Data from: Present-day genetic structure of Atlantic salmon (Salmo salar) in Icelandic rivers and ice-cap retreat models

Due to an improved understanding of past climatological conditions, it has now become possible to study the potential concordance between former climatological models and present-day genetic structure. Genetic variability was assessed in 26 samples from different rivers of Atlantic salmon in Iceland (total of 2,352 individuals), using 15 microsatellite loci. F-statistics revealed significant differences between the majority of the populations that were sampled. Bayesian cluster analyses using both prior information and no prior information on sampling location revealed the presence of two distinguishable genetic pools - namely, the Northern (Group 1) and Southern (Group 2) regions of Iceland. Furthermore, the random permutation of different allele sizes among allelic states revealed a significant mutational component to the genetic differentiation at four microsatellite loci (SsaD144, Ssa171, SSsp2201 and SsaF3), and supported the proposition of a historical origin behind the observed variation. The estimated time of divergence, using two different ABC methods, suggested that the observed genetic pattern originated from between the Last Glacial Maximum to the Younger Dryas, which serves as additional evidence of the relative immaturity of Icelandic fish populations, on account of the re-colonisation of this young environment following the Last Glacial Maximum. Additional analyses suggested the presence of several genetic entities which were likely to originate from the original groups detected.

随着对古气候条件认知的不断深化，当前已可开展过往气候模型与当代遗传结构间潜在一致性的相关研究。本研究以15个微卫星位点（microsatellite loci）为分子标记，对采自冰岛不同河流的26份大西洋鲑鱼样本（共计2352个个体）的遗传变异水平进行了评估。F统计量（F-statistics）分析结果显示，绝大多数采样种群间存在显著的遗传分化。分别引入采样地点先验信息与不使用先验信息开展的贝叶斯聚类分析（Bayesian cluster analyses），均揭示了两个可区分的遗传基因库：即冰岛北部种群（组1）与南部种群（组2）。此外，对不同等位基因状态间的等位基因长度进行随机置换分析后发现，4个微卫星位点（SsaD144、Ssa171、SSsp2201及SsaF3）的遗传分化存在显著的突变贡献，这为观测到的遗传变异具有历史起源这一假说提供了有力支持。采用两种不同的近似贝叶斯计算（Approximate Bayesian Computation，ABC）方法估算的分化时间显示，本次观测到的遗传模式形成于末次盛冰期至新仙女木事件之间。鉴于冰岛在末次盛冰期后才完成对该年轻生境的重新殖民，这一结果进一步佐证了冰岛鱼类种群相对不成熟的结论。后续补充分析显示，本研究还检测到若干遗传类群，它们大概率源自本次研究中发现的两个原始种群组。