DISSERTATION RESEARCH: Examining the role of reinforcement in driving genomic divergence between and within species in darters

新技术使研究人员能够快速获得不同物种的大量基因组信息，从而彻底改变了物种如何产生的研究。这项技术已被用于确定不同环境中出现的种群之间的基因组差异区域，这可能对防止密切相关的物种形成杂交种很重要。这个项目使用类似的方法来比较不同的种群，这些种群是否与它们可以杂交的近亲共存。该项目的重点是橙黄镖鲈。 该项目将确定与偏好与自己的物种交配相关的基因组区域，并测试是否在所有共存的密切相关的物种中发生相同的遗传变化，或者是否每次都发生独特的遗传变化。从这项研究中获得的数据将为生物群落的差异如何推动物种多样性提供重要的见解。该项目将为本科生提供宝贵的研究机会和教材。此外，这项研究的结果将用于教育社区成员了解当地本地鱼类的生物学。强化起着至关重要的作用，在完成过程中的物种形成后，二次接触，通过增加前合子之间的隔离，产生不适合的杂交种。由于强化直接选择同域种群中交配性状的分歧，它也可能偶然导致物种内种群之间的行为隔离（即，级联增强）。这个项目的目的是开发基因组工具，以研究如何加强影响全基因组的分歧之间和两组镖（orangethroat镖分支Ceasia和彩虹镖Caerurophe）内的物种。以前的研究提供了强有力的行为证据，即强化是驱动同域Ceasia和E之间的行为隔离。caeruplasty，并随后导致级联强化和Ceasia内物种之间的行为隔离。本研究将研究经历强化的物种之间的基因组差异，并调查物种之间的这种差异是否会偶然导致物种内种群（或最近分化的物种）之间的基因组差异。具体而言，下一代测序将用于（1）鉴定Ceasia和E.（2）确定Ceasia和E.通过对杂种和回交个体进行基因分型，以及（3）进行基因组扫描，比较同域和异域的Ceasia多个群体之间关于E. caeruplasty，以确定高度分化的离群位点之间的同域和异域人群可能与前合子隔离。

The study of how species arise has been revolutionized by new technologies that allow researchers to get large amounts of genomic information from different species quickly. This technology has been used to identify areas of the genome that differ between populations occurring in different environments, and which may be important in preventing closely-related species from forming hybrids. This project uses similar methods to compare populations that differ in whether they co-exist with a close relative with which they can hybridize. The project focuses on orangethroat darter fish. The project will identify genome areas associated with a preference to mate with one's own species, and test whether the same genetic changes happen in all closely-related species that coexist, or whether unique genetic changes occur each time. Data obtained from this study will provide critical insight into how differences in biological communities can drive species diversity. This project will provide valuable research opportunities and teaching materials for undergraduate students. Furthermore, the results of this research will be used to educate community members about the biology of local native fish species. Reinforcement plays a critical role in finalizing the process of speciation after secondary contact by increasing prezygotic isolation between taxa that produce unfit hybrids. As reinforcement directly selects for divergence in mating traits in sympatric populations, it can also incidentally lead to behavioral isolation among populations within species (i.e., cascade reinforcement). The objective of this project is to develop genomic tools to examine how reinforcement affects genome-wide divergence between and within species in two groups of darters (the orangethroat darter clade Ceasia and the rainbow darter Etheostoma caeruleum). Previous studies have provided strong behavioral evidence that reinforcement is driving behavioral isolation between sympatric Ceasia and E. caeruleum, and subsequently causing cascade reinforcement and behavioral isolation between species within Ceasia. This research will examine genomic divergence between species experiencing reinforcement, and investigate whether this divergence between species may incidentally be causing genomic divergence among populations within species (or among recently diverged species). Specifically, Next-Generation Sequencing will be utilized to (1) identify any differences in chromosomal structure between Ceasia and E. caeruleum that may be contributing to postzygotic isolation and facilitating reinforcement, (2) identify loci responsible for postzygotic isolation between Ceasia and E. caeruleum by genotyping hybrid and backcross individuals, and (3) conduct genome scans that compare genetic differentiation between multiple populations of Ceasia that are sympatric and allopatric with respect to E. caeruleum, in order to identify highly differentiated outlier loci between sympatric and allopatric populations that are likely associated with prezygotic isolation.