Exaggerated Trait Growth in Insects

Exaggerated structures function in a variety of ecological contexts, and these contexts, in turn, favor very different properties of expression: extreme plasticity and among-individual variability in some cases, for example, but canalization and minimal variability in others. Linking ecological contexts such as sexual signaling, prey capture, locomotion, and colony defense with specific types of underlying developmental mechanisms promises to reveal much more than the alleles and genes responsible for morphological evolution; it promises insight into why particular types of pathways underlie the evolution of each type of structure¿why, for example, mutations in genes affecting tissue-level responses to whole-animal signals of nutrition or condition might underlie the evolution of exaggerated size in ornaments and weapons of sexual selection, whereas mutations in genes acting in within-tissue patterning mechanisms underlie the evolution of extreme size in locomotor or prey-capture traits. Despite their compelling biology and fantastic diversity, very few species with exaggerated morphological structures have been studied at the genetic or physiological level.