中文摘要：

采用PCR结合DNA测序技术,测定分析了易危鱼类小口白甲鱼（Onychostoma lini）都柳江种群36个个体mtDNA D环约470bp序列的变异及遗传多样性。结果表明,在36个个体中,该序列的长度为469～475bp,其碱基组成为A＋T的平均含量（68.4%）高于G＋C（31.6%）。共检测到25个多态位点,其中转换19个、颠换6个。核苷酸多样性（π）为0.00575,平均核苷酸差异数（K）为2.695。36个个体分属5个单倍型,单倍型多样度（Hd）为0.260,单倍型间的平均遗传距离（P）为0.026。5个单倍型构建的UPGMA系统树聚为2个分支。目前小口白甲鱼都柳江种群mtDNA D环序列存在着较丰富的变异和遗传多样性。

英文摘要：

The genetic diversity and sequence variation of mtDNA D-loop in the population of vulnerable species Onychostoma lini from the Duliu River in Guizhou were studied for the first time on the basis of determination of about 470 bp sequences of mtDNA D-loop in 36 individuals by the methods of PCR and DNA sequencing. The results showed that the length of the determined sequence in 36 individuals varied from 469 to 475 bp,and the total percentage of bases A and T （68. 4% ） was more than that of bases G and C （31. 6% ） in the sequence. A total of 25 polymorphic loci,including 19 transitions and 6 transversions,were detected in the sequence of the population. The nucleotide diversity （π） of the 36 individuals was 0. 005 75,and the average number of nucleotide differences （K） of them was 2. 695. The 36 individuals belonged to 5 haplotypes according to the determined sequences. The haplotypic diversity （ Hd） was 0. 260,and the average genetic distance （ P） between the haplotypes of the population was 0. 026. The UPGMA phylogenetic tree of the 5 haplotypes comprised 2 branches. The data show that the population of O. lini in the Duliu River has abundant variation in mtDNA D-loop sequence and high genetic diversity,which may play an important role in the conservation and recovery of the species.