Prezygotic and postzygotic barriers to gene flow between two species of house mice (Mus musculus and Mus domesticus)

Alana Kurosaki
University of Arizona

A central goal in evolutionary biology is to identify barriers to gene flow. The speciation process begins when gene flow is disrupted and populations become genetically isolated. Disruption of gene flow may occur before mating (premating isolation), after mating, but before fertilization (postmating, prezygotic isolation) or after fertilization (postzygotic isolation). This project measures the degree of postmating, prezygotic isolation and of postzygotic isolation between two species of house mice, Mus musculus and Mus domesticus. Wild populations were surveyed for natural frequency of litters of mixed paternity. Postmating, prezygotic isolation is being measured by mating females of one species with two males (conspecific and heterospecific) consecutively. Conspecific sperm precedence is being quantified by counting the number of offspring that are from conspecific and heterospecific fathers respectively. Postzygotic isolation is being measured by comparing the viability and fertility of conspecific and heterospecific F1 male offspring. Viability is assessed from the size and weight of offspring at regular intervals. Fertility is assessed in males from testes weight and size, and from sperm counts. Together these studies will help identify the barriers to gene flow that are important in these recently diverged species.