DISSERTATION RESEARCH: Testing the Mutation Models for the Evolution of Microsatellites: An Experimental and Simulation Approach

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Microsatellites are stretches of DNA composed of small sequence units that are repeated many times in tandem. The number of repeats is highly mutable, and the appropriate model for the mutational processes affecting repeat length remains an unsolved problem. This research will use experimental evolution to address this problem. Twenty replicate populations of the yeast Saccharomyces cerevisiae will be evolved for 2000 generations and the variation that has accumulated at 6 microsatellite loci will be characterized. The results will be compared to predictions from computer simulation studies based on the three major mutational models that have been proposed. If none of these preexisting models is confirmed, then the extensive and novel data set obtained in this experiment will be employed to develop a more appropriate model.Microsatellites are present in the genomes of most organisms. Analysis of microsatellite variation is used to study such basic scientific questions as population sizes, genetic divergence between populations, and evolutionary relationships between species. At a more applied level, microsatellites are important tools in genome mapping in medical research and forensic analyses in legal proceedings. Interpretation of results in all of these areas typically requires assumptions about the mutational processes affecting microsatellite variation. The results of this project will thus have important implications in diverse areas of biology.