International Research Fellowship Program: Nutritional Ecology and the Evolution of Seasonal Color Polymorphism in a Butterfly

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0754487MorehouseThe International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four month research fellowship by Dr. Nathan I. Morehouse to work with Dr. Jerome Casas at the University of Tours in France.Large color ornaments are some of the most eye-catching traits in the natural world, and yet many aspects of their production and evolution remain poorly understood. For example, in all but a select few animal species, our understanding of the costs and physiological tradeoffs associated with producing color patterns is still incomplete. This is particularly true for coloration in invertebrates, which represent some of the most conspicuously colored members of the animal kingdom. The PI is working to better understand the costs of coloration within an evolutionary framework using the European Map Butterfly, Araschnia levana, a butterfly species known for its two seasonal color morphs, a bright orange spring morph and a black-and-white summer morph. While these two color morphs are distinct visually, their color patterns are perhaps even more different biochemically. The wing patterns of the spring morph require the synthesis and deposition of large amounts of orange ommochrome pigments, whereas the summer morph uses large amounts of melanin pigments to produce its wing patterns. These two pigment types draw on different pools of basic nutrients for their synthesis: ommochromes require the amino acid tryptophan, whereas melanin is synthesized from tyrosine and/or phenylalanine. Such basic biochemical differences are likely to have a strong influence on the physiological mechanisms and tradeoffs associated with the production of each color morph. He is investigating the nutrient dynamics that underlie the development of A. levana?s two color morphs, seeking to quantify 1) seasonal variation in available resources, 2) seasonal differences in nutrient uptake, 3) differences between seasonal morphs in nutrient allocation and resulting life-history tradeoffs, and 4) the role of ecdysone and/or juvenile hormone in mediating competition between growing tissues for resources involved in color production. Results from his work will allow us to better understand the evolution of this color polymorphism, and perhaps color traits more generally.