基于mtDNA Cyt b序列分析齐口裂腹鱼群体遗传多样性

研究测定了长江上游4个齐口裂腹鱼(Schizothorax prenanti)野生群体(重庆巫溪、重庆城口、四川雅安、四川阿坝)共104个个体的线粒体Cyt b基因部分序列, 以探讨齐口裂腹鱼野生群体的遗传多样性和遗传结构。结果表明: 在104个个体Cyt b序列中共检测到43个多态性位点, 25个单倍型。4个齐口裂腹鱼群体的单倍型多样性介于0.704—0.884, 核苷酸多样性介于0.007—0.012。群体间Kimura双参数遗传距离介于0.008—0.017, 其中四川雅安群体与四川阿坝群体间遗传距离最近, 基因交流频繁。重庆城口群体与四川雅安群体间遗传距离最远, 基因交流受阻。AMOVA分析表明, 齐口裂腹鱼的遗传分化主要来自群体内部, 且组群间、组群内群体间和群体内存在显著的遗传分化。中性检验得到Tajima’s D和 Fu’s F_s的值不显著, 且歧点分布图呈多峰, 表明长江上游4个齐口裂腹鱼野生群体未经历过种群扩张。研究旨为齐口裂腹鱼野生资源保护提供必要参考意见, 同时为齐口裂腹鱼种质资源合理开发和利用提供理论依据。

GENETIC DIVERSITY OF THE PRENANT'S SCHIZOTHORACIN (SCHIZOTHORAX PRENANTI) BASED ON PARTIAL MTDNA CYTB SEQUENCES

Prenant's schizothoracin,Schizothorax prenanti (Tchang), a valuable and economic fish, distributes in the main streams and tributaries of the upper reaches of the Yangtze River in China. To assess genetic diversity and gene-tic structure of the wild populations ofS. prenanti, we amplified partial Mitochondrial Cytb gene sequences from 104 individuals of the four wild populations ofS. pregnant (Wuxi, Chengkou, Ya'an and A'ba) from the upper reaches of the Yangtze River. The results showed that 43 polymorphic nucleotide sites and 25 haplotypes were detected among the Cytb sequences of 104 individuals. The haplotype diversity was ranged from 0.704 to 0.884, and nucleotide diversity index was ranged from 0.007 to 0.012 among the four populations. Kimura 2-parameter distance was ranged from 0.008 and 0.017. The genetic distance between Ya'an and A'ba population was the smallest and the gene exchange between the two populations was frequent. The largest genetic distance was observed between Ya'an and Chengkou population, which might be explained by the little gene exchange between the two populations. AMOVA analysis showed that the genetic differentiation ofS. prenanti was mainly occurred within populations variation. There were significant genetic differentiations between the groups, among populations within groups, and within populations. The results of neutrality test showed that the values of Tajima'sD and Fu'sFs were not significant and the mismatch distribution was multimod-al, indicating that the four populations ofS. prenanti from the upper reaches of the Yangtze River had not experienced population expansion. This study provides valuable knowledge for protectingSchizothorax prenanti and theore-tic information for a rational utilization of the germplasm resources.