Insect Development and Evolution: Perspectives on Individual and Colony-Level Phenotypes

Abstract

This dissertation analyzes the develop and evolution of insect phenotypes, ranging from the level of individuals to colonies. The first four chapters focus on wing patterning in the bella moth Utetheisa ornatrix. I begin by quantifying the pattern variation in the species, then attempt to identify some of the mechanisms that give rise to the observed phenotypic differences. After describing how the primitive patterns of U. ornatrix can be construed as evidence that nymphalid groundplan symmetry systems arose from the fusion of irregular spots, I present the results of a series of artificial selection experiments that highlight the species’ capacity for phenotypic evolvability. I then detail how changes in Wnt expression can lead to the evolution of bold phenotypes, and show that pterin pigments provide the primary source of coloration in U. ornatrix patterns. The final chapter focuses on the evolution of social phenotypes in insect societies. I suggest that the evolution of a physically differentiated reproductive and worker castes marks an irreversible major evolutionary transition to superorganismality. Social groups of this type are fundamentally different than monomorphic cooperative breeders, and can meaningfully be compared to metazoan organisms with differentiated germ and soma.