International Research Fellowship Program: The Evolution of Polyandry in Heterogeneous Environments

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The International Research Fellowship Program enables U.S. scientists and engineers to conduct three 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-two-month research fellowship by Dr. Tracie M. Ivy to work with Dr. Paul I. Ward at the University of Zurich in Switzerland. The aim of this project is to investigate the evolutionary process of sexual selection in a model study organism, the yellow dung fly (Scathophaga stercoraria). Females of many animal species choose their mates based on males' potential quality as genetic sires. However, recent research has demonstrated that male genetic quality varies across different environments due to gene-by-environment interactions (GEIs), in which environmental conditions influence the way genes are expressed. For females in heterogeneous environments, the existence of GEIs implies that one mate is probably inadequate to provide a female with the best genetic sire over all microhabitats within a particular habitat. To produce offspring that perform well in multiple environments, females may mate with many different males, ensuring the production of genetically diverse offspring. If polyandry is selectively advantageous in heterogeneous habitats due to gene-by-environment interactions, then I predict that polyandrous females will leave more surviving offspring than monandrous females because their offspring are of higher genetic variability. The idea that male genetic quality is not absolute represents a new direction in the study of sexual selection. As well as contributing to this new avenue of investigation, the work outlined in this proposal seeks to test a hypothesis that has long been offered as an explanation for the evolution of female multiple mating, but which has rarely been empirically investigated.