Butterflies, inchworms, and plants: revisiting long-standing hypotheses of codiversification

The purpose of this dissertation was to understand how changes in short-term ecological factors have lead to long-term evolutionary consequences, with a particular focus on the diversification of herbivorous insects and the plants they feed on. I begin with a general discussion of current theory on how changes to a species’ niche, or general way of life, can shape evolutionary processes across a broad diversity of organisms, including adaptation, selection, diversification, and hybridization. Additionally, I discuss two important and unresolved questions specifically regarding the diversification of herbivorous insects and discuss how the subsequent three dissertation chapters attempt to address these areas of investigation. In Chapter 1, I investigate the evolutionary history of Neotropical moths in the hyperdiverse genus Eois (Geometridae), with an emphasis on documenting the roles of host conservatism, geography, and elevation in promoting diversification. In Chapter 2, I examine the evolution of secondary defense chemistry in one clade of Piper plants (Radula), the predominant genus that Eois caterpillars feed on. Finally in chapter 3, I elucidate patterns of novel host using Californian butterflies and exotic plants as a model system in an effort to determine the characteristics of herbivores that promote host shifting, which is typically the predominant mechanism by which diversification is thought to occur in herbivorous insect lineages