DISSERTATION RESEARCH: Evolution of Sexual Dichromatism in Butterfly Wing Coloration: Evaluating the Importance of Nitrogen Limitation and Sexual Signaling

Arizona State University, Scottsdale AZ

Investigators

Abstract

Bright colors are some of the most fascinating and poorly understood traits in the animal kingdom. Morehouse and Rutowski will investigate colors found in butterflies that are produced by pterin pigments. In the Cabbage White butterfly (Pieris rapae), male butterflies deposit more pterins in their wings than do females, which results in the males having a more colorful appearance to other butterflies. Intriguingly, these pterin pigments are rich in nitrogen, an element which these butterflies have limited access to during larval development. This suggests that these pigments might be costly to produce, especially given the amounts that males deposit in their wings. Why then do males invest in these wing colors? Perhaps males use their bright wing colors to advertise their quality as potential mates, either as a demonstration that they fed on a particularly rich diet early in life, or as an indication that they are more efficient at extracting nitrogen from their diet. Morehouse and Rutowski will examine how genes and larval diet affect the wing colors of these butterflies to better understand the information these bright colors encode. They will also evaluate the response of female butterflies to males with varying wing colors to better understand whether females choose among potential mates on the basis of male coloration. The results of these studies will not only illuminate why these butterflies are brightly colored, but will also reveal how these animals juggle the various demands on their limited nutrient resources. In addition to these anticipated accomplishments, this research will provide outstanding opportunities to recruit students from underrepresented groups into career paths in science. Morehouse and Rutowski will continue to mentor undergraduate researchers from a diversity of backgrounds and ethnicities, and communicate their fascination with colorful animals to public audiences in local classrooms, community organizations and scientific meetings.