中文摘要：

测定了广西合山、柳州、仕平和广东郁南等4个地理群体43尾卷口鱼线粒体Cytb基因1041bp，结果检测到8个单倍型，7个多念位点。4个地理群体的单倍型多样性为0．248～0．700，核苷簸多样性为0．00022～0．00070，表明所分析的卷口鱼群体单倍型多样性和核苷酸多样性低。在分子系统树上，不同地理来源的卷口鱼混杂分布在一起，没有形成明显的谱系结构和地理聚群；4个群体两两问的Fst值为-0．028～0．116，但均不显著（P〉0．08）；AMOVA分析表明1．70％（P=0．211的分子差异来自群体间，而98．3％的分子差异位于群体内部；表明4个地理群体间没有显著遗传分化。单倍型网络图呈星状结构，中性检测Tajima’SD和Fu’sFS均为显著负值，核苷酸不对称分布分析呈单峰模式，表明珠江卷口鱼可能曾经历过种群的快速扩张，推测在晚更新世（1.5-3．9万年前）出现种群扩张。

英文摘要：

1 041 bp sequence of mitochondrial cytochrome b gene of 43 individuals representing 4 populations from Heshan,Liuzhou and Gulping in Guangxi Province and Yunan in Guangdong Province in the Pearl River （PR） system were sequenced,and 8 hapohypes and 7 variable sites were detected. Haplotype diversity ranged from 0.248 to 0.700 and nucleotide diversity ranged from 0.00022 to 0.00070, suggesting that haplotype diversity and nucleotide diversity were both poor in the studied populations. In the Neighbor-Joining tree individuals from different locality were inter/wined without obvious genealogical nor geographic clusters; Pair-wise Fst ranged from -0.028 to 0.116, but not significant （P〉0.08）,AMOVA analysis suggested that geuetie variation within and among populations were 98.3% and 1.70 respectively,indicating that there were no significant genetic divergence among 4 populations. As expected from the star-like networks,the Tajima＇s D tests and Fu＇s FS tests of the whole populations were negative and significant,and the mismatch distributions were unimodal,indicating a late Pleistocene population expansion at about 15-39 kaBP.