DISSERTATION RESEARCH: The Evolutionary Puzzle of Warning Coloration

Purdue University, West Lafayette IN

Investigators

Abstract

Title: The Evolutionary Puzzle of Warning Coloration Name: Jeffrey R. Lucas and Adam Robert Boyko Abstract: Many toxic animals advertise their distastefulness with bright warning patterns. These patterns help predators learn to avoid them, but how the patterns evolve is poorly understood. When a warning pattern first arises, predators are unfamiliar with it and attack the pattern disproportionately. Only after many individuals share the new pattern do predators learn to avoid them. It is difficult to explain how new warning patterns overcome their initial disadvantage, yet warning patterns have not only evolved in numerous species, but they have diversified extensively in many of them. In the Heliconius genus of tropical butterflies, new warning patterns have evolved dozens of times in some species but only once in others. Evolutionary theory predicts that differences in population structure between these species are responsible for their different diversification rates, but this theory is unproven. In this study, the structure of natural populations of Heliconius inhabiting isolated treefall gaps will be measured. This research will be combined with computational simulations of warning pattern evolution in Heliconius to see if evolutionary theory correctly predicts the observed rates of warning pattern diversification in this genus. Alternatively, differences in sexual selection between Heliconius species may account for the different diversification rates by promoting or constraining color pattern evolution. To examine this possibility, mate choice and mate competition will be studied in greenhouse colonies of these species.