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

这项研究将探讨嗅觉（气味）线索的进化如何帮助维持加州田鼠两个新近进化的亚种之间的遗传差异。田鼠和许多哺乳动物一样，利用嗅觉来选择配偶。这可能导致个体群体（种群）之间的行为隔离，并最终导致遗传分离（分化）和物种形成。研究人员将记录嗅觉线索如何在接触区发生变化，这是这两种密切相关的田鼠相遇并可能交配的区域。将从整个接触区收集化学剖面数据和遗传数据，然后进行统计比较，以确定模式是否相互镜像；密切的相关性将表明，化学线索和交配偏好是导致遗传差异的原因。研究最近分化的亚种之间的接触区可以揭示物种如何形成并作为不同实体维持的重要信息。此外，该项目将为本科生提供独立研究的机会。外展包括发展适合公立学校学生的教育活动。这个项目将描述加利福尼亚田鼠（Microtus californicus）的两个亚种在选择配偶时使用的嗅觉线索的地理差异。主要目的是确定嗅觉线索的差异是否与亚种之间的遗传分化程度有关。调查人员将分析从两个亚种之间的接触区收集的尿液样本。尿液样本中挥发性和半挥发性分子的化学特征（化学组成和相对丰度）将使用固相微萃取（SPME）和气相色谱-质谱联用技术进行定量分析。克莱恩分析将用于确定化学变化是否反映了环境差异（例如栖息地差异或地理梯度），或者相反，它们是否反映了两种田鼠谱系之间已知的遗传断裂。尿液化学特征的地理差异模式反映了遗传数据，这表明行为上的生殖隔离有助于维持这两种遗传上不同的谱系。

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.