于线粒体COI基因的6个黄鳝群体遗传多样性

为研究我国主要养殖区域黄鳝（Monopterus albus）的遗传多样性，利用线粒体细胞色素c氧化酶亚基I（cytochrome C oxidase subunit I，COI）基因对来源于湖北、江西、安徽、湖南、重庆和山东的6个黄鳝群体共187个样本进行遗传多样性分析。结果表明长度为646 bp的COI基因序列在6个群体的碱基含量基本相同，碱基T、C、A和G的平均含量分别为27.7%，30.7%，24.5%和17.1%，包括61个变异位点，其中单位点突变16个，简约信息位点45个，变异位点以C/T间的转换为主。6个群体中共检测到38种单倍型，单倍型多样性（H_d）为0.886，核苷酸多样性（π）为0.01094，群体整体遗传多样性高，湖北和山东群体遗传多样性都较高（H_d>0.8），湖南群体和江西群体的遗传多样性次之（H_d>0.5），而安徽和重庆两个群体的遗传多样性都较低（H_d<0.5）。6个群体间有显著的遗传分化，基因交流贫乏（N_m<1）。群体分子变异分析（AMOVA）显示，6个黄鳝地理种群群体内的遗传变异高于群体间的遗传变异，其遗传变异主要发生在群体内部。遗传结构和系统发育树显示湖南群体与其他5个群体的遗传关系较远。重庆群体可能由单一或很少几个群体进化而来的，起源比较单一。就目前而言，黄鳝野生种质资源遗传多样性丰富，苗种频繁流动和人工养殖尚未对其种群结构造成较大影响，仍有较强的环境适应能力和良好的育种潜力。

Genetic diversity of six Monopterus albus populations based on COI gene sequences

The swamp eel () belongs to the family Synbranchidae, order Synbrachiformes. It is widely distributed in shallow lakes, rice fields, and swamps areas, especially in the Yangtze River region in China. It is one of the most important economic freshwater fishes because of its high meat quality, delicious taste, and medicinal value. Recently, it has been widely cultured in some regions, such as Hubei, Jiangxi, Anhui, and Hunan provinces. The production of in China in 2016 was 386,137,000 kg. However, most fries are sourced from fishing natural populations owing to a scarcity in fingerling resources from artificial reproduction. Therefore, with the challenges of overfishing and environmental deterioration, natural resources are sharply decreasing. It is vital to analyze the genetic background to conserve and utilize this fish effectively. The genetic diversity of six populations with 187 individuals from Hubei, Jiangxi, Anhui, Hunan, Chongqing, and Shandong was investigated based on the mitochondrial cytochrome oxidase I (COI) gene sequence. The results showed that the nucleotide composition of 646 bp in length was similar in the six populations. The average content of T, C, A, and G was 27.7%, 30.7%, 24.5%, and 17.1%, respectively. There were 61 mutation sites containing 16 singleton mutation and 45 parsimony informative sites. A total of 38 haplotypes were defined in all populations, and overall haplotype diversity () were 0.886 and 0.01094, respectively. In the six populations, the genetic diversity of Hubei and Shandong populations were the highest ( > 0.8), Hunan and Jiangxi populations were relatively high ( > 0.5), and Anhui and Chongqing populations were the lowest ( < 0.5). There was obvious genetic differentiation among six populations and gene flow was limited. An AMOVA analysis indicated that the source of variation within the populations was higher than between the populations. The major genetic variation was derived from variation within populations. A neighbor-joining phylogenetic tree showed that the genetic distance between the Hunan and other five populations was distant. The Chongqing population could originate from one single ancestor and a few populations. To date, the genetic diversity of natural populations is abundant. Furthermore, the genetic diversity did not sharply decrease, owing to the impact of the transaction and culture of M. albus to the environment and its breeding potential make this species a potentially excellent germplasm resource.