Data from: Southern montane populations did not contribute to the recolonization of West Siberian Plain by Siberian larch (Larix sibirica): a range-wide analysis of cytoplasmic markers

While many species were confined to southern latitudes during the last glaciations, there has lately been mounting evidence that some of the most cold-tolerant species were actually able to survive close to the ice sheets. The contribution of these higher latitude outposts to the main recolonization thrust remains, however, untested. In the present study, we use the first range-wide survey of genetic diversity at cytoplasmic markers in Siberian larch (Larix sibirica; four mitochondrial (mt) DNA loci and five chloroplast (cp) DNA SSR loci) to (i) assess the relative contributions of southern and central areas to the current L. sibirica distribution range; and (ii) date the last major population expansion in both L. sibirica and adjacent Larix species. The geographic distribution of cpDNA variation was uninformative, but that of mitotypes clearly indicates that the southernmost populations, located in Mongolia and the Tien-Shan and Sayan Mountain ranges, had a very limited contribution to the current populations of the central and northern parts of the range. It also suggests that the contribution of the high latitude cryptic refugia was geographically limited and that most of the current West Siberian Plain larch populations likely originated in the foothills of the Sayan Mountains. Interestingly, the main population expansion detected through Approximate Bayesian Computation (ABC) in all four larch species investigated here pre-dates the LGM, with a mode in a range of 220 000–1 340 000 years BP. Hence, L. sibirica, like other major conifer species of the boreal forest, was strongly affected by climatic events pre-dating the Last Glacial Maximum.

末次冰期（Last Glaciations）期间，多数物种被局限于南部纬度区域，但近年来越来越多的证据表明，部分最耐寒的物种实际上能够在冰盖附近存活。
然而，这些高纬度避难所种群对区域主要再定植过程的贡献，迄今仍未得到验证。
本研究开展了首个针对西伯利亚落叶松（Larix sibirica）细胞质分子标记的全分布区遗传多样性调查，共纳入4个线粒体（mt）DNA位点与5个叶绿体（cp）DNA SSR（Simple Sequence Repeat，简单序列重复）位点，以此实现两大研究目标：（i）评估南部与中部种群对西伯利亚落叶松当前分布范围的相对贡献；（ii）估算西伯利亚落叶松及其近缘落叶松物种的末次大规模种群扩张时间。
叶绿体DNA变异的地理分布未提供有效信息，但线粒体单倍型的分布则清晰表明：分布于蒙古国、天山山脉与萨彦岭的最南部种群，对当前分布区中部与北部种群的贡献极为有限。
该结果同时表明，高纬度隐秘避难所的种群贡献具有地理局限性，当前绝大多数西西伯利亚平原的落叶松种群，其起源大概率为萨彦岭山麓地带。
值得注意的是，本研究通过近似贝叶斯计算（ABC）在所有4个被调查落叶松物种中检测到的主要种群扩张事件，均早于末次冰盛期（Last Glacial Maximum，LGM），其峰值时间分布区间为220000至1340000年前（BP，即Before Present）。
因此，与北方针叶林的其他主要针叶树种一样，西伯利亚落叶松同样受到了末次冰盛期之前的气候事件的强烈影响。