Academic literature on the topic 'Sex-related constraints'

Oestradiol application during embryonic development reverses the sex of male embryos and results in normal female differentiation in reptiles lacking heteromorphic sex chromosomes, but fails to do so in birds and mammals with heteromorphic sex chromosomes. It is not clear whether the evolution of heteromorphic sex chromosomes in amniotes is accompanied by insensitivity to oestradiol, or if the association between oestradiol insensitivity and heteromorphic sex chromosomes can be attributable to phylogenetic constraints in these taxa. Turtles provide an ideal system to examine the potential relationship between oestradiol insensitivity and sex chromosome heteromorphy, since there are species with heteromorphic sex chromosomes that are closely related to species lacking heteromorphic sex chromosomes. We investigated this relationship by examining the long-term effects of oestradiol-17β application on sex determination in Staurotypus triporcatus and Staurotypus salvinii , two turtle species with male heterogamety. After raising the turtles in the lab for 3 years, we found follicular and Müllerian duct morphology in oestradiol-treated turtles that was identical to that of untreated females. The lasting sex reversal suggests that the evolutionary transition between systems lacking heteromorphic sex chromosomes and those with heteromorphic sex chromosomes is not constrained by a fundamental mechanistic difference.

Abstract Examination of 1622 specimens indicates that North American Falconiformes show a wide variety of remigial (primary and secondary) replacement strategies, detectable throughout the year by evaluation of replacement patterns in the wings. Most Falconidae undergo complete prebasic molts whereas most Accipitridae display retained secondaries or show stepwise molt replacement patterns (“Staffelmäuser”). Among individuals exhibiting Staffelmäuser, minimum age can be inferred up to 5 years (fifth-basic plumage) by the number of “replacement waves” present among the primaries. It may also be able to infer breeding status during the previous summer by “suspension limits,” resulting from the interruption of molt during breeding. Among Accipitridae, Staffelmäuser occurred in species with greater mass, higher wing loading, longer migration distance, and more open rather than wooded foraging habitats: species that experience time constraints on molting and incur greater costs from large gaps in the wing. Thus, this study supports both the “time-constraints hypothesis,” suggesting that Staffelmäuser is a consequence of insufficient time for a complete annual molt, and the “aerodynamic hypothesis,” suggesting that Staffelmäuser reflects an adaptive need to replace as many feathers as possible without inhibiting flight efficiency. Time constraints may have been a proximate cause of Staffelmäuser among Falconiformes, with improvements to flying efficiency being an ultimate adaptive benefit.

The song-control system, a neural circuit that controls the learning and production of birdsong, provided the first example in vertebrates of prominent macro-morphological sex differences in the brain. Forebrain nuclei HVC, robust nucleus of the arcopallium (RA) and area X all exhibit prominent male-biased sex differences in volume in zebra finches and canaries. Subsequent studies compared species that exhibited different degrees of a sex difference in song behaviour and revealed an overall positive correlation between male biases in song behaviour and male biases in the volume of the song nuclei. However, several exceptions have been described in which male biases in HVC and RA are observed even though song behaviour is equal or even female-biased. Other phenotypic measures exhibit lability in both sexes. In the duetting plain-tailed wren ( Pheugopedius euophrys ), males and females have auditory cells in the song system that are tuned to the joint song the two sexes produce rather than just male or female components. These findings suggest that there may be constraints on the adaptive response of the song system to ecological conditions as assessed by nucleus volume but that other critical variables regulating song can respond so that each sex can modify its song behaviour as needed.

Sexes and also within sex phenotypes, frequently differ in morphological traits associated with efficiency and performance in foraging and mating behaviours. In butterflies and other flying animals, phenotypic differences in wing size and traits associated with flight are involved in flight performance and individual fitness, but explorations of links among two or more traits and intrasexual differences are scarce. Foraging patterns were studied in a population of Heliconius charitonia butterflies having three phenotypes (females and two male phenotypes) which differ in their wing morphology and reproductive behaviour. As in previous studies, intersexual differences in foraging patterns were found; more interestingly, intrasexual differences were found between alternative male mating strategies. Using morphological and behavioural data, as well as data from previous flight analyses in Heliconius butterflies, we show that intrasexual differences may be explained by the energetic demands of each phenotype. Energetic expenditure is partially related to phenotypic variability in flight morphology and efficiency, and at least in both male phenotypes, differences may also be related to the energetic demands of alternative mating strategies.

Common scientific wisdom assumes that spider sexual dimorphism (SD) mostly results from sexual selection operating on males. However, testing predictions from this hypothesis, particularly male size hyperallometry, has been restricted by methodological constraints. Here, using geometric morphometrics (GMM) we studied for the first time sex-differential shape allometry in a spider (Donacosa merlini, Araneae: Lycosidae) known to exhibit the reverse pattern (i.e., male-biased) of spider sexual size dimorphism. GMM reveals previously undetected sex-differential shape allometry and sex-related shape differences that are size independent (i.e., associated to the y-intercept, and not to size scaling). Sexual shape dimorphism affects both the relative carapace-to-opisthosoma size and the carapace geometry, arguably resulting from sex differences in both reproductive roles (female egg load and male competition) and life styles (wandering males and burrowing females). Our results demonstrate that body portions may vary modularly in response to different selection pressures, giving rise to sex differences in shape, which reconciles previously considered mutually exclusive interpretations about the origins of spider SD.

Abstract Increased constraints and lost opportunities inherent in the COVID-19 pandemic can threaten important life goals and erode emotional well-being. Theories of lifespan development have identified goal adjustment capacities (goal disengagement and goal reengagement) as core self-regulatory resources that can buffer against declines in well-being. However, little is known about the pandemic-related contextual circumstances under which goal adjustment capacities may become more or less beneficial for well-being. Using longitudinal data from a nationally-representative sample of Americans across the adult lifespan (aged 18-80, n=286), we examined the consequences of goal adjustment capacities for emotional well-being under circumstances when individuals reported lower or higher constraints than normal in their lives. Specifically, multilevel models tested whether the influence of between-person differences in (Level 2) goal disengagement and goal reengagement on well-being were moderated by (Level 1) within-person fluctuations in perceived constraints. Analyses controlled for age, sex, education, and income. We observed cross-level Goal Reengagement x Perceived Constraints interactions for depressive symptoms, perceived stress, and positive affect (bs = -.11 to .07, ps < .05), but not negative affect. Results showed that the benefits of goal reengagement for depressive symptoms, perceived stress, and positive affect were pronounced on occasions when participants reported lower (vs. higher) than average perceived constraints in their lives. Findings point to the moderating role of pandemic-related contextual circumstances and suggest that goal reengagement may be most beneficial when individuals have fewer constraints than usual in their lives and may thus able to capitalize on opportunities to pursue new attainable goals.

Four studies examined the reliability and validity of a short form of Zuckerman's Sensation Seeking Scale. The short form demonstrated high retest reliability ( r = .78), correlated with drug- and sex-related behavior to the same extent as longer forms, gave higher scores for men than for women (as do the longer forms), and correlated .78 with Form V. The short form provides a reliable and valid measure of sensation seeking for use when time constraints preclude use of a longer form.

Abstract Evidence shows that women face additional constraints because of their gender that affect their economic performance. A review of recent evaluation research demonstrates the types of gender-related constraints women face and the role that economic empowerment interventions can play in overcoming them, especially if they incorporate aspects of smart design, increasing their development impact. The evidence suggests that financial services and training programs are not gender-neutral and that specific design features can yield more positive economic outcomes for women by helping them overcome gender-related constraints. These features include savings and “Graduation” programs that increase women's economic independence, self-reliance and self-control, and the practice of repeated micro-borrowing that increases financial risk-taking and choice. “Smart” design also includes high-quality business management and jobs skills training, and stipends and other incentives in these training programs that address women's and young women's additional time burdens and childcare demands. Peer support may also help to increase financial risk-taking and confidence in business decisions. However, when social norms are too restrictive, and women are prevented from doing any paid work, no design will be smart enough. Subjective economic empowerment appears to be an important intermediate outcome for women that should be promoted and more reliably and accurately measured. Lastly, whenever possible, results should be sex-disaggregated and reported for individuals as well as households.

The existence of dispersal syndromes contrasting disperser from resident phenotypes within populations has been intensively documented across taxa. However, how such suites of phenotypic traits emerge and are maintained is largely unknown, although deciphering the processes shaping the evolution of dispersal phenotypes is a key in ecology and evolution. In this study, we created artificial populations of a butterfly, in which we controlled for individual phenotypes and measured experimentally the roles of selection and genetic constraints on the correlations between dispersal-related traits: flight performance and wing morphology. We demonstrate that (i) trait covariations are not due to genetic correlations, (ii) the effects of selection are sex-specific, and (iii) both divergent and stabilizing selection maintain specific flight performance phenotypes and wing morphologies. Interestingly, some trait combinations are also favoured, depending on sex and fitness components. Moreover, we provide evidence for the role of (dis)assortative mating in the evolution of these dispersal-related traits. Our results suggest that dispersal syndromes may have high evolutionary potential, but also that they may be easily disrupted under particular environmental conditions.

Vincoli evolutivi, fisiologici, anatomici potrebbero determinare diverse risposte individuali a fattori di stress ambientali (e.g. fattori climatici, stagionalità delle risorse), da parte di maschi e femmine. In ambienti montani, l'accesso a pascoli di alta qualità per gli erbivori è limitato ai mesi primaverili-estivi, rendendo così l’alimentazione estiva cruciale per la sopravvivenza invernale, in particolare per le femmine, che devono affrontare i costi della maternità, e per i nuovi nati. Nelle specie che vivono in gruppo, la stagionalità delle risorse può influenzare anche il comportamento sociale: la diminuzione della disponibilità e della qualità di risorse alimentari può aumentare la competizione alimentare e i livelli di stress, portando a sua volta un aumento delle interazioni aggressive intraspecifiche. La mia tesi riguarda un ungulato di montagna, il camoscio alpino. Ho studiato il comportamento riproduttivo e spaziale di maschi adulti, per i quali sono state descritte due tattiche riproduttive alternative (AMTs) (territorialità e non territorialità). Comprendere le differenze in aspetti importanti quali età, successo di accoppiamento, aggressività e comportamento tra individui che adottano AMTs diverse aiuterebbe a spiegare la loro coesistenza nella popolazione. Ho analizzato dati raccolti su maschi individualmente riconoscibili durante 5 stagioni riproduttive (2011-2012, 2015-2017). Studiare come fattori ambientali e individuali influenzino le opportunità riproduttive dei maschi territoriali aiuterebbe a capire come la territorialità (una AMT) venga mantenuta nella popolazione. Ho considerato dati su comportamento riproduttivo di maschi territoriali e caratteristiche ambientali, registrati durante 5 stagioni riproduttive (2011-2012, 2015-2017). L'adozione di una AMT potrebbe influenzare l'uso dello spazio nei maschi. Al contrario, il comportamento spaziale femminile può essere influenzato dalla presenza delle prole. Ho studiato le differenze nell'uso dello spazio tra femmine, maschi territoriali e non territoriali (una differente AMT) (2011-2012-2017), usando radio-telemetria GPS-GSM. Sono stati inoltre valutati gli effetti di fattori meteorologici sul comportamento spaziale di entrambi i sessi. La variazione della frequenza delle interazioni aggressive intra-sessuali, della risposta endogena, della qualità nutrizionale della dieta, nonché la variazione delle dimensioni dei gruppi sono state studiate nelle femmine attraverso osservazioni comportamentali su individui riconoscibili e analisi di campioni fecali (Giugno-Novembre 2017-2018).
Sex-related constraints could determine different individual responses to environmental stressors (e.g. climate, seasonality of resources). On mountains, the access to high quality pasture for herbivores is limited to the warm months, thus making summer forage crucial for winter survival, in particular to females, who face the costs of motherhood, and kids. In gregarious species, seasonality of resources may also influences social behaviour: thus, pasture depletion may increase feeding interference and endogenous stress levels, in turn leading to the increase of intraspecific aggressive interactions. My thesis concerns a mountain-dwelling ungulate, the Alpine chamois. I investigated mating and spatial behaviour of adult males, for which two alternative mating tactics (AMTs) have been described (territoriality and non-territoriality). Understanding differences in key aspects of life-history, such as age, mating success, aggressiveness, and behaviour between individuals adopting different AMTs would help explain their coexistence in the population. I analysed data collected on individually marked males during 5 rutting seasons (2011-2012, 2015-2017). Studying how environmental and individual factors influence mating opportunities of territorial male chamois would help understand how territoriality (an AMT) is maintained in the population. I evaluated mating behaviour of territorial males and environmental features, recorded during 5 rutting seasons (2011-2012, 2015-2017). The adoption of a mating tactic may influence space use in males. Conversely, female spatial behaviour may be influenced by the presence of offspring. I investigated differences in space use between females, territorial and non-territorial (a different AMT) males (2011-2012-2017), using intensive GPS-GSM radio-tracking. The effects of meteorological factors on the spatial behaviour of both sexes have also been evaluated. Variation of the frequency of intra-sexual aggressive interactions, endocrine correlates, nutritional quality of diet, as well as grouping patterns have been investigated in females through behavioural observations on recognisable individuals and analyses of fresh faecal samples (June-November 2017-2018).

This thesis examines South African policies addressing gender inequality in education management, and interrogates whether or not these policies made a difference to the career route of women principals of secondary schools. The under-representation of women in education management has been a long observed problem in many countries including South Africa. A number of initiatives have been put in place to address this issue but little improvement is seen in the South African situation in education management. The purpose was to understand why women are still under represented in school management and to learn from their experiences. The study used data from three sources. Firstly, policy documents and practices were analysed in terms of their symbolic, regulative and procedural functions. Secondly, the personal accounts of 28 women principals in KwaZulu-Natal who had been appointed after 1994 were collected through the use of extended interviews, and thirdly, interviews were conducted with key officials and members of School Governing Bodies that had participated in the selection of principals. The data generated were analysed at two levels in order to understand the factors constraining the participation of women in education management. At the micro level, I use the 'management route model' as an analytical framework that identifies the three phases women principals go through in their career route, namely anticipation, acquisition and performance (van Eck and Volman, 1996). The model reveals that factors influencing women's career paths into management are very complex and based firstly on the individual agency where women grapple with more internal issues such as professional qualifications and experience, aspirations, lack of ambition and family responsibilities. Secondly, these factors are at the organisational level where women suffer discrimination at the recruitment and selection processes, and lack of institutional support through mentoring and sponsorship. Thirdly, it is the social level, which involves the cultural discourses in which women operate. These discourses include sex role stereotypes that inform the social expectations about the role of men and women in society. On the macro level, I use feminist theory to interpret and understand the women's experiences and findings in general. The findings reveal that policy interventions put in place since 1994 to close the gender gap were mostly informed by liberal feminism that focused on affirming women in order to gain access into the school management without tackling the social practices that are defined by sex role socialisation and which therefore continue to work subtly and insidiously towards the discrimination of women. I conclude that although the liberal feminist interventions that have been put in place have been useful to some extent, the problems impeding women's full participation in education management cannot only be tackled at a policy level because this attempt leaves the most problematic social practices intact. However, I argue for policy and legal intervention as a starting point to combat the gender crisis in a society that has inherited so much inequality. While I acknowledge that women of all races in South Africa have all been negatively impacted upon by the historical and traditional values and expectations on the role of women and men in society, I argue that the situation has been worse for women of the Black African race, who suffered dual oppression in terms of gender and race. The study proposes the need to look beyond provision of legal and democratic reforms and more into social practices that prevent legal reforms from reaching the desired goals. Social structures and cultural practices that hamper the greater representation of women should be dealt with in order to allow women freedom to participate in discourses where their choice is not informed by gender subordination.
Theses (Ph.D.)-University of KwaZulu-Natal, 2006.

This multi-disciplinary volume brings together international scholarship from across cultural studies, humanities and social sciences. It involves critical review of a comparatively neglected issue – the desexualization of older people – that itself forms part of an emerging field of knowledge that relates to older people’s sexuality and intimacy. Funnelling down from more general to more particular experiences (often related to identity difference), the volume explores the various ways that older people encounter constraints on their sexual and intimate self-expression. Indeed, risk and surveillance can be seen as structuring conditions of ageing sexualities and the issues addressed concern difficulties in relation to consent, relating and relatives erotic aesthetics, gendered ageing sexuality (menopause), disabilities, dementia, care homes and their residents, sex and older lesbian, gay bisexual, trans and intersex people, and care services and ageing sexuality. As well as providing an overview of broader themes to which chapter point, the final chapter also outlines a research agenda that itself points towards creative forms of resexualization of diverse older selves. Although the volume’s focus is on desexualization, resexualization is to some extent acknowledged in each chapter.

AbstractSex workers face a number of health and human rights challenges including heightened risk for HIV infection and suboptimal care and treatment outcomes, institutional and interpersonal violence, labour rights violations, and financial insecurity. In response, sex worker-led groups have been formed and sustained across geographic settings to address these challenges and other needs. Over the last several decades, a growing body of literature has shown that community empowerment approaches among sex workers are associated with significant reductions in HIV and other sexually transmitted infections. Yet legal and policy environments, as well as funding constraints, have often limited the reach, along with the impact and sustainability, of such approaches.In this chapter, we first review the literature on community empowerment and mobilisation strategies as a means to collectively address HIV, violence, and other health and human rights issues among sex workers. We then utilise two case studies, developed by the sex worker-led groups APROASE in Mexico and Ashodaya Samithi in India, to illustrate and contextualise community empowerment processes and challenges, including barriers to scale-up. By integrating the global literature with context-specific case studies, we distil lessons learned and recommendations related to community empowerment approaches among sex workers.

Abstract This research develops a computer-aided system for health professionals which helps them to prevent injury related to manual lifting by workers in a manufacturing operation. The heart of the system is a computer program which prescribes the motion that a given person should follow while lifting an object according to different conditions. The system compares the prescribed path to the true motion data taken from a motion tracking system so the health professional can make suggestions on how the person should modify his/her movement. The prescribed motion is generated with a new technique called spacetime optimization. The health professional describes the simplified characteristics of the human subject such as sex, height, weight, and harmful conditions that the subject should avoid, such as maximum low back stress or shoulder stress. He/she also describes the task involved, such as the starting and ending positions of the load, its shape and weight, and the positions of any intermediate obstacles in the path. The spacetime optimization engine generates the path that the person should follow in order to minimize the harmful conditions according to an objective function and constraints. In this research, two dimensional dynamic human models are used and a graphical user interface is added to this system to display and compare the motion between real motion and simulation models.