青杨的遗传分化

分析了10个省市自治区的30个群体的青杨(Populus cathayana Rehd.),共169株,用RAPD方法分析群体间和群体内的DNA多态性。结果显示群体间的DNA多态度远高于群体内的,而且东部群体与西部群体间存在较大的遗传差异,相邻产地之间的遗传差异相对较小。聚类分析结果表明,东、西部群体已出现明显分化。整个聚类图与青杨的地理分布区大致相对应。西部群体内DNA多态性比东部群体高,因此西部群体在研究青杨的起源与演化中将显得更为重要。按照多样性中心与起源中心的关系,青杨可能起源于我国西北部,逐渐向东扩散,形成现代分布格局。

GENETIC DIFFERENTIATION OF POPULUS CATHAYANA

169 clones chosen from 30 localities of Popidus cathayana Rehd. covering ten provinces were colleced for analysis of DNA polymorphisms between populations and within population by RAPD. The result showed that the degree of DNA polymorphism between populations was much larger than that within population, and the degree was greater between eastern and western population than that between the neighbor populations. The UPGMA and Neighbor-Joining cluster analysis based on net genetic distance were used to investigate phylogenetic relationship among populations. They both showed apparent genetic differentiation between eastern and western population. The dendrogram had correspondence with geographic distribution region of P. cathayana. The western revealed much more polymorphisms than the eastern population. Therefore, the western populations had more important role in the origin and evolution of P. cathayana. According to the relationship between diversity center and origin center of species, it is possible that P. cathayana originated from the northwestern China and then spreaded to the eastern region forming modern distribution region.