Evidence of neutral and adaptive genetic divergence between European trout populations sampled along altitudinal gradients

Species with a wide geographical distribution are often composed of distinct subgroups which may be adapted to their local environment. European trout (Salmo trutta species complex) provide an example of such a complex consisting of several genetically and ecologically distinct forms. However, trout populations are strongly influenced by human activities, and it is unclear to what extent neutral and adaptive genetic differences have persisted. We sampled 30 Swiss trout populations from heterogeneous environments along replicated altitudinal gradients in three major European drainages. More than 850 individuals were genotyped at 18 microsatellite loci which included loci diagnostic for evolutionary lineages and candidate markers associated with temperature tolerance, reproductive timing and immune defence. We find that the phylogeographic structure of Swiss trout populations has not been completely erased by stocking. Distinct genetic clusters corresponding to the different drainages cou...地理分布范围广泛的物种往往由多个独特亚群组成，这些亚群或已适应其所在的局部生境。欧洲褐鳟（Salmo trutta物种复合体）便是这类物种复合体的典型范例，其包含多个遗传与生态特征均存在显著差异的类群。然而，鳟鱼种群受人类活动的影响极为强烈，目前仍不清楚中性与适应性遗传差异的留存程度究竟几何。本研究沿欧洲三大主要水系内重复布设的海拔梯度异质生境，采集了30个瑞士鳟鱼种群样本；我们对超过850尾个体的18个微卫星位点（microsatellite loci）进行了基因分型，这些位点涵盖可区分进化支系的诊断性位点，以及与温度耐受、繁殖时机和免疫防御相关的候选标记。研究发现，瑞士鳟鱼种群的系统地理结构并未因人工放流而被完全抹去。对应不同水系的独特遗传聚类……