中国亚热带喜冷植物裂叶星果草谱系地理学研究

Aimed to achieve a better understanding of the evolutionary history of the rich flora in subtropical China and to inform conservation policy and management, phylogeographic studies in this region have greatly advanced during the past decade. However, most studies focused on temperate species, little attention has paid to high-elevation cold-adapted plants. Compared with temperate plants, cold-adapted plants may have responded to the climatic changes since the late Cenozoic (particularly the Quaternary) in much more complex modes. Three models, namely interglacial refugia model, glacial refugia model, and altitudinal shift model, have been recommended to accomodate the range shift of cold-adapted organisms. A few phylogeographic studies on cold-adapted plants in subtropical China are mostly involved with several species-rich genera of conifer (e.g., Abies, Pinus, Tsuga), which are prone to hybridization among closely related species. The molecular markers used in those studies (chloroplast and mitochondrial DNA) are always low in sequence variation and thus provide limited historical information. More importantly, population divergence time and demographic dynamics have rarely been analyzed, which makes it difficult to establish a link between the evolutionary history of plants and climatic events. Therefore, limited knowledge has been acquired by far about how cold-adapted plants in subtropical China have shifted their range in response to the climatic changes since the late Cenozoic. Asteropyrum cavaleriei (H. Léveillé & Vaniot) J. R. Drummond & Hutchinson (Ranunculaceae) is a typical cold-adapted plant in subtropical China. Several attributes of this species make it suitable for inferring the range shift mode of cold-adapted plants in subtropical China, namely, relatively wide distribution range, no co-distributed relatives (just one related species but rarely overlap in distribution) which means hybridization is less likely to influence phylogeographic inference. In this proposal, we’d like to investigate genetic variation and genetic structure of two or three chloroplast genomic fragments and 10 nuclear loci of A. cavaleriei. By means of IMa (Isolation with Migration) and EBSP (Extended Bayesian Skyline Plot), we’ll calculate the population divergence time and infer the dynamics of effective population size of this species. The aim of this proposal is to unravel the range shift mode of cold-adapted plants in subtropical China, which would provide new insights into the evolution of the rich flora in subtropical China. The results will also have profound implications for the conservation of biodiversity on “sky islands” in subtropical China under the circumstance of global warming that is induced by human activities.

中国亚热带植物谱系地理学近年来进展显著。然而，前人研究大多集中于喜温植物，对高海拔山地喜冷植物研究甚少。喜冷植物应对晚新生代以来气候变化的方式远比喜温植物复杂，有间冰期避难所模式、冰期避难所模式和垂直迁移模式等。中国亚热带喜冷植物的研究多局限于杂交频繁的裸子植物类群，研究体系复杂；采用的分子标记变异较低，遗传信息不够丰富；大多没有推测群体分化时间和种群动态过程，难以将群体历史与气候事件进行关联。因此，中国亚热带喜冷植物如何应对气候变化？这一问题尚未明确回答。毛茛科裂叶星果草分布较广泛，是亚热带典型的喜冷植物，近缘种少（1种）且分布几乎不重叠。本研究拟对其进行广泛的居群采样，检测2-3个叶绿体片段和10个核基因位点的遗传变异和遗传结构，计算群体分化时间和有效种群大小动态。研究结果可以揭示中国亚热带喜冷植物分布区变迁模式，对全球气候变暖背景下保护“空中岛屿”的生物多样性，具有重要的科学意义。