赤水河半(鱼)的遗传多样性和种群历史动态分析

摘要

This study investigated the genetic diversity and population demographic history of Hemiculterella sauvagei based on the sequence analysis of mtDNA (Cyt b) of 168 individuals from five geographical populations including Shuiliao, Maotai, Erhe, Taiping and Chishui. After alignment, 1137 bp sequence including 42 variable sites, 13 singleton sites, 29 parsimony informative sites and 38 haplotypes were acquired and revealed, among which Hap1, Hap2 and Hap6 were shared by all populations. The haplotype diversity (Hd) and nucleotide diversity (Pi) were 0.895±0.012 and 0.00487±0.00695, respectively. Analysis of molecular variance (AMOVA) indicated that genetic varia-tions between different geographical populations in the Chishui River were mainly within group. Genetic differentia-tion index (Fst) indicated high genetic differentiation between Chishui and Maotai, Erhe and Shuiliao population as well as medium genetic differentiation between Chishui and Taiping population. The overall mean genetic distances among five populations were between 0.004—0.006. Tajima's D and Fu's Fs neutral tests showed that historical population ex-pansion observed in Taiping, Shuiliao and Chishui population but not in Maotai and Erhe. The population expansion of Shuiliao, Taiping and Chishui appeared in 0.43 Mya, 0.40 Mya and 0.37 Mya, respectively.%在赤水河的水潦、茅台、二合、太平、赤水市5个样点共采集了168尾半(鱼)Hemiculterella sauvagei,通过线粒体DNA的细胞色素b(Cyt b)基因序列分析了半(鱼)种群遗传多样性和种群历史动态.获得序列长度为1137 bp,其中包含42个变异位点,13个单突变位点,29个简约信息位点.168条序列共检测到38种单倍型,单倍型多样性(Hd)和核苷酸多样性(Pi)分别为0.895±0.012和0.00487±0.00695.分子方差分析(Analysis of Molecular Variance,AMOVA)显示:遗传变异主要来源于种群内部(80.95％).Fst值统计表明,赤水市种群与茅台、二合、水潦种群之间存在高度分化,与太平镇种群之间存在中度分化,其他种群之间无显著差异,这表明分布在赤水市和其他4个地理种群的半(鱼)应作为不同的管理单元(MU)进行保护.Mega 6.0软件计算5个种群之间的平均净遗传距离范围为0.004—0.006.中性检验结果为水潦、太平和赤水市的Fs值为负值,表明这3个地理种群的半(鱼)曾发生过种群扩张.采用1％per Myr的突变速率推算出半(鱼)水潦种群扩张时间大约在0.43百万年前,太平镇种群大约在0.40百万年前,赤水市种群大约在0.37百万年前.