9318919 Rausher Genetic variation is the raw material for evolutionary change. Consequently, understanding the processes that produce and maintain genetic variation in natural populations is a requisite for understanding how, and at what rate, organisms evolve. In addition, understanding how genetic variation is maintained in natural populations may contribute to the development of strategies for conserving genetic diversity in natural ecosystems. Over the last thirty years, numerous investigations have indicated that natural populations of organisms harbor extensive amounts of genetic variation. Nevertheless, although theoretical investigations have indicated that there are more than a dozen processes that could maintain these levels of genetic variation in natural populations, very few definitive examples of any of these processes exist. Consequently, understanding of why organisms are so genetically variable is at best rudimentary. The purpose of this research is to address this issue using flower color variation in the annual morning glory, Ipomoea purpurea, as a model system. In particular, the goal of this project is to determine why genetic variation for flower color persists in natural populations of this species. Through a series of field and laboratory experiments, the evolutionary forces that act on a gene that influences the intensity of pigmentation (the W locus) at all stages of the life cycle will be assessed. From these assessments, a determination will be made of which, if any, of the theoretically described processes for maintaining genetic variation operate on this character.***
