DISSERTATION RESEARCH: Selective Pressures Shaping Aggressive Behavior in Females: An Experimental Approach

在动物行为中，一个长期存在的假设是，雌性和雄性在交配策略上存在根本差异，雌性会仔细选择配偶，而雄性则会相互竞争，以获得雌性和资源。这一假设受到了越来越多的认识的挑战，即女性也会积极竞争。然而，目前尚不清楚的是，雌性是否直接受益于它们的攻击性，或者雌性的攻击性行为是否是雄性选择攻击性的副产品。本研究以自由生活的树燕（Tachycineta bicolor）为模型，旨在了解选择压力对雌性攻击行为的影响。初步研究表明，更具攻击性的雌性会通过进入有限的巢穴而获益。然而，更具攻击性的雌性的后代发育得更慢，因此，它们的适应性可能更低。因此，雌性也经历了与她们的攻击性相关的代价。本研究采用实验和观察相结合的方法：(1)测试更具攻击性的雌性后代发育更慢的机制；(2)确定雄性行为在多大程度上可以减轻雌性攻击性的代价。将攻击性作为女性的一种性选择特征的研究重点，提供了一种非常需要的平行信息，这种信息与已经知道的关于男性性选择特征形成的选择压力的丰富信息是一致的。这项工作的广泛影响包括对动物行为和基础生物学的公众教育，保护腔巢鸟类，促进科学教育和对本科生和科学女性的培训。

A long-held assumption in animal behavior is that females and males differ fundamentally in their mating strategies, with females carefully choosing their mates, and males competing among themselves for access to females and resources. This assumption is challenged by the increasing realization that females also compete aggressively. It remains unclear, however, whether females benefit directly from their aggressiveness, or whether aggressive behavior in females is a byproduct of selection for aggressiveness in males. The proposed research aims to understand the selective pressures shaping aggressive behavior in females, using free-living tree swallows (Tachycineta bicolor) as a model. Preliminary work has demonstrated that more aggressive females benefit by gaining access to limited nest sites. Offspring of more aggressive females develop more slowly, however, and as a result, may have lower fitness. Thus, females also experience a cost associated with their aggressiveness. The proposed studies use experimental and observational approaches (1) to test mechanisms by which offspring of more aggressive females develop more slowly, and (2) to determine the extent to which the behavior of males may mitigate the cost of female aggressiveness. The focus on aggressiveness as a sexually selected trait in females provides a much needed parallel to the wealth of information already known about the selective pressures shaping sexually selected traits in males. The broader impacts of this work include public education about animal behavior and basic biology, conservation of cavity-nesting birds, and advancement of the scientific education and training of undergraduates and women in science.