中文摘要：

虎耳草属Saxifraga山羊臭组sect.Ciliatae是该属中最大的一个组，共有175种，主要分布在喜马拉雅地区，我国分布有166种，占总种数的95%；其中，112种为中国特有。约80%的种类分布在我国青藏高原和西南地区，是中国喜马拉雅植物成分的代表类群。山羊臭组内物种分化十分显著，分类处理也很困难，该组是否为单系类群，组下的系统发育关系也不清楚，均需进一步验证。本文测定了虎耳草属山羊臭组及其他组33种植物样品的核糖体DNA内转录间隔区ITS序列，并从GenBank调取虎耳草组sect.Saxifraga等组和近缘属唢呐草属Mitella共22种植物的该序列。ITS分析结果表明：（1）所研究的山羊臭组类群聚为单独一支，而且与垫状组sect.Porphyrion、虎耳草组、球茎组sect.Mesogyne和仅在欧洲分布的sect.Cymbalaria和sect.Cotylea等8个组聚成的另一分支构成姊妹群；（2）根据形态特征建立的山羊臭组的3个亚组即唐古拉亚组subsect.Hirculoideae、莲座状亚组subsect.Rosulares和具芽亚组subsect.Gemmiparae各自聚为一支，但是莲座状亚组这一支的支持率较低。同时，山羊臭组的鞭匐枝亚组subsect.Flagellares和subsect.Hemisphaericae的代表类群单独聚为一支，位于具芽亚组类群分支内部而不能成立；（3）唐古拉亚组和莲座状亚组又聚为一亚分支与具芽亚组构成姊妹群，而且具芽亚组最早从山羊臭组这一支中分化出来。我们的研究还发现山羊臭组内种间形态分化较大，而ITS碱基变异较小，这可能是山羊臭组类群在青藏高原及毗邻地区的高山环境下物种快速分化的结果。

英文摘要：

The largest section of the genus Saxifraga （Saxifragaceae）, sect. Ciliatae, consists of 175 morphologically diverse species. This section is mainly distributed in the Qinghai-Tibetan Plateau and adjacent regions of southwest China and more than 80% of the total number of species are endemic to this region. It remains unknown whether this section is monophyletic and up to now no study has been conducted on the infra-sectional phylogeny. In this study, ITS sequences of the nuclear ribosomal DNA were firstly determined for 33 species mainly from this section and related sections. We further downloaded the corresponding sequences of the same DNA region for the other 22 species of Saxifraga and Mitella from GenBank. All sequences were together used to construct the phylogenetic trees. The main implications of the phylogenetic analyses include： （1） sect. Ciliatae, as traditionally defined, constitutes as a monophyletic clade and its sister group is a well supported clade that includes species from 8 sections such as sect. Porphyrion, sect. Saxifraga and sect. Mesogyne; （2） three morphological subsections, i.e., subsect. Gemmiparae, subsect. Hirculoideae and subsect. Rosulares were tentatively recovered despite the relatively low statistic bootstrap support for the last one; however, subsect. Flagellares and subsect. Hemisphaericae were not recognized as separate entities, and nested within subsect. Gemmiparae; （3） subsect. Hirculoideae and subsect. Rosulares clustered together as sister subclades while subsect. Gemrniparae diverged early. In addition, our results suggest that the paired variation of ITS sequences in sect. Ciliatae is relatively low between the sampled species in spite of their diverse morphology. It is suggested that such a scenario may mirror rapid speciation in this section that probably trigged by the uplifts of the Qinghai-Tibetan Plateau and the extensive selection pressure under the alpine environments.