半滑舌鳎DNA的群体遗传变异

采用AFLP、RAPD和线粒体细胞色素b基因(Cytb)片段序列分析技术对半滑舌鳎(Cynoglossus semilaevis)群体遗传变异进行研究。分别采用5对选择性引物和18条随机引物对半滑舌鳎3个群体(黄海野生群体、渤海野生群体、养殖群体)进行分析。AFLP和RAPD分析结果表明,黄海群体的遗传多样性高于渤海群体,养殖群体的遗传多样性最低。利用Shannon多样性指数和基因分化系数进行遗传变异来源估算,结果表明,遗传变异主要来自于群体内。同其他鱼类相比,半滑舌鳎群体遗传多样性水平较低。对黄海、渤海野生群体共37个个体的线粒体Cytb基因片段序列进行分析,共检测出5种单倍型,渤海群体内个体序列完全相同,共享单倍型H1;在黄海群体中除检测到单倍型H1外,还检测到其余4种单倍型。Cytb序列分析结果表明,黄海群体遗传多样性较渤海群体丰富,个体间序列变异很小,个体间核苷酸差异数在0~1之间,两群体间无显著遗传差异。通过比较3种分子标记对半滑舌鳎群体间遗传差异的检测和群体间遗传距离的计算,显示AFLP标记对群体间遗传差异的检测最为灵敏,是一种理想的分子标记。

Genetic diversity in Cynoglossus semilaevis by AFLP,RAPD and mtDNA markers

Cynoglossus semilaevis is a commercially important marine fish species,which is widely distributed in the Yellow Sea and the Bohai Sea.C.semilaevis has been intensively studied in China,including its basic biological characteristics and artificial reproduction.However,very few studies on C.semilaevis were focused on genetic diversity,which has become an obstacle to further researches on the protection,management,rational exploitation and sustainable utilization of C.semilaevis resources.The information of genetic diversities in different populations will give us theoretical guidance in breeding and genetic improvement.In this study,three molecular markers including AFLP,RAPD and the mitochondrial cytochrome b gene sequencing techniques were used to analyze the genetic diversity and variation of three populations of C.semilaevis.The genetic diversity in C.semilaevis was detected by five selective primer pairs and 18 random primers.The AFLP and RAPD analysis results indicated that the genetic diversity in the Yellow Sea population is higher than that in the Bohai Sea population and the genetic diversity in cultured population is the lowest among these three populations.Shannon index and Gst suggested that the partition of genetic variation be mainly distributed within populations.Compared with other species,populations of C.semilaevis presented relatively low genetic diversity.As detected by cytochrome b sequencing,a total of five haplotypes were found in 37 individuals from the Yellow Sea and the Bohai Sea populations.There were five haplotypes(H1,H2,H3,H4 and H5) in the Yellow Sea population,but only one haplotype(H1) in the Bohai Sea population.However,to significant genetic differentiation between these two populations was detected based on Cyt b gene.According to the results,it can be concluded that AFLP is one of the useful molecular markers to detect genetic diversities.However,AFLP markers are inherited as dominant markers,further studies in terms of utilizing co-dominant markers are needed for a better understanding of the genetic diversity in this species.