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

Duke University, Durham NC

Investigators

Abstract

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.