中国东南沿海弹涂鱼科常见鱼类的遗传多样性和DNA条形码

为了探究中国东南沿海海岸线经济开发、海水污染等对该区域生物遗传多样性的潜在影响,本文使用COI基因作为DNA条形码,对从中国东南沿海广东汕头、福建东山、福建云霄、福建泉州、福建霞浦、上海崇明6个地点采集的大弹涂鱼(Boleophthalmus pectinirostris)、弹涂鱼(Periophthalmus modestus)和青弹涂鱼(Scartelaos histophorus)进行种间和种内的遗传学分析。遗传多样性分析显示,青弹涂鱼的核苷酸多样性(0.0018)在3个种中最低;青弹涂鱼广东汕头种群的核苷酸多样性(0.0018)比福建云霄种群低;大弹涂鱼的上海崇明种群核苷酸多样性(0.0021)低于其他5个地理种群。物种水平分析表明,3个物种间分化明显,种间与种内遗传距离有明显差异;不同种的单倍型在系统发育树上聚成3个高度支持的独立分支。种群水平分析显示,大弹涂鱼的6个不同地理种群之间有共享单倍型,地理种群间与地理种群内的遗传距离重叠;各地理种群之间的基因流较频繁(Nm>4);青弹涂鱼的分析情况与大弹涂鱼基本一致。大弹涂鱼和青弹涂鱼的单倍型在系统发育树上均呈现多系或并系分布格局,并未按地理位置分成不同的单系群。本研究表明,应及时加强3种鱼类及其野生种群遗传多样性的保护,且COI基因对种一级的识别明确可靠,而在地理种群水平的识别则比较困难,有待进一步深入研究。

Genetic diversity and DNA barcoding of mudskipper common species along southeast coasts of China

In order to explore the potential impacts of economic development and seawater pollution along the southeast coasts of China on the regional biological resources genetic diversity, the samples of three mudskipper common species (Boleophthalmus pectinirostris, Periophthalmus modestus, and Scartelaos histophorus) were collected from six localities (Shantou of Guangdong; Dongshan, Yunxiao, Quanzhou and Xiapu of Fujian; and Chongming of Shanghai), with their mitochondrial cytochrome c oxidase subunit I (COI) sequenced to make their intra- and interspecies genetic analysis. Among the three mudskipper species, S. histophorus possessed the lowest nucleotide diversity (0.0018). The nucleotide diversity of the S. histophorus population in Shantou was lower than that in Yunxiao. Among the populations of B. pectinirostris, the population in Chongming possessed the lowest nucleotide diversity (0.0021). A total of 100 haplotypes were identified. There was an obvious differentiation among the three mudskipper species, and an obvious difference between the intra- and interspecies genetic distances. Phylogenetic analysis showed that the halotypes of the species could be clustered into three highly supported independent clades. The six B. pectinirostris geographic populations had the same halotypes and the overlapped genetic distances between and within the populations, and the gene flow between the populations was quite frequent (Nm>4). S. histophorus had the similar situations. The halotypes of B. pectinirostris and S. histophorus on phylogenetic trees presented disordered distribution pattern, and didn’t form monophyletic clades based on geographic division. It was suggested that the preservation of the three mudskippers and their wild populations’ genetic diversity should be timely intensified, and, as a DNA barcoding, COI gene could be credible in identifying species at species level, but less feasible at population level.