我国不同地理梯度下紫茎泽兰种群遗传多样性的变化

利用ISSR分子标记技术分析了我国不同地理梯度下的32个紫茎泽兰种群的遗传多样性。结果表明,我国境内的紫茎泽兰种群内遗传多样性呈现随地理纬度由南到北而降低(R2=0.131 1,P<0.05),随地理经度由西到东而增高(R2=0.167 7,p<0.05)的趋势。紫茎泽兰种群遗传多样性与其生境地的年平均温度高度相关(R2=0.273 1,p<0.01),但与年平均降雨量的相关性不明显(R2=0.074 9,p>0.1)。系统聚类分析表明,紫茎泽兰的地缘性分布较为明显,地理区位接近的种群遗传相似性较大,在聚类分析中大多聚为一类。我国境内的紫茎泽兰基本可分为2大亚群:第一亚群主要地处我国热带季雨林、雨林植被区域,包括云南南部的种群、广西种群和贵州西部种群;第二亚群则地处亚热带常绿阔叶林植被区域西部(半湿润)常绿阔叶林亚区域,主要包括云南中、西部种群和四川种群及随长江流域扩散形成的种群。各紫茎泽兰种群间的遗传距离和地理距离之间高度相关(R2=0.294,p<0.001),说明地理距离是影响种群间基因交流的重要因素。

Genetic Variation among Populations of Ageratina adenophora at Different Geographical Locations in China

The genetic diversity of thirty-two Chinese populations of crofton weed Ageratina adenophora in different altitudes was analyzed with the inter-simple sequence repeat(ISSR) technique.The result indicated that genetic diversity of Chinese A.adenophora populations decreased along with the increased latitude(R~2=(0.131 1),p < 0.05),whereas increased along with the longitude shift from west to east(R~2 =(0.167 7),p < 0.05).Genetic diversity of A.adenophora correlated highly with the annual mean temperature of its habitat(R~2 =(0.273 1),p < 0.01),whereas there was no significant correlation between its genetic diversity and the annual mean rainfall(R~2 =(0.074 9),p > 0.1).Cluster analysis grouped the Chinese crofton weed populations into two subgroups,which were corresponding with their geographical origins.The first subgroup included the populations located in the vegetation regions of tropic seasonal rain forest and rain forest,i.e,populations in southern Yunnan,Guangxi and southwestern Guizhou.The second subgroup included the populations located in the western semi-humid subregion of the subtropical evergreen broadleaf tree vegetation region,i.e,populations in middle to western Yunnan,Sichuan and area along the Yangtze River.The Mantel Z-statistic test showed that the genetic distance of A.adenophora populations was corresponded highly with their geographic distance(R~2 = 0.294,p < 0.001),indicating that the geographic isolation is a main factor to block the gene flow of A.adenophora.