基于线粒体控制区部分序列的大青鲨种群遗传结构研究

摘要

The sequence variations and population genetic structures were studied by partial fragments of mtDNA control region in 165 blue shark Prionace glauca samples collected from 5 locations in Pacific, Atlantic and Indian oceans. A total of 145 mtDNA haplotypes and 110 variable sites were detected in the 694 bp fragments of the mito-chondrial control region, with nucleotide composition of A:33. 46%, T:36. 40%, C:18. 61%, G:11. 53%. The haplotype diversities were found to be high and the mean haplotype diversity was 0. 997 3±0. 001 4,while the nu-cleotide diversity was found to be 0. 015 10±0. 000 91. The AMOVA test revealed that there was 99. 28% of the ge-netic variation within populations and 0. 72% of the genetic variation among populations. The neighbor-joining tree revealed no significant genetic differentiation among five sampling locations. Low Fst values and high Nm values from this investigation indicated that there were no significant genetic differentiations among the five localities due to the high rates of gene flow between the sampled populations.%基于线粒体DNA ( mtDNA)控制区部分序列对采集自太平洋、大西洋、印度洋的5个大青鲨Prion-ace glauca群体165尾成鱼样本进行遗传多样性与遗传结构分析。结果表明：165尾大青鲨的mtDNA控制区片段长为694 bp,共得到110个变异位点,定义了145个单倍型,碱基组成中A为33.46%, T为36.40%, C为18.61%, G为11.53%, G+C含量为30.14%；单倍型多样性指数( Hd )在各个采样点都较高,平均值为0.9973±0.0014,核苷酸多样性指数(π)为0.01510±0.00091,这表明大青鲨群体的遗传多样性水平很高,遗传资源丰富；分子方差分析表明,99.28%的遗传变异出现在种群内,0.72%的遗传变异来自于种群间；采用邻接法构建的系统发育树表明,5个群体间未形成显著的遗传结构,群体间的高基因交流值( Nm )和低遗传分化指数( Fst )揭示了三大洋的大青鲨群体间基因交流频繁,不存在显著的遗传分化。