福建近海蓝圆鲹群体遗传结构分析

测定了福建近海蓝圆鲹(Decapterus maruadsi Temminck&Schlegel)2个群体共60尾个体的线粒体DNA(mtDNA)控制区序列,探讨了闽东和闽南群体遗传结构和遗传多样性.结果显示:获得长度为834～838 bp的控制区部分序列,在所测的60个样本中,共检测到23个变异位点,定义了28个单倍型,平均单倍型多样性(h)为0.948±0.0145,核苷酸多样性(π)为0.004 99±0.002 79,核苷酸差异数(K)为4.173±2.104,提示了福建近海蓝圆鲹具有较高的遗传多样性水平.构建的单倍型邻接关系树没有明显的以地理群体为单位的家系式分支出现,单倍型网络图也未显示出单倍型和地理位置的对应关系.Tajima's D和Fu's Fs中性检验及核苷酸不配对分析暗示了蓝圆鲹闽南群体在63 000年前可能发生过扩张事件,而闽东群体符合中性理论进化,2个群体不同的历史动态可能是由于小冰河期海区间的气候差异和闽东群体的过度利用所致.分子方差分析(AMOVA)表明,遗传变异全部存在于群体内,2个群体间具有紧密的基因流和较低的遗传分化,群体问和群体内的Kimura双参数遗传距离均较小.可知:福建近海蓝圆鲹遗传多样性较高,闽东和闽南群体的遗传结构相似,不存在显著的遗传分化.因此,建议将闽南渔场和闽东渔场作为一个种质资源评估、管理和保护单元.

Population Genetic Structure Analysis of Decapterus maruadsi from Fujian Coastal Waters

The partial mitochondrial DNA(mtDNA)control region sequences were amplified from two Decapterus maruadsi populations collected from coastal waters in Eastern Fujian(n=30)and Southern Fujian(n=30)and then sequenced to test the population genetic structure and genetic diversity.The results showed that a total of 23 variable sites were found in the aligned sequences of 834~838 bp,and 28 haplotypes were defined in 60 specimens.High levels of haplotype diversity(h=0.948±0.0145),low levels nucleotide diversity(π=0.004 99±0.002 79)and the pairwise nucleotide differences(K=4.173±2.104)were detected,indicating a high level of genetic diversity.Neighbor-joining(NJ) phylogenetic tree was constructed based on the haplotypes from the two populations.However,there was not any genealogy appearing in the haplotypes tree.The star burst structure of the haplotype network also suggested no population structure existed.The demographic history of D.maruadsi was examined by using neutrality tests and mismatch distribution analysis.Demographic expansion was observed in Southern Fujian,starting within the interglacial period before 63 000 a,whereas no population expansion was detected in Eastern Fujian.The regional climate variations caused by the Little Ice Age and overexploitation of Eastern Fujian were predicted to account for the distinct demographic history among clades.Analysis of molecular variance(AMOVA) by ARLEQUIN Version 3.1 revealed all variation occured within populations,which signaled no significant genetic structure throughout the examined range which was in conformity with Neighbor-joining phylogenetic tree and haplotype network.The pairwise Kimura 2-paramter genetic distances calculated by the MEGA Version 4.0 were also small between the two populations.The result showed that D.maruadsi had high genetic diversity and genetically homogeneous population structure between the two populations in Eastern Fujian and Southern Fujian,this might be emerge from strong diffusion capacity,big population size,population expansion and oceanographic current in Fujian coastal waters.The knowledge on genetic diversity and genetic structure will be crucial to establish appropriate fishery management stocks for the fish.