734 resultados para Sex biases


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General note: Title and date provided by Bettye Lane.

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General note: Title and date provided by Bettye Lane.

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General note: Title and date provided by Bettye Lane.

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General note: Title and date provided by Bettye Lane.

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Inbreeding avoidance is predicted to induce sex biases in dispersal. But which sex should disperse? In polygynous species, females pay higher costs to inbreeding and thus might be expected to disperse more, but empirical evidence consistently reveals male biases. Here, we show that theoretical expectations change drastically if females are allowed to avoid inbreeding via kin recognition. At high inbreeding loads, females should prefer immigrants over residents, thereby boosting male dispersal. At lower inbreeding loads, by contrast, inclusive fitness benefits should induce females to prefer relatives, thereby promoting male philopatry. This result points to disruptive effects of sexual selection. The inbreeding load that females are ready to accept is surprisingly high. In absence of search costs, females should prefer related partners as long as delta<r/(1+r) where r is relatedness and delta is the fecundity loss relative to an outbred mating. This amounts to fitness losses up to one-fifth for a half-sib mating and one-third for a full-sib mating, which lie in the upper range of inbreeding depression values currently reported in natural populations. The observation of active inbreeding avoidance in a polygynous species thus suggests that inbreeding depression exceeds this threshold in the species under scrutiny or that inbred matings at least partly forfeit other mating opportunities for males. Our model also shows that female choosiness should decline rapidly with search costs, stemming from, for example, reproductive delays. Species under strong time constraints on reproduction should thus be tolerant of inbreeding.

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A study was conducted to investigate the timing of the breeding season of western hedgehogs (Erinaceus europaeus) in a rural landscape in Ireland, their courtship activity and the first appearance and possible dispersal of juveniles. Between June 2008 and June 2010, 24 hedgehogs (18 ♂ and 6 ♀) were caught and monitored by radio tracking and direct following. A preponderance of males was recorded in both adults and juveniles at the study site and the sex ratio deviated significantly from a 1:1 ratio. Courtship behaviour took place between April and July and occurred almost exclusively in a nine ha pasture. An individual female paired with up to seven males in a season. The first appearance of juveniles was recorded in September (2008) and July (2009). The majority (n=22) of juvenile sightings, both alive and as road kill, occurred in July but they continued to be recorded up until November (n=3). The presence of juveniles at the study site in October 2008 and a pregnant female being found in September 2009 indicated that late litters occur in Ireland.

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One topic covered in Australian queer university student print media is the legalisation of same-sex marriage. The legalisation of same-sex marriage is currently generating much debate in Western queer communities. Same-sex marriage is legalised in some countries such as, Canada, Spain, the Netherlands and Belgium. It has been outlawed in Australia and most states in the US. Campaigns continue to reverse these restrictions. Other countries, such as the UK and New Zealand allow same-sex civil unions, providing couples with the rights afforded to married couples. There is a range of research documenting queer communities’ attitudes towards this issue (for example Lannutti 2005; Clarke, Burgoyne and Burns 2006; Yep, Lovaas and Elia 2003; Wolfson 1993; Egan and Sherrill 2005). These studies document broad community views as well as those of community sub-sections. For example, Yip (2004) looks at the views of gay and lesbian Christians on same-sex marriage and Lahey and Alderson (2004) document the experiences of same-sex couples who have gotten married or who are waiting to get married. Philosophical analyses consider the legalisation of same-sex marriage in relation to, for example, liberalism, equal rights, liberation, queer theory, citizenship, history, activism, religious discourse and feminism (Ferguson 2007; Jordan 2005; Josephson 2005; Lipton 2006; Sullivan and Chauncey 2005; Riggs 2007). This paper explores Australian queer university student activist media’s representation of same-sex marriage, and the debates surrounding its legalisation. It examines a selection of queer student media from four metropolitan Australian universities, and the 2003 and 2004 editions of national queer student publication, Querelle. This paper uses discourse analysis of queer student activists’ media representations of marriage to investigate this issue in one specific context – metropolitan Australian universities. This paper thus contributes to the history of queer activism, documenting what one group of young people say about the legalisation of same-sex marriage, and furthers research on queer perspectives of marriage and same-sex relationships.

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Transmissible diseases are re-emerging as a global problem, with Sexually Transmitted Diseases (STDs) becoming endemic. Chlamydia trachomatis is the leading cause of bacterially-acquired STD worldwide, with the Australian cost of infection estimated at $90 - $160 million annually. Studies using animal models of genital tract Chlamydia infection suggested that the hormonal status of the genital tract epithelium at the time of exposure may influence the outcome of infection. Oral contraceptive use also increased the risk of contracting chlamydial infections compared to women not using contraception. Generally it was suggested that the outcome of chlamydial infection is determined in part by the hormonal status of the epithelium at the time of exposure. Using the human endolmetrial cell line ECC-1 this study investigated the effects of C. trachomatis serovar D infection, in conjunction with the female sex hormones, 17β-estradiol and progesterone, on chlamydial gene expression. While previous studies have examined the host response, this is the first study to examine C.trachomatis gene expression under different hormonal conditions. We have highlighted a basic model of C. trachomatis gene regulation in the presence of steroid hormones by identifying 60 genes that were regulated by addition of estradiol and/or progesterone. In addition, the third chapter of this thesis discussed and compared the significance of the current findings in the context of data from other research groups to improve our understanding of the molecular basis of chlamydial persistence under hormonal different conditions. In addition, this study analysed the effects of these female sex hormones and C. trachomatis Serovar D infection, on host susceptibility and bacterial growth. Our results clearly demonstrated that addition of steroid hormones not only had a great impact on the level of infectivity of epithelial cells with C.trachomatis serovar D, but also the morphology of chlamydial inclusions was affected by hormone supplementation.

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For nearly twenty-five years, the field of youth studies has employed the same conceptual tools to explain the conduct of young people, tools that inexorably lead to the same recurrent conclusions-youth equals resistance, youth equals alienation, youth equals problem. This book offers a way out of this theoretical Groundhog Day. Starting with the familiar notion of youth subcultures, but also addressing topics such as young women's magazines, 'at risk' youth, anorexia nervosa, and HIV/AIDS programs, this book examines the way in which youth is produced as both a governmental object and a set of practices of the self. Employing the ideas of Foucault, Rose and Mauss, this new approach attempts to reinvigorate what is an important-yet slumbering-area of research.

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The intention of this paper is to call into question the apparent dichotomy between left and right wing positions concerning the implementation of sex education in Queensland Schools. By adopting a more historicised approach, it is suggested that these positions are part of dual and supplementary strategies which work through specific problematisations associated with youth. Accordingly, the emphasis should be shifted from generalised depictions of the adolescent/youth to more focused accounts, questioning how teaching children to manage their sex became a governmental imperative.