Gao Qing-Bo, Li Yan, Gengji Zhuo-Ma, Gornall Richard J, Wang Jiu-Li, Liu Hai-Rui, Jia Liu-Kun, Chen Shi-Long
Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of SciencesXining, China.
Key Laboratory of Crop Molecular Breeding of Qinghai Province, Northwest Institute of Plateau Biology, Chinese Academy of SciencesXining, China.
Front Plant Sci. 2017 Jul 28;8:1325. doi: 10.3389/fpls.2017.01325. eCollection 2017.
The effects of rapid, recent uplift of the Hengduan Mountains on evolution and diversification of young floristic lineages still remain unclear. Here, we investigate diversification of three closely related species with a distribution restricted to the Hengduan Mountains (HM) and southern Tibet, and comment on their taxonomy based on molecular evidence. Three chloroplast DNA fragments () and the nuclear ribosomal DNA internal transcribed spacer (ITS) were employed to study genetic structure across 104 individuals from 12 populations of , and . Chloroplast DNA (cpDNA) phylogenies revealed two well supported clades, corresponding to and plus . Topology of the ITS phylogeny was largely congruent with that generated from cpDNA haplotypes, but with minor conflicts which might be caused by incomplete lineage sorting. Analyses of molecular variance of both cpDNA and ITS datasets revealed that most variation was held between s.l. (with ) and (92.31% for cpDNA; 69.78% for ITS), suggesting a high degree of genetic divergence between them. Molecular clock analysis based on ITS dataset suggested that the divergence between s.l. and can be dated to 8.50 Ma, probably a result of vicariant allopatric diversification associated with the uplift events of the HM. Vicariance associated with HM uplifts may also have been responsible for infraspecific differentiation in . In contrast, infraspecific differentiation in was most likely triggered by Quaternary glaciations. The much lower levels of gene diversity within populations of compared with could have resulted from both range contractions and human collection on account of its putative medicinal properties. Combining evidence from morphology, geographical distributions and molecular phylogenetic data, we recommend that should be treated as a synonym of which in turn, and based on the same sources of evidence, should be treated as a separate species rather than as a variety of .
横断山脉近期快速隆升对年轻植物谱系的演化和多样化的影响仍不清楚。在此，我们研究了分布局限于横断山脉和藏南地区的三个近缘物种的多样化，并基于分子证据对它们的分类进行评论。采用三个叶绿体DNA片段（）和核糖体DNA内转录间隔区（ITS）研究了来自12个种群的104个个体的遗传结构。叶绿体DNA（cpDNA）系统发育树显示出两个得到充分支持的分支，分别对应于和加上。ITS系统发育树的拓扑结构与cpDNA单倍型产生的拓扑结构基本一致，但存在一些小冲突，可能是由于不完全谱系分选导致的。对cpDNA和ITS数据集的分子方差分析表明，大部分变异存在于广义的（含）和之间（cpDNA为92.31%；ITS为69.78%），表明它们之间存在高度的遗传分化。基于ITS数据集的分子钟分析表明，广义的和之间的分化可追溯到850万年前，这可能是与横断山脉隆升事件相关的替代异域多样化的结果。与横断山脉隆升相关的替代可能也导致了中的种下分化。相比之下，中的种下分化最有可能是由第四纪冰川作用引发的。与相比，种群内较低的基因多样性水平可能是由于其分布范围收缩和因其假定的药用特性而被人类采集所致。综合形态学、地理分布和分子系统发育数据的证据，我们建议应被视为的异名，而基于相同证据来源，应被视为一个独立的物种，而不是的一个变种。
