基于AFLP分析的伯乐树(Bretschneidera sinensis)谱系地理学研究

Phylogeographic study on Bretschneidera sinensis inferred from AFLP data

伯乐树(Bretschneidera sinensis Hemsl.)是主要分布于中国的濒危物种。采用AFLP分子标记对分布于中国11个省的24个伯乐树居群192个个体进行谱系地理学研究。结果显示,伯乐树有相对较高的遗传多样性水平,基因多样性指数(He)和Shannon指数(Ⅰ)分别为0.2728和0.4070。伯乐树居群间的遗传分化远大于居群内遗传分化,遗传分化系数G_(ST)=0.7138,基因流N_m=0.2005。通过聚类分析、STRUCTURE分析和BAPS分析发现,24个伯乐树居群可形成4大地理居群组和进化谱系;云贵高原东部地区居群遗传多样性较高,可能是伯乐树在中国的扩散中心和冰期避难所,伯乐树在冰期后由此向外进行居群扩散;南岭地区各居群遗传多样性水平普遍高于其他地区,与邻近地区各居群的亲缘关系较近,可能为伯乐树演化历史上的另一个冰期避难所。

Bretschneidera sinensis Hemsl. is a rare plant species mainly distributed in China. In this study,amplified fragment length polymorphism（ AFLP） data were used to analyze genetic diversity,genetic structure,and phylogeography of this species. A total of 192 individuals from24 populations in 11 provinces were sampled. Results showed a relatively high level of genetic diversity for B. sinensis,with an expected heterozygosity（ He） and Shannon＇s diversity index（Ⅰ） of 0.2728 and 0.4070,respectively. Relatively high genetic differentiation（ G_（ST）= 0.7138）and lower gene flow（ N_m= 0.2005） among B. sinensis populations were detected. The infrapopulation genetic variations were significantly greater than the inter-population variations. Four phylogeographic groups were discovered from cluster,STRUCTURE,and BAPS analyses.Populations in the East Yungui Plateau showed high levels of genetic diversity with unique hereditary constitution. This area is a possible diversity center and glacial refuge for B. sinensis in China,which expanded northward,eastward,and southeastward after the last ice age.Populations from the Nanling Mountains,with a close relationship to their neighbor population,had higher genetic diversity than other areas. The Nanling Mountains are another probable glacial refuge in the evolutionary history of B. sinensis.