Data from: Genetic drift linked to heterogeneous landscape and ecological specialization drives diversification in the Alpine endemic columbine Aquilegia thalictrifolia

The European Alpine system is an extensive mountain range, whose heterogeneous landscape together with Quaternary climatic oscillations significantly affected organismal diversity and distribution in Europe. The model genus Aquilegia represents a textbook example of a rapid and recent radiation through the Northern hemisphere, with the majority of the European taxa occuring in the Alpine system. However, the processes governing genetic differentiation of the genus in this complex geographic area are still widely unexplored. In this work, we used nine microsatellite loci to study the genetic structure and diversity of 11 populations of Aquilegia thalictrifolia Schott & Kotschy, an alpine taxon characterized by a marked ecological specificity. We found that, despite the endemic and fragmented distribution, A. thalictrifolia has overall high levels of heterozigosity, which is consistent to the substantial inbreeding depression that characterizes the genus. Strong spatial genetic structuring of populations suggests a historical prevalence of genetic drift over gene flow, with natural barriers and ecological niche hindering migration. An analytical comparison of fixation (GST) and population differentiation (Dest) indexes allowed us to infer hypotheses of the post-glacial history and more recent demographic events that have influenced the genetics of the species. Overall, our results indicate allopatry as a major force of differentiation in the European scenario, likely to underlie the development of taxonomic boundaries in a broader geographic context. This adds to previous notions on the primary evolutionary forces shaping the Aquilegia radiation in Europe.欧洲阿尔卑斯山系（European Alpine system）是一片广袤的山系，其复杂多样的地貌与第四纪气候震荡（Quaternary climatic oscillations），显著影响了欧洲境内的生物多样性与物种分布格局。耧斗菜属（Aquilegia）是北半球近期快速辐射演化的经典范例，其多数欧洲类群均分布于阿尔卑斯山系范围内。然而，驱动该属在这片复杂地理区域内遗传分化的过程，迄今仍未得到充分研究。本研究利用9个微卫星位点（microsatellite loci），对11个种群的唐松草叶耧斗菜（Aquilegia thalictrifolia Schott & Kotschy）——一种具有显著生态特异性的高山类群——的遗传结构与多样性展开研究。研究发现，尽管唐松草叶耧斗菜呈特有且碎片化的分布格局，但其整体杂合度（heterozygosity）水平较高，这与该属典型的近交衰退（inbreeding depression）特征相符。种群显著的空间遗传结构表明，历史上遗传漂变相较于基因流占据主导地位，自然屏障与生态位特征阻碍了种群间的基因迁移。对固定指数（fixation index, GST）与种群分化指数（population differentiation index, Dest）的分析比较，使我们得以推断影响该物种种群遗传特征的冰期后历史与近期种群动态事件的相关假说。总体而言，本研究结果表明，地理隔离（allopatry）是欧洲区域内物种分化的主要驱动力，这一结论或可解释更大地理尺度下分类学界限的形成机制。该研究结果补充了此前关于驱动欧洲耧斗菜属辐射演化的主要进化动力的认知。