory of Open Access Journals (Sweden)
L. Bütow-Dûtoit
2006-01-01
Full Text Available No study has been conducted on sexual harassment of physiotherapists in South Africa and it is therefore not known whether harassment occurs and if it does, to what extent. To this purpose, a questionnaire on sexual harassment and other sexual-related issues in the physiotherapy work environment in South Africa, was sent to a random selection of 982 physiotherapists registered with the Health Professions Council of South Africa. The response rate was 32%. This paper presents the results of the first half of the questionnaire, which was devoted to sexual harassment of the physiotherapist. Approximately 60% had experienced sexual harassment, of which 83.98% had been perpetrated by patients. Only 5.82% of the respondents had received some form of information in this regard. The most common form of harassment was requests for a hug or kiss.
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Statistical analysis of disruptions in JET
International Nuclear Information System (INIS)
De Vries, P.C.; Johnson, M.F.; Segui, I.
2009-01-01
The disruption rate (the percentage of discharges that disrupt) in JET was found to drop steadily over the years. Recent campaigns (2005-2007) show a yearly averaged disruption rate of only 6% while from 1991 to 1995 this was often higher than 20%. Besides the disruption rate, the so-called disruptivity, or the likelihood of a disruption depending on the plasma parameters, has been determined. The disruptivity of plasmas was found to be significantly higher close to the three main operational boundaries for tokamaks; the low-q, high density and β-limit. The frequency at which JET operated close to the density-limit increased six fold over the last decade; however, only a small reduction in disruptivity was found. Similarly the disruptivity close to the low-q and β-limit was found to be unchanged. The most significant reduction in disruptivity was found far from the operational boundaries, leading to the conclusion that the improved disruption rate is due to a better technical capability of operating JET, instead of safer operations close to the physics limits. The statistics showed that a simple protection system was able to mitigate the forces of a large fraction of disruptions, although it has proved to be at present more difficult to ameliorate the heat flux.
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Feeding ecology and sexual dimorphism in a speciose flower beetle clade (Hopliini: Scarabaeidae
Directory of Open Access Journals (Sweden)
Jonathan F. Colville
2018-06-01
Full Text Available The relationship between feeding ecology and sexual dimorphism is examined in a speciose South African monkey beetle clade. We test whether feeding and mating at a fixed site (embedding guild is associated with greater levels of sexual dimorphism and possibly sexual selection than species using unpredictable feeding resources (non-embedding guild. Sexual dimorphism was measured using a point scoring system for hind leg and colour across the two feeding guilds for >50% of the regional fauna. Quantification of hind leg dimorphism using a scoring system and allometric scaling were used to identify traits subject to sexual selection. Feeding guild had a significant effect on hind leg dimorphism, with embedders having high and non-embedders low scores. The sessile and defendable distribution of females on stable platform flowers may favour contests and associated hind leg weaponry. In contrast, degree of colour dimorphism between the sexes was not associated with any particular feeding guild, and may serve to reduce male conflict and combat. Embedder males had high proportions (∼76% of species with positive allometric slopes for almost all hind leg traits. For male non-embedders, only ∼37% of species showed positive scaling relationships. Phylogenetic data, in conjunction with behavioural data on the function of leg weaponry and visual signalling among males is needed to better understand the link between sexual dimorphism and sexual selection in the radiation of the monkey beetles.
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Improvements in disruption prediction at ASDEX Upgrade
Energy Technology Data Exchange (ETDEWEB)
Aledda, R., E-mail: raffaele.aledda@diee.unica.it; Cannas, B., E-mail: cannas@diee.unica.it; Fanni, A., E-mail: fanni@diee.unica.it; Pau, A., E-mail: alessandro.pau@diee.unica.it; Sias, G., E-mail: giuliana.sias@diee.unica.it
2015-10-15
Highlights: • A disruption prediction system for AUG, based on a logistic model, is designed. • The length of the disruptive phase is set for each disruption in the training set. • The model is tested on dataset different from that used during the training phase. • The generalization capability and the aging of the model have been tested. • The predictor performance is compared with the locked mode detector. - Abstract: In large-scale tokamaks disruptions have the potential to create serious damage to the facility. Hence disruptions must be avoided, but, when a disruption is unavoidable, minimizing its severity is mandatory. A reliable detection of a disruptive event is required to trigger proper mitigation actions. To this purpose machine learning methods have been widely studied to design disruption prediction systems at ASDEX Upgrade. The training phase of the proposed approaches is based on the availability of disrupted and non-disrupted discharges. In literature disruptive configurations were assumed appearing into the last 45 ms of each disruption. Even if the achieved results in terms of correct predictions were good, it has to be highlighted that the choice of such a fixed temporal window might have limited the prediction performance. In fact, it generates confusing information in cases of disruptions with disruptive phase different from 45 ms. The assessment of a specific disruptive phase for each disruptive discharge represents a relevant issue in understanding the disruptive events. In this paper, the Mahalanobis distance is applied to define a specific disruptive phase for each disruption, and a logistic regressor has been trained as disruption predictor. The results show that enhancements on the achieved performance on disruption prediction are possible by defining a specific disruptive phase for each disruption.
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Improvements in disruption prediction at ASDEX Upgrade
International Nuclear Information System (INIS)
Aledda, R.; Cannas, B.; Fanni, A.; Pau, A.; Sias, G.
2015-01-01
Highlights: • A disruption prediction system for AUG, based on a logistic model, is designed. • The length of the disruptive phase is set for each disruption in the training set. • The model is tested on dataset different from that used during the training phase. • The generalization capability and the aging of the model have been tested. • The predictor performance is compared with the locked mode detector. - Abstract: In large-scale tokamaks disruptions have the potential to create serious damage to the facility. Hence disruptions must be avoided, but, when a disruption is unavoidable, minimizing its severity is mandatory. A reliable detection of a disruptive event is required to trigger proper mitigation actions. To this purpose machine learning methods have been widely studied to design disruption prediction systems at ASDEX Upgrade. The training phase of the proposed approaches is based on the availability of disrupted and non-disrupted discharges. In literature disruptive configurations were assumed appearing into the last 45 ms of each disruption. Even if the achieved results in terms of correct predictions were good, it has to be highlighted that the choice of such a fixed temporal window might have limited the prediction performance. In fact, it generates confusing information in cases of disruptions with disruptive phase different from 45 ms. The assessment of a specific disruptive phase for each disruptive discharge represents a relevant issue in understanding the disruptive events. In this paper, the Mahalanobis distance is applied to define a specific disruptive phase for each disruption, and a logistic regressor has been trained as disruption predictor. The results show that enhancements on the achieved performance on disruption prediction are possible by defining a specific disruptive phase for each disruption.
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Neutronic analysis of LMFBRs during severe core disruptive accidents
International Nuclear Information System (INIS)
Tomlinson, E.T.
1979-01-01
A number of numerical experiments were performed to assess the validity of diffusion theory and various perturbation methods for calculating the reactivity state of a severely disrupted liquid metal cooled fast breeder reactor (LMFBR). The disrupted configurations correspond, in general, to phases through which an LMFBR core could pass during a core disruptive accident (CDA). Two-reactor models were chosen for this study, the two zone, homogeneous Clinch River Breeder Reactor and the Large Heterogeneous Reactor Design Study Core. The various phases were chosen to approximate the CDA results predicted by the safety analysis code SAS3D. The calculational methods investigated in this study include the eigenvalue difference technique based on both discrete ordinate transport theory and diffusion theory, first-order perturbation theory, exact perturbation theory, and a new hybrid perturbation theory. Selected cases were analyzed using Monte Carlo methods. It was found that in all cases, diffusion theory and perturbation theory yielded results for the change in reactivity that significantly disagreed with both the discrete ordinate and Monte Carlo results. These differences were, in most cases, in a nonconservative direction
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Amos, Natalie; McCabe, Marita
2017-10-01
Limited research exists on the implications of feeling sexually attractive for various aspects of sexuality and sexual relationships. This article examined associations between self-perceived sexual attractiveness and sexual esteem, sexual satisfaction and amount of sexual experience, among both men and women who identified as heterosexual (n = 1017), gay or lesbian (n = 1225) or bisexual (n = 651). Results of the study demonstrated that positive self-perceptions of sexual attractiveness predicted greater sexual esteem, greater sexual satisfaction, a higher frequency of sexual activity with others and a larger number of sexual partners among both men and women who identified as heterosexual, gay, lesbian or bisexual. The findings suggest that feeling sexually attractive may have implications for how an individual experiences their sexuality and sexual relationships regardless of their gender or sexual orientation. The importance of considering an individual's self-perceptions of sexual attractiveness when they present with concerns related to their sexual experiences or relationships, and the potential benefits of educational and therapeutic interventions designed to enhance self-perceptions of sexual attractiveness are discussed. © 2015 International Union of Psychological Science.
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Early Life Exposure to Endocrine Disrupting Chemicals and Childhood Obesity and Neurodevelopment
Braun, Joseph M.
2017-01-01
Endocrine disrupting chemicals (EDCs) may increase the risk of childhood diseases by disrupting hormonally mediated processes critical for growth and development during gestation, infancy, or childhood. The fetus, infant, and child may have enhanced sensitivity to environmental stressors like EDCs due to rapid development and greater exposure to some EDCs that results from their developmentally appropriate behavior, anatomy, and physiology. This review summarizes epidemiological studies examining the relations of early-life exposure to bisphenol A (BPA), phthalates, triclosan, and perfluoroalkyl substance (PFAS) with childhood neurobehavioral disorders and obesity. The available epidemiological evidence suggests that prenatal exposure to several of these ubiquitous EDCs is associated with adverse neurobehavior (BPA and phthalates) and excess adiposity or increased risk of obesity/overweight (PFAS). Quantifying the effects of EDC mixtures, improving EDC exposure assessment, reducing bias from confounding, identifying periods of heightened vulnerability, and elucidating the presence and nature of sexually dimorphic EDC effects would result in stronger inferences from epidemiological studies. Ultimately, better estimates of the causal effects of EDC exposures on child health could help identify susceptible sub-populations and lead to public health interventions to reduce these exposures. PMID:27857130
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Variables Associated with Disrupted Placement in a Select Sample of Abused and Neglected Children.
Cooper, Carolyn S.
1987-01-01
Examination of the placement history of 172 abused and/or neglected children found that children had a more disrupted foster care placement history if they: (1) had severe behavior problems; (2) were very young when first removed from the natural home; or (3) had drug-addicted and/or alcoholic parents. (Author/DB)
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International Nuclear Information System (INIS)
Hou, Jie; Li, Li; Wu, Ning; Su, Yujing; Lin, Wang; Li, Guangyu; Gu, Zemao
2016-01-01
Microcystin-LR (MC-LR) has been found to cause reproductive and developmental impairments as well as to disrupt sex hormone homeostasis of fish during acute and sub-chronic toxic experiments. However, fish in natural environments are continuously exposed to MC-LR throughout their entire life cycle as opposed to short-term exposure. Here, we tested the hypothesis that the mechanism by which MC-LR harms female fish reproduction and development within natural water bodies is through interference of the reproductive endocrine system. In the present study, zebrafish hatchlings (5 d post-fertilization) were exposed to 0, 0.3, 3 and 30 μg/L MC-LR for 90 d until reaching sexual maturity. Female zebrafish were selected, and the changes in growth and developmental indicators, ovarian ultrastructure as well as the levels of gonadal steroid hormones and vitellogenin (VTG) were examined along with the transcription of related genes in the hypothalamic–pituitary–gonadal–liver axis (HPGL-axis). The results showed for the first time, a life cycle exposure to MC-LR caused growth inhibition, decreased ovary weight and ovarian ultra-pathological lesions. Decreased ovarian testosterone levels indicated that MC-LR disrupted sex steroid hormone balance. Significantly up-regulated transcription of brain FSHβ and LHβ along with ovarian ERα, FSHR and LHR suggested positive feedback regulation in the HPGL-axis was induced as a compensatory mechanism for MC-LR damage. It was also noted that ovarian VTG content and hepatic ERα and VTG1 expression were all down-regulated, which might be responsible for reduced vitellus storage noted in our histological observations. Our findings indicate that a life cycle exposure to MC-LR impairs the development and reproduction of female zebrafish by disrupting the transcription of related HPGL-axis genes, suggesting that MC-LR has potential adverse effects on fish reproduction and thus population dynamics in MCs-contaminated aquatic
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The influence of a conducting wall on disruptions in HBT-EP
International Nuclear Information System (INIS)
Kombargi, R.
1997-01-01
The characteristics of long wavelength magnetohydrodynamic (MHD) disruptive instabilities have been studied in a tokamak device with segmented and movable conducting walls. Coupling between the wall and the plasma was varied by systematically adjusting the radial position, b, of the conducting plates relative to the plasma surface of minor radius a. By pre-selecting the total plasma current ramp rate (dI p /dt), disruptive instabilities driven either by large edge currents or high plasma pressure were studied. Specifically, three types of disruptions caused by both external (to the plasma) and internal instabilities were obtained by changing the plasma-wall separation (b/a) and the temporal evolution of the total plasma current. The properties of these disruptions were examined using a variety of magnetic pickup coils and arrays of soft x-ray detectors. Experiments demonstrated that rapidly developing, low-n kink instabilities were suppressed if the conducting wall was positioned sufficiently near the plasma (b/a p /dt > 0) was maintained. Conducting wall stabilization of fast growing external instabilities was observed in discharges with high edge current and in plasmas with β-values near the ideal MED stability boundary. When the conducting wall was near the plasma surface and as the current profile evolved in time (dI p /dt < 0), slowly growing internal instabilities would also lead to disruptions. Disruption mechanisms for plasmas with b/a=1.52 and b/a=1.07 were compared. Differences in the precursor modes, the speed of the thermal collapse and the chronological sequence of events were found. In summary, the disruptions with an external character were eliminated when the conducting wall was moved from b/a=1.52 to b/a<1.2. Internal disruptions could not be averted even with b/a=1.07
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Sexuality and Sexual Rights in Muslim Societies
Liz Ercevik Amado
2009-01-01
In August 2008, the Coalition for Sexual and Bodily Rights in Muslim Societies (CSBR) organized the CSBR Sexuality Institute, the first international Institute on sexuality and sexual rights in Muslim societies in Malaysia. Liz Amado presents how the Institute expanded the discourse, knowledge and thinking around sexuality in Muslim societies, as well as providing a unique space for the much needed exchange of information and experience among sexual rights advocates. Development (2009) 52, 59...
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Sexual dysfunction among Ghanaian men presenting with various medical conditions
Directory of Open Access Journals (Sweden)
Quaye Lawrence
2010-10-01
Full Text Available Abstract Background Several medical conditions can affect and disrupt human sexuality. The alteration of sexuality in these medical conditions often hinder effective communication and empathy between the patients and their sexual partners because of cultural attitudes, social norms and negative feelings such as anxiety and guilt. Validated and standardized sexual inventories might therefore help resolve this problem. The objective of this cross-sectional study was to obtain data on the prevalence of male sexual dysfunction (SD among Ghanaians with various medical conditions residing in Kumasi. Methods The Golombok Rust Inventory of Sexual Satisfaction (GRISS was administered to 150 Ghanaian men with various medical conditions between 19 and 66 years old (mean ± standard deviation: 40.01 ± 12.32 years domiciled in the Kumasi metropolis. Results Out of the total 150 questionnaires administered, 105 (70.0% men returned the questionnaires. Questionnaires from 3 men were incomplete, leaving 102 complete and evaluable questionnaires, indicating a 68.0% response rate. Of the remaining 102 men, 88.2% were married, 70.6% had attained higher education, 88.2% were non-smokers. Whereas 54.9% were engaged in exercise, 61.8% indulged in alcoholic beverages. The prevalence of the various medical conditions include: diabetes (18%, hypertension (24.5%, migraine (11.8%, ulcer (7.8%, surgery (6.9%, STD (3.9 and others (26.5%. The prevalence of SD among the respondents in the study was 59.8%. The highest prevalence of SD was seen among ulcer patients (100%, followed by patients who have undergone surgery (75%, diabetes (70%, hypertension (50%, STD (50% and the lowest was seen among migraine patients (41.7%. Conclusions SD rate is high among Ghanaian men with medical conditions (about 60% and vary according to the condition and age.
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Exploring infertile women's experiences about sexual life: A qualitative study.
Kohan, Shahnaz; Ghasemi, Zahra; Beigi, Marjan
2015-01-01
Infertility is a serious problem in a couple's life that affects their marriage relationships. So, dissatisfaction with sexual function resulting from interpersonal problems is common among these couples. This qualitative study aimed to explore the experiences of infertile women in their sexual life. This is a qualitative study with a phenomenological approach. The participants were 20 infertile women referring to the health care centers and infertility clinics of Isfahan and were selected through purposive sampling. Data were collected by tape recording of deep interviews and analyzed by Colaizzi's method. Analysis of the participants' experiences led to five main concepts: "Disturbed in femininity-body image," "discouragement of sexual relations," "sacrifice of sexual pleasure for the sake of getting pregnant," "confusion in sexual relation during infertility treatment," and "striving to protect their marriage." Findings revealed that infertility affects women's different aspects of sexual life, especially disturbance in femininity-body image and sexual reluctance. With regard to women's willingness to protect their matrimonial life and prevent sexual trauma as a destroying factor for their family's mental health, it seems sexual counseling is necessary for infertile couples.
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International Nuclear Information System (INIS)
Milani, F.
1998-12-01
The sudden loss of the plasma magnetic confinement, known as disruption, is one of the major issue in a nuclear fusion machine as JET (Joint European Torus). Disruptions pose very serious problems to the safety of the machine. The energy stored in the plasma is released to the machine structure in few milliseconds resulting in forces that at JET reach several Mega Newtons. The problem is even more severe in the nuclear fusion power station where the forces are in the order of one hundred Mega Newtons. The events that occur during a disruption are still not well understood even if some mechanisms that can lead to a disruption have been identified and can be used to predict them. Unfortunately it is always a combination of these events that generates a disruption and therefore it is not possible to use simple algorithms to predict it. This thesis analyses the possibility of using neural network algorithms to predict plasma disruptions in real time. This involves the determination of plasma parameters every few milliseconds. A plasma boundary reconstruction algorithm, XLOC, has been developed in collaboration with Dr. D. O'Brien and Dr. J. Ellis capable of determining the plasma wall/distance every 2 milliseconds. The XLOC output has been used to develop a multilayer perceptron network to determine plasma parameters as l i and q ψ with which a machine operational space has been experimentally defined. If the limits of this operational space are breached the disruption probability increases considerably. Another approach for prediction disruptions is to use neural network classification methods to define the JET operational space. Two methods have been studied. The first method uses a multilayer perceptron network with softmax activation function for the output layer. This method can be used for classifying the input patterns in various classes. In this case the plasma input patterns have been divided between disrupting and safe patterns, giving the possibility of
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Sexual Well-Being in Older Women: The Relevance of Sexual Excitation and Sexual Inhibition.
Bell, Suzanne; Reissing, Elke D
2017-01-01
The aim of this study was to use the dual control model of sexual response (DCM) to investigate variation in sexual well-being among women 50 years of age and older. Data from 185 women 50 years of age and older (M = 59.46, SD = 6.96) were used to examine the relationships between sexual excitation (SE) and sexual inhibition (SI) and their lower-order factors to indicators of sexual well-being (i.e., sexual functioning, satisfaction, distress, frequency of sexual activity, and breadth of sexual behavior). Possible moderating factors were also explored. Independently, SE and SI were associated with the majority of the indicators of sexual well-being, and the directions of associations were consistent with the tenets of the DCM. SE and SI lower-order factors were significant predictors of sexual function, satisfaction, and frequency of sexual activity. Sexual distress was predicted more strongly by SI factors and breadth of sexual behavior by one SE lower-order factor (arousability). Partner physical and mental health and participant's own mental health were identified as moderating variables of these associations. Findings of this study are discussed considering the contribution of the DCM to understanding the role of diversity in older women's sexual well-being.
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Directory of Open Access Journals (Sweden)
Olivia Nankinga
2016-05-01
Full Text Available Abstract Background Sexually transmitted infections (STIs are a major reproductive and public health concern, especially in the era of HIV/AIDS. This study examined the relationship between sexual empowerment and STI status of women in union (married or cohabiting in Uganda, controlling for sexual behaviour, partner factors, and women’s background characteristics. Methods The study, based on data from the 2011 Uganda Demographic and Health Survey (UDHS, analysed 1307 weighted cases of women age 15–49 in union and selected for the domestic violence module. Chi-squared tests and multivariate logistic regressions were used to examine the predicators of STI status. The main explanatory variables included sexual empowerment, involvement in decision making on own health, experience of any sexual violence, condom use during last sex with most recent partner, number of lifetime partners and partner control behaviours. Sexual empowerment was measured with three indicators: a woman’s reported ability to refuse sex, ability to ask her partner to use a condom, and opinion regarding whether a woman is justified to refuse sex with her husband if he is unfaithful. Results Results show that 28 % of women in union reported STIs in the last 12 months. Sexual violence and number of lifetime partners were the strongest predictors of reporting STIs. Women’s sexual empowerment was a significant predictor of their STI status, but, surprisingly, the odds of reporting STIs were greater among women who were sexually empowered. Reporting of STIs was negatively associated with a woman’s participation in decision-making with respect to her own health, and was positively associated with experience of sexual violence, partner’s controlling behaviour, and having more than one life partner. Conclusions Our findings suggest that, with respect to STIs, sexual empowerment as measured in the study does not protect women who have sexually violent and controlling
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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.
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Sex-specific selection under environmental stress in seed beetles.
Martinossi-Allibert, I; Arnqvist, G; Berger, D
2017-01-01
Sexual selection can increase rates of adaptation by imposing strong selection in males, thereby allowing efficient purging of the mutation load on population fitness at a low demographic cost. Indeed, sexual selection tends to be male-biased throughout the animal kingdom, but little empirical work has explored the ecological sensitivity of this sex difference. In this study, we generated theoretical predictions of sex-specific strengths of selection, environmental sensitivities and genotype-by-environment interactions and tested them in seed beetles by manipulating either larval host plant or rearing temperature. Using fourteen isofemale lines, we measured sex-specific reductions in fitness components, genotype-by-environment interactions and the strength of selection (variance in fitness) in the juvenile and adult stage. As predicted, variance in fitness increased with stress, was consistently greater in males than females for adult reproductive success (implying strong sexual selection), but was similar in the sexes in terms of juvenile survival across all levels of stress. Although genetic variance in fitness increased in magnitude under severe stress, heritability decreased and particularly so in males. Moreover, genotype-by-environment interactions for fitness were common but specific to the type of stress, sex and life stage, suggesting that new environments may change the relative alignment and strength of selection in males and females. Our study thus exemplifies how environmental stress can influence the relative forces of natural and sexual selection, as well as concomitant changes in genetic variance in fitness, which are predicted to have consequences for rates of adaptation in sexual populations. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.
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Sexual dysfunction among youth: an overlooked sexual health concern.
Moreau, Caroline; Kågesten, Anna E; Blum, Robert Wm
2016-11-18
There is growing recognition that youth sexual health entails a broad range of physical, emotional and psychosocial responses to sexual interactions, yet little is known about sexual dysfunctions and well being in youth populations. This study explored sexual dysfunctions among youth and its associations with other domains of sexual health. Sexual dysfunctions were defined as: problems related to orgasm, pain during intercourse, lack of sexual desire or sexual pleasure. Data were drawn from the 2010 French national sexual and reproductive health survey comprising a random sample of 2309 respondents aged 15-24 years. The current analysis included 842 females and 642 males who had sexual intercourse in the last 12 months. Chi square tests were used to test for differences in sexual dysfunctions by sex and explore associations with other domains of sexual health. Half of females (48%) reported at least one sexual dysfunction versus 23% of males. However, over half (57%) of youth reporting at least one dysfunction did not consider this to hinder their sexuality. Altogether, 31% of females cited at least one sexual dysfunction hindering their sexuality-more than three times the 9% of males. Sexual dysfunction was strongly and inversely related to sexual satisfaction for both males and females and additionally to a recent diagnosis of STI or unintended pregnancy for females. Sexual dysfunctions hindering sexuality were also correlated with a history of unintended pregnancy among males. While most youth in France enjoy a satisfying sexual life, sexual dysfunction is common, especially among females. Public health programs and clinicians should screen for and address sexual dysfunction, which substantially reduce youth sexual wellbeing.
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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.
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Walker, Dave P; Messman-Moore, Terri L; Ward, Rose Marie
2011-01-01
In previous studies, number of sexual partners and sexual assertiveness were examined as independent risk factors for sexual victimization among college women. Using a sample of 335 college women, this study examined the interaction of number of sexual partners and sexual assertiveness on verbal sexual coercion and rape. Approximately 32% of the sample reported unwanted sexual intercourse, 6.9% (n = 23) experienced verbal sexual coercion, 17.9% (n = 60) experienced rape, and 7.2% (n = 24) experienced both. As number of sexual partners increased, instances of verbal sexual coercion increased for women low in relational sexual assertiveness but not for women high in relational sexual assertiveness. A similar relationship was not found for rape. Among women who experienced both verbal sexual coercion and rape, increases in number of partners in the context of low refusal and relational assertiveness were associated with increases in verbal sexual coercion and rape. Findings suggest sexual assertiveness is related to fewer experiences of sexual coercion.
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van Anders, Sari M
2015-07-01
Sexual orientation typically describes people's sexual attractions or desires based on their sex relative to that of a target. Despite its utility, it has been critiqued in part because it fails to account for non-biological gender-related factors, partnered sexualities unrelated to gender or sex, or potential divergences between love and lust. In this article, I propose Sexual Configurations Theory (SCT) as a testable, empirically grounded framework for understanding diverse partnered sexualities, separate from solitary sexualities. I focus on and provide models of two parameters of partnered sexuality--gender/sex and partner number. SCT also delineates individual gender/sex. I discuss a sexual diversity lens as a way to study the particularities and generalities of diverse sexualities without privileging either. I also discuss how sexual identities, orientations, and statuses that are typically seen as misaligned or aligned are more meaningfully conceptualized as branched or co-incident. I map out some existing identities using SCT and detail its applied implications for health and counseling work. I highlight its importance for sexuality in terms of measurement and social neuroendocrinology, and the ways it may be useful for self-knowledge and feminist and queer empowerment and alliance building. I also make a case that SCT changes existing understandings and conceptualizations of sexuality in constructive and generative ways informed by both biology and culture, and that it is a potential starting point for sexual diversity studies and research.
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Lou, Jiunn-Horng; Chen, Sheng-Hwang; Li, Ren-Hau; Yu, Hsing-Yi
2011-06-01
The purpose of this study was to test a model of sexual self-concept and sexual risk cognition affecting sexual communication in Taiwanese adolescents. Parent-adolescent sexual communication has been shown to influence adolescent sexual behaviour. Self-concept is an important predictor of human behaviour, especially sexual behaviour. Few researchers have assessed sexual self-concept in adolescents, despite its clear relevance to understanding adolescent sexual behaviour. A cross-sectional survey with convenience sampling was used in this study. In 2009, data were collected by questionnaire from 748 adolescent students at a junior college in Taiwan. The results revealed that the postulated model fits the data from this study well. Sexual self-concept significantly predicts sexual risk cognition and sexual communication. Sexual risk cognition significantly predicts sexual communication and has an intervening effect on the relationship between sexual self-concept and sexual communication. Sexual risk cognition is important in explaining sexuality in adolescents. Sexual self-concept has both direct and indirect effects on sexual communication. Our findings provide concrete directions for school educators in developing sexual health programmes to increase adolescent sexual self-concept and sexual communication with their parents. Future sexual health programmes about sexual self-concept and sexual risk cognition must add for increasing adolescent's sexual communication with their parents. © 2010 Blackwell Publishing Ltd.
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Liney, Katherine E.; Jobling, Susan; Shears, Jan A.; Simpson, Peter; Tyler, Charles R.
2005-01-01
Surveys of U.K. rivers have shown a high incidence of sexual disruption in populations of wild roach (Rutilus rutilus) living downstream from wastewater treatment works (WwTW), and the degree of intersex (gonads containing both male and female structural characteristics) has been correlated with the concentration of effluent in those rivers. In this study, we investigated feminized responses to two estrogenic WwTWs in roach exposed for periods during life stages of germ cell division (early life and the postspawning period). Roach were exposed as embryos from fertilization up to 300 days posthatch (dph; to include the period of gonadal sex differentiation) or as postspawning adult males, and including fish that had received previous estrogen exposure, for either 60 or 120 days when the annual event of germ cell proliferation occurs. Both effluents induced vitellogenin synthesis in both life stages studied, and the magnitude of the vitellogenic responses paralleled the effluent content of steroid estrogens. Feminization of the reproductive ducts occurred in male fish in a concentration-dependent manner when the exposure occurred during early life, but we found no effects on the reproductive ducts in adult males. Depuration studies (maintenance of fish in clean water after exposure to WwTW effluent) confirmed that the feminization of the reproductive duct was permanent. We found no evidence of ovotestis development in fish that had no previous estrogen exposure for any of the treatments. In wild adult roach that had previously received exposure to estrogen and were intersex, the degree of intersex increased during the study period, but this was not related to the immediate effluent exposure, suggesting a previously determined programming of ovotestis formation. PMID:16203238
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Does Sexual Selection Influence Ornamentation of Hemipenes in Old World Snakes?
Andonov, Kostadin; Natchev, Nikolay; Kornilev, Yurii V; Tzankov, Nikolay
2017-09-01
In the present study, we investigated and documented the morphology of the male copulatory organs (hemipenes) in fifteen wide-ranging snake species. The species represent four families (Boidae, Colubridae, Lamprophiidae, and Viperidae) and ten genera. We applied the same preparation techniques for all species, successfully everting and expanding the organs completely. The detailed description of the general morphology of the male copulatory organs was based on 31 specimens. Our data were compared with published observations and we point out some incorrectly described details in previous investigations. We provide the first description of the hemipenial morphology for three ophidian species (Elaphe sauromates, Telescopus fallax, and Malpolon insignitus). In addition to the morphological characteristics of the hemipenes presented in the research, we propose the adoption of a standardized index describing the hemipenial proportions. The immense variation in hemipenial morphology presupposes its dynamic evolution, but we suggest that many of the significant structures observed here may have escaped previous researchers due to differing methodologies. Some of the highly ornamented morphologies that we describe are consistent with a locking mechanism during copulation. However, other morphologies may relate to the variety of mating behaviors observed. As a result, we propose that sexual selection is the major driver affecting the hemipenial ornamentation in snakes. Anat Rec, 300:1680-1694, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.
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Human sexual conflict from molecules to culture.
Gorelik, Gregory; Shackelford, Todd K
2011-12-15
Coevolutionary arms races between males and females have equipped both sexes with mutually manipulative and defensive adaptations. These adaptations function to benefit individual reproductive interests at the cost of the reproductive interests of opposite-sex mates, and arise from evolutionary dynamics such as parental investment (unequal reproductive costs between the sexes) and sexual selection (unequal access to opposite-sex mates). Individuals use these adaptations to hijack others' reproductive systems, psychological states, and behaviors--essentially using other individuals as extended phenotypes of themselves. Such extended phenotypic manipulation of sexual rivals and opposite-sex mates is enacted by humans with the aid of hormones, pheromones, neurotransmitters, emotions, language, mind-altering substances, social institutions, technologies, and ideologies. Furthermore, sexual conflict may be experienced at an individual level when maternal genes and paternal genes are in conflict within an organism. Sexual conflict may be physically and emotionally destructive, but may also be exciting and constructive for relationships. By extending the biological concept of sexual conflict into social and cultural domains, scholars may successfully bridge many of the interdisciplinary gaps that separate the sciences from the humanities.
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Everett, Bethany G
2013-02-01
The terms MSM (men who have sex with men) and WSW (women who have sex with women) have been used with increasing frequency in the public health literature to examine sexual orientation disparities in sexual health. These categories, however, do not allow researchers to examine potential differences in sexually transmitted infection (STI) risk by sexual orientation identity. Using data from the National Longitudinal Survey of Adolescent Health, this study investigated the relationship between self-reported STIs and both sexual orientation identity and sexual behaviors. Additionally, this study examined the mediating role of victimization and STI risk behaviors on the relationship between sexual orientation and self-reported STIs. STI risk was found to be elevated among heterosexual-WSW and bisexual women, whether they reported same-sex partners or not, whereas gay-identified WSW were less likely to report an STI compared to heterosexual women with opposite sex relationships only. Among males, heterosexual-identified MSM did not have a greater likelihood of reporting an STI diagnosis; rather, STI risk was concentrated among gay and bisexual identified men who reported both male and female sexual partners. STI risk behaviors mediated the STI disparities among both males and females, and victimization partially mediated STI disparities among female participants. These results suggest that relying solely on behavior-based categories, such as MSM and WSW, may mischaracterize STI disparities by sexual orientation.
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Sexual dysfunction among youth: an overlooked sexual health concern
Directory of Open Access Journals (Sweden)
Caroline Moreau
2016-11-01
Full Text Available Abstract Background There is growing recognition that youth sexual health entails a broad range of physical, emotional and psychosocial responses to sexual interactions, yet little is known about sexual dysfunctions and well being in youth populations. This study explored sexual dysfunctions among youth and its associations with other domains of sexual health. Sexual dysfunctions were defined as: problems related to orgasm, pain during intercourse, lack of sexual desire or sexual pleasure. Methods Data were drawn from the 2010 French national sexual and reproductive health survey comprising a random sample of 2309 respondents aged 15-24 years. The current analysis included 842 females and 642 males who had sexual intercourse in the last 12 months. Chi square tests were used to test for differences in sexual dysfunctions by sex and explore associations with other domains of sexual health. Results Half of females (48% reported at least one sexual dysfunction versus 23% of males. However, over half (57% of youth reporting at least one dysfunction did not consider this to hinder their sexuality. Altogether, 31% of females cited at least one sexual dysfunction hindering their sexuality—more than three times the 9% of males. Sexual dysfunction was strongly and inversely related to sexual satisfaction for both males and females and additionally to a recent diagnosis of STI or unintended pregnancy for females. Sexual dysfunctions hindering sexuality were also correlated with a history of unintended pregnancy among males. Conclusion While most youth in France enjoy a satisfying sexual life, sexual dysfunction is common, especially among females. Public health programs and clinicians should screen for and address sexual dysfunction, which substantially reduce youth sexual wellbeing.
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GENDER DIFFERENCES IN PERCEPTIONS OF SEXUAL INTENT: A QUALITATIVE REVIEW AND INTEGRATION
Lindgren, Kristen P.; Parkhill, Michele R.; George, William H.; Hendershot, Christian S.
2009-01-01
Men appear to interpret people’s behaviors more sexually than do women. This finding, which has been replicated in scores of studies using a variety of methodological approaches, has been linked to important social concerns, including sexual assault and sexual harassment. This article provides a critical review of the published literature on gender differences in sexual intent perception, using selective examples to illustrate and summarize the field’s major constructs, methodologies, and empirical findings. Theoretical explanations for gender differences in sexual intent perceptions are reviewed. Finally, we highlight the field’s remaining issues and make several recommendations for future research directions. PMID:19763282
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Disrupting Mating Behavior of Diaphorina citri (Liviidae).
Lujo, S; Hartman, E; Norton, K; Pregmon, E A; Rohde, B B; Mankin, R W
2016-12-01
Severe economic damage from citrus greening disease, caused by 'Candidatus Liberibacter asiaticus' bacteria, has stimulated development of methods to reduce mating and reproduction in populations of its insect vector, Diaphorina citri (Hemiptera: Liviidae). Male D. citri find mating partners by walking on host plants, intermittently producing vibrational calls that stimulate duetting replies by receptive females. The replies provide orientational feedback, assisting the search process. To test a hypothesis that D. citri mating can be disrupted using vibrational signals that compete with and/or mask female replies, courtship bioassays were conducted in citrus trees with or without interference from female reply mimics produced by a vibrating buzzer. Statistically significant reductions occurred in the rates and proportions of mating when the buzzer produced reply mimics within 0.4 s after male courtship calls compared with undisturbed controls. Observations of courtship behaviors in the two bioassays revealed activity patterns that likely contributed to the reductions. In both disruption and control tests, males reciprocated frequently between structural bifurcations and other transition points where signal amplitudes changed. Males in the disruption bioassay had to select among vibrational signals combined from the buzzer and the female at each transition point. They often turned towards the buzzer instead of the female. There was a statistically significant reduction in the proportion of males mating if they contacted the buzzer, possibly due to its higher vibration amplitude and duration in comparison with female replies. Potential applications of D. citri mating disruption technology in citrus groves are discussed. Published by Oxford University Press on behalf of Entomological Society of America 2016. This work is written by US Government employees and is in the public domain in the US.
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[Sexuality of the elderly: a survey and management].
Ribes, G; Cour, F
2013-07-01
To evaluate sexuality in elderly couples and have the knowledge of its specific therapeutic options. Review of articles published on this subject in the Medline database, selected according to their scientific relevance together with a reflexion from our own experience. Due to increased life expectancy and the changes in society leading to a life with more than one consecutive partner, couples expect to continue sexual activity after the age of 65. Clinicians are asked to address this issue frequently. With age the frequency of genital sexual relations decreases. Sexual activity should be higher both for males and females. The quality of the relationship of the couple is a key element in maintaining sexual relations in this age group. Sexual satisfaction depends on the understanding, by both partners, of the physical and psychological changes due to increased age. The sexuality of the elderly couple must be analysed using specific criteria. The clinician's task is to explain to the patients the physiological change due to aging and give them advice on how to adapt their sexual behavior accordingly. Management will, at the same time, include pharmacological treatment, notably for erectile dysfunction, in order to restore satisfactory sexual relations. For women, vaginal lubrication products are essential. This global management should allow many elderly couples wishing to continue sexual relations, to enjoy this period of their lives in harmony with what they desire. Copyright © 2012 Elsevier Masson SAS. All rights reserved.
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Sexually Dimorphic Effects of Ancestral Exposure to Vinclozolin on Stress Reactivity in Rats
Gillette, Ross; Miller-Crews, Isaac; Nilsson, Eric E.; Skinner, Michael K.; Gore, Andrea C.; Crews, David
2014-01-01
How an individual responds to the environment depends upon both personal life history as well as inherited genetic and epigenetic factors from ancestors. Using a 2-hit, 3 generations apart model, we tested how F3 descendants of rats given in utero exposure to the environmental endocrine-disrupting chemical (EDC) vinclozolin reacted to stress during adolescence in their own lives, focusing on sexually dimorphic phenotypic outcomes. In adulthood, male and female F3 vinclozolin- or vehicle-linea...
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Oshri, Assaf; Tubman, Jonathan G; Morgan-Lopez, Antonio A; Saavedra, Lissette M; Csizmadia, Annamaria
2013-01-01
This study evaluated relations between sexual sensation seeking, co-occurring sex and alcohol use, and sexual risk behaviors (eg, unprotected intercourse and multiple sex partners) among adolescents receiving treatment for substance abuse problems. The ethnically diverse sample included 394 adolescents recruited from outpatient treatment (280 males; Mage = 16.33 years, SDage = 1.15). Structural equation modeling (SEM) was used to test direct and indirect paths between sexual sensation seeking and sexual risk behaviors via the frequency of co-occurring sex and alcohol use. Conditional indirect effects by gender were also tested. Analyses identified significant effects of sexual sensation seeking on co-occurring sex and alcohol use and sexual risk behaviors. The path from co-occurring sex and alcohol use to unprotected intercourse was significantly stronger among adolescent girls, suggesting a mediation effect moderated by gender. No gender difference was found for the indirect path from sexual sensation seeking and number of past year sexual partners via co-occurring sex and alcohol use. Selected prevention efforts are needed to promote HIV risk reduction among adolescents in substance abuse treatment. The documented conditional indirect effect for unprotected intercourse suggests that HIV prevention programs should pay special attention to gender-specific patterns of alcohol use and sexual risk behavior when tailoring program content. (Am J Addict 2013; 22:197-205). Copyright © American Academy of Addiction Psychiatry.
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Thompson, Aaron M.
2012-01-01
To attain academic goals, school personnel must effectively manage 20% of students who engage in the disruptive behaviors that interrupt instruction, create teacher stress, and contribute to poor student outcomes. Without effective strategies, school personnel often respond to disruptive students with ineffective authoritarian tactics,…
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Directory of Open Access Journals (Sweden)
Abigail Weitzman
2016-03-01
Full Text Available Natural disasters have inherently social dimensions because they exacerbate preexisting inequalities and disrupt social norms and institutions. Despite a growing interest in the sociological aspects of disasters, few studies have quantitatively explored how disasters alter intrahousehold family dynamics. In this article, we develop and test a conceptual framework that explicates how natural disasters affect an important component of family life: intimate partner violence (IPV. We combine two waves of geocoded Demographic and Health Surveys data, collected before and after the 2010 earthquake in Haiti, with spatial data on variation in the earthquake’s destruction. Our findings indicate that exposure to earthquake devastation increased the probability of both physical and sexual IPV one to two years following the disaster. These increases were accompanied by substantial changes in family functioning, the household economy, and women’s access to their social networks. Select household-level experiences during and after the earthquake, such as displacement, were also positively associated with IPV. These findings provide new insights into the multidimensional effects of disasters on family life and have important theoretical and policy implications that extend beyond the particular case of Haiti.
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Higgs, Tamsin; Carter, Adam J; Stefanska, Ewa B; Glorney, Emily
2017-08-01
Establishing a model of sexual assault reflecting psychosocial and behavioral characteristics of perpetrators of sexual killing and rape is necessary for development in risk assessment and intervention. Methodological variations in defining sexual killing have amalgamated serial and non-serial offenders and perpetrators with direct and indirect associations between killing and sexual arousal. This study defined sexual killing specifying that killing should be directly linked to sexual arousal, and sampled 48 sexual killers, operationalized to include only those engaging in post-mortem sexual interference, with one or two known female victims (non-serial), from prison service national (England and Wales) databases. These sexual killers were compared with 48 non-homicide, life or indeterminately sentenced sexual aggressors on psychological and crime scene characteristics. Contrary to previous research, fatal outcomes were associated with neither stranger victims nor weapon presence; sexual killing was characterized by severity of violence less so than non-fatal assault. Sexual killers more often reported problems with emotional loneliness, empathic concern, and sexual entitlement than the sexual aggressors. Theoretical and applied implications are discussed.
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Monitoring-induced disruption in skilled typewriting.
Snyder, Kristy M; Logan, Gordon D
2013-10-01
It is often disruptive to attend to the details of one's expert performance. The current work presents four experiments that utilized a monitor to report protocol to evaluate the sufficiency of three accounts of monitoring-induced disruption. The inhibition hypothesis states that disruption results from costs associated with preparing to withhold inappropriate responses. The dual-task hypothesis states that disruption results from maintaining monitored information in working memory. The implicit-explicit hypothesis states that disruption results from explicitly monitoring details of performance that are normally implicit. The findings suggest that all three hypotheses are sufficient to produce disruption, but inhibition and dual-task costs are not necessary. Experiment 1 showed that monitoring to report was disruptive even when there was no requirement to inhibit. Experiment 2 showed that maintaining information in working memory caused some disruption but much less than monitoring to report. Experiment 4 showed that monitoring to inhibit was more disruptive than monitoring to report, suggesting that monitoring is more disruptive when it is combined with other task requirements, such as inhibition. PsycINFO Database Record (c) 2013 APA, all rights reserved.
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Disruptive Intelligence - How to gather Information to deal with disruptive innovations
Vriens, D.J.; Solberg Søilen, K.
2014-01-01
Disruptive innovations are innovations that have the capacity to transform a whole business into one with products that are more accessible and affordable (cf. Christensen et al. 2009). As Christensen et al. argue no business is immune to such disruptive innovations. If these authors are right, it
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An epidemiological study of sexual disorders in south Indian rural population
Sathyanarayana Rao, T. S.; Darshan, M. S.; Tandon, Abhinav
2015-01-01
Background: Sexuality is an important aspect of the personality of an individual and influences psychological, physical and social well-being of both men and women. It is a paradox, that in the country where ?kamasutra? (by Vatsyayana) took birth, there is a lack of research publications and sexuality related literature; hence the current study was conducted, to estimate the prevalence and association of sexual disorders with various socio-demographic variables, in the selected rural populati...
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Cole, Jennifer; Sprang, Ginny; Lee, Robert; Cohen, Judith
2016-01-01
This study examined the demographic features, trauma profiles, clinical severity indicators, problem behaviors, and service utilization characteristics of youth victims of commercial sexual exploitation (CSE) compared with a matched sample of sexually abused/assaulted youth who were not exploited in commercial sex. Secondary data analysis and propensity score matching were used to select a sample of 215 help-seeking youth who were exploited in prostitution (n = 43) or who were sexually abused/assaulted but not exploited in prostitution (n = 172) from the National Child Traumatic Stress Network Core Data Set (NCTSN CDS). Propensity Score Matching was used to select a comparison sample based on age, race, ethnicity, and primary residence. Statistically significant differences were noted between the groups on standardized (e.g., UCLA Posttraumatic Stress Disorder Reaction Index [PTSD-RI], Child Behavior Checklist [CBCL]) and other measures of emotional and behavioral problems (e.g., avoidance and hyperarousal symptoms, dissociation, truancy, running away, conduct disorder, sexualized behaviors, and substance abuse). This study provides useful insight into the symptom and service utilization profiles of youth exploited in commercial sex as compared with youth with other types of sexually exploitive experiences. Targeted screening and event-sensitive measures are recommended to more accurately identify youth exploited in commercial sex. More research is needed to determine if and what modifications to trauma therapies may be required to address the more severe symptomatology and behavior problems associated with youth exploited in commercial sex. © The Author(s) 2014.
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Sex Attracts: Investigating Individual Differences in Attentional Bias to Sexual Stimuli
Kagerer, Sabine; Wehrum, Sina; Klucken, Tim; Walter, Bertram; Vaitl, Dieter; Stark, Rudolf
2014-01-01
We investigated the impact of sexual stimuli and the influence of sexual motivation on the performance in a dot-probe task and a line-orientation task in a large sample of males and females. All pictures (neutral, erotic) were rated on the dimensions of valence, arousal, disgust, and sexual arousal. Additionally, questionnaires measuring sexual interest/desire/motivation were employed. The ratings of the sexual stimuli point to a successful picture selection because sexual arousal did not differ between the sexes. The stimuli were equally arousing for men and women. Higher scores in the employed questionnaires measuring sexual interest/desire/motivation led to higher sexual arousal ratings of the sex pictures. Attentional bias towards sex pictures was observed in both experimental tasks. The attentional biases measured by the dot-probe and the line-orientation task were moderately intercorrelated suggesting attentional bias as a possible marker for a sex-attention trait. Finally, only the sexual sensation seeking score correlated with the attentional biases of the two tasks. Future research is needed to increase the predictive power of these indirect measures of sexual interest. PMID:25238545
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Antidepressant induced sexual dysfunction Part 1: epidemiology ...
African Journals Online (AJOL)
Adele
Abstract. Sexual dysfunction is a common side effect of treatment with antidepressants, particularly those with a predominantly .... free of serotonergic effects or have highly selective receptor .... received little attention in the current literature.
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Clarke, Juanne
2009-05-01
The purpose of this paper is to report on an exploratory content analysis of the portrayal of sexuality, sexual health and disease in select magazines designed for two groups of women: teenagers and women in the 40-50-year-old age category in the USA. The analysis found that magazine portrayal was both similar for the two groups of women and distinctly different. Neither group of magazines focused on women's sexual desire. Both kinds of magazines emphasized that it was women's work and worry to control sexual expression. Teenagers were described as responsible for avoiding sex in order to prevent pregnancy, fearsomely described STIs and untrustworthy male sexual partners. Abstinence was presented as the only viable option for young women. Women in the 40-50-year-old age group were portrayed as responsible for the emotion work and sexual relations linked to their responsibility for maintaining their marriages and fulfilling their tasks of motherhood, especially through the monitoring of the sexuality of their female children. Sex was characterized in terms akin to women's work within the home. Possible explanations for, and consequences of, these presentations of sexuality are discussed.
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Peixoto, Maria Manuela; Nobre, Pedro
2017-04-01
Despite the existence of conceptual models of sexual dysfunction based on cognitive theory, few studies have tested the role of vulnerability factors such as sexual beliefs as moderators of the activation of cognitive schemas in response to negative sexual events. To test the moderator role of dysfunctional sexual beliefs in the association between the frequency of negative sexual episodes and the activation of incompetence schemas in gay and heterosexual men. Five-hundred seventy-five men (287 gay, 288 heterosexual) who completed an online survey on cognitive-affective dimensions and sexual functioning were selected from a larger database. Hierarchical regression analyses were conducted to test the hypothesis that dysfunctional sexual beliefs moderate the association between the frequency of unsuccessful sexual episodes and the activation of incompetence schemas. Participants completed the Sexual Dysfunctional Beliefs Questionnaire and the Questionnaire of Cognitive Schemas Activated in Sexual Context. Findings indicated that men's ability for always being ready for sex, to satisfy the partner, and to maintain an erection until ending sexual activity constitute "macho" beliefs that moderate the activation of incompetence schemas when unsuccessful sexual events occur in gay and heterosexual men. In addition, activation of incompetence schemas in response to negative sexual events in gay men was moderated by the endorsement of conservative attitudes toward moderate sexuality. The main findings suggested that psychological interventions targeting dysfunctional sexual beliefs could help de-catastrophize the consequences of negative sexual events and facilitate sexual functioning. Despite being a web-based study, it represents the first attempt to test the moderator role of dysfunctional sexual beliefs in the association between the frequency of unsuccessful sexual episodes and the activation of incompetence schemas in gay and heterosexual men. Overall, findings
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Directory of Open Access Journals (Sweden)
Guilherme Vanoni Polanczyk
2003-02-01
Full Text Available OBJETIVO: Verificar a prevalência da exposição à violência sexual entre adolescentes estudantes de escolas estaduais. MÉTODOS: Foram selecionadas 52 escolas estaduais de Porto Alegre, RS, Brasil, com ensino fundamental completo, por meio de um processo de amostragem aleatória, estratificada de acordo com o tamanho das escolas. Foi selecionada, em cada escola, uma turma de oitava série por sorteio aleatório e foram incluídos todos os adolescentes presentes nas salas de aula que consentiram em participar do estudo. Foi utilizado o instrumento Triagem da Exposição de Crianças à Violência na Comunidade para identificar jovens que foram vítimas, testemunhas ou que conheciam vítimas de atos de violência sexual. RESULTADOS: Foram incluídos 1.193 adolescentes, representando 10,3% dos alunos matriculados na oitava série da rede estadual da cidade. Vinte e sete (2,3% adolescentes relataram ter sido vítimas de violência sexual, 54 (4,5% ter sido testemunhas de algum tipo de violência sexual e 332 (27,9% relataram conhecer alguém que tenha sido vítima de violência sexual. CONCLUSÕES: A exposição à violência sexual pelas três formas de contato relatadas mostrou-se freqüente entre os adolescentes estudados. São necessários estudos que abordem a violência sexual como um fenômeno social amplo, com múltiplos fatores associados, amparando estratégias comunitárias de prevenção e de tratamento.OBJECTIVE: To assess the prevalence o sexual violence among adolescents of public schools. METHODS: Fifty-two public elementary schools of Porto Alegre, Brazil, were selected through random sampling stratified by school size. An 8th grade class was selected in each school through simple random sampling and all adolescents attending the classes who agreed to participate were included in the study. The Screening Survey of Children's Exposure to Community Violence was used to identify adolescents who were victims, witnesses or knew
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DEFF Research Database (Denmark)
Tække, Jesper
2018-01-01
Dette blogindlæg giver en kort analyse af hvordan de sociale medier ved at give en ny tid har åbnet for den disruption af de politiske processer som især Trump stå som et eksempel på.......Dette blogindlæg giver en kort analyse af hvordan de sociale medier ved at give en ny tid har åbnet for den disruption af de politiske processer som især Trump stå som et eksempel på....
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Overbeek, Geertjan; van de Bongardt, Daphne; Baams, Laura
2018-03-13
One main source of sexual socialization lies within family interactions. Especially sexuality-specific parenting may determine adolescents' sexual development-adolescents' sexual behavior and sexual risk behavior, sexualized media consumption and permissive sexual attitudes-to a significant extent, but different ideas exist about how this works. In this longitudinal study, we examined two hypotheses on how sexuality-specific parenting-parenting aimed specifically at children's sexual attitudes and behaviors-relates to adolescents' sexual development. A first buffer hypothesis states that parents' instructive media discussions with their children-called instructive mediation-buffers the effect of sexualized media consumption on adolescents' sexual attitudes and behavior and, vice versa, the effect of adolescents' sexual attitudes and behavior on sexualized media consumption. A second brake hypothesis states that parents, by communicating love-and-respect oriented sexual norms, slow down adolescents' development toward increased sexualized media use, permissive sexual attitudes, and sexual behavior and sexual risk behavior. Using four-wave longitudinal data from 514 Dutch adolescents aged 13-16 years (49.8% female), we found evidence to support a brake effect. More frequent parental communication of love-and-respect oriented sexual norms was associated with less permissive sexual attitudes and, for boys, with less advanced sexual behavior and a less rapid increase in sexual risk behavior. Parents' instructive mediation regarding adolescents' sexualized media consumption was associated with less permissive sexual attitudes at baseline, but only for girls. No systematic evidence emerged for a buffer effect of parents' instructive mediation. In conclusion, although our data seem to suggest that parent-child communication about sex is oftentimes "after the fact", we also find that more directive parental communication that conveys love-and-respect oriented sexual norms
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Mutual ornamentation, sexual selection, and social dominance in the black swan
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
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Backup Sourcing Decisions for Coping with Supply Disruptions under Long-Term Horizons
Directory of Open Access Journals (Sweden)
Jing Hou
2016-01-01
Full Text Available This paper studies a buyer’s inventory control problem under a long-term horizon. The buyer has one major supplier that is prone to disruption risks and one backup supplier with higher wholesale price. Two kinds of sourcing methods are available for the buyer: single sourcing with/without contingent supply and dual sourcing. In contingent sourcing, the backup supplier is capacitated and/or has yield uncertainty, whereas in dual sourcing the backup supplier has an incentive to offer output flexibility during disrupted periods. The buyer’s expected cost functions and the optimal base-stock levels using each sourcing method under long-term horizon are obtained, respectively. The effects of three risk parameters, disruption probability, contingent capacity or uncertainty, and backup flexibility, are examined using comparative studies and numerical computations. Four sourcing methods, namely, single sourcing with contingent supply, dual sourcing, and single sourcing from either of the two suppliers, are also compared. These findings can be used as a valuable guideline for companies to select an appropriate sourcing strategy under supply disruption risks.
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Towards a Disruptive Digital Platform Model
DEFF Research Database (Denmark)
Kazan, Erol
that digital platforms leverage on three strategic design elements (i.e., business, architecture, and technology design) to create supportive conditions for facilitating disruption. To shed light on disruptive digital platforms, I opted for payment platforms as my empirical context and unit of analysis......Digital platforms are layered modular information technology architectures that support disruption. Digital platforms are particularly disruptive, as they facilitate the quick release of digital innovations that may replace established innovations. Yet, despite their support for disruption, we have...... not fully understood how such digital platforms can be strategically designed and configured to facilitate disruption. To that end, this thesis endeavors to unravel disruptive digital platforms from the supply perspective that are grounded on strategic digital platform design elements. I suggest...
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Gaioso, Vanessa Pirani; Villarruel, Antonia Maria; Wilson, Lynda Anne; Azuero, Andres; Childs, Gwendolyn Denice; Davies, Susan Lane
2015-01-01
to test a theoretical model based on the Parent-Based Expansion of the Theory of Planned Behavior examining relation between selected parental, teenager and cultural variables and Latino teenagers' intentions to engage in sexual behavior. a cross-sectional correlational design based on a secondary data analysis of 130 Latino parent and teenager dyads. regression and path analysis procedures were used to test seven hypotheses and the results demonstrated partial support for the model. Parent familism and knowledge about sex were significantly associated with parents' attitudes toward sexual communication with their teenagers. Parent Latino acculturation was negatively associated with parents' self-efficacy toward sexual communication with their teenagers and positevely associated with parents' subjective norms toward sexual communication with their teenagers. Teenager knowledge about sex was significantly associated with higher levels of teenagers' attitudes and subjective norms about sexual communication with parents. Only the predictor of teenagers' attitudes toward having sex in the next 3 months was significantly associated with teenagers' intentions to have sex in the next 3 months. the results of this study provide important information to guide future research that can inform development of interventions to prevent risky teenager sexual behavior among Latinos.
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Female sexual arousal: genital anatomy and orgasm in intercourse.
Wallen, Kim; Lloyd, Elisabeth A
2011-05-01
In men and women sexual arousal culminates in orgasm, with female orgasm solely from sexual intercourse often regarded as a unique feature of human sexuality. However, orgasm from sexual intercourse occurs more reliably in men than in women, likely reflecting the different types of physical stimulation men and women require for orgasm. In men, orgasms are under strong selective pressure as orgasms are coupled with ejaculation and thus contribute to male reproductive success. By contrast, women's orgasms in intercourse are highly variable and are under little selective pressure as they are not a reproductive necessity. The proximal mechanisms producing variability in women's orgasms are little understood. In 1924 Marie Bonaparte proposed that a shorter distance between a woman's clitoris and her urethral meatus (CUMD) increased her likelihood of experiencing orgasm in intercourse. She based this on her published data that were never statistically analyzed. In 1940 Landis and colleagues published similar data suggesting the same relationship, but these data too were never fully analyzed. We analyzed raw data from these two studies and found that both demonstrate a strong inverse relationship between CUMD and orgasm during intercourse. Unresolved is whether this increased likelihood of orgasm with shorter CUMD reflects increased penile-clitoral contact during sexual intercourse or increased penile stimulation of internal aspects of the clitoris. CUMD likely reflects prenatal androgen exposure, with higher androgen levels producing larger distances. Thus these results suggest that women exposed to lower levels of prenatal androgens are more likely to experience orgasm during sexual intercourse. Copyright © 2011. Published by Elsevier Inc.
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Sexual education, gender ideology, and youth sexual empowerment.
Grose, Rose Grace; Grabe, Shelly; Kohfeldt, Danielle
2014-01-01
Sexual education plays an essential role in preventing unplanned pregnancy and the transmission of sexually transmitted infections (STIs). School-based sexual education programs, in particular, may be well positioned to address social factors that are empirically linked to negative sexual health outcomes, such as traditional social norms surrounding gender and sexuality. However, youth are seldom granted access to sexual education programs that explicitly address these issues. This study presents findings from a pretest-posttest survey of a sexual education program that did. It was designed for eighth graders (N=95) in the context of a school-community collaboration. The study assessed the links between several components of sexual empowerment, including gender ideology, sexual knowledge, and contraceptive beliefs. Findings link participation in the sexual education program to more progressive attitudes toward girls and women, less agreement with hegemonic masculinity ideology, and increases in sexual health and resource knowledge. Structural equation models suggest that traditional attitudes toward women were significantly related to hegemonic masculinity ideology among both boys and girls, which was in turn negatively related to safer contraceptive beliefs.
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International Nuclear Information System (INIS)
Ikeda, Masahiko; Mitsui, Tetsuo; Setani, Kaoru; Tamura, Masashi; Kakeyama, Masaki; Sone, Hideko; Tohyama, Chiharu; Tomita, Takako
2005-01-01
The effects of in utero and lactational exposure of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on brain sexual differentiation were investigated. TCDD was orally administered to pregnant Holtzman rats on gestation day (GD) 15, and the activity of brain aromatase, a key enzyme for sexual differentiation, was measured in offspring on postnatal day (PND) 2. Changes in sexual dimorphisms of saccharin preference and the volume of the sexually dimorphic nucleus of the preoptic area (SDN-POA) were examined in adult offspring. In controls, litter means of brain aromatase activity were higher in males than in females. In utero exposure to 200 ng/kg TCDD significantly decreased the sex ratio of aromatase activity (male/female) on PND 2. Offspring were weaned on PND28 and the saccharin test was started on PND84. In controls, saccharin (0.25%) intake (g/kg body weight) was significantly higher in female offspring than in males. In utero exposure to 200 ng/kg TCDD significantly increased saccharin intake in male offspring compared with control males, whereas 800 ng/kg TCDD had no effect. Neither dose of TCDD influenced saccharin intake of female offspring. In controls, SDN-POA volume was significantly greater in males than in females at 14 weeks of age. Exposure to 200 ng/kg TCDD significantly decreased SDN-POA volume in males, whereas 800 ng/kg TCDD had no effect. Neither doses of TCDD influenced the SDN-POA volume in female offspring. These results suggest that in utero and lactational TCDD exposure dose-dependently induces demasculinization in male offspring by inhibiting brain aromatase activity in the hypothalamus-preoptic area during central nervous system development
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Sexual dimorphism of head morphology in three-spined stickleback Gasterosteus aculeatus.
Aguirre, W E; Akinpelu, O
2010-09-01
This study examined sexual dimorphism of head morphology in the ecologically diverse three-spined stickleback Gasterosteus aculeatus. Male G. aculeatus had longer heads than female G. aculeatus in all 10 anadromous, stream and lake populations examined, and head length growth rates were significantly higher in males in half of the populations sampled, indicating that differences in head size increased with body size in many populations. Despite consistently larger heads in males, there was significant variation in size-adjusted head length among populations, suggesting that the relationship between head length and body length was flexible. Inter-population differences in head length were correlated between sexes, thus population-level factors influenced head length in both sexes despite the sexual dimorphism present. Head shape variation between lake and anadromous populations was greater than that between sexes. The common divergence in head shape between sexes across populations was about twice as important as the sexual dimorphism unique to each population. Finally, much of the sexual dimorphism in head length was due to divergence in the anterior region of the head, where the primary trophic structures were found. It is unclear whether the sexual dimorphism was due to natural selection for niche divergence between sexes or sexual selection. This study improves knowledge of the magnitude, growth rate divergence, inter-population variation and location of sexual dimorphism in G. aculeatus head morphology. © 2010 The Authors. Journal compilation © 2010 The Fisheries Society of the British Isles.
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Thigmotaxis Mediates Trail Odour Disruption.
Stringer, Lloyd D; Corn, Joshua E; Sik Roh, Hyun; Jiménez-Pérez, Alfredo; Manning, Lee-Anne M; Harper, Aimee R; Suckling, David M
2017-05-10
Disruption of foraging using oversupply of ant trail pheromones is a novel pest management application under investigation. It presents an opportunity to investigate the interaction of sensory modalities by removal of one of the modes. Superficially similar to sex pheromone-based mating disruption in moths, ant trail pheromone disruption lacks an equivalent mechanistic understanding of how the ants respond to an oversupply of their trail pheromone. Since significant compromise of one sensory modality essential for trail following (chemotaxis) has been demonstrated, we hypothesised that other sensory modalities such as thigmotaxis could act to reduce the impact on olfactory disruption of foraging behaviour. To test this, we provided a physical stimulus of thread to aid trailing by Argentine ants otherwise under disruptive pheromone concentrations. Trail following success was higher using a physical cue. While trail integrity reduced under continuous over-supply of trail pheromone delivered directly on the thread, provision of a physical cue in the form of thread slightly improved trail following and mediated trail disruption from high concentrations upwind. Our results indicate that ants are able to use physical structures to reduce but not eliminate the effects of trail pheromone disruption.
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Supply disruption cost for power network planning
International Nuclear Information System (INIS)
Kjoelle, G.H.
1992-09-01
A description is given of the method of approach to calculate the total annual socio-economic cost of power supply disruption and non-supplied energy, included the utilities' cost for planning. The total socio-economic supply disruption cost is the sum of the customers' disruption cost and the utilities' cost for failure and disruption. The mean weighted disruption cost for Norway for one hour disruption is NOK 19 per kWh. The customers' annual disruption cost is calculated with basis in the specific disruption cost referred to heavy load (January) and dimensioning maximum loads. The loads are reduced by factors taking into account the time variations of the failure frequency, duration, the loads and the disruption cost. 6 refs
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Correlates of sexual initiation among European adolescents.
Directory of Open Access Journals (Sweden)
Pietro Gambadauro
Full Text Available Sexuality is a physiological component of adolescent development, though early initiation is associated with reproductive health risk. This study aimed at identifying correlates and predictors of sexual initiation in a large multinational cohort of European adolescents.A questionnaire addressing socio-demographics, behaviours, mental health and sexual activity, was delivered to 11,110 adolescents recruited from 168 randomly selected schools in 10 European countries between 2009 and 2011. A follow-up questionnaire was delivered after 12 months. The longitudinal association of baseline risk behaviors, psychological attributes and contextual vulnerabilities, with sexual initiation during follow-up was evaluated through simple and multivariable age/sex stratified logistic regression. Multinomial logistic regression measured the association between predictors and sexual initiation with or without coexisting reproductive risk factors, such as multiple partners or infrequent condom use.Baseline sexual experience was reported by 19.2% of 10,757 respondents (median age 15; IQR 14-15; females 59.6%. This was significantly more frequent among pupils older than 15 (41% and males (20.8%. Of 7,111 pupils without previous experience who were available at follow-up (response rate 81.8%, 17% reported sexual initiation, without differences between females and males. Baseline smoking (age/sex adjusted odds ratio [aOR] 3.63, alcohol use (aOR 2.95, illegal drugs use (aOR 2.72, and poor sleep (aOR 1.71 predicted sexual initiation. Stratified analyses showed a particularly strong association in case of younger and female pupils, and, among girls, when initiation was reported together with multiple partners and/or infrequent condom use. Externalizing (i.e. conduct and hyperactivity symptoms independently predicted sexual initiation. Internalizing difficulties (i.e. emotional and peer problems were negatively associated with early and risky sexual initiation among boys
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G.J. Overbeek (Geertjan); van de Bongardt, D. (Daphne); Baams, L. (Laura)
2018-01-01
textabstractOne main source of sexual socialization lies within family interactions. Especially sexuality-specific parenting may determine adolescents’ sexual development—adolescents’ sexual behavior and sexual risk behavior, sexualized media consumption and permissive sexual attitudes—to a
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Disrupting the Industry with Play
DEFF Research Database (Denmark)
Lund, Henrik Hautop
2016-01-01
or two ago. This is significantly disrupting the industry in several market sectors. This paper describes the components of the playware and embodied artificial intelligence research that has led to disruption in the industrial robotics sector, and which points to the next disruption of the health care...
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Overbeek, Geertjan; van de Bongardt, Daphne; Baams, Laura
2018-01-01
One main source of sexual socialization lies within family interactions. Especially sexuality-specific parenting may determine adolescents’ sexual development—adolescents’ sexual behavior and sexual risk behavior, sexualized media consumption and permissive sexual attitudes—to a significant extent,
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Cell disruption for microalgae biorefineries.
Günerken, E; D'Hondt, E; Eppink, M H M; Garcia-Gonzalez, L; Elst, K; Wijffels, R H
2015-01-01
Microalgae are a potential source for various valuable chemicals for commercial applications ranging from nutraceuticals to fuels. Objective in a biorefinery is to utilize biomass ingredients efficiently similarly to petroleum refineries in which oil is fractionated in fuels and a variety of products with higher value. Downstream processes in microalgae biorefineries consist of different steps whereof cell disruption is the most crucial part. To maintain the functionality of algae biochemicals during cell disruption while obtaining high disruption yields is an important challenge. Despite this need, studies on mild disruption of microalgae cells are limited. This review article focuses on the evaluation of conventional and emerging cell disruption technologies, and a comparison thereof with respect to their potential for the future microalgae biorefineries. The discussed techniques are bead milling, high pressure homogenization, high speed homogenization, ultrasonication, microwave treatment, pulsed electric field treatment, non-mechanical cell disruption and some emerging technologies. Copyright © 2015 Elsevier Inc. All rights reserved.
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Psychopathology and personality in juvenile sexual homicide offenders.
Myers, W C; Blashfield, R
1997-01-01
This project describes the psychopathology and personality findings in 14 juveniles who committed sexual homicide. These incarcerated youth were assessed using a structured interview, a personality assessment instrument, correctional files review, and an author-designed clinical interview. Nearly all of these youth met DSM-III-R conduct disorder criteria at the time of the crime. The presence of personality disorders and moderately high psychopathy scores at follow-up were common. Two-thirds of these youth reported the presence of violent sexual fantasies before their crimes. Weapons, most often knives, were used by these juvenile sexual murderers to kill known victims in a majority of the cases. They usually acted alone and selected a low risk victim. These findings suggest that juvenile sexual murderers are an emotionally and behaviorally disturbed population with identifiable psychopathology, personality disturbances, and criminal patterns.
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Factors influencing fluoxetine-induced sexual dysfunction in female rats
Adams, Sarah; Heckard, Danyeal; Hassell, James; Uphouse, Lynda
2012-01-01
Treatment with selective serotonin reuptake inhibitors, such as fluoxetine, produces sexual side effects with low sexual desire being the most prevalent effect in females. In few studies have preclinical models for such antidepressant-induced sexual dysfunction been fruitful. In the current manuscript, the effects of fluoxetine on multiple measures of female sexual motivation and sexual receptivity were examined. Ovariectomized, Fischer rats were primed with 10 μg estradiol benzoate and 500 μg progesterone. Partner preference, active investigation of the male, and measures of sexual behavior were examined after injection with 15 mg/kg fluoxetine. Factors (pretesting for sexual behavior, size of the test arena, non-contact time with a male) that differ among experiments designed to study antidepressant-induced female rat sexual dysfunction were studied. The male preference ratio was not affected by fluoxetine treatment but active investigation of the male was reduced; lordosis behavior was inhibited and pretesting for sexual receptivity amplified fluoxetine's inhibition; size of the testing arena or non-contact experience with the male had no effect. Regardless of test condition, when given the opportunity to escape from the male, fluoxetine-treated females displayed escape behavior. Measures of male preference and active investigation, but not lordosis behavior, appeared to be affected by fluoxetine's impact on activity. The collective data provided a behavioral profile of fluoxetine-induced sexual dysfunction. These findings reinforce the value of multiple measures when attempting to model antidepressant-induced female sexual dysfunction. PMID:22835821
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The reciprocal relationship between sexual victimization and sexual assertiveness.
Livingston, Jennifer A; Testa, Maria; VanZile-Tamsen, Carol
2007-03-01
Low sexual assertiveness has been proposed as a possible mechanism through which sexual revictimization occurs, yet evidence for this has been mixed. In this study, prospective path analysis was used to examine the relationship between sexual refusal assertiveness and sexual victimization over time among a community sample of women. Results provide support for a reciprocal relationship, with historical victimization predicting low sexual assertiveness and low sexual assertiveness predicting subsequent victimization. The effect of recent sexual victimization on subsequent sexual assertiveness also was replicated prospectively. These findings suggest that strengthening sexual assertiveness may help reduce vulnerability to future victimization.
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Williams' paradox and the role of phenotypic plasticity in sexual systems.
Leonard, Janet L
2013-10-01
As George Williams pointed out in 1975, although evolutionary explanations, based on selection acting on individuals, have been developed for the advantages of simultaneous hermaphroditism, sequential hermaphroditism and gonochorism, none of these evolutionary explanations adequately explains the current distribution of these sexual systems within the Metazoa (Williams' Paradox). As Williams further pointed out, the current distribution of sexual systems is explained largely by phylogeny. Since 1975, we have made a great deal of empirical and theoretical progress in understanding sexual systems. However, we still lack a theory that explains the current distribution of sexual systems in animals and we do not understand the evolutionary transitions between hermaphroditism and gonochorism. Empirical data, collected over the past 40 years, demonstrate that gender may have more phenotypic plasticity than was previously realized. We know that not only sequential hermaphrodites, but also simultaneous hermaphrodites have phenotypic plasticity that alters sex allocation in response to social and environmental conditions. A focus on phenotypic plasticity suggests that one sees a continuum in animals between genetically determined gonochorism on the one hand and simultaneous hermaphroditism on the other, with various types of sequential hermaphroditism and environmental sex determination as points along the spectrum. Here I suggest that perhaps the reason we have been unable to resolve Williams' Paradox is because the problem was not correctly framed. First, because, for example, simultaneous hermaphroditism provides reproductive assurance or dioecy ensures outcrossing does not mean that there are no other evolutionary paths that can provide adaptive responses to those selective pressures. Second, perhaps the question we need to ask is: What selective forces favor increased versus reduced phenotypic plasticity in gender expression? It is time to begin to look at the question
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The readability and suitability of sexual health promotion leaflets.
Corcoran, Nova; Ahmad, Fatuma
2016-02-01
To investigate the readability and suitability of sexual health promotion leaflets. Application of SMOG, FRY and SAM tests to assess the readability and suitability of a selection of sexual health leaflets. SMOG and FRY scores illustrate an average reading level of grade 9. SAM scores indicate that 59% of leaflets are superior in design and 41% are average in design. Leaflets generally perform well in the categories of content, literacy demand, typography and layout. They perform poorly in use of graphics, learning stimulation/motivation and cultural appropriateness. Sexual health leaflets have a reading level that is too high. Leaflets perform well on the suitability scores indicating they are reasonably suitable. There are a number of areas where sexual health leaflets could improve their design. Numerous practical techniques are suggested for improving the readability and suitability of sexual health leaflets. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
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Major disruption process in tokamak
International Nuclear Information System (INIS)
Kurita, Gen-ichi; Azumi, Masafumi; Tuda, Takashi; Takizuka, Tomonori; Tsunematsu, Toshihide; Tokuda, Shinji; Itoh, Kimitaka; Takeda, Tatsuoki
1981-11-01
The major disruption in a cylindrical tokamak is investigated by using the multi-helicity code, and the destabilization of the 3/2 mode by the mode coupling with the 2/1 mode is confirmed. The evolution of the magnetic field topology caused by the major disruption is studied in detail. The effect of the internal disruption on the 2/1 magnetic island width is also studied. The 2/1 magnetic island is not enhanced by the flattening of the q-profile due to the internal disruption. (author)
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Plasma disruption modeling and simulation
International Nuclear Information System (INIS)
Hassanein, A.
1994-01-01
Disruptions in tokamak reactors are considered a limiting factor to successful operation and reliable design. The behavior of plasma-facing components during a disruption is critical to the overall integrity of the reactor. Erosion of plasma facing-material (PFM) surfaces due to thermal energy dump during the disruption can severely limit the lifetime of these components and thus diminish the economic feasibility of the reactor. A comprehensive understanding of the interplay of various physical processes during a disruption is essential for determining component lifetime and potentially improving the performance of such components. There are three principal stages in modeling the behavior of PFM during a disruption. Initially, the incident plasma particles will deposit their energy directly on the PFM surface, heating it to a very high temperature where ablation occurs. Models for plasma-material interactions have been developed and used to predict material thermal evolution during the disruption. Within a few microseconds after the start of the disruption, enough material is vaporized to intercept most of the incoming plasma particles. Models for plasma-vapor interactions are necessary to predict vapor cloud expansion and hydrodynamics. Continuous heating of the vapor cloud above the material surface by the incident plasma particles will excite, ionize, and cause vapor atoms to emit thermal radiation. Accurate models for radiation transport in the vapor are essential for calculating the net radiated flux to the material surface which determines the final erosion thickness and consequently component lifetime. A comprehensive model that takes into account various stages of plasma-material interaction has been developed and used to predict erosion rates during reactor disruption, as well during induced disruption in laboratory experiments
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Nyokangi, Doris; Phasha, Nareadi
2016-05-01
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. Data were collected using focus groups and individual interviews with 16 learners with mild intellectual disability at two special schools in South Africa. This was followed by individual interviews with the school nurse and social worker, and an analysis of schools' books of incidents. Factors contributing to sexual violence at schools for learners with mild intellectual disability included: (i) peer pressure, (ii) concealment of reported incidents of sexual violence, (iii) unsupervised areas linked to schools and (iv) arranged relationships. The following suggestions are put forth: (i) awareness programmes, (ii) sensitization of teachers about the consequences and prevention of sexual violence, (iii) boundaries within which the arranged relationship occurs, (iv) intensification of sexuality education and (v) supervision around the school premises. © 2015 John Wiley & Sons Ltd.
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Martig, Adria K; Mizumori, Sheri J Y
2011-02-01
Hippocampus (HPC) receives dopaminergic (DA) projections from the ventral tegmental area (VTA) and substantia nigra. These inputs appear to provide a modulatory signal that influences HPC dependent behaviors and place fields. We examined how efferent projections from VTA to HPC influence spatial working memory and place fields when the reward context changes. CA1 and CA3 process environmental context changes differently and VTA preferentially innervates CA1. Given these anatomical data and electrophysiological evidence that implicate DA in reward processing, we predicted that CA1 place fields would respond more strongly to both VTA disruption and changes in the reward context than CA3 place fields. Rats (N = 9) were implanted with infusion cannula targeting VTA and recording tetrodes aimed at HPC. Then they were tested on a differential reward, win-shift working memory task. One recording session consisted of 5 baseline and 5 manipulation trials during which place cells in CA1/CA2 (N = 167) and CA3 (N = 94) were recorded. Prior to manipulation trials rats were infused with either baclofen or saline and then subjected to control or reward conditions during which the learned locations of large and small reward quantities were reversed. VTA disruption resulted in an increase in errors, and in CA1/CA2 place field reorganization. There were no changes in any measures of CA3 place field stability during VTA disruption. Reward manipulations did not affect performance or place field stability in CA1/CA2 or CA3; however, changes in the reward locations "rescued" performance and place field stability in CA1/CA2 when VTA activity was compromised, perhaps by trigging compensatory mechanisms. These data support the hypothesis that VTA contributes to spatial working memory performance perhaps by maintaining place field stability selectively in CA1/CA2. Copyright © 2009 Wiley-Liss, Inc.
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Disrupt mig vel: Fire gode råd om disruption
DEFF Research Database (Denmark)
Rydén, Pernille; Ringberg, Torsten; Østergaard Jacobsen, Per
2017-01-01
Forandring. Ønsket om at være teknologisk foran, kommer ofte til at ske på bekostning af fokus på kundernes oplevelser. Lighedstegnet mellem disruption og ny teknologi er kun den halve sandhed.......Forandring. Ønsket om at være teknologisk foran, kommer ofte til at ske på bekostning af fokus på kundernes oplevelser. Lighedstegnet mellem disruption og ny teknologi er kun den halve sandhed....
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Sales, Jessica M.; Smearman, Erica; Brody, Gene H.; Milhausen, Robin; Philibert, Robert A.; DiClemente, Ralph J.
2013-01-01
Sexuality-related constructs such as sexual arousal, sexual sensation seeking (SSS) and sexual satisfaction have been related to sexual behaviors that place one at risk for adverse consequences such as sexually transmitted infections (STIs), HIV, and unintended pregnancy. The biopsychosocial model posits an array of factors, ranging from social environmental factors, biological, and psychological predispositions that may be associated with these sexuality constructs in adolescent samples. Afr...