云南金钱槭 等位酶 遗传多样性 生境片段化 保育策略

云南金钱槭（Dipteronia dyeriana）是我国特有的国家Ⅱ级重点保护珍稀濒危植物,仅分布于云南的文山、屏边和蒙自三县交界地区。采用水平切片淀粉凝胶电泳等位酶分析方法,对采自三个县的天然居群的63个样品进行了遗传多样性检测。8个酶系统的13个等位基因位点分析表明,云南金钱槭的遗传多样性水平低,其平均多态位点百分率P=15.4%,每位点平均等位基因数A=1.2,平均预期杂合度He=0.064,各居群都偏离Hardy-Weinberg平衡,杂合子过量,居群间的基因分化系数GST=0.099,遗传变异主要发生在居群内（90.1%）,居群间分化较小,居群间遗传一致度较高（I=0.985～1）,具有一定的基因流（Nm=2.669）。不加权对平均法（UPGMA）聚类可将4个居群分为两支,水头箐居群和马家寨居群亲缘关系最近,聚类后与黑洞居群形成一支再和中槽子居群聚类,这与其地理分布格局大致吻合。据此提出了关于云南金钱槭保育策略的建议。

Allozyme-based Genetic Diversity of Dipteronia dyeriana in China

Dipteronia dyeriana Henry is a rare and endangered species restricted in a small adjacent corner of Wenshan,Pingbian and Mengzi counties of Yunnan,southwest China.The genetic diversity of four natural populations was estimated using allozyme markers.Thirteen loci of eight enzyme systems were scored for the analysis of population genetic diversity and structure.A low genetic diversity was observed in this rare species,with a mean percentage of polymorphic loci P=15.4%,an average number of alleles per locus A=1.2,and an average of expected heterozygosity H_e=0.064.All populations deviated significantly from the Hardy-Weinberg equilibrium.Very slight population differentiation was detected (G_(ST)=0.099).Nei's genetic identity ranged from 0.985 to 1.Moderate gene flow was inferred(Nm=2.669).According to the Unweighted Pair Group Method with Arithmetic（UPGMA）cluster analysis based on the genetic distance,Mengzi and Majiazhai populations are clustered in one clade and its genetic distances are positively related to the geographic disance.For conservation purpose,we strongly suggest strict protection of the natural populations of the species should be conducted,and ex situ conservation could be an effective supplement.