Color and pigmentation vary widely in the natural world--between sexes, among individuals, among populations, and among species. Often these patterns reflect the process of natural 10 Return to top of directory selection and are adaptive, and represent some of the best examples of evolution over contemporaneous timescales. However, we still lack a true understanding of the genetic basis and architecture of color/pigmentation in the wild. Natural populations of the genetic model organism, Drosophila melanogaster, vary in color and degree of pigmentation as a function of latitude, altitude, and season. Surprisingly, these patterns can be easily replicated in field experiments over ten generations: color and pigmentation evolve rapidly and predictably, and can be modulated by experimental manipulation of such factors as temperature, density, and sexual conflict. This project will address the mechanistic basis of this rapid evolutionary change in a classic trait. The work involves classical genetics with line crosses and associated analysis, molecular genetics involving cis regulation and RNA sequencing, and experimental manipulations in both the field and laboratory. This work is part of a NIH funded project that involves technicians, graduate students, and postdoctoral associates, as well as collaborators at the University of Florida, University of Fribourg (Switzerland), and Sorbonne CNRS (France).