DISSERTATION RESEARCH: Origins of Parthenogenesis in the Common Checkered Whiptail

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One of the primary advantages of sexual reproduction is its ability to generate and maintain biodiversity, yet some species reproduce clonally. This project will address the ability of clonal reproduction to generate genetic diversity in unisexual lizards, the only group of vertebrates capable of reproducing without any input from males. Understanding the evolutionary trajectories of unisexual populations will help identify why sex is the prevalent mode of reproduction for multicellular life. Results and discoveries from this project will connect with the broader community by: 1) promoting training and mentoring, 2) clarifying species level relationships in a taxonomically-challenged species complex, and 3) facilitating exchange of intellectual expertise via international collaborations with Mexican researchers. Using emerging genomic approaches, unique lizard models, and the talents of an international team of researchers, this project addresses a persistent evolutionary question about the evolution and maintenance of sexual reproduction.The goals of this project are to identify the evolutionary processes that shape organismal diversity in a clonally-reproducing lizard. Most vertebrate species maintain genetic variation by reproducing sexually, but several all-female lizards reproduce without males by cloning themselves; mothers beget daughters whose genomes are all but identical. However, cloning is imperfect, as individuals may not produce genetically-identical clones due to mutation. To investigate what generates diversity (including phenotypic diversity) among clones this project uses DNA sequence from one parthenogenetic, all-female species and its related sexual species to determine if either multiple founding events or genetic mechanisms after inception best explain the diversity in phenotypes. Combining genome-wide genotyping with a novel approach to sequence entire mitochondrial genomes, these data should permit a clear picture into the origins of the parthenogenetic species and infer species level relationships among the sexual species. This research will investigate the tempo and mode of mutation processes generating diversity in a clonally-reproducing lizard, thus providing insight into the origins and evolution of unisexuality in vertebrates.