We study the evolutionary interplay between behaviour and morphology, using insects. Our work focuses on the evolution of the weapons of sexual selection, insect-plant interactions (especially insects feeding on plants), and the role of nutrition on the expression and evolution of the insect cuticle.

Animal weapons. Animal weapons are highly diverse, even across closely related species (think about the horns of African antelope). Understanding the evolutionary forces that have led to this diversity can help us understand more broadly why animals are so varied in their forms.

Our work has revealed the influence of environmental factors on the expression and evolution of sexually selected weapons and behaviours. We found that the form of sexual selection by male-male competition changes when females are present. Further, we learned that both current and prior nutritional resources can shape the form, and even the direction, of sexual selection. 

We traced the evolution of multi-component male weapons in the leaf-footed bug superfamily, discovering that sexually selected weapons tend to add more and more components over evolutionary time. Yet, there have been spectacular losses of weapon components, and even entire weapons, across the phylogeny. We learned that certain trait combinations have evolved repeatedly across the superfamily, suggesting that certain combinations may function together especially well in battle.

We have also discovered resource allocation trade-offs between sexually selected weapons and male testes. Trade-offs such as these may shape evolutionary trajectories.

Feeding. We discovered extreme phenotypic plasticity in the mouthparts of the leaf-footed bugs. Their straw-like mouthparts can be long or short depending upon what these insects feed upon when they are young. Our work has also revealed that mouthpart length can also evolve and varies genetically across natural populations. We are now investigating the forces that can maintain such extreme (and costly) plasticity as well as the consequences for crop pests. Do pests seek out crops that are well matched for the mouthparts they grew as juveniles? Could this knowledge help farmers by informing how they should plant different plants?

Exoskeletal Cuticle. Insect species comprise over 75% of animal species on this planet, and yet we have so much to learn about how they are constructed and how environmental factors change this process. Our investigations, in collaboration with Prof Walter Federle, have revealed that nutritional quality can have a profound influence on the insect cuticle. We are currently following up on recent findings to understand what these patterns mean for sexual selection, dispersal, and evolution.