Ecological genomics of anadromous migrations in a changing Arctic

鲑鱼是加拿大北部的主要水生物种，它们支撑着当地的经济发展和粮食安全。预测对快速变化的北极可能做出的适应性反应是一个优先事项。逆流(即淡水和咸水之间的迁徙)是北方鲑鱼生态成功和经济重要性的一个关键特征，因为逆流生物体型更大，质量更高。但与咸水相比，不断变化的气候增加了新鲜鱼类的生产力，因此有利于非滨水生物。这可能对自给自足和新兴商业渔业产生毁灭性影响。我们的工作将使用尖端基因组工具来记录可能推动适应不断变化的北极的遗传多样性，并将描述两种具有重要经济意义的北方鲑鱼顺水迁徙的遗传基础：目标一：预测北极地区对不断变化的北极的适应北极赤潮是世界上分布在最北端的淡水鱼，也是努纳武特和努纳维克捕捞最多的鱼类。这一目标的工作将利用最近测序的北极Char基因组，使用全基因组重新测序的方法来解决对预测物种对变化的北极的反应至关重要的两个问题。首先，我们将记录加拿大北极冰川后重新殖民对范围基因组多样性的影响。我们将建立历史人口学模型，绘制有利等位基因和有害等位基因的分布图。其次，我们将用北极查尔种群的样本来确定滨水迁徙的基因组基础，在北极查尔种群中，顺水和非顺水个体共存，从而显著有助于我们预测这一特征对气候变化的反应。目的II：鲑湖中的逆流迁徙通常被认为是淡水专有物种。然而，在北极的两个地点，已经观察到了顺流而下的个体。这些种群提供了一个绝佳的机会来理解像失控这样的复杂特征的基因基础是如何保持的。首先，我们将使用声学遥测来跟踪鲑鱼湖的海洋运动。然后，我们将使用RNAseq比较在野外捕获的顺水和非顺水个体，以表征与顺水相关的遗传和功能差异。最后，我们将在水产养殖环境中实验性地将来自淡水限制种群的湖鲑鱼暴露在咸水中，并进行RNAseq以了解耐受咸水的能力是如何保持的。我们的工作将大大提高我们预测北方主要水生资源对快速变化的北极的反应的能力，并将培训4名研究生和至少3名本科生，他们将获得北极野外生态学、生物信息学和基因组学方面的各种市场技能。

Salmonids are dominant aquatic species in Canada's North and they underpin local economic development and food security. Predicting possible adaptive responses to a rapidly changing Arctic is a priority. Anadromy (i.e. migrations between fresh- and saltwater) is a key trait underlying the ecological success and the economic importance of northern salmonids because anadromous individuals are larger and higher-quality. But a changing climate increases the productivity of fresh- compared to saltwater, thus favoring non-anadromous individuals. This could have devastating impacts on subsistence and emerging commercial fisheries. Our work will use cutting-edge genomic tools to document extent genetic diversity likely to fuel adaptation to a changing Arctic, and will describe the genetic basis of anadromous migrations in two Northern salmonids of economic importance: Objective I: Predicting adaptation to a changing Arctic in Arctic Char Arctic Char are the freshwater fish with the northernmost distribution in the world and they are the most harvested fish in Nunavut and Nunavik. Work in this objective will leverage the recently sequenced Arctic Char genome to use a whole-genome resequencing approach to address two questions crucial to predicting the species response to a changing Arctic. First, we will document the impacts of post-glacial recolonization of the Canadian Arctic on extent genomic diversity. We will model historical demography and map the distribution of both putatively advantageous and deleterious alleles. Second, we will identify the genomic underpinnings of anadromous migrations with samples from Arctic Char populations where both anadromous and non-anadromous individuals co-exist in sympatry, thus significantly contributing to our ability to predict response of this trait to climate change. Objective II: Anadromous migrations in Lake Trout Lake Trout are generally regarded as a freshwater specialist species. In two Arctic locations, however, anadromous individuals have been observed. These populations offer an exceptional opportunity to understand how the genetic underpinnings of a complex trait like anadromy have been maintained. First, we will track the marine movements of Lake Trout using acoustic telemetry. We will then compare anadromous and non-anadromous individuals captured in the wild using RNAseq to characterize genetic and functional differences associated with anadromy. Finally, we will experimentally expose Lake Trout derived from freshwater-restricted populations to saltwater in an aquaculture setting and perform RNAseq to understand how the capacity to tolerate saltwater is maintained. Our work will contribute significantly to our ability to predict the response of key northern aquatic resources to a rapidly changing Arctic and will train 4 graduate and at least 3 undergraduate students who will acquire diverse marketable skills in Arctic field ecology, bioinformatics, and genomics.