Schönswetter Peter, Schneeweiss Gerald M
Institute of Botany University of Innsbruck Innsbruck Austria.
Department of Botany and Biodiversity Research University of Vienna Vienna Austria.
Ecol Evol. 2019 Mar 7;9(7):4078-4086. doi: 10.1002/ece3.5037. eCollection 2019 Apr.
Temperate mountain ranges such as the European Alps have been strongly affected by the Pleistocene glaciations. Glacial advances forced biota into refugia, which were situated either at the periphery of mountain ranges or in their interior. Whereas in the Alps peripheral refugia have been repeatedly and congruently identified, support for the latter scenario, termed "nunatak hypothesis," is still limited and no general pattern is recognizable yet. Here, we test the hypothesis of nunatak survival for species growing in the high alpine to subnival zones on siliceous substrate using the cushion plant (Primulaceae), endemic to the European Alps, as our model species. To this end, we analyzed AFLP and plastid DNA sequence data obtained from a dense and range-wide sampling. Both AFLPs and plastid sequence data identified the southwestern-most population as the most divergent one. AFLP data did not allow for discrimination of interior and peripheral populations, but rather identified two to three longitudinally separated major gene pools. In contrast, in the eastern half of the Alps several plastid haplotypes of regional or local distribution in interior ranges-the Alpine periphery mostly harbored a widespread haplotype-were indicative for the presence of interior refugia. Together with evidence from other Alpine plant species, this study shows that in the eastern Alps silicicolous species of open habitats in the alpine and subnival zone survived, also or exclusively so, in interior refugia. As the corresponding genetic structure may be lost in mostly nuclear-derived, rapidly homogenizing marker systems such as AFLPs or RAD sequencing tags, markers not prone to homogenization, as is the case for plastid sequences (Sanger-sequenced or extracted from an NGS data set) will continue to be important for detecting older, biogeographically relevant patterns.
诸如欧洲阿尔卑斯山这样的温带山脉受到更新世冰川作用的强烈影响。冰川推进迫使生物群进入避难所，这些避难所位于山脉边缘或内部。虽然在阿尔卑斯山，边缘避难所已被反复且一致地确定，但对后一种情况（即“冰原假说”）的支持仍然有限，尚未识别出一般模式。在这里，我们以欧洲阿尔卑斯山特有的垫状植物（报春花科）为模式物种，检验在硅质基质上生长于高山区至亚雪山区的物种的冰原存活假说。为此，我们分析了从密集且涵盖整个分布范围的采样中获得的AFLP和质体DNA序列数据。AFLP和质体序列数据均将最西南端的种群确定为差异最大的种群。AFLP数据无法区分内部种群和边缘种群，而是识别出两到三个纵向分离的主要基因库。相比之下，在阿尔卑斯山的东半部，内部山脉中几种区域或局部分布的质体单倍型（阿尔卑斯山边缘大多含有一种广泛分布的单倍型）表明存在内部避难所。与来自其他阿尔卑斯植物物种的证据一起，这项研究表明，在阿尔卑斯山的东部，高山和亚雪山区开阔生境的硅质植物物种在内部避难所中存活，也可能仅在内部避难所中存活。由于相应的遗传结构可能会在大多由核衍生的、迅速同质化的标记系统（如AFLP或RAD测序标签）中丢失，不易同质化的标记（如质体序列，通过桑格测序或从NGS数据集中提取）对于检测更古老的、与生物地理学相关的模式将继续至关重要。
