How the Dogface got its color: How genetics and the environment influence color variation within and between species in the Zerene butterfly

Abstract

A fundamental question in biology is: How is variation generated? At a basic level, the vast amount of variation and biodiversity is generated through a combination of genetic and environmental processes. Traditionally these processes were treated independently, but recently fields such as evolutionary development have worked to unify our understanding of these mechanisms and to investigate how these processes interact with each other to generate variation. Developmental plasticity provides a fantastic framework for studying how genetic and environmental (GxE) interactions shape and maintain natural variation. Butterflies and their wing color patterns have long been model systems for plasticity. This dissertation seeks to address the gxe mechanisms responsible for generating color variation in the Dogface butterfly, Zerene. Zerene is comprised of only two species Z. cesonia, the Southern Dogface, and Z. eurydice, the California Dogface, that differ in their color patterns. Z. cesonia also exhibits a seasonal plastic color pattern, where Z. eurydice does not. These features make the Zerene system an excellent model for disentangling the gxe processes contributing to variation both within and between species. Using an integrative approach these studies address the role of 1.) larval host plant divergence 2.) seasonal fluctuations and 3.) hybridization on the development of wing coloration variation. The findings of these studies contribute not only to our understanding of how butterflies generate their colors, but also to the wider knowledge base on how genetics and the environment influence the generation and maintenance of biological variation.