岩原鲤遗传多样性和种群历史动态研究

研究基于线粒体DNA细胞色素b (mtDNA Cyt b)基因序列,对2013—2017年间采自我国长江上游贵州省赤水市和重庆市万州区共161尾岩原鲤(Procypris rabaudi)个体进行了遗传多样性分析。结果表明,在所有个体序列中, A、T、C、G碱基的平均含量分别为30.2%、27.9%、28.2%和13.7%,(A+T)含量(58.1%)明显大于(G+C)含量(41.9%),表现出较强的反G偏倚性。161条序列检测到18个变异位点,定义了15种单倍型,整体单倍型多样性指数(Hd)、核苷酸多样性指数(Pi)分别为0.590、0.00132;岩原鲤赤水群体遗传多样性水平低于万州群体;万州群体的单倍型多样性和核苷酸多样性均呈现逐年降低的趋势,但是赤水群体的单倍型多样性和核苷酸多样性呈现逐年增加的趋势。基于最大似然法构建的系统发育树和单倍型网络图结果一致,万州和赤水群体并未形成明显的地理分布格局。Mega 6.0软件计算2个群体之间的遗传距离为0.001。Fst值统计表明, 2个地理群体间Fst值为0.01749 (P>0.05),群体间没有出现遗传分化现象。两群体间基因交...

STUDY ON GENETIC DIVERSITY AND POPULATION HISTORICAL DYNAMICS OF PROCYPRIS RABAUDI (TCHANG) ENDEMIC IN THE UPPER YANGTZE RIVER

The rock carp, Procypris rabaudi (Tchang), is an endemic and economic fish in the upper reaches of the Yangtze River and its biological resource had markedly declined. This study analyzed mitochondrial DNA (mtDNA) cytochrome b (Cyt b) gene sequence analysis to investigate the genetic diversity of 161 individuals in Chishui ranges and Wanzhou ranges of the upper Yangtze River from 2013 to 2017. The results indicated that the average content of base composition was 30.2% A, 27.9% T, 28.2% C and 13.7% G, and the content of A+T (58.1%) was significantly higher than that of G+C (41.9%). The data showed a strong bias against G. Fifteen haplotypes were identified in 161 sequences, and 15 haplotypes were defined. The overall haplotype diversity index (H_d) and nucleotide diversity index (P_i) were 0.590 and 0.00132, respectively. The results of phylogenetic tree by Maximum likelihood method were consistent with haplotype network map, and no obvious geographical distribution pattern was formed. The genetic distance between the two populations was 0.001, and the mean genetic distance within the population was 0.001. F_st statistics showed that the F_st (fixation index) value was 0.01749 (P>0.05), and there was no significant partition differentiation between the two geographical populations. There were frequent gene flows between Wanzhou and Chishui populations (value of Nm is 24.71). Analysis of Molecular Variation (AMOVA) on Cyt b gene revealed that the largest component of variance mainly occurred within populations (98.25%). The neutrality test indicated that the population expansion had already occurred among the rock carp in Wanzhou populations about 0.15 million years ago. According to the comprehensive analysis, the genetic diversity of Chishui population is lower than that of Wanzhou population, but there are widely gene flows among these two local populations. The genetic diversity of rock carp is relatively lower than other endemic fishes. It is urgent to propose reasonable management measures to strengthen the protection of this species in the Yangtze River.