中国巨蚓科蚯蚓系统发生地理学研究

Deep analysis on the evolutionary principle and process of earthworms in geographical pattern, from the molecular evolution view, is of great significance in theory. The geographical origin, evolution and distribution of terrestrial earthworms are related to multi-factors, such as paleogeographic variance, historical climate and biological factors. But the evolutionary process of Chinese earthworms of the Family Megascolecidae has not been clear yet. In this study, species and populations of widespread species belonging to the Family Megascolecidae, will be collected in the whole country and used to analyze their geographical pattern. Mitochondrial genes COI, COII, 12S, 16S and ND1 of each species or populations, as well as Cytb gene and D-loop sequences of each populations, will be extracted and sequenced to construct the molecular phylogenetic trees on the interspecific and intraspecific level. The earthworm evolutionary history will be completed by molecular clock and coalescent theory. The evolutionary process on the interspecific and intraspecific level will be discussed by combining phylogeny results, paleogeographic and historical climatological data of China and its neighboring countries. Finally, phylogeography of Chinese earthworms of the Family Megascolecidae, including their origin, evolution and distribution, will be illustrated.

从分子系统发育角度，深入研究陆栖蚯蚓基因谱系地理格局的历史演化过程及形成原理具有重要理论意义。陆栖蚯蚓的地理起源、演化与分布，受古地理变迁、历史气候变化以及生物因素等综合作用影响。但是，我国主要陆栖蚯蚓类群- - 巨蚓科物种及种群的分化与扩散历程还不明确。本研究将全面系统地采集我国各地的巨蚓科蚯蚓物种及代表性广布种种群标本，分析其地理分布格局；同时提取标本的线粒体COI、COII、12S、16S与ND1基因，以及广布种的线粒体Cytb基因及D-loop区序列测序，构建物种与种群两个阶元的分子系统发育关系，并重建祖先特征及序列等；再结合相关的古地理变迁与历史气候等资料，分析物种的分化历程与广布种种群的扩散过程，全面阐释我国巨蚓科蚯蚓的系统发生地理学，阐明其起源、演化与分布情况。

2015-2018年期间，课题组对中国数十个自然保护区及周边区域进行系统地蚯蚓采集，获得研究所需物种及种群标本。经形态分类与鉴定后进一步分析了主要类群的地理分布格局。研究提取了321个物种的线粒体5基因（COI、COII、ND1、12S与16S），以及22个广布物种不同地理种群的线粒体基因相应序列，分别构建物种阶元及种群阶元的系统发育树，探讨物种亲缘关系及种群遗传结构。研究还估计了巨蚓科蚯蚓物种与种群的分化时间，重建了类群的祖先分布区域，分析类群分化与扩散路径，进而分析物种、种群在时间和空间尺度上的演化历程，从而阐述了中国巨蚓科蚯蚓的系统发生地理学。研究表明，中国巨蚓科主要类群的祖先起源于中南半岛，于白垩纪末期至新生代初期进入中国，在新生代得以繁荣发展；广布物种种群在中国的分化与扩散也存在着连续而复杂的规律。