Hybridization, sex determination, and evolutionary diversification in freshwater fishes

淡水鱼类的杂交、性别决定和进化多样化

• 批准号: RGPIN-2020-05021
• 负责人: Mandeville, Elizabeth
• 金额: $ 2.4万
• 依托单位: University of Guelph
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=740353
• 关键词: Hybridization; sex; determination; evolutionary; diversification

Hybridization, when closely related species produce offspring, has been an integral part of evolutionary diversification, and is deeply entwined in the evolutionary history of many lineages of plants and animals. While hybridization can promote evolutionary diversification through providing raw material for the rapid formation of new species and promoting novel traits, hybridization can also inhibit diversification by homogenizing newly differentiated lineages. My research focuses on describing how evolutionary processes, specifically hybridization, influence the evolution and maintenance of biodiversity. One relatively unexplored area is describing exactly how major genomic rearrangements, including evolutionary turnover in sex determination mechanisms, influences hybridization outcomes. Sex determining regions of the genome are believed to have been crucially important in the evolution of new species and maintenance of reproductive isolation between nascent species, but our understanding of genetic mechanisms of sex determination is still incomplete in many taxa, including fish. Fish have extremely variable sex determination mechanisms that include genetic sex determination with differentiated sex chromosomes, genetic sex determination without differentiated sex chromosomes (including polygenic systems), individuals that are hermaphrodites, and environmental sex determination. Sex determination systems in fish are known to differ within closely related groups of fish, and even across populations within a species. I hypothesize that sex determination mechanisms have shaped outcomes of hybridization in two groups of freshwater fishes in North America, specifically Catostomus suckers and Chrosomus dace. Both of these evolutionary lineages have been influenced by hybridization, but in very different ways. Catostomus suckers are part of a species-rich, phenotypically diverse, and geographically widespread family (Catostomidae) that arose from an allotetraploid hybrid ancestor approximately 50 million years ago, and extant Catostomus species hybridize extensively. In contrast, Chrosomus dace present a much different outcome of a hybridization event believed to have occurred between C. eos and C. neogaeus approximately 50,000 years ago, namely the origin of gynogenesis, a rare phenomenon where unisexual, asexual hybrid lineages reproduce clonally. I will use genomic data to describe the genetic basis of sex determination for both Catostomus and Chrosomus species, and identify how genetic sex determination mechanisms have shaped outcomes of both historical and contemporary hybridization in these lineages. By explicitly linking sex determination with hybridization outcomes for these two lineages, I will advance our understanding of how sex-determining loci might be more broadly implicated in evolutionary diversification and the maintenance of biodiversity.

杂交，当密切相关的物种产生后代，一直是进化多样化的一个组成部分，并深深地嵌入在许多动植物谱系的进化史中。虽然杂交可以通过为新物种的快速形成提供原材料和促进新特征来促进进化多样化，但杂交也可以通过重新分化的谱系来抑制多样化。我的研究重点是描述进化过程，特别是杂交，如何影响生物多样性的进化和维持。一个相对未探索的领域是描述主要的基因组重排，包括性别决定机制的进化周转，如何影响杂交结果。基因组的性别决定区域被认为在新物种的进化和维持新生物种之间的生殖隔离中至关重要，但我们对性别决定的遗传机制的理解在许多分类群中仍然是不完整的，包括鱼类。鱼类具有极其多变的性别决定机制，包括具有分化的性染色体的遗传性别决定、没有分化的性染色体的遗传性别决定（包括多基因系统）、雌雄同体的个体和环境性别决定。已知鱼类的性别决定系统在密切相关的鱼类群体中是不同的，甚至在一个物种的种群中也是不同的。我推测，性别决定机制已经形成了杂交的结果在两组淡水鱼在北美，特别是Catostomus吸盘和Dace。这两种进化谱系都受到了杂交的影响，但方式截然不同。Catostomus吸盘是一个物种丰富，表型多样，地理分布广泛的家庭（Catostomidae）的一部分，从一个异源四倍体杂交祖先大约50万年前，和现存的Catostomus物种广泛杂交。相比之下，Dace的杂交结果与C. eos和C.大约50，000年前，即雌核发育的起源，这是一种罕见的现象，单性，无性杂交谱系克隆繁殖。我将使用基因组数据来描述Catostomus和Chrosomus物种性别决定的遗传基础，并确定遗传性别决定机制如何塑造这些谱系中历史和当代杂交的结果。通过明确地将性别决定与这两个谱系的杂交结果联系起来，我将推进我们对性别决定基因座如何更广泛地参与进化多样性和生物多样性维持的理解。