Research over the past 20 years has shown that trait differences acting after copulation but before the fusion of sperm and egg nuclei, often termed postmating, prezygotic trait differences, play a primary role in reducing gene exchange between populations within a species and between closely related species. The genetic basis of these trait differences is poorly understood and thus, constitutes the primary goal of Marshall and Howard's research plan. Specifically, the proposed research focuses on identifying the seminal fluid and sperm proteins that differ, whether in abundance or structure, between closely related ground cricket species that are isolated by postmating, prezygotic trait differences. Once identified, gene silencing technology will be used to evaluate the function of each protein and its influence on preventing or reducing fertilization between species.
Barriers to fertilization have been intensively studied in the Allonemobius socius complex of crickets, providing an excellent model for evaluating the genes and proteins that underlie successful fertilization. Understanding the genetic basis of fertilization incompatibilities between populations and species can provide insight into a wide-range of topics, including the development of infertility within species (including humans) and the role of sexual selection and sexual conflict in driving the divergence of fertilization proteins. The project provides training for undergraduate and graduate students and outreach to K-12 schools.
