【作者】 马雅真；

【导师】 王玉金；

【作者基本信息】 兰州大学 ， 生态学， 2013， 硕士

【摘要】 已有研究证据表明,青藏高原的多次隆升与第四纪气候的反复波动造成了高原及其邻近地区大量的异域物种分化,使得该地区具有极为丰富的物种多样性。然而,由于自然生态系统中的建群物种可以更加快速地适应气候以及其它生境条件的变化,在一些地质历史事件的间隔期或者间冰期,这些类群可能会发生较为明显的分布变迁,进而减弱之前的异域分化。本论文以青藏高原广布灌木金露梅属植物为研究对象,进行谱系地理学研究,进而验证上述假设。该属植物包含两个物种：金露梅和银露梅,二者在形态上的差异主要为前者花瓣为黄色,后者为白色。这两个物种都是青藏高原高山灌木从的建群物种。本研究在该属的自然地理分布区内选取了71个居群的558个个体,对其进行了两套叶绿体DNA片段(rbcL和trnT-L)及一套核基因片段(ITS)的测序工作。最终获得了112个叶绿体联合片段单倍型和134个ITS基因型。系统发育分析的结果显示,该属植物的叶绿体单倍型和ITS序列均构成了明显的单系遗传分支。研究得到所有叶绿体DNA单倍型聚类到三个有着明显分化的遗传分组,且这三个遗传谱系不为任何一个物种所特有。在其中的两个遗传分组中,检测到了显著的扩张信号；经分子钟分析,估算出不同单倍型分组之间发生分化的时间以及组内发生明显扩张的时间处于上新式和晚更新世之间。基于核基因ITS变异,同样检测到六个具有明显遗传分化的序列分组；但单独分析仍然不能成功界定两个物种。不过,在研究中所检测到的两套分子标记的遗传分化都具有着一定程度的地理相关性。以上结果表明,青藏高原的近期隆升和气候的反复震荡,可能引起了金露梅属内较大的遗传分化；而之后在地质或气候历史事件间隔期所发生的植物类群分布变迁及扩张事件可能会使得之前发生的异域分化变的模糊,同时也模糊了两物种之间界限。本次研究的结果证实了青藏高原自然生态系统建群物种具有非常复杂的进化历史。造成这种复杂性的可能原因是：在地质气候条件不断发生变化的情况下,相对于其他高山物种,这些建群物种可以更加快速的做出适应性响应,发生分布范围的变迁。更多还原

【Abstract】 The uplifts of the Qinghai-Tibetan Plateau (QTP) and the Quaternary climatic oscillations are suggested to have caused extensive allopatric divergences that account for this region’s high species diversity. However, range shifts during the inter-geological or interglacial stages may have counteracted such allopatric divergences due to mutual introgressions involving dominant species, which adapted rapidly to changes in the climate and their habitats. We tested this hypothesis by performing a phylogeographic study on the shrub genus Dasiphora (Rosaceae). Two species within this genus can be distinguished based on their petal colors and are widely distributed dominant shrubs on the QTP. We sequenced two chloroplast DNA (cpDNA) fragments (rbcL and trnT-L) and the nuclear ribosomal internal transcribed spacer (ITS) for558individuals from71populations. In total,112cpDNA haplotypes and134ITS genotypes were recovered. All of these haplotypes or genotypes comprised a monophyletic lineage within the expanded samples from this genus and the related ones. The cpDNA haplotypes clustered into three distinct groups with deep divergences, none of which was species-specific. Significant and distinct expansion signals were detected within two of the three cpDNA groups. The divergences between the identified cpDNA haplotype groups and the expansions within these groups were dated to between the Pliocene and the late Pleistocene. Similarly, different and deeply diverged ITS sequence groups were identified; these also did not exhibit complete interspecific delimitation. However, all of the identified cpDNA or ITS groups were geographically correlated to some extent. These results suggest that recent plateau uplifts and climatic oscillations might have caused the deep divergences observed within this genus. However, later range expansions probably blurred these allopatric divergences and species boundaries. Our results highlight the evolutionary complexity of the dominant components of the QTP ecosystems, which arose from rapid range shifts in response to geological and/or climatic oscillations.更多还原