Sexual selection under social constraints

性选择是一种强大的进化力量，它在动物中产生了许多惊人的特征，包括专门的武器、色彩鲜艳的装饰品和精心设计的求爱表演。它也一直是大量国际研究活动的焦点。因此，我们现在对潜在的过程（例如，配偶选择，性内竞争）有了很好的机制理解。然而，这些过程对生殖成功和性选择特征进化的重要性仍不清楚。一个原因是，尽管越来越多的证据表明这些过程可以相互作用，但它们往往是独立研究的。第二个原因是，在群居动物中，研究忽视了社会因素的重要性。例如，在配偶选择研究中，雌性通常被单独测试，这样她们就可以和自己喜欢的雄性交配。这种方法受到了批评，因为它模拟了一种罕见的情况——只有少数占主导地位的雌性才会经历这种情况。在自然的社会条件下，群居动物大多处于从属地位。

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.