Data from: Historical and anthropogenic factors affecting the population genetic structure of Ontario’s inland lake populations of walleye (Sander vitreus)

Populations existing in formerly glaciated areas often display composite historical and contemporary patterns of genetic structure. For Canadian freshwater fishes, population genetic structure is largely reflective of dispersal from glacial refugia and isolation within drainage basins across a range of scales. Enhancement of sport fisheries via hatchery stocking programs and other means has the potential to alter signatures of natural evolutionary processes. Using 11 microsatellite loci genotyped from 2182 individuals, we analyzed the genetic structure of 46 inland lake walleye (Sander vitreus) populations spanning five major drainage basins within the province of Ontario, Canada. Population genetic analyses coupled with genotype assignment allowed us to; 1) characterize broad and fine scale genetic structure among Ontario walleye populations; and 2) determine if the observed population divergence is primarily due to natural / historical processes or recent anthropogenic events. The partitioning of genetic variation revealed higher genetic divergence among lakes than among drainage basins or proposed ancestries—indicative of relatively high isolation among lakes, study-wide. Walleye genotypes were clustered into three major groups, likely reflective of Missourian, Mississippian, and Atlantic glacial refugial ancestry. Despite detectable genetic signatures indicative of anthropogenic influences, province-wide spatial genetic structure remains consistent with the hypothesis of dispersal from distinct glacial refugia and subsequent isolation of lakes within primary drainage basins. Our results provide a novel example of minimal impacts from fishery enhancement to the broad-scale genetic structure of inland fish populations.

曾受冰川作用影响的区域内的种群，往往兼具历史与当代双重特征的遗传结构模式。针对加拿大淡水鱼类而言，其种群遗传结构在很大程度上反映了从冰期避难所（glacial refugia）扩散，以及不同尺度下流域内种群隔离的过程。通过孵化场育苗放流计划及其他手段开展的游钓渔业增殖活动，有可能改变自然演化过程的遗传印记。本研究基于2182尾个体的11个微卫星位点（microsatellite loci）分型数据，对加拿大安大略省境内覆盖5大主要流域的46个内陆湖大眼梭鲈（*Sander vitreus*）种群开展了遗传结构分析。结合种群遗传分析与基因型归属鉴定，我们实现了两项研究目标：1）刻画安大略省大眼梭鲈种群的大尺度与微尺度遗传结构；2）探明观测到的种群分化主要源于自然/历史过程，还是近期人为活动。遗传变异分区分析结果显示，湖泊间的遗传分化程度高于流域或推定祖先谱系间的分化——这表明本研究范围内的湖泊间存在较高的隔离水平。大眼梭鲈的基因型可聚类为三大类群，这大概率对应密苏里、密西西比及大西洋三大冰期避难所的祖先谱系。尽管可检测到反映人为影响的遗传印记，但全省范围的空间遗传结构仍与“源自不同冰期避难地的扩散，以及随后主要流域内湖泊的隔离”这一假说相符。本研究结果为“渔业增殖活动对内陆鱼类种群的大尺度遗传结构影响极小”提供了全新例证。