Does testosterone produce duds or studs? A performance-based examination of the Immunocompetence Handicap Hypothesis. The evolutionary persistence of testosterone (T) as a vertebrate reproductive hormone is viewed as a double-edged sword. On the one hand T secretion is required for development and expression of appropriate reproductive functions. On the other hand T is known to suppress immune functions and is thus considered a liability to male health. We are examining an alternate hypothesis: ....Does testosterone produce duds or studs? A performance-based examination of the Immunocompetence Handicap Hypothesis. The evolutionary persistence of testosterone (T) as a vertebrate reproductive hormone is viewed as a double-edged sword. On the one hand T secretion is required for development and expression of appropriate reproductive functions. On the other hand T is known to suppress immune functions and is thus considered a liability to male health. We are examining an alternate hypothesis: that T-induced immunosuppression benefits breeding males by protecting their physical performance levels during immune challenge. We will examine this hypothesis by quantifying the interactive effects of T and immune challenge on the aerobic capacity of male birds.Read moreRead less
Evolution of viviparity in reptiles: the fundamental role of junctional complexes. This project utilises unique Australian reptile fauna to understand global questions in fundamental biology. We will discover basic biological information on native species, which will be important in future conservation of Australian ecosystems and animals and ultimately in helping to maintain Australia's biodiversity. The project also provides training opportunities for graduate and undergraduate students in ....Evolution of viviparity in reptiles: the fundamental role of junctional complexes. This project utilises unique Australian reptile fauna to understand global questions in fundamental biology. We will discover basic biological information on native species, which will be important in future conservation of Australian ecosystems and animals and ultimately in helping to maintain Australia's biodiversity. The project also provides training opportunities for graduate and undergraduate students in several different research methods that are widely applicable in the more general Australian workforce. Because the research work is genuinely cross-disciplinary research, its findings are applicable to both biological and medically oriented technologies.Read moreRead less
Uterodomes and the evolution of viviparity. We will test the hypothesis that uterodomes, which are cell structures unique to the early pregnant uterus in mammals, and the cellular changes accompanying their development, are essential to the evolution of viviparity in amniotes. The proposal stems from our recent discovery that uterodomes develop in the uteri of viviparous lizards as well as in mammals, suggesting key commonalities at the cellular level in the evolution of live birth across amnio ....Uterodomes and the evolution of viviparity. We will test the hypothesis that uterodomes, which are cell structures unique to the early pregnant uterus in mammals, and the cellular changes accompanying their development, are essential to the evolution of viviparity in amniotes. The proposal stems from our recent discovery that uterodomes develop in the uteri of viviparous lizards as well as in mammals, suggesting key commonalities at the cellular level in the evolution of live birth across amniote vertebrates. We will take advantage of the unique combination of placental types among Australian lizards, including a species with both oviparous and viviparous populations.Read moreRead less
How and why do female lizards manipulate the sex and size of their offspring. Mathematical models suggest that reproducing females may be able to enhance their evolutionary fitness by modifying the relative allocation of resources to sons versus daughters. This project uses a model reptile system and an integrated series of experimental and field studies to examine patterns of maternal allocation to sons versus daughters and differential male and female offspring fitness in a range of environmen ....How and why do female lizards manipulate the sex and size of their offspring. Mathematical models suggest that reproducing females may be able to enhance their evolutionary fitness by modifying the relative allocation of resources to sons versus daughters. This project uses a model reptile system and an integrated series of experimental and field studies to examine patterns of maternal allocation to sons versus daughters and differential male and female offspring fitness in a range of environments. This study will provide robust tests of adaptationist hypotheses from sex-allocation theory and provide quantitative data necessary to understand the evolution of sex-determination systems in reptiles.Read moreRead less