华东地区两种植被带内天女花的遗传结构

The genetic structure of Oyama sieboldii (K.Koch) N.H.Xia & C.Y.Wu within two vegetation zones in Eastern China

天女花是一种名贵的珍稀观赏树种,现已被列为国家Ⅲ级保护植物,其自然分布区的植被类型可大致分为温带落叶阔叶林带(长江以北)和暖温带常绿阔叶林带(长江以南)。华东地区是天女花分布比较集中的区域之一,也是两种植被带的分界区。论文采用微卫星标记对华东地区两种植被带内的8个天女花自然种群的遗传多样性和遗传结构进行了分析。结果表明:华东地区天女花种群遗传多样性与近缘种相比较低(N_A=3.83、H_O=0.25、H_E=0.40);大别山(落叶阔叶林带)种群的遗传多样性(均值为H_O=0.18和H_E=0.28)明显低于皖南种群(常绿阔叶林带)的(均值为H_O=0.33和H_E=0.51),并且两者已发生了明显的遗传分化;两种植被带内的种群特征(如种群大小、胸径或丛枝数)差异不显著,种群内年幼亚群体的遗传多样与年老亚群体相比没有发生显著的变化。因此,推测大别山天女花种群经历的种群历史较短(较皖南种群)是导致其遗传多样性较低的主要原因,建议两种植被带内的天女花种群应视为不同的进化单元进行保护,当前仍应以就地保护为主。

Oyama sieboldii （K.Koch）N.H. Xia ＆ C.Y.Wu is a rare species and has been listed as the national Ⅲ grade protection plants in China. The species is naturaly distributed in two different zones of forest vegetation, i.e., temperate deciduous broad-leaved forest （North of the Yangtze River） and warm temperate evergreen broad-leaved forest （South of the Yangtze River）. The east region of China is one of the concentrated distribution areas of O. sieboldii, and also is the boundary zone of these two different vegetations. The genetic diversity and structure of eight wild populations of O. sieboldii, within two different vegetations from Eastern China, were analyzed by microsatellite markers. The results indicated that the genetic diversity of O. sieboldii in this region was relatively low （mean NA=3.83, HO=0.25 and HE=0.40） and lower than its closely related species. The mean population size, diameter at breast height （DBH） and number of branch were not significantly different between populations from different vegetations. However, the genetic diversity of Dabieshan populations （mean HO=0.18 and HE=0.28）, within the temperate deciduous broad-leaved forest, was significantly lower than that of the Southern Anhui populations （mean HO=0.33 and HE=0.51）, within the temperate evergreen broad-leaved forest, and their genetic characters obviously differentiated from each other. The distinct population history might mainly explain the difference of genetic diversity between these two zones. The genetic diversity of young individuals was not significantly lower than that of the old individuals within each population. Therefore, we proposed that the populations in Dabieshan area and Southern Anhui area should be considered as two different evolutionary significant units for conservation, and an in situ conservation strategy should be taken as the main protecting measures at present, given that the regeneration ability of wild populations was normal and the genetic diversity of young individuals did not significantly decreased.