Sexual selection and molecular evolution of postmating reproductive incompatibilities

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Reproduction has a central role in evolutionary biology because disruptions in reproductive activities, from mating to gamete ability to compete for fertilization, reduce fitness. Among related species, differences in reproductive traits are more pronounced than differences in other traits and such differences can affect species compatibility and contribute to speciation. My work focuses on two phenomena that influence reproductive success after copulation; conspecific sperm precedence (CSP) and gamete development disruption in sterile hybrids. I am also interested in understanding the role of sexual selection on genes linked to postcopulatory success. During the next phase of my research I aim to: 1) identify and functionally test candidate CSP genes, 2) discern between sexual selection and rapid divergence driven by other factors, such as relaxed selective constraints or mutational bias at CSP validated genes and other genes linked to postcopulatory reproductive fitness, 3) evaluate the role of genetic divergence in regulatory sequences in the down regulation of spermatogenesis genes in interspecies male hybrids. In my lab, we have successfully used a combination of classical genetics, genomics and molecular evolution approaches to identify candidate genes associated with variation in reproductive success, particularly genes involved in CSP and gene variants affecting spermatogenesis. In this grant, I expand upon this research by testing the functional significance of these candidate genes using SNP-phenotype associations and genetic knockdowns, thus providing definitive evidence for gene validation. Genes linked to reproductive success and fertilization will be used to test how sexual selection molded their evolution. These results will contribute to our knowledge of species differentiation and the impact of sexual selection at the molecular level during the evolution of reproductive genes. Identified genes will become immediate targets for comparative genomic searches and the identification of conservation and divergence linked to evolutionary transitions.