基于线粒体D-loop区的抚仙湖鱇浪白鱼遗传多样性分析

为了解鱇浪白鱼(Anabarilius grahami)种质资源和遗传多样性现状, 采集抚仙湖7个地理群体共计133尾鱇浪白鱼, 基于线粒体D-loop控制区全序列开展遗传多样性分析。结果表明: 鱇浪白鱼D-loop控制区序列的A+T含量(62.28%)高于G+C(37.72%); 共发现变异位点40个, 定义单倍型36个, 整体单倍型多样性指数(H_d)为0.791±0.036, 核酸多样性指数(π)为0.00254±0.00027, 呈“高H_d低π遗传分布”; 抚仙湖西岸各群体(H_d = 0.826—0.846, π=0.00236—0.0031)较东岸各群体(H_d =0.657—0.805, π=0.00204—0.00271)的平均遗传多样性呈现出“西高东低”的分布特征; 其中, 明星鱼洞(MX)群体的鱇浪白鱼单倍型多样性和核酸多样性指数最高, 下坝(XB)群体的鱇浪白鱼单倍型多样性和核酸多样性指数最低; 路岐(LQ)群体与海镜(HJ)群体遗传距离最远(0.00296), 但7个群体遗传分化不显著(F_st=0.01954, P＞0.05); 中性检验(Tajima’s D=–1.73617, P=0.03729; Fu’s F_s=–1.64259, P=0.23943)与核酸错配分布均表明抚仙湖鱇浪白鱼群体未经历种群扩张事件。综上所述, 抚仙湖鱇浪白鱼展现出高单倍型多样性和低核酸性的遗传多样性特征, 可能与线粒体进化速度较快有关; 而鱇浪白鱼扩散式生活史及人工增殖放流可能是造成其群体间遗传分化不显著的主要原因。研究利用线粒体DNA开展了抚仙湖鱇浪白鱼遗传多样性现状的初步评估, 为后续鱇浪白鱼种质资源保护及种业开发提供重要理论依据。

GENETIC DIVERSITY ANALYSIS OF MITOCHONDRIAL D-LOOP REGION OF ANABARILIUS GRAHAM IN FUXIAN LAKE

Anabarilius graham is a kind of native fish in the Fuxian Lake, Yunnan Province, and its germplasm resources had been drastically reduced since the 1990s due to overfishing and invasive species. After many years of artificial propagation and releasing, in order to realize the present genetic diversity, we sampled a total of 133 Anabarilius graham from 7 geographic populations and conducted genetic diversity analysis based on sequences of D-loop control region. The results showed that A+T base composition (62.28%) was higher than the C+G combination (37.72%); A total of 40 polymorphic sites were identified and 36 haplotypes were defined. The overall haplotype diversity index (H_d) was 0.791±0.036 and the overall nucleic acid diversity index (π) was 0.00254±0.00027, which suggested a distribution of “high H_d and low π”. The average H_d and π of west group (H_d=0.826—0.846, π=0.00236—0.0031) was higher than that of east group (H_d=0.657—0.805, π=0.00204—0.00271). The highest and lowest index value of nucleic acid diversity and haplotype diversity were identified in MX and XB population, respectively. What’s more, the furthest genetic distance was found between LQ and HJ population, but insignificant genetic differentiations were identified in 7 populations. The results of the neutrality test (Tajima’s D=–1.73617, P=0.03729; Fu’s F_s=–1.64259, P=0.23943) and nucleotide mismatch distribution revealed that no population expansion happened in evolutionary history of Anabarilius graham. In conclusion, the distribution of “high H_d and low π” was identified in Anabarilius graham, which could be caused by faster evolutionary speed in mitochondrion. Meanwhile, insignificant genetic differentiations among each population may be caused by the dispersive life history of Anabarilius graham and artificial releasing. This study preliminarily revealed the current genetic diversity of Anabarilius graham in the Fuxian Lake, and provided necessary basis for the protection of germplasm resources and genetic breeding.