Signal partitioning allows butterfly wing surfaces to evolve under opposing selective pressure Fredna K¹ and Reinke BA Ph.D.² kelseyfredna@gmail.com Department of Biology, Northeastern Illinois University, Chicago, IL 60625 Animal coloration is typically the evolutionary compromise of two, often opposing, processes, natural and sexual selection, that is inherently dependent on the environment in which the color is viewed. Sexual dichromatism is a widespread phenomenon typically driven by sexual selection. This dorsal surface of the wing of most butterflies (Order: Lepidoptera) is only visible during flying, courtship displays, or basking, while the ventral surface is visible while resting. Given this physical separation of colors, referred to as signal partitioning, dorsal and ventral wing surfaces can potentially evolve under completely separate selective pressures; this may be evident by comparing the evolution of sexual dichromatism of dorsal and ventral surfaces. We propose that there will be more sexual dichromatism on the dorsal surface of Lepidopteran wings than on the ventral side, and that since these signals are dependent on the light under which they are perceived, we predict that environments with a high percentage of vegetative cover and areas with a low percentage vegetative cover would produce the most profound sexual dichromatism, while intermediate areas would have little to no sexual dichromatism. To test these predictions, we use photographs of adults of the group Biblidinae, which consists of approximately 340 identified species. We will then use phylogenetically controlled methods (PCM) to assess whether the evolution of the sexual dichromatism on the dorsal and ventral surfaces occurs independently and varies by environment as hypothesized. This work is important for understanding signal partitioning and the evolution of sexual dichromatism.