Genetic structure and differentiation of the fire salamander Salamandra salamandra at the northern margin of its range in the Carpathians

Amphibian populations occurring at the margin of the species range exhibit lower genetic variation due to strong genetic drift and long-term isolation. Limited mobility and site fidelity together with habitat changes may accelerate genetic processes leading to local extinction. Here, we analyze genetic variation of the fire salamander subspecies Salamandra s. salamandra inhabiting the Outer Carpathian region in Poland, at the northern border of its distribution. Nuclear DNA polymorphism based on 10 microsatellite loci of 380 individuals sampled in 11 populations were analysed to measure gene flow between subpopulations and possible long-term isolation. Mitochondrial DNA control region analysis among 17 individuals representing 13 localities was used to detect the origin of populations which colonized Northern Europe after the last glaciation. Overall, pairwise F ST’s and AMOVA test of ‘among group’ variation showed little differences in the allele frequencies and relatively high local gene flow. However, Bayesian clustering results revealed subtle structuring between eastern and western part of the studied region. Two extreme marginal populations from the Carpathian Piedmont revealed reduced genetic variation which may be attributed to strong influence of genetic drift. Only one mitochondrial DNA haplotype (type IIb) was found in all individuals and suggest that after the Last Glacial Maximum Salamandra salamandra migrated to the North-Western Europe from the single glacial refugium placed in the Balkan Peninsula.

在物种分布范围的边缘地区，两栖动物种群由于强烈的遗传漂变和长期的隔离而表现出较低的遗传多样性。受限于移动能力和对栖息地的忠诚度，加之栖息地变化，可能会加速导致局部灭绝的遗传过程。本研究对栖息于波兰外喀尔巴阡地区的火蜥蜴亚种 Salamandra s. salamandra 的遗传多样性进行了分析，该地区位于其分布的北部边界。通过对380个个体在11个种群中的10个微卫星位点的核DNA多态性进行分析，以衡量亚种群间的基因流和可能的长期隔离。通过对17个代表13个地点的个体的线粒体DNA控制区域进行分析，用于检测在末次冰期后殖民北欧的种群起源。总体而言，成对F ST和AMOVA对‘组间’变异的检验显示等位基因频率差异不大，且本地基因流相对较高。然而，贝叶斯聚类结果显示，研究区域的东西部之间存在微妙的结构。来自喀尔巴阡低地的两个极端边缘种群显示出降低的遗传多样性，这可能是由于遗传漂变的影响强烈。所有个体中只发现了一种线粒体DNA单倍型（IIb型），这表明在末次冰期最大冰期之后，Salamandra salamandra 从位于巴尔干半岛的单个冰川避难所迁移至西北欧洲。