The origin and accumulation of hybrid incompatibilities in Tigriopus californicus

了解新物种产生的机制是生物学的一个基本目标。分散的种群积累了遗传差异，当种群重新聚集并杂交时，这些差异可能会导致冲突(适合度降低)。这导致了种群的进一步隔离，并最终导致物种形成。模式系统中的物种形成工作集中在性别决定染色体的冲突上，但生命之树上的大量生物缺乏这些染色体。该项目使用一种小型海洋无脊椎动物--桡足类动物，来了解在没有决定性别的染色体的情况下，物种形成背后的遗传冲突是如何在生物体中进化的。通过将已知进化树中的一对种群杂交，这项研究将评估不同类型的冲突(核-核与核-线粒体)是如何随着时间的推移而积累的，以及相同的染色体区域是否会在进化上独立的谱系中进化出冲突。它将通过跟踪基于实验室的大型杂交种群中的遗传变化来评估进化轨迹的重复性，并将确定参与冲突的潜在候选基因。该项目通过探索性染色体的缺乏如何影响物种多样性和杂交的后果，与生物多样性和保护问题有关。它的重点是核-线粒体冲突的进化，这是疾病的重要原因，使这项研究具有潜在的生物医学应用。该项目将培养一名博士后研究员、博士生和众多本科生研究人员。它还将包括与洛杉矶及其周围的不同社区进行外联，包括与太平洋水族馆合作，旨在提高对目前在海洋中发挥作用的进化过程及其重要性的认识。

Understanding the mechanisms by which new species arise is a fundamental goal of biology. Diverging populations accumulate genetic differences that may cause conflicts (reduced fitness) when populations come back together and hybridize. This leads to further isolation of the populations, and, eventually, to speciation. Speciation work in model systems has concentrated on conflicts involving the gender-determining chromosomes, but a great number of organisms across the tree of life lack these chromosomes. This project uses a copepod, a small marine invertebrate, to understand how genetic conflicts underlying speciation evolve in organisms without gender-determing chromosomes. By hybridizing pairs of populations from a known evolutionary tree, the study will assess how different types of conflicts (nuclear-nuclear vs. nuclear-mitochondrial) accumulate over time and whether the same chromosomal regions evolve conflicts in evolutionarily independent lineages. It will assess the repeatability of evolutionary trajectories by tracking genetic changes in large, lab-based hybrid populations and will identify potential candidate genes involved in conflicts.This project relates to issues of biodiversity and conservation by exploring how the lack of sex chromosomes impacts species diversification and consequences of hybridization. Its focus on the evolution of nuclear-mitochondrial conflicts, an important cause of disease, gives this study potential biomedical applications. The project will train a postdoctoral researcher, Ph.D. students, and numerous undergraduate researchers. It will also include outreach to diverse communities in and around Los Angeles, including a collaboration with the Aquarium of the Pacific aimed at promoting awareness of the evolutionary processes currently at work in the ocean and their importance.