Sexual selection under social constraints

点击翻译按钮获取中文摘要

Sexual selection is a powerful evolutionary force that has generated many spectacular traits among animals, including specialized weapons, brightly coloured ornaments, and elaborate courtship displays. It has also been the focus of tremendous international research activity. As a result, we now have an excellent mechanistic understanding of the underlying processes (e.g., mate choice, intrasexual competition). Yet, the importance of each of these processes to reproductive success and the evolution of sexually selected traits has remained unclear. One reason is that the processes are often studied independently, despite accumulating evidence that they can interact. A second reason is that, among group-living animals, studies have neglected the significance of social factors. In mate choice studies, for example, females are typically tested individually, such that they can each mate with their preferred male. This approach has been criticized because it simulates a rare condition - one that only the minority of dominant females ever experience. Under natural social conditions, the majority of group-living animals are subordinate. I will experimentally control the expression of mate choice, intrasexual competition, and social dominance to reveal how they interact to shape reproductive success and secondary sexual characteristics in a complex social system. Studies will focus on the black-capped chickadee, which is an ideal avian system characterized by stable group structure and linear dominance hierarchies in both sexes. Experiments will reveal the causal effects of dominance on secondary sexual characteristics, the importance of mate choice and intrasexual competition in both sexes, the role of post-copulatory sperm competition, and the behavioural mechanisms underlying extrapair copulations. I will analyze the whole population, considering not just dominant individuals able to exercise their ideal choice, but also subordinates whose choices are constrained. Sexual selection is a hot topic that continues to attract the attention of an international research community; my findings will hence make a distinctive Canadian contribution to a high-profile research area. My research program will also provide a stimulating environment in which to train the next generation of Canadian scientists. Participants will gain valuable experience with aviary and field-based research, with cutting-edge techniques for quantifying secondary sexual characteristics (e.g., acoustic analysis, spectrophotometry, analysis of sperm quality), and with laboratory procedures used in quantifying hormones and genetic parentage. Results will be communicated through leading international journals, conference presentations, science documentaries, and the popular press. This will maximize the impact of my research, as well as my ability to attract young people to careers in science.