乌苏里江2种细鳞鲑种群遗传多样性及亲缘关系的微卫星分析

Genetic diversity and relationship between two species of Brachymystax in Wusuli River revealed by microsatellites

尖吻细鳞鲑（Brachymystax lenok）28尾和钝吻细鳞鲑（B．tumensis）26尾，均采自乌苏里江中游。利用9对微卫星引物（10个位点）对其种群遗传多样性进行比较研究，以期从分子水平上探讨2个种间的遗传多样性差异水平及其亲缘关系。结果表明，尖吻细鳞鲑和钝吻细鳞鲑种群的平均杂合度（H）分别为0．3230和0．3391，多态信息含量（PIC）分别为0．3229和0．4353；在检测到的10个基因位点中有9个位点上的等位基因及其在2种细鳞鲑间的分布存在显著差异，2种细鳞鲑各自拥有大量的特有等位基因，而共有等位基因很少；2种细鳞鲑在4个微卫星位点上的遗传相似度（J）为0，在其他6个具有相同等位基因的位点上的遗传距离（D）为0．0115～2．5759，平均为0．9393。研究表明，2种细鳞鲑在种群遗传多样性上差异显著，亲缘关系很远，物种间可能存在生殖隔离，遗传分化程度远达到种以上的分类水平。本研究从分子水平上验证了对2种细鳞鲑的形态学分类结论，并对2种细鳞鲑的起源及其演化进行了探讨。

Brachymystax fish are economically important cold water species, which are mainly distributed over waters in Russia, Korea and China. In China, they can be found in northeast and southwest areas. There are two different opinions about its taxonomy. Most of researchers thought that there is only one species in Brachymystax, but the author found that there were two species of Brachymystax in the rivers in Heilongjiang, i. e. B. lenok and B. tumensis. These two species had ranged over many water areas in northern China. Little genetic information is available for Brachymystax fish, and there are currently no genetic diversity data about Brachymystax fish in China, although progress has been made in characterizing its ecology and morphological characters. In this paper, population genetic diversity and divergence of these two species in Wusuli River were investigated with 9 pairs of microsatellite primers. The average heterozygosity across 10 loci were 0. 323 0 in B. lenok and 0. 339 1 in B. tumensis, and polymorphic information content were 0.322 9 and 0.435 0 respectively. The average number of effective alleles were distinctly different between the two species for 10 microsatellite loci tested. The two species shared few alleles and each has a lot of specific alleles compositions. The genetic similarity at four loci （ Lenok02 - 2, Lenok 06, Lenok 08 and Lenok 09 ） between the two species was 0, but the two species shared some alleles at the other six loci and their mean genetic distance was 0.939 3（ranging from 0.011 5 to 2.575 9）. These results suggest that there is significant difference of population genetic diversity and for genetic relationship between B. lenok and B. tumensis, which is in accordance with their morphological differences. Moreover, origin and evolution of Brachymystax are also discussed in this paper.