测定了捕自福建近海闽东渔场和闽南渔场竹荚鱼(TrACHuruS JAPOnICuS)的线粒体dnA(MTdnA)控制区和细胞色素b基因(CyT b)序列。获得了长度为861--866 bP的控制区全序列。60个样本中共检测到66个变异位点和53个单倍型,平均单倍型多样性(H)为0.993,核苷酸多样性(π)为1.093。930 bP的CyT b部分序列共有37个变异位点,从41个样本中得到25个单倍型,平均单倍型多样性(H)和核苷酸多样性(H)分别为0.937和0.336。CyT b片段编码330个氨基酸,氨基酸序列无变异位点,仅有1个氨基酸单倍型。竹荚鱼闽南群体MTdnA序列的遗传多样性高于闽东群体。构建的单倍型系统树未出现明显的以地方群体为单位的家系式分支或者聚簇,群体间的遗传距离(0.01)也较小。分子方差分析(AMOVA)显示,2个群体的遗传变异绝大部分来自群体内部,群体间无显著遗传分化。中性检验和核苷酸不配对分析显示,福建近海竹荚鱼近期经历过种群扩张。种群扩张、扩散能力和东海环流可能促进闽东渔场和闽南渔场竹荚鱼群体间频繁的基因交流,并导致群体间较高的遗传同质性。Trachurus japonicus is a pelagic fish in Carangidae family mainly distributing in coastal waters of China,Japan and Korea.It has been an important commercially marine fish in China since 1960s.But the natural population genetics and resource quantity of T.japonicas have been declined rapidly due to over-fishing,degrada-tion of its natural habitats and so on in recent years,whereas little knowledge is available about its population ge-netic structure.The distribution of genetic diversity and genetic structure in wild stocks of T.japonicus seems emergent and the conservation strategies should be developed nowadays.The complete mitochondrial DNA con-trol region(861-866 bp) was amplified by means of PCR and sequenced from two T.japonicus populations col-lected from coastal waters in Eastern Fujian(n=30)and Southern Fujian(n=30).The result showed that 66 variable nucleotide sites were detected and 53 haplotypes were identified in two populations for control region sequence,but only three shared haplotypes were observed.The global haplotype diversity(h) and nucleotide diversity() were 0.993 and 1.093,respectively.Thirty-seven variable sites were recoded in the aligned sequences of partial cytochrome b gene(930 bp),and 25 haplotypes were recovered in 41 specimens.The average haplotype diversity(h) and nucleotide diversity() of two populations were 0.937 and 0.336,respectively.Cytochrome b gene en-coded 330 amino acids and the amino acid chain had only one haplotype.Each population had good haplotypic diversity and low nucleotide diversity in both mtDNA control region and cytochrome b,and the genetic diversity in Southern Fujian population was higher than that in Eastern Fujian one.Decapterus maruadsi was chosen as out-group in this study,and neighbor-joining(NJ) phylogenetic tree was constructed based on the haplotypes from the two populations of T.japonicus.The result showed that the two populations might have originated from one clade.Analysis of molecular variance(AMOVA) by ARLEQUIN version 3.1 revealed that the variation occurred mostly within the two populations for no significant population genetic structure existed throughout examined range,which was in consistent with neighbor-joining phylogenetic tree and haplotype network.The pairwise Ki-mura 2-paramter genetic distances calculated by MEGA version 4.0 were also small between the two populations.The demographic history of T.japonicus was examined by using neutrality tests and mismatch distribution analy-sis.The neutral test of Fu' Fs,which is devised specifically to detect population expansion and is sensitive to the presence of singletons in a sample,showed several highly significant negative values and the pairwise nucleotide differences distribution showed a singlet,indicating population expanded 62 000-205 000 years ago.The result showed that T.japonicus had low genetic diversity and genetically homogeneous population structure between the two populations,and this might be caused by population expansion,strong diffusion capacity and oceanographic current in East China.All these results would be very important and useful for making scientific strategy for the natural resource protection and genetic breeding of this fish.福建省科技项目(2007I0005
