Abstract

Sexually selected weapons show incredible shape and performance variation across taxa and even within closely related groups of animals. To understand the evolution of trait diversity, it is crucial to consider trait function. Sexually selected weapons, unlike sexually selected ornaments, are fighting structures; they have been selected to perform in physical combat. I will present projects from my research group that examine the evolution and expression of these traits while explicitly considering their functional nature. The first project uses phylogenetic comparative analyses to look across a group of insects that fight with a highly complex, multi-component weapon. We test the hypothesis that the gains and losses of weapon components, such as spines and curves, are not random. Instead, some components are more likely to arise when others are present, suggesting a coordinated function during battle. The second project dives deep into the weapons of a single species to understand how environmental variation affects their construction and to address the puzzling question of why sexually selected weapons so often break.