Intra-genomic conflict and the evolution of sexually selected traits. The dynamics of sexual selection may prevent the simultaneous optimization of traits shared by the sexes, or of different traits within each sex. This proposal focuses on the consequences of these conflicts for phenotypic and genomic evolution. First, I will compare selection acting on a sexually dimorphic trait in males and females. Second, I will use artificial selection to create a novel sexually dimorphic trait, and track ....Intra-genomic conflict and the evolution of sexually selected traits. The dynamics of sexual selection may prevent the simultaneous optimization of traits shared by the sexes, or of different traits within each sex. This proposal focuses on the consequences of these conflicts for phenotypic and genomic evolution. First, I will compare selection acting on a sexually dimorphic trait in males and females. Second, I will use artificial selection to create a novel sexually dimorphic trait, and track the evolutionary response. Third, I will investigate the link between two important fitness traits: body size and ageing rate. This work will enhance important on-going research in the laboratory of Robert Brooks (UNSW).Read moreRead less
Evolutionary signficance of sexual conflict in orb-web spiders. Multiple mating by females creates intense competition between ejaculates over the fertilisation of her eggs, and has a profound influence on male and female life history and mating strategies. In orb-web spiders, sexual cannibalism creates further conflicts of interest because the male may forfeit future matings. This project examines how life-history and mating strategies interact in these spiders, by identifying the mechanisms t ....Evolutionary signficance of sexual conflict in orb-web spiders. Multiple mating by females creates intense competition between ejaculates over the fertilisation of her eggs, and has a profound influence on male and female life history and mating strategies. In orb-web spiders, sexual cannibalism creates further conflicts of interest because the male may forfeit future matings. This project examines how life-history and mating strategies interact in these spiders, by identifying the mechanisms that determine the outcome of sperm competition; the selection pressures favouring sexual size dimorphism and male size variation; the influence of sexual cannibalism on male mating strategies; and the relationship between female feeding history and her mating behaviour.Read moreRead less
Life history constraints on sexual selection: an investigation using territoriality in butterflies. Contemporary studies into the evolution of male contest behaviour largely ignore the influence of life history. However, contest behaviour should be influenced by life history because the costs of fighting (injury or death) are extracted in a life history currency. Here I aim to measure reproductive value in a territorial butterfly, and to isolate the effects of this parameter, physiological condi ....Life history constraints on sexual selection: an investigation using territoriality in butterflies. Contemporary studies into the evolution of male contest behaviour largely ignore the influence of life history. However, contest behaviour should be influenced by life history because the costs of fighting (injury or death) are extracted in a life history currency. Here I aim to measure reproductive value in a territorial butterfly, and to isolate the effects of this parameter, physiological condition and fighting experience upon male aggression. I propose an innovative experimental approach to unraveling the effects of these covarying life history influences which promises exciting and highly original insights into the evolution of contest behaviour.Read moreRead less
Boom and bust: the role of fire and rain in driving the dynamics of seeds and rodents in arid Australia. The arid Australian environment oscillates between spectacular boom periods, when biotic productivity and diversity are high, and busts, when biotic resources are depleted. This project first outlines a conceptual model of this dynamic and complex system. It then investigates the roles of rainfall and fire in driving boom-bust events, focusing particularly on food resources (seeds) and their ....Boom and bust: the role of fire and rain in driving the dynamics of seeds and rodents in arid Australia. The arid Australian environment oscillates between spectacular boom periods, when biotic productivity and diversity are high, and busts, when biotic resources are depleted. This project first outlines a conceptual model of this dynamic and complex system. It then investigates the roles of rainfall and fire in driving boom-bust events, focusing particularly on food resources (seeds) and their consumers (desert rodents) in the hyper-variable Simpson Desert. We propose observations and experiments to quantify how these climatic events affect seed production, seed fate, and ultimately the dynamics of desert rodents, and outline their importance for effective management of the desert environment.Read moreRead less
Population dynamics and genetic variation of plants with contrasting fire responses. We combine the traditional concerns of population viability analyses with the modern techniques of DNA fingerprinting for precise genotyping of individual plants and their seeds. We expect major breakthroughs in our understanding of how fire-killed species have survived thousands of years of frequent burning by Aborigines (by identifying seeds dispersed long distances from burnt parents); how paternity of offspr ....Population dynamics and genetic variation of plants with contrasting fire responses. We combine the traditional concerns of population viability analyses with the modern techniques of DNA fingerprinting for precise genotyping of individual plants and their seeds. We expect major breakthroughs in our understanding of how fire-killed species have survived thousands of years of frequent burning by Aborigines (by identifying seeds dispersed long distances from burnt parents); how paternity of offspring changes over the lifespan of plants which retain their seeds for many years; at what age within-plant genetic variation is at a maximum as a guide to optimal fire management; and the extent that deleterious somatic mutations explain low seed set among long-lived species.Read moreRead less
The role of plant chemical defences in the population ecology of mammal herbivores. Plants defend themselves against herbivores by producing toxic compounds in their leaves. Many studies show that such compounds influence diet selection by mammal herbivores, but we understand much less about their effects on populations of such species. This project will investigate how concentrations of leaf toxins in eucalypts affect reproductive success, distribution and abundance of the marsupials that feed ....The role of plant chemical defences in the population ecology of mammal herbivores. Plants defend themselves against herbivores by producing toxic compounds in their leaves. Many studies show that such compounds influence diet selection by mammal herbivores, but we understand much less about their effects on populations of such species. This project will investigate how concentrations of leaf toxins in eucalypts affect reproductive success, distribution and abundance of the marsupials that feed on them. The knowledge gained by this study will be important in modelling populations of these marsupial species and predicting their responses to environmental change.Read moreRead less
Evolution of cooperative breeding in birds. The incidence of cooperative breeding in birds varies from 0 to 100% between families of birds, and from <1 to >25% among birds from different regions. However, there has been no theory that successfully predicts these differences. Recent comparative analysis shows the differences result largely from the early evolution of obligate cooperative breeding in some groups, and their subsequent slow rates of speciation. I will use model systems to investiga ....Evolution of cooperative breeding in birds. The incidence of cooperative breeding in birds varies from 0 to 100% between families of birds, and from <1 to >25% among birds from different regions. However, there has been no theory that successfully predicts these differences. Recent comparative analysis shows the differences result largely from the early evolution of obligate cooperative breeding in some groups, and their subsequent slow rates of speciation. I will use model systems to investigate how birds can become committed to cooperative breeding despite the inevitable conflicts, and how one group of birds have been freed from the general rules governing the evolution of sociality.Read moreRead less
Influence of energy intake on reproduction. Understanding reproduction is fundamentally important to ecology and conservation. Despite intensive research, the processes that regulate energy acquisition and allocation for reproduction are still unclear for most animal species. Many of the obstacles to progress in this field of research are logistical, reflecting the complexity and temporal overlap of significant components of energy allocation pathways. Our proposed study avoids many of these l ....Influence of energy intake on reproduction. Understanding reproduction is fundamentally important to ecology and conservation. Despite intensive research, the processes that regulate energy acquisition and allocation for reproduction are still unclear for most animal species. Many of the obstacles to progress in this field of research are logistical, reflecting the complexity and temporal overlap of significant components of energy allocation pathways. Our proposed study avoids many of these logistical difficulties by focusing on animals (snakes) that display clear temporal partitioning between successive segments of the reproductive cascade (i.e., vitellogenesis, ovulation, embryogenesis); and by adopting a simple but novel method (based on stable isotope analysis) to tease apart the relationship between energy acquisition and energy expenditure in different phases of the animal's life-history.Read moreRead less
Why do females mate with multiple partners? Tests of key hypotheses in the wild. Female animals commonly mate with several males at each reproductive cycle, but we do not know why. Six plausible, testable hypotheses have been proposed to explain how females could benefit directly, or by obtaining advantageous genes for their offspring. The few empirical investigations so far carried out have been in captivity and have not considered all alternative explanations. I propose to experimentally test ....Why do females mate with multiple partners? Tests of key hypotheses in the wild. Female animals commonly mate with several males at each reproductive cycle, but we do not know why. Six plausible, testable hypotheses have been proposed to explain how females could benefit directly, or by obtaining advantageous genes for their offspring. The few empirical investigations so far carried out have been in captivity and have not considered all alternative explanations. I propose to experimentally test the key hypotheses in the wild, using a small mammal uniquely-suited to this purpose because of its unusual, but well-known reproductive strategy. The results will improve our understanding of the role of female behaviour in evolutionary processes.Read moreRead less
Sex, parthenogenesis and adaptation: a novel laboratory 'natural selection' experiment testing the adaptive significance of sexual and asexual reproduction. One of the greatest challenges for evolutionary biology is explaining the widespread occurrence of sexual reproduction. Many theoretical models show some inherent benefits of sex, however these models make assumptions that little or no empirical data exists for. Using a novel phenomenon found in the parasitoid wasp genus Trichogramma, I will ....Sex, parthenogenesis and adaptation: a novel laboratory 'natural selection' experiment testing the adaptive significance of sexual and asexual reproduction. One of the greatest challenges for evolutionary biology is explaining the widespread occurrence of sexual reproduction. Many theoretical models show some inherent benefits of sex, however these models make assumptions that little or no empirical data exists for. Using a novel phenomenon found in the parasitoid wasp genus Trichogramma, I will investigate the adaptive significance of sexual and asexual reproduction in a laboratory natural selection experiment and therefore directly test the theory for the evolution and maintenance of sex. This will be the first such test in a higher organism.Read moreRead less