Abstract：
The northern pike Esox lucius is a freshwater fish with low genetic diversity but ecological success throughout the Northern Hemisphere. Here we generate an annotated chromosome-level genome assembly of 941 Mbp in length with 25 chromosome-length scaffolds. We then genotype 47 northern pike from Alaska through New Jersey at a genome-wide scale and characterize a striking decrease in genetic diversity along the sampling range. Individuals west of the North American Continental Divide have substantially higher diversity than those to the east (e.g., Interior Alaska and St. Lawrence River have on average 181K and 64K heterozygous SNPs per individual, or a heterozygous SNP every 5.2 kbp and 14.6 kbp, respectively). Individuals clustered within each population with strong support, with numerous private alleles observed within each population. Evidence for recent population expansion was observed for a Manitoba hatchery and the St. Lawrence population (Tajima\'s D = -1.07 and -1.30, respectively). Several chromosomes have large regions with elevated diversity, including LG24, which holds amhby, the ancestral sex determining gene. As expected amhby was largely male-specific in Alaska and the Yukon and absent southeast to these populations, but we document some amhby(-) males in Alaska and amhby(+) males in the Columbia River, providing evidence for a patchwork of presence of this system in the western region. These results support the theory that northern pike recolonized North America from refugia in Alaska and expanded following deglaciation from west to east, with probable founder effects resulting in loss of both neutral and functional diversity (e.g., amhby).
摘要：
北部梭鱼Esoxlucius是一种淡水鱼，遗传多样性低，但在整个北半球都取得了生态成功。在这里，我们使用25个染色体长度支架生成了一个带注释的长度为941Mbp的染色体水平基因组组装。然后，我们在全基因组范围内对从阿拉斯加到新泽西州的47只北梭鱼进行了基因分型，并表征了沿采样范围的遗传多样性显着下降。北美大陆分界线以西的个人比东部的个人具有更高的多样性(例如，内部阿拉斯加和圣劳伦斯河平均每个个体有181K和64K杂合SNP，或每5.2kbp和14.6kbp的杂合SNP，分别)。每个群体中的个体聚集在强有力的支持下，在每个群体中观察到许多私人等位基因。在曼尼托巴孵化场和圣劳伦斯种群中观察到了最近种群扩张的证据（Tajima的D分别为-1.07和-1.30）。几个染色体有很大的区域，多样性提高，包括持有Amhby的LG24，祖先的性别决定基因.正如预期的那样，在阿拉斯加和育空地区，amhby主要是男性特有的，在这些人群的东南部没有，但是我们记录了阿拉斯加的一些amhby（-）雄性和哥伦比亚河的amhby（）雄性，为该系统在西部地区的存在提供了证据。这些结果支持以下理论：北梭鱼从阿拉斯加的避难所重新定居北美，并在从西向东的冰川消退后扩展，可能的创始人效应导致中性和功能多样性的丧失(例如，amhby）。
