Dissertation Research: Small Population Evolution and Slightly Deleterious Mutations: A Test of Nearly-Neutral Theory

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Martin9972737Populations of endangered species are of special concern because they typically persist as small populations. Small population size heightens the probability of extinction. In addition, theoretical studies indicate that small populations accumulate deleterious mutations because genetic drift overwhelms the purifying effects of selection, a phenomenon that further increases the likelihood of extinction. The investigators will conduct theoretical studies of genetic drift to determine the accumulation of deleterious mutations in populations. Populations of pupfishes in the deserts of western Nevada provide an excellent system to test whether extremely small populations accumulate significantly more mutations than larger populations. One of the populations, that of the Devil's Hole pupfish, has the unfortunate distinction of being the smallest vertebrate population. For a series of populations of different size, the rates and patterns of mutation accumulation will be assessed by comparative analysis of DNA sequences for several mitochondrial genes to test the predictions of the theoretical models.By documenting genetic effects of small population size, conservation biologists will gain insights into how small populations evolve. Information about the relationship between population size and mutation accumulation will advance understanding about the influence of evolutionary forces in extinction.