Dissertation Research: Gene Leakage into a Hybridogenetic Fish of the Genus Poeciliopsis

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9902224VrijenhoekAsexually reproducing species (clones) are considered evolutionary dead-ends due to an irreversible accumulation of slightly deleterious mutations (mutational meltdown). Despite this expectation, some asexual organisms are widespread and abundant. Several mechanisms are believed to retard mutational accumulation in an asexual lineage. One mechanism is to occasionally mate with a related sexual species and incorporate new gene copies that mask or replace mutational defects. The proposed studies will examine evidence for gene replacements in asexual lineages of topminnow fishes (genus Poeciliopsis). Genetic markers (protein and DNA sequences) will be examined to clarify the origin of the asexual lineage, and establish whether its genome contains novel genes from a related sexual species.Now that cloning of mammals is no longer a fantasy, scientists must look to natural models to assess the long- and short-term risks of asexual reproduction. Fish of the genus Poeciliopsis are among the most extensively studied organisms with closely related sexual and asexual forms. The proposed project builds on a 40-year history of genetic, ecological, and evolutionary studies with these fish. This study will provide insights on mechanisms that some asexual species use to circumvent mutational meltdown and avoid extinction.