中国亚热带山顶矮林代表植物吊钟花组谱系地理学研究

Quaternary climatic changes have greatly affected the distribution of the forest biomes in subtropical China. Most phylogeographic studies in this region focused on genetic structure and range shift of plants in evergreen broadleaved forest, deciduous broadleaved forest and warm coniferous forest. However, little attention has been paid to the montane elfin forest, another typical vegetation in subtropical China. Furthermore, those studies rarely considered the impact of climatic changes on the formation of species diversity. Enkianthus sect. Enkianthus is comprised of four species, which are typical montane elfin plants in subtropical China. These species will be selected in this project as a paradigm to illustrate the influence of historical climatic changes on the formation of species diversity and the range shift history in the montane elfin forest. In order to achieve this goal, we’ll examine and compare the phylogeographical structure of the four species using maternally inherited chloroplast and biparentally inherited nuclear markers. More importantly, we’ll jointly use population genetic analysis, coalescence-based simulation methods (ABC and IMa) and ecological niche modeling to study the speciation and demographic histories of Enkianthus sect. Enkianthus. The results of this project will not only advance the understanding of the evolutionary history of plants in subtropical montane elfin forest, but also have profound implications for the conservation of subtropical forest in China in the face of global warming.

第四纪以来地球气候变化对中国亚热带地区植被产生重大影响，该地区常绿阔叶林、落叶阔叶林和暖性针叶林等植被成分的谱系地理格局和分布区变迁历史逐渐被解析出来。然而，中国亚热带地区另一特色植被类型——山顶矮林植物的谱系地理学研究一直少有问津，而且以往研究很少探讨气候变化对群落中物种多样性形成的影响。本项目拟以中国亚热带山顶矮林代表类群吊钟花组4个近缘种为研究对象，通过对双亲遗传的核基因与母系遗传的叶绿体DNA多个片段的比较，采用群体遗传学分析和多种种群动态模型（ABC和IMa）模拟以及生态位模型检测方法，研究吊钟花组物种的分化历史和种群动态历史，探讨地质历史时期气候变化对中国亚热带山顶矮林物种多样性形成和植物分布区变迁的影响。本研究结果有助于理解中国亚热带山顶矮林植物的进化历史，为全球气候变暖背景下中国亚热带地区森林植被的保护提供重要理论基础。

本研究的目的是采用多个核基因手段，揭示地质历史时期气候变化对中国亚热带山顶矮林代表类群吊钟花组的物种分化和种群动态历史的影响。本研究以中国亚热带地区吊钟花组46个群体为研究对象，利用1个叶绿体片段和8个核基因片段调查其遗传多样性，并利用Structure聚类分析、溯祖模拟分析以及生态位模型分析等多种方法，揭示其群体遗传结构、种间分化、种群动态和分布格局变迁历史。结果表明：1）吊钟花、齿缘吊钟花和台湾吊钟花三个物种之间存在显著的遗传分化，且分化时间与晚上新世或早更新世全球气候变冷时间高度吻合；2）吊钟花与齿缘吊钟花在第四纪间冰期发生了种群扩张；3）种群扩张以及随之而来的二次接触使得吊钟花和齿缘吊钟花在重叠分布区的群体产生明显的基因渐渗。本研究结果揭示了中国亚热带山顶矮林代表植物吊钟花组的种间分化及分布区变迁历史，为此类植物保护提供坚实理论基础。