基于线粒体控制区序列的三疣梭子蟹增殖放流亲蟹遗传多样性研究

为研究山东沿海三疣梭子蟹增殖放流亲蟹群体的遗传多样性状况,实验采用536 bp的线粒体DNA控制区片段作为分子标记,对4个亲蟹群体的遗传多样性和遗传结构进行了分析。结果显示,301个三疣梭子蟹个体共检测到155个单倍型,4个群体的单倍型多样度为0.972 3~0.993 0,核苷酸多样度为0.021 2~0.023 6,表现出丰富的遗传多样性。AMOVA分析和Fst分析结果均显示,4个三疣梭子蟹亲蟹群体间遗传分化微弱,未形成明显的遗传结构,NJ系统树中未出现与各群体相对应的的谱系分支。研究表明,4个增殖放流亲蟹群体的遗传多样性丰富,且其遗传结构与放流海域的野生群体间没有明显分化,种质资源质量较好。此外,群体历史动态分析显示,渤海南部和黄海北部的三疣梭子蟹历史上曾经历过群体扩张事件。

Genetic diversity of swimming crab(Portunus trituberculatus)from four broodstock populations in stock enhancement inferred from mitochondrial control region

Portunus trituberculatus is an economically important marine crab distributed along the coast waters of China, Japan, Korea and Malaysia Islands. In recent decades, the wild population has been constantly decreased due to overfishing and habitats destruction. To protect and recover the P. trituberculatus resource, a large scale of stock enhancement has been carried out in the coastal waters of China. As the stock enhancement activities may change the genetic variability and genetic composition of the recipient wild populations, it is necessary to carry out genetic monitoring of broodstocks and their offsprings for the long-term sustainability of wild populations. In present study, genetic diversity and population structure of 4 P. trituberculatus broodstock populations used in stock enhancement were detected according to the sequence of mitochondrial control region. 155 mtDNA haplotypes were observed in 301 P. trituberculatus individuals, among which only 20 haplotypes were shared by different populations. The gene diversity index ranged from 0.9723 to 0.9930, while the nucleotide diversity index ranged from 0.0212 to 0.0236, both of which showed a high level of genetic diversity for broodstock populations. The result of AMOVA suggested that 98.70% of the genetic differentiation occurred within populations. The Fst values between populations ranged from -0.0025 to 0.0230, which indicated a little genetic differentiation and no significant genealogical structure among 4 populations together with the result of AMOVA. And no pedigree branch corresponding to different populations had been observed in the neighbor-joining tree. All above suggested that wild populations from where the broodstocks were collected had little genetic differentiation between each other. To sum up, each of the 4 broodstock populations had abundant genetic diversity and similar genetic structure with the wild populations to be supplemented, which reflected a good quality of the germplasm resource. The mismatch distribution of pairwise nucleotide and the negatively selective neutrality test suggested that P. trituberculatus of the south Bohai sea and north Yellow sea had experienced a demographic or spatial expansion in history.