澜沧江老挝纹胸鮡Cytb基因的序列变异与遗传结构分析

老挝纹胸鮡是分布于澜沧江流域的一种特有鱼类,喜激流底栖生活。为了解其各地理种群间的遗传结构与遗传变异,文章分析了129尾采自澜沧江8条支流水系的老挝纹胸鮡mtDNA细胞色素b基因1 138 bp的序列变异,共发现16个多态性位点,定义了15个单倍型。澜沧江老挝纹胸鮡遗传变异较低,平均单倍型多样性指数和核苷酸多样性指数分别是h=0.299,π=0.299,有3个种群甚至没有变异,分子变异方差分析结果表明各种群内变异大于各种群间变异,种群间没有差异。对老挝纹胸鮡所有种群进行的单倍型错配分布呈现单峰型,中性检验结果均为负值(Tajima’s D=?2.36965,P<0.02;Fu’s Fs=?20.975,P<0.05)表明,澜沧江老挝纹胸鮡自然种群可能经历过近期的种群扩张事件。

Genetic structure and variation of Glyptothorax laosensis of the Lancang River based on cytochrome b

The hillstream catfish, Glyptothorax laosensis, is endemic to basin of Lancang River (also known as Mekong River). Genetic variation was detected within and among 8 populations of G. laosensis in Lancang River based on mitochondrial cytochrome b sequences. A total 16 nucleotides sites were detected in 1 138 bp fragment, which defined 15 haplotypes from 129 sequences. The variation level was very low, with mean h=0.299 and π=0.00032, respectively, and no variation was detected in some populations. Hierarchical analysis of molecular variance (AMOVA) showed no significant genetic structuring among populations. The unimodel mismatch distribution of pairwise haplotype difference and the negatively selective neutrality test (Tajima's D=2.3696, P<0.02; Fu's Fs=20.975, P<0.05) suggested that a recent population expansion had occurred.