北半球历史生物地理学问题探讨：基于RAD taqs方法的紫荆属亲缘地理学研究

The intercontinental biogeographic disjunction of plant species in northern hemisphere has long been a hot topic for biogeographic research. The genus Cercis L. has been studied for a long time as a potential group to provide insight into historical biogeography in northern hemisphere. China is the major distribution region for Cercis in eastern Asia. However, most of the previous studies have focused on northern American and European species with relatively less attention to the eastern Asian species. Though, the phylogenetic relationship was well resolved based on previous phylogenetic analyses, the evolutionary mechanism of intercontinental disjunction of Cercis has not be well explored due to the limitation of sample collection, data resources and expreiment techeniques. In our research, we intend to conduct a comprehensive phylogeographic study of Cercis based on world wide large scale population sampling and by the means of a genome wide SNP loci identified within restriction site-associated DNA (RAD) taqs in combination with traditional cpDNA haplotypes and SSR analyses. Population genetic diversity, spatial distribution pattern of genetic variation, lineage divergence and population evolutinary history will be detected. We aim to 1) elucidate the historical biogeographical scenarios involved with intercontinental disjuncttion of Cercis, such as vicariance-dispersal associated with land bridge changes and climatic oscillation, 2) reveal the role of the eastern Aisan species in intercontinental disjuction of Cercis based on its geographical diversification and lineage evolutionary history, and furthermore, 3) interpret the evolutionary mechanism of intercontinental disjunction of Cercis in northern hemisphere. Our study will make contributions to a better understanding of the evolutionary history of the northern hemisphere flora and the phylogeographic studies of plant species in eastern Asia.

北半球温带成分间断分布的生物地理格局一直以来是全球生物地理学家研究的热点。紫荆属为北半球洲际间断分布，我国是其在东亚的主要分布区。前人研究揭示了紫荆属各大陆类群之间的系统发育关系，但是由于样品采集、实验技术及分析方法的局限性，其洲际间断分布格局的形成机制尚未得到充分阐释，仍然存在争议。本项目将在前人研究的基础上，以第二代测序技术RAD taqs方法为主，结合传统的cpDNA单倍型分析和SSR分子标记，首次开展紫荆属亲缘地理学研究，检测该属群体遗传多样性、谱系地理结构、谱系分化过程和群体进化历史等，检测陆桥变迁、气候波动所带来的隔离分化、迁移扩散等历史事件，揭示东亚类群在该属洲际间断分布格局形成过程中的作用和地位，探明紫荆属洲际间断分布格局的形成机制及物种进化历史，进而阐释北半球古生物或广布类群的历史生物地理学问题，为北半球植物区系演化历史、东亚植物亲缘地理学等相关研究提供实例、积累数据。

北半球温带成分间断分布的生物地理格局一直以来是全球生物地理学家研究的热点。紫荆属为北半球洲际间断分布，我国是其在东亚的主要分布区。前人研究揭示了紫荆属各大陆类群之间的系统发育关系，但是由于样品采集、实验技术及分析方法的局限性，其洲际间断分布格局的形成机制尚未得到充分阐释，仍然存在争议。本项目在前人研究的基础上，结合第二代测序技术GBS和叶绿体基因组序列，开展了紫荆属生物地理学研究。检测该属群体遗传多样性、谱系地理结构、谱系分化过程和群体进化历史等。结合地质历史事件，如陆桥变迁、气候波动等，对紫荆属洲际间断分布格局的形成机制进行阐释，并探讨隔离分化、迁移扩散等历史事件对紫荆属洲际间断分布格局形成的影响。此外，针对东亚的类群，本研究进一步对湖北紫荆和垂丝紫荆进行物种形成和分化的研究，探讨紫荆属在东亚的物种形成和分化。同时，针对分布于南部的广西紫荆进行群体遗传学分析，探讨中国东南部山地在该种物种形成和群体进化历史过程中的作用。本研究为具备相似地理分布格局的北半球物种的生物地理学研究提供了实例，并为进一步探讨北半球植物洲际间断分布格局的形成机制以及东亚植物物种多样性和物种进化历史，提供了证据。