RUI: The Effects of Natural Selection on Molecular Variation in Structured Populations

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During the past decade it has become clear that natural selection has major effects on patterns of DNA sequence variation across entire chromosomes of organisms as diverse as Drosophila, mice, humans, and tomato. However, the extent to which the levels and patterns of molecular variation reflect adaptive Darwinian evolution versus purifying selection of deleterious mutations remains a mystery. The studies proposed here will take advantage of the highly structured nature of Drosophila ananassae populations in Southeast Asia to estimate the extent to which limited gene flow, local adaptation, genetic drift, and recombination influence the architecture of the genome. A dense set of molecular markers will be used to scan the genome for genes involved in local adaptation in populations along a latitudinal cline representing different climatic regions in Southeast Asia. Genetic and physical maps will provide a means to examine the effect of natural selection across broad expanses of the genome. Studies will also be performed to examine the patterns of polymorphism at genes in population samples of D. ananassae from the ancestral range of the species to estimate the geographic boundaries of natural selection on DNA sequence variation.These studies explore the fundamental mechanisms shaping genome variation and diversity in structured Drosophila populations, providing insight into the processes responsible for molding genome diversity in other organisms with structured populations such as humans. The research involves international collaborations between the United States and Germany, and training opportunities for undergraduate students.