中文摘要：

草本植物由于较短的生活周期以及对环境变化的敏感性,可能会更好地揭示第四纪冰期以来植物居群变化的历史过程。分子亲缘地理学研究是揭示动植物居群历史的有力工具,但到目前为止对青藏高原草本植物的分子亲缘地理学研究几乎是空白。因此,本文选择在青藏高原及邻近地区生长的一年生高山草本植物条纹狭蕊龙胆为研究对象,进行了13个居群155个个体的叶绿体基因组（cpDNA）非编码片段trnH（GUG）-psbA基因间区序列变异检测,共发现7种单倍型,其中单倍型Hap A是分布最广的,而单倍型Hap E、Hap F和Hap G是拥有的居群所特有的。青藏高原东北部、东部及邻近地区的每个居群拥有的单倍型非常单一,而高原东南部横断山区的单倍型分布很集中,遗传多样性也相对较高。分子变异分析（AMOVA）结果表明整个分布区条纹狭蕊龙胆的遗传变异主要存在于居群间（73.05%）,且居群间的遗传分化很高（GST=0.805,FST=0.731,NST=0.859）,有着显著的亲缘地理学结构（NST〉GST,P〈0.05）和较低的居群间的平均基因流（Nm=0.184）。结合巢式支系法分析（NCA）,根据本文的研究结果推测青藏高原东南部横断山区是该植物第四纪冰期时可能的避难所,而且在间冰期或冰期后,伴随着异域片段化和过去片段化从避难所发生范围扩张而形成当前单倍型及居群的分布格局。

英文摘要：

Herbaceous plants have a short life cycle and are sensitive to environmental changes. Thus, they may serve as good models to elucidate historical processes of plant populations since Quaternary glaciations. Molecular phylogeographic analysis is a powerful tool to reveal the population history of plants and animals. To understand the geographic history of alpine plants in the Qinghai-Tibet Plateau, which is still poorly known, we surveyed sequence variation of the chloroplast DNA （cpDNA） noncoding fragment trnH （GUG）-psbA intergenic spacer throughout the range of Metagentiana striata （Maxim.） T. N. Ho, S. W. Liu ＆ S. L, Chen, an annual and herbaceous alpine plant in the Qinghai-Tibet Plateau and adjacent areas. Seven haplotypes were detected by analyzing 155 individuals from 13 populations of this species. One haplotype （A） was common and widespread, and three haplotypes （E, F and G） were unique in their populations. The center of haplotype diversity is located in the Hengduan Mountains of southeastern Qinghai-Tibet Plateau, with 2-3 haplotypes present in each of four populations. In populations from the northeastern and eastern Qinghai-Tibet Plateau as well as from adjacent regions, however, only a single haplotype was found in each population, with different populations having different haplotypes. An analysis of molecular variance （AMOVA） for populations of M. striata showed that the genetic variation mainly resided among populations （73.05%）, and the estimates of interpopulation differentiation were very high （GST=0.805, FST=0.731, NST=0.859）. Further, a significant phylogeographic structure was present （NST 〉 GST, P〈0.05） whereas the value of average gene flow was low （Nm=0.184） in the entire geographical range. Along with the nested clade analysis （NCA）, our results suggested that the Hengduan Mountains of southeastern Qinghai-Tibet Plateau served as a possible refugium during the Quaternary glaciations, and the interglacial or postglacial range expansion by