Evolution of sex ratios in social hymenoptera: consequences of finite brood size

Evolutionarily stable sex ratios are determined for social hymenoptera under local mate competition (LMC) and when the brood size is finite. LMC is modelled by the parameter d. Of the reproductive progeny from a single foundress nest, a fraction d disperses (outbreeding), while (1-d) mate amongst themselves (sibmating). When the brood size is finite, d is taken to be the probability of an offspring dispersing, and similarly, r, the proportion of male offspring, the probability of a haploid egg being laid. Under the joint influence of these two stochastic processes, there is a nonzero probability that some females remain unmated in the nest. As a result, the optimal proportion of males (corresponding to the evolutionarily stable strategy, ESS) is higher than that obtained when the brood size is infinite. When the queen controls the sex ration, the ESS becomes more female biased under increased inbreeding (lower d), However, the ESS under worker control shows an unexpected pattern, including an increase in the proportion of males with increased inbreeding. This effect is traced to the complex interaction between inbreeding and local mate competition.

Colony sex ratios vary with breeding structure but not relatedness asymmetry in the facultatively polygynous ant Pheidole pallidula

We investigated sex allocation in a Mediterranean population of the facultatively polygynous (multiple queen per colony) ant Pheidole pallidula. This species shows a strong split sex ratio, with most colonies producing almost exclusively a single-sex brood. Our genetic (microsatellite) analyses reveal that P. pallidula has an unusual breeding system, with colonies being headed by a single or a few unrelated queens. As expected in such a breeding system, our results show no variation in relatedness asymmetry between monogynous (single queen per colony) and polygynous colonies. Nevertheless, sex allocation was tightly associated with the breeding structure, with monogynous colonies producing a male-biased brood and polygynous colonies almost only females. In addition, sex allocation was closely correlated with colony total sexual productivity. Overall, our data show that when colonies become more productive (and presumably larger) they shift from monogyny to polygyny and from male production to female production, a pattern that has never been reported in social insects.

SEX DETERMINATION IN BEES .30. EFFECTS OF JUVENILE-HORMONE ON THE DEVELOPMENT OF TERGAL GLANDS IN MELIPONA

Worker larvae of Melipona rufiventris, M. quadrifasciata and M. compressipes were treated topically with juvenile hormone (JH) during the cocoon-spinning phase. Examination of the tergites of the queens obtained following JH application showed induced differentiation into adults with full female (queen) traits. Melipona workers had tergal glands only in tergite II, whereas natural and JH-induced queens had tergal glands in tergite II plus additional glands in at least one other of tergites Ill to VII.

Sex allocation in the polydomous leaf-cutting ant Acromyrmex balzani

Logistic regression analysis was used to analyse sex allocation in a population of the leaf-cutting ant Acromyrmex balzani occurring in a pasture in southern Brazil. The field sample consisted of 151 fungus-garden chambers (18 queenright and 133 queenless), belonging to 50 nests with three vertically stacked chambers per nest on average. Taking nest chamber as the unit of analysis, seven predictor variables were considered: sampling date, chamber depth, chamber volume, weight of fungus garden, presence of a queen, number of large workers, and number of small to medium workers. The population-level numerical proportion of females was 0.548 and the inferred proportional energetic investment in females 0.672. The former was not significantly different from 0.5 (P=0.168), but the latter was (P=0.0003). The proportional investment in females per fungus garden increased with the number of large workers present (P=0.0002) and decreased with the dry weight of the fungus garden (P=0.012). This implies that resource acquisition through foraging is likely to be a major proximate determinant of sex allocation. The negative correlation between female bias and fungus garden weight might be due to developing adult females requiring more food than males, but this hypothesis could not be confirmed by direct statistical evidence.

Cuticular Hydrocarbon Variation of Castes and Sex in the Weaver Ant Camponotus textor (Hymenoptera: Formicidae)

Cuticular hydrocarbons play important roles as chemical signatures of individuals, castes, sex and brood. They also can mediate the regulation of egg laying in ants, by informing directly or indirectly the reproductive status of queens. In this study we asked whether cuticular hydrocarbon profiles are correlated with castes and sex of Camponotus textor. Cuticular hydrocarbons were extracted from part of a mature colony (80 workers, 27 major workers, 27 queens, 27 virgin queens and 27 males). Results showed that cuticular hydrocarbons varied quantitatively and qualitatively among the groups and this variation was sufficiently strong to allow separation of castes and genders. We discuss the specificity of some compounds as possible regulatory compounds of worker tasks and reproduction in C. textor.

Sex-Specific Differences in Pathogen Susceptibility in Honey Bees (Apis mellifera)

Sex-related differences in susceptibility to pathogens are a common phenomenon in animals. In the eusocial Hymenoptera the two female castes, workers and queens, are diploid and males are haploid. The haploid susceptibility hypothesis predicts that haploid males are more susceptible to pathogen infections compared to females. Here we test this hypothesis using adult male (drone) and female (worker) honey bees (Apis mellifera), inoculated with the gut endoparasite Nosema ceranae and/or black queen cell virus (BQCV). These pathogens were chosen due to previously reported synergistic interactions between Nosema apis and BQCV. Our data do not support synergistic interactions between N. ceranae and BQCV and also suggest that BQCV has limited effect on both drone and worker health, regardless of the infection level. However, the data clearly show that, despite lower levels of N. ceranae spores in drones than in workers, Nosema-infected drones had both a higher mortality and a lower body mass than non-infected drones, across all treatment groups, while the mortality and body mass of worker bees were largely unaffected by N. ceranae infection, suggesting that drones are more susceptible to this pathogen than workers. In conclusion, the data reveal considerable sex-specific differences in pathogen susceptibility in honey bees and highlight the importance of ultimate measures for determining susceptibility, such as mortality and body quality, rather than mere infection levels

Developmental Pathways in Microcerotermes turneri (Termitidae: Termitinae): Biometric Descriptors of Worker Caste and Instar

The foraging process of location and exploitation of food in complex termite societies is in part reliant upon unequal division of specific tasks amongst its members (polyethism). To conduct studies assessing the role of individuals in foraging activities it is necessary to have descriptors of worker caste and instar. Here we provide biometric descriptors of specific caste and instar for worker caste and instars of Microcerotermes turneri (Froggatt) (Termitidae: Termitinae) for the worker castes (male and female) for the identification of individuals in laboratory assays applicable across multiple nests. The use of head width for determining sex of workers was successful across multiple nests. The length of the first three flagellum segments of the antenna and tibia three could be used to determine worker instar.

Employer evasion of worker entitlements 1986-95 : what and whose?

Employer non-compliance with workers’ entitlements is an area seldom explored in Australian industrial relations, generally considered uncommon or the province of ‘rogue’ employers. This paper provides a picture of the categories of entitlements against which complaints of evasion were made in the federal industrial relations jurisdiction in Australia, between 1986 and 1995 and the characteristics of complainants. The “top 30” awards ranked by extent of underpayment recovered by the federal enforcement agency (1987-95) are also explored to support arguments that intense competition, reduced union density, precarious employment, youth and being female are strongly associated with employer evasion. The increasing prevalence of these factors in the labour market suggests that employer compliance should be more carefully explored in the Australian context.

Health professional partnerships and their impact on Aboriginal health : an occupational therapist's and Aboriginal health worker's perspective

Objective: To describe the extent and nature of demonstrated professional partnerships between occupational therapists and Aboriginal health workers in rural and remote communities of North Queensland. The study identifies ways in which professional partnerships improve client services and enhance occupational therapy outcomes through exploring the aspects of communication, collaboration and bridging cultural boundaries.---------- Design: Data collected via in-depth, semistructured telephone interviews. ---------- Setting: Aboriginal and mainstream health and human service organisations in rural and remote North Queensland. Rural and remote areas were identified using the Accessibility and Remoteness Index of Australia codes. ---------- Participants: Seven participants working in rural and remote areas of North Queensland, comprising four occupational therapists and three Aboriginal health workers. All participants were female. ---------- Results: Participants identified five core themes when describing the extent and nature of professional partnerships between occupational therapists and Aboriginal health workers. Themes include: professional interaction; perception of professional roles; benefits to the client; professional interdependence; and significance of Aboriginal culture. According to participants, when partnerships between occupational therapists and Aboriginal health workers were formed, clients received a more culturally appropriate service, were more comfortable in the presence of the occupational therapist, obtained a greater understanding of occupational therapy assessment and intervention, and felt valued in the health care process. ---------- Conclusions: This study substantiates the necessity for the formation of professional partnerships between occupational therapists and Aboriginal health workers. The findings suggest that participation in professional partnerships has positive implications for occupational therapists working with Aboriginal clients and Aboriginal health workers in rural and remote regions of North Queensland.

‘Live your liberation, don’t lobby for it’ : Australian queer student activists’ perspectives of same-sex marriage

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.

Effect of female sex hormones on Chlamydia trachomatis growth and gene expression

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.