小毛茛居群的遗传分化及其与空间隔离的相关性

采用聚丙烯酰胺凝胶电泳技术，对分布于华中地区的11个小毛茛（Ranunculus ternatus）居群的遗传分化进行了检测。对8个酶系统17个酶位点上的分析结果表明，该种各居群 的各项遗传多样性指标处于一个相对较低的水平：多态位点比率（P）为0～53.0%，平均每位点等位基因数（A）为1～1.647，平均预期杂合度（H_e）和观察杂合度（H_o）分别为0～0.108和0～0.102。居群间遗传一致度甚高（I＝0.9754～0.9991）。根据Nei′s遗传距离所作出的聚类分析表明,豫南信阳地区3个居群与湖北省武汉地区8 个居群之间关系较远。而在武汉地区，长江以北的居群及长江以南的部分居群分别相聚在一 起。用GPS定位方法得到居群间空间距离并据此聚类，结果显示了该种的遗传分化与地理因 素 的相关性，并推测出长江的隔离作用加强了两岸居群间的遗传分化。同时发现一个生于独特 生境的居群在表型和遗传结构上都已与其他邻近居群有了很大分异，由于该居群在所检测的 酶位点上均无特有等位基因出现，作者认为不宜将其作为新种或新变种处理。

Genetic differentiation and the relation to spatial isolation among populations of Ranunculus ternatus

Genetic differentiation of 11 populations in Ranunculus ternatus Thunb. from Central China was detected by means of PAGE. Eight enzymes encoded by seventeen loci were assessed. Genetic diversity within populations was relatively low. The proportion of polymorphic loci (P) ranged from 0 to 41.2%, the average number of alleles per locus (A) from 1 to 1.647, the mean expected and observed heterozygosity (He, Ho) per locus were from 0 to 0.108 and 0 to 0.102 respectively. The genetic identities between populations were remarkably high (I=0.9754～0.9991). According to the results of cluster analysis based on Nei′s genetic distances, three populations distributed in the southern part of Henan Province were far from the populations in Wuhan, Hubei Province. In Wuhan, very high similarity appeared among populations situated north of the Yangtze River (Changjiang), and among those on the area south of the river. Analysis based on the spatial distance measured by GPS indicated a relationship between genetic distances and geographical factors. The authors deduced that the genetic differentiation of populations was enhanced by the isolating effect of the Yangtze River. A population from Wuhan was found to be remarkably different from the others in both morphological characters and genetic structures. But this population was not suggested as a new species or a new variety because no unusual allele was found in the enzyme loci detected.