DISSERTATION RESEARCH: Evolutionary genetics of crossover rate differences across the Drosophila phylogeny

点击翻译按钮获取中文摘要

Meiosis is a specialized form of cell division that ultimately produces gametes (i.e., sperm and egg). This project will examine recombination, the exchange of genetic information between paired chromosomes, that occurs during meiosis. The project has broad educational and societal impacts, including opportunities to train undergraduate and high school students in classical genetics, basic molecular biology, and evolutionary biology. Furthermore, the portability of the experimental system facilitates outreach efforts involving middle school students participating in summer programs in science education. The research has potential societal impacts including human health as meiotic disruptions contribute to infertility and aberrant chromosome number in progeny. The recombination that occurs during the first stage of meiosis serves two important functions. First, recombination ensures the distribution of the appropriate number of chromosomes into gamete cells. Second, recombination generates novel genetic combinations that are potentially beneficial to the progeny. Despite these benefits, recombination has risks because it can generate deleterious duplication and deletion mutations. The frequency of recombination may therefore evolve to balance the benefits of recombination against its risks. Using the fly genus Drosophila, this research will investigate how the frequency and physical placement of recombination events along chromosomes has evolved between species. In particular, this research will investigate how the rapid molecular evolution of a meiosis gene has resulted in the evolution of differences in recombination rate observed across the evolutionary tree of Drosophila species. The project will investigate the rapidly evolving mei-218 gene which is responsible for most of the crossover rate difference between Drosophila melanogaster and Drosophila mauritiana using a candidate gene approach. The project will test the degree to which molecular evolution at mei-218 contributes to the variation in recombination rates across the Drosophila phylogeny using a molecular evolutionary analysis to test for histories of recurrent positive selection at mei-218 in multiple Drosophila lineages. The project will also use a transgenic approach to assay the phenotypic effects of the mei-218 gene from multiple Drosophila species.