Phylogeography of eastern Asian plants associated with vicariance in the northwestern Yunnan Province, China.

与世界其他植物区系相比，东亚中日植物区系具有明显的丰富性，但对其植物区系演化的认识相当有限。我们的目的是根据几个分类群的分子系统发育和基因组分化(染色体信息)来洞察东亚植物区系的进化。3个DNA区域的系统发育分析证实，菊科Ainliaea由3个与物种分布相对应的主要分支组成。据估计，这三个谱系的演化发生在第四纪早更新世的1.1年左右。我们的结果表明，Ainslaea种是异地进化的，其后代被隔离在中日区域的东部(中国东南部和日本之间，通过台湾和琉球群岛)和西部(云南省及其周边地区，包括喜马拉雅山脉、东南亚温带地区和四川省)。从Ainslaea物种的系统发育来看，中日地区内的两个环境异质性地区由于气候和地形的不同而独立地保持了丰富的原始植物区系。此外，从尼泊尔到日本到中国、泰国北部和台湾的东亚鱼腥草样本的种内多倍体和细胞地理学研究。共检测到5条染色体数目(2n=72、80、96、112和128)，其中4条为新记录。这些染色体数目表明，鱼腥草的基本染色体数为x=8。观察到的细胞型分别为2n=72、80、96、112和128，分别代表9x、10x、12x、14x和16x。东亚大陆的种内多倍体从9x到16x不等，在亚洲大陆东部台湾和日本之间只发现了一个12x(2n=96)的细胞型。

The flora of the Sino-Japanese plant region of Eastern Asia is distinctively rich compared with other floristic regions in the world ; however, knowledge of its floristic evolution is fairly limited. Our aim was to provide insight into floristic evolution in eastern Asia on the basis of a molecular phylogeny and genomic differentiation (chromosome information) of several taxa. Phylogenetic analyses' of three DNA regions confirmed that Ainsliaea (Compositae) is composed of three major clades that correspond to species distributions. Evolution of the three lineages was estimated to have occurred around 1.1 MYA in the early Pleistocene of the Quaternary. Our results suggest that Ainsliaea species evolved allopatrically and that the descendants were isolated in the eastern (between SE China and Japan, through Taiwan and the Ryukyu Islands) and western (Yunnan Province and its surrounding areas, including the Himalayas, the temperate region of Southeast Asia, and Sichuan Province) sides of the Sino-Japanese region. From the phylogeny of Ainsliaea species, two environmentally heterogeneous regions within the Sino-Japanese region have independently maintained rich and original floras due to their diverse climates and topographies. Moreover, intraspecific polyploidy and cytogeography were examined for samples of Houttuynia cordata from eastern Asia, ranging from Nepal to Japan through China, northern Thailand, and Taiwan. Five chromosome numbers (2n=72, 80, 96, 112, and 128) were detected, four of which were first recorded here. These chromosome numbers suggest that the basic chromosome number of Houttuynia is x=8. The observed cytotypes were evaluated as 2n=72, 80, 96, 112, and 128, and represent 9x, 10x, 12x, 14x, and 16x, respectively. The continental part of east Asia harbors intraspecific polyploidy ranging from 9x to 16x, and only one cytotype, 12x (2n=96), was found from the eastern edge of the Asian continent, between Taiwan and Japan.