Dissertation Research: A Hybrid Zone Lens on Rapid Speciation During Refugial Isolation in the Field Vole (Microtus agrestis)

杂交区是天然的实验室，研究人员可以通过它们来识别导致种群分化为不同的、繁殖隔离的物种的变化。这个项目将调查一个杂交区，在那里，两个历史上孤立的田鼠种群现在进行了杂交。研究人员将对杂交区的多个个体进行采样，并确定与新物种形成有关的基因组区域。一名研究生和一些来自不同教育、文化和经济背景的本科生将接受尖端基因技术培训。这项研究还将被用作一门专门为生物科学领域历史上代表性不足的一年级本科生设计的课程中的积极学习工具。田鼠属是研究物种形成过程的模式系统，因为它的多样化比率是其他脊椎动物的60-100倍。田鼠(Microtus Agrestis)内遗传变异的分布在很大程度上受到冰川周期的影响。该物种包括不同的进化谱系，这些进化谱系在最近冰期最大时期的单独冰川避难所中幸存下来，并且高度分化。这项研究将集中在其中两个谱系之间的杂交区，并使用转录组测序来确定它们之间固定的遗传差异。这些基因组区域将作为随后对杂交区内个体进行分析的目标。使用考虑这一样带上个体的遗传组成的基因组倾角分析，研究人员将描述杂交区的变异，揭示显示限制性渗入的基因座。这些基因座将被认为是与生殖隔离相关的候选基因，对一些因素做出反应，如与杂交形式的不同环境相关的选择差异，以及它们之间的遗传不亲和性。这些分析的结果将为冰川避难所隔离驱动物种形成的遗传结构提供概念性和经验性的基础，并为研究其他哺乳动物群体的物种形成提供一套候选基因座。

Hybrid zones are natural laboratories that allow researchers to identify the changes that have caused populations to diverge into different, reproductively isolated species. This project will investigate a hybrid zone where two historically isolated populations of field voles now interbreed. Researchers will sample multiple individuals across the hybrid zone and identify the genomic regions involved in the formation of new species. One graduate student and a number of undergraduate students from diverse educational, cultural, and economic backgrounds will be trained in cutting-edge genetic techniques. This research will also be used as an active learning tool during a course specifically designed for first-year undergraduate students from historically underrepresented groups in the biological sciences. The vole genus, Microtus, is a model system to investigate the process of speciation because it has a diversification rate 60-100 times higher than other vertebrates. The distribution of genetic variation within the field vole (Microtus agrestis) has been heavily shaped by glacial cycles. The species includes distinct evolutionary lineages that survived in separate glacial refugia during recent glacial maxima and are highly differentiated. This research will focus on a hybrid zone between two of these lineages and use transcriptome sequencing to identify fixed genetic differences between them. These genomic regions will serve as targets for subsequent analyses of individuals from across the hybrid zone. Using genomic cline analyses that consider the genetic composition of individuals across this transect, researchers will characterize variation across the hybrid zone revealing loci that show restricted introgression. These loci will be considered candidate genes related to reproductive isolation responding to factors, such as selective differences associated with the differing environments of the hybridizing forms, and genetic incompatibilities between them. The results from these analyses will provide a conceptual and empirical groundwork for the genetic architecture underlying speciation driven by isolation in glacial refugia and provide a set of candidate loci to investigate speciation in other mammalian groups.