蒙古栎天然群体等位酶遗传多样性研究

Genetic Diversity of Allozymes of Quercus mongolica in China

以中国蒙古栎全分布区的8个天然群体和辽东栎1个天然群体为研究对象,进行了水平淀粉凝胶电泳技术的同工酶分析,共分析了13种酶系统产生22个位点。结果表明:(1)蒙古栎在种和群体水平的遗传变异水平较低,多态位点百分率P分别为52 38%、28 976%,期望杂合度He分别为0 099、0 085,观测杂合度Ho分别为0 092、0 088;(2)蒙古栎群体间遗传分化程度较高,分化度Gst为0 107,遗传多样性中的遗传变异量89 27%存在于群体内;蒙古栎群体水平的基因流Nm值为2 080。(3)蒙古栎群体间的平均遗传距离D较低,为0 0121,各群体之间的遗传一致度I为0 974～1 00;(4)东灵山辽东栎群体的遗传多样性较低,多态位点百分率P为36 36%,期望杂合度He为0 083,观测杂合度Ho为0 070;(5)利用群体间遗传距离进行的UPGMA聚类结果表明,蒙古栎自然分布区的东北部的4个群体和西南部的2个群体分别聚为一亚类,这与其地理分布格局大致吻合,但群体间遗传距离与地理距离无明显的相关性。(6)长期的砍伐和破坏,造成有效群体较小,而且经受繁殖瓶颈效应,是蒙古栎遗传多样性下降的主要原因。

A gel electrophoresis method was used to study the genetic diversity of eight Quercus mongolica populations located at Daxing′anling, Jiayin, Shuangyashan, Xiaoxing′anling Mountains of Heilongjiang Province, Jiaohe of Jilin Province, Kuandian of Liaoning Province,Daqinggou of Inner Mongolia Autonomous Region, Wulingshan, Zanhuang of Hebei Province, and one Quercus liaotungensis (a variety of Q. mongolica) population at Donglingshan of Beijing. Twelve of 22 loci from 13 enzymes assayed were polymorphic. Quercus mongolica maintained low level of genetic variation as compared with the average Quercus species. At species level, the mean number of alleles per locus (A) was 1905, thepercentage of polymorphic loci (P) was 5238%, and the observed heterozygosity (Ho) was 0092 At population level, the estimates were A=1421, P=28976%,and Ho=0088 Genetic differentiation (Gst) was high among populations, Gst was 0107, and the means of genetic distance 0012 1 The Nei's genetic identity ranged from 0974～100 The gene flow was 2079 9 In contrast, the estimates for Quercus liaotungensis were almost the same (A=15, P=3636%, Ho=0070).According to the UPGMA cluster analysis based on the genetic distance, 4 populations located in northeast and 2 populations in southwest of the geographical distribution are classified into 2 subgroups in separate, there was no clear relationship between genetic distance and geographic distance among populations. The low level of genetic diversity of Quercus mongolica might related to the longterm utilization as economic tree species in history, comparatively serious disturbance and damage by human beings, and secondary forests of most the existed stands.