Intraspecific biodiversity and speciation in Atlantic Canadian fishes

物种如何形成是生物学中的一个关键问题。一种理论提出物种形成是由生态驱动的——食物或栖息地使用的差异导致种群的一部分成为生殖隔离，形成新的物种。生态物种形成对鱼类来说可能很重要，因为它们的环境可能缺乏其他物种形成理论所援引的物理障碍。我的研究考察了两种正在经历生态物种形成的鱼类，但对它如何发生的概念提出了挑战。湖中的彩虹鱼有专门吃浮游生物的小身体，但在少数湖泊中，也有专门吃鱼的大身体。小胡瓜和大胡瓜在繁殖上是隔离的，但这是如何发展起来的是个谜，因为它们是在夜间重叠的地点和时间传播卵子和精子的。两种形式的三刺鱼，白刺鱼和普通刺鱼，共同出现在新斯科舍省。雄性白棘鱼和普通棘鱼在颜色和繁殖行为上都不同，并且在繁殖上是隔离的，但实验室研究表明它们可以杂交。它们可能是不同的物种，但它们没有已知的生态差异。我将通过研究这些鱼类的基因组如何分化来研究物种形成是如何发生的，并将这些信息与生态特征联系起来。我将对白棘鱼和普通棘鱼的整个基因组进行测序，并使用相关方法扫描胡瓜鱼的基因组。我将研究鱼类携带的寄生虫，因为寄生虫反映了猎物的选择、栖息地和与捕食者的接触，因此提供了生态学的线索。我将研究与抵抗寄生虫有关的基因，因为这些也反映了生态适应，因为它们也影响配偶选择，因此可能与物种形成有关。在熔炼中，我将使用化学痕迹（稳定同位素）来研究摄食行为。在这两个物种中，我将研究身体形态的细节，作为生态分化的进一步线索。基因组数据将揭示，尽管存在一些杂交，但与分化有关的基因的组织方式是否可能使分化得以发展。我们可能会了解，特别是在棘鱼身上，究竟哪些基因对物种形成最重要。在胡瓜鱼和棘鱼中，基因组数据还将告诉我们，不同位置的表型平行分化（小与大、白与普通）是否发生了涉及基因组相同变化的情况。其他数据将为棘鱼和胡氏鱼分化的生态基础提供许多线索。这项研究将促进对生态物种形成如何发生的认识，特别是在鱼类中。它将有助于了解加拿大的生物多样性，并将为管理和保护措施提供信息。两名博士研究生、一名硕士研究生和五名本科生将接受基因组和生态分析先进方法的培训。

How species form is a key question in biology. One theory proposes that speciation is driven by ecology - differences in food or habitat use lead parts of a population to become reproductively isolated, forming new species. Ecological speciation may be important for fishes, because their environments may lack physical barriers invoked in other theories of how speciation occurs. My research examines two fishes that are undergoing ecological speciation, yet challenge notions of how it can occur. Rainbow Smelt in lakes have small bodies specialized for eating plankton, but in a few lakes, a Large' form, specialized for eating fish, also occurs. Small and Large smelt are reproductively isolated, but how this has developed is a mystery, given that they breed by spreading eggs and sperm at night in places and times that overlap. Two forms of Threespine Stickleback, White' and Common', co-occur in Nova Scotia. Male White and Common sticklebacks differ in colour and breeding behaviour, and are reproductively isolated, but lab studies show they can interbreed. They may be different species, but they have no known ecological differences.I will investigate how speciation is occurring in these fishes by examining how their genomes have diverged, and linking that information to ecological traits. I will sequence entire genomes of White and Common sticklebacks, and scan the genomes of smelt using a related method. I will examine the parasites the fish carry, because parasites reflect prey choice, habitat, and predator exposure, and so offer clues about ecology. I will examine genes involved in fighting off parasites, because these too reflect ecological adaptations, and because they also influence mate choice, and so may be involved in species formation. In smelt, I will use chemical traces (stable isotopes) to investigate feeding behaviour. In both species, I will examine details of body form as further clues about ecological divergence.The genome data will reveal whether genes involved in divergence are organized in ways that might enable divergence to develop despite some interbreeding. We may learn, particularly in stickleback, exactly which genes are most important for speciation. In both smelt and stickleback, the genomic data will also tell us whether parallel divergence in phenotype (Small vs. Large and White vs. Common) in different locations has occurred involving the same changes in the genome. The other data will provide many clues about the ecological basis of divergence in stickleback and smelt. This research will advance knowledge of how ecological speciation can occur, particularly in fishes. It will contribute to knowledge of Canadian biodiversity, and for smelt, will provide information that may inform management and conservation measures. Two PhD students, one MSc student, and five undergraduate students will be trained in advanced methods of genomic and ecological analyses.