DISSERTATION RESEARCH: The dynamics of socio-chemo cues across a contact zone in the California vole (Microtus californicus)

University Of California-Berkeley, Berkeley CA

Investigators

Abstract

This study will investigate how evolution of olfactory (odor) cues helps maintain genetic differences between two recently evolved subspecies of the California vole. Voles, like many mammals, use olfactory cues to choose their mates. This can lead to behavioral isolation between groups of individuals (populations) and ultimately lead to genetic separation (divergence) and speciation. The researchers will document how olfactory cues change across a contact zone, an area where these two closely related vole species meet and potentially interbreed. Chemical profile data and genetic data will be collected from across the contact zone and then statistically compared to determine whether patterns mirror each other; a close correlation will suggest that chemical cues and mating preferences are responsible for genetic divergence. Studying contact zones between recently diverged subspecies can reveal important information about how species form and are maintained as distinct entities. In addition, the project will provide independent research opportunities for undergraduate students. Outreach includes the development of educational activities appropriate for public school students. This project will characterize geographic variation in the olfactory cues used by two subspecies of the California vole, Microtus californicus, when choosing mates. The main goal is to determine if differences in olfactory cues are correlated with the degree of genetic differentiation between subspecies. The investigators will analyze urine samples collected from across a contact zone between the two sub-species. Chemical profiles (chemical composition and relative abundances) of volatile and semi-volatile molecules in urine samples will be quantified using solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry. Cline analysis will be conducted to determine whether chemical changes reflect environmental differences (e.g. habitat differences or geographic gradients) or conversely whether they mirror the known genetic break between the two vole lineages. A pattern of geographic variation in urine chemical profiles that mirrors the genetic data would suggest that behavioral reproductive isolation contributes to maintaining these two genetically distinct lineages.