Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, and College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
Am J Bot. 2014 Mar;101(3):521-9. doi: 10.3732/ajb.1400043.
Both historical and contemporary microevolutionary processes greatly influence the genetic patterns of East Asian plant endemics, but the spatial and temporal contexts of these processes remain poorly understood. Here, we investigate the relative influences of historical and contemporary gene flow and drift on the population genetic structure of Kirengeshoma palmata, a perennial herb from East China and South Japan.
We used data from nine polymorphic microsatellite loci to assess the levels of genetic diversity, effective population size, and contemporary and historical gene flow for six of the seven known populations.
We found high levels of inbreeding and allelic diversity within populations. Both contemporary and historical migration rates among populations were low, and a test of alternate models of population history strongly favored a model of long-term drift-migration equilibrium. We inferred declines in population size ca. 10,000-100,000 yr ago, but failed to detect recent declines. Bayesian clustering divided K. palmata populations into three genetic clusters, two of which were consistent with a glacial refugium hypothesis for two mountain ranges in East China.
These results suggest that anthropogenic fragmentation has had little effect on the genetic characteristics of Chinese K. palmata. Rather, past decline in population size due to Late Pleistocene climate change as well as restricted pollen and seed dispersal may have contributed to low levels of both historical and contemporary gene flow, resulting in high genetic differentiation between adjacent mountain ranges due to genetic drift and inbreeding.
历史和当代的微观进化过程极大地影响了东亚植物特有种的遗传模式，但这些过程的时空背景仍知之甚少。在这里，我们研究了历史和当代基因流动和漂变对东亚特有种戟叶虾脊兰（Kirengeshoma palmata）种群遗传结构的相对影响，戟叶虾脊兰是一种来自华东和日本南部的多年生草本植物。
我们使用来自九个多态微卫星位点的数据，评估了六个已知种群中的七个种群的遗传多样性、有效种群大小以及当代和历史基因流动水平。
我们发现种群内存在高度的近亲繁殖和等位基因多样性。种群间的当代和历史迁移率都很低，对种群历史替代模型的检验强烈支持长期漂变-迁移平衡的模型。我们推断，种群规模在大约 10000 到 100000 年前就已经下降，但未能检测到最近的下降。贝叶斯聚类将戟叶虾脊兰种群分为三个遗传群，其中两个与中国华东两个山脉的冰川避难所假说一致。
这些结果表明，人为的破碎化对中国戟叶虾脊兰的遗传特征几乎没有影响。相反，由于更新世晚期气候变化导致的种群规模下降，以及有限的花粉和种子传播，可能导致历史和当代基因流动水平都较低，从而导致由于遗传漂变和近亲繁殖，相邻山脉之间的遗传分化较高。
