962 resultados para Sexual reproduction
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Secondary sexual traits in males of polygynous species are important determinants of reproductive success. It is, however, unknown if and how the development of continuously growing traits at different life-stages is related to reproduction in long-lived male mammals. In this study, we evaluated the relationship of early and late horn growth on social status and reproduction in long-lived male Alpine ibex (Capra ibex). For this, we analysed individual horn growth and assessed its effect on dominance and reproduction. No evidence was detected for compensatory horn growth, as late-life horn growth positively depended on early-life horn growth in males. Still, individuals with longer horn segments grown during early adulthood experienced a stronger age-dependent length decline in annual horn growth during the late development. Accordingly, a divergence between individual growth potential and realized horn growth late in life has to be assumed. Residual age-specific horn length and length of early grown horn segments both positively affected dominance and reproductive success, whereas, contrary to our expectation, no significant effect of the length of horn segments grown during the late development was detected. Suspected higher somatic costs incurred by high-quality males during their late development might at least partly be responsible for this finding. Overall, our study suggests that the total length of horns and their early development in long-lived male Alpine ibex is a reliable indicator of reproductive success and that individuals may be unable to compensate for poor early-life growth performance at a later point in life.
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Funding: The research was financially supported by the Holsworth Wildlife Research Endowment.
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Speciation rates among extant lineages of organisms vary extensively, but our understanding of the causes of this variation and, therefore, the processes of speciation is still remarkably incomplete. Both theoretical and empirical studies have indicated that sexual selection is important in speciation, but earlier discussions have focused almost exclusively on the potential role of female mate choice. Recent findings of postmating reproductive conflicts of interest between the sexes suggest a quite different route to speciation. Such conflicts may lead to perpetual antagonistic coevolution between males and females and may thus generate rapid evolutionary divergence of traits involved in reproduction. Here, we assess this hypothesis by contrasting pairs of related groups of insect species differing in the opportunity for postmating sexual conflict. Groups where females mate with many males exhibited speciation rates four times as high as in related groups where females mate only once. Our results not only highlight the general importance of postmating sexual selection in speciation, but also support the recent suggestion that sexual conflict is a key engine of speciation.
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Despite the benefits of resistance, susceptibility to infectious disease is commonplace. Although specific susceptibility may be considered an inevitable consequence of the co-evolutionary arms race between parasite and host, a more general constraint may arise from the cost of an immune response. This “cost” hypothesis predicts a tradeoff between immune defense and other components of fitness. In particular, a tradeoff between immunity and sexually selected male behavior has been proposed. Here we provide experimental support for the direct phenotypic tradeoff between sexual activity and immunity by studying the antibacterial immune response in Drosophila melanogaster. Males exposed to more females showed a reduced ability to clear a bacterial infection, an effect that we experimentally link to changes in sexual activity. Our results suggest immunosuppression is an important cost of reproduction and that immune function and levels of disease susceptibility will be influenced by sexual selection.
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Los migrantes y sus parejas han sido incorporados en los discursos institucionales de salud como “sujetos en riesgo” frente a las Infecciones de Trasmisión Sexual (ITS), sin embargo la incorporación de esta población específica en la comunicación y gestión del riesgo de ITS ha sido ambigua en el contexto mexicano. El objetivo del presente acercamiento fue conocer las prácticas de autocuidado sexual y reproductivo que adoptan en su cotidianeidad mujeres parejas de migrantes y la relación de dichas medidas con la comunicación y gestión del riesgo que los Servicios de Salud realizan. Se trató de una aproximación de tipo cualitativo con 20 mujeres “de migrantes” localizadas mediante los servicios de salud, la información se recabó a través de entrevistas a profundidad que focalizaron en las esferas de “percepción del riesgo” y “Autocuidado sexual y reproductivo”. Se encontró que la mayoría de las mujeres no se reconoce vulnerable frente a las ITS y que la percepción del riesgo no es determinante en la confrontación que respecto a la amenaza puedan desarrollar, dado que los imaginarios patriarcales que prevalecen en ellas, sus parejas y el personal de salud desestiman la utilización de medidas de prevención y detección oportuna.
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Sexual selection involves two main mechanisms: intrasexual competition for mates and intersexual mate choice. We experimentally separated intrasexual (male-male interference competition) and intersexual (female choice) components of sexual selection in a freshwater fish, the European bitterling (Rhodeus sericeus). We compared the roles of multiple morphological and behavioural traits in male success in both components of sexual competition, and their relation to male reproductive success, measured as paternity of offspring. Body size was important for both female choice and male-male competition, though females also preferred males that courted more vigorously. However, dominant males often monopolized females regardless of female preference. Subordinate males were not excluded from reproduction and sired some offspring, possibly through sneaked ejaculations. Male dominance and a greater intensity of carotenoid-based red colouration in their iris were the best predictors of male reproductive success. The extent of red iris colouration and parasite load did not have significant effects on female choice, male dominance or male reproductive success. No effect of parasite load on the expression of red eye colouration was detected, though this may have been due to low parasite prevalence in males overall. In conclusion, we showed that even though larger body size was favoured in both intersexual and intrasexual selection, male-male interference competition reduced opportunities for female choice. Females, despite being choosy, had limited control over the paternity of their offspring. Our study highlights the need for reliable measures of male reproductive success in studies of sexual selection.
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Peer reviewed
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Sex differences occur in most non-communicable diseases, including metabolic diseases, hypertension, cardiovascular disease, psychiatric and neurological disorders and cancer. In many cases, the susceptibility to these diseases begins early in development. The observed differences between the sexes may result from genetic and hormonal differences and from differences in responses to and interactions with environmental factors, including infection, diet, drugs and stress. The placenta plays a key role in fetal growth and development and, as such, affects the fetal programming underlying subsequent adult health and accounts, in part for the developmental origin of health and disease (DOHaD). There is accumulating evidence to demonstrate the sex-specific relationships between diverse environmental influences on placental functions and the risk of disease later in life. As one of the few tissues easily collectable in humans, this organ may therefore be seen as an ideal system for studying how male and female placenta sense nutritional and other stresses, such as endocrine disruptors. Sex-specific regulatory pathways controlling sexually dimorphic characteristics in the various organs and the consequences of lifelong differences in sex hormone expression largely account for such responses. However, sex-specific changes in epigenetic marks are generated early after fertilization, thus before adrenal and gonad differentiation in the absence of sex hormones and in response to environmental conditions. Given the abundance of X-linked genes involved in placentogenesis, and the early unequal gene expression by the sex chromosomes between males and females, the role of X- and Y-chromosome-linked genes, and especially those involved in the peculiar placenta-specific epigenetics processes, giving rise to the unusual placenta epigenetic landscapes deserve particular attention. However, even with recent developments in this field, we still know little about the mechanisms underlying the early sex-specific epigenetic marks resulting in sex-biased gene expression of pathways and networks. As a critical messenger between the maternal environment and the fetus, the placenta may play a key role not only in buffering environmental effects transmitted by the mother but also in expressing and modulating effects due to preconceptional exposure of both the mother and the father to stressful conditions.
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This chapter explores the ways in which sexuality has been understood, embodied and negotiated by a cohort of Irish women through their lives. It is based on qualitative data generated as part of an oral history project on Irish women’s experiences of sexuality and reproduction during the period 1920–1970.1 The interviews, which were conducted with 21 Irish women born between 1914 and 1955, illustrate that social and cultural discourses of sexuality as secretive, dangerous, dutiful and sinful were central to these women’s interpretative repertoires around sexuality and gender. However, the data also contains accounts of behaviours, experiences and feelings that challenged or resisted prevailing scripts of sexuality and gender. Drawing on feminist conceptualisations of sexuality and embodiment (Holland et al., 1994; Jackson and Scott, 2010), this chapter demonstrates that the women’s sexual subjectivities were forged in the tensions that existed between normative sexual scripts and their embodied experiences of sexual desires and sexual and reproductive practices. While recollections of sexual desire and pleasure did feature in the accounts of some of the women, it was the difficulties experienced around sexuality and reproduction that were spoken about in greatest detail. What emerges clearly from the data is the confusion, anxiety and pain occasioned by the negotiation of external demands and internal desires and the contested, unstable nature of both cultural power and female resistance.
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Sexual harassment at work is a form of gender violence barely made visible but still present in labor organizations, where it keeps generating high levels of suffering, discrimination and inequality mainly affecting women. To address it properly it is necessary an organizational change towards equity arising from the knowledge of the subjective meanings that stakeholders (staff, union representatives, employers, public administration, etc.) attribute to that reality. In this article we present the main findings of a qualitative study on the social perception of sexual harassment. The work highlights the existence of many strategies aimed at legitimize and minimize the relevance of the problem, blaming the victim, justifying the lack of support from the environment and / or the involvement of the organization in the solutions. Among the conclusions we underline the need for new models of business management involving all stakeholders in the prevention and control of the in a responsible way.
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Care has come to dominate much feminist research on globalized migrations and the transfer of labor from the South to the North, while the older concept of reproduction had been pushed into the background but is now becoming the subject of debates on the commodification of care in the household and changes in welfare state policies. This article argues that we could achieve a better understanding of the different modalities and trajectories of care in the reproduction of individuals, families, and communities, both of migrant and nonmigrant populations by articulating the diverse circuits of migration, in particular that of labor and the family. In doing this, I go back to the earlier North American writing on racialized minorities and migrants and stratified social reproduction. I also explore insights from current Asian studies of gendered circuits of migration connecting labor and marriage migrations as well as the notion of global householding that highlights the gender politics of social reproduction operating within and beyond households in institutional and welfare architectures. In contrast to Asia, there has relatively been little exploration in European studies of the articulation of labor and family migrations through the lens of social reproduction. However, connecting the different types of migration enables us to achieve a more complex understanding of care trajectories and their contribution to social reproduction.
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This paper presents the "state of the art" and some of the main issues discussed in relation to the topic of transnational migration and reproductive work in southern Europe. We start doing a genealogy of the complex theoretical development leading to the consolidation of the research program, linking consideration of gender with transnational migration and transformation of work and ways of survival, thus making the production aspects as reproductive, in a context of globalization. The analysis of the process of multiscale reconfiguration of social reproduction and care, with particular attention to its present global dimension is presented, pointing to the turning point of this line of research that would have taken place with the beginning of this century, with the rise notions such as "global care chains" (Hochschild, 2001), or "care drain" (Ehrenreich and Hochschild, 2013). Also, the role of this new agency, now composed in many cases women who migrate to other countries or continents, precisely to address these reproductive activities, is recognized. Finally, reference is made to some of the new conceptual and theoretical developments in this area.
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Trata-se de um estudo exploratório-descritivo, com abordagem qualitativa, que teve por objetivo analisar as mensagens, acerca da promoção da saúde sexual e reprodutiva, produzidas por adolescentes de escolas públicas e particulares da cidade do Rio Grande, num concurso de redação e música promovido pelo Grupo Gestor Municipal (GGM) do Projeto Saúde e Prevenção nas Escolas (SPE), nos anos de 2007 e 2008. Após autorização pelo GGM para realização deste estudo, foram disponibilizadas para reprodução, via xérox, as 29 redações e as três letras de músicas inscritas nos concursos. Para o tratamento dos dados utilizou-se a técnica de análise de conteúdo na modalidade temática. Participaram 35 adolescentes, sendo 25 moças e dez rapazes, com idades entre onze e dezessete anos. Quanto à escolaridade, dois frequentavam a quinta série; doze a sexta, doze a sétima e nove a oitava. Apreendeu-se que, em sua produção textual, os(as) adolescentes revelaram as vulnerabilidades e fortalezas referentes à saúde sexual e reprodutiva. Entre os inúmeros fatores que aumentam a vulnerabilidade individual, social e programática, discorreram sobre a carência de informações, a dificuldade para transformar o conhecimento em prática, a sensação de imunidade, a violência familiar, a conduta repressora de pais e mães, as mensagens de cunho sexual veiculadas pela mídia, a necessidade de serem aceitos(as) pelo grupo, preconceitos, e falta de ações governamentais direcionadas a adolescentes. No que se refere às fortalezas, sabem que a informação é uma importante aliada para a promoção da saúde sexual e reprodutiva citando, entre as fontes acessíveis, os serviços públicos de saúde, a família e a escola. Demonstraram conhecimento acerca da alarmante propagação da epidemia da AIDS entre jovens, conhecendo os sinais e sintomas das DSTs mais comuns e as formas de prevenção. As moças enfatizaram a necessidade de compartilhar a responsabilidade preventiva com os rapazes, bem como de amor próprio e respeito mútuo. O acesso aos serviços de saúde também foi apresentado como indispensável ao adolescer saudável. Os(as) jovens demonstraram conhecimento sobre drogas seus efeitos e consequências. Referem-se à adolescência como um período gostoso, repleto de dúvidas, mas também cheio de potencialidades. Assim, os mesmos componentes apresentados como desencadeadores de vulnerabilidade podem torná-los(as) fortes e capazes de superar os desafios comuns a essa etapa da vida. Para que tal superação ocorra, é necessário que tenham acesso à informação e a problematizem; que sejam capazes de incorporá-las ao cotidiano, adotando práticas protegidas e protetoras; que haja diálogo, despido de tabus, censuras e preconceitos no ambiente familiar; que as escolas adotem de forma transversalizada temáticas referentes à saúde sexual e reprodutiva; que os serviços de saúde tenham infraestrutura para assegurar os direitos contidos no Estatuto da Criança e do Adolescente; entre outras estratégias fortalecedoras.