基于线粒体Cytb序列的伯氏肩孔南极鱼群体遗传结构初步分析

选择线粒体Cytb序列为遗传标记分析了伯氏肩孔南极鱼(Trematomus bernacchii)在5个采样点(凯西站、罗斯海、长城站、戴维斯站和中山站)的种群多样性、遗传结构与种群演化历史。从5个采样点98个样本的线粒体Cytb序列中共检测到27种单倍型。与其它分布于南大洋的鱼类相比,伯氏肩孔南极鱼有着相似的遗传多样性特征,即较高的单倍型多样性(haplotype diversity,h=0. 685 90±0. 002 36)和较低的核苷酸多样性(nucleotide diversity,Pi=0. 002 59±0. 013 43)。伯氏肩孔南极鱼种群间的平均遗传距离为0. 39%,分子变异分析(AMOVA)结果显示,组群间的变异为4. 42%(P <0. 05),群体内的为95. 58%(P <0. 05),基于单倍型构建的进化树的结果均表明伯氏肩孔南极鱼群体不具有明显的地理谱系结构。中性进化分析表明伯氏肩孔南极鱼群体在10万年前(大约中更新世时期)经历过快速扩张时期。分子方差分析和Fst表明伯氏肩孔南极鱼的遗传变异主要来自种群内的个体之间,极少数遗传变异来自于群体之间。研究结果显示南极地区的伯氏肩孔南极鱼5个采样点之间具有一定的基因交流,是一个随机交配的群体。

Population genetic structure of Trematomus bernacchii based on the mitochondrial Cytb sequence

The general PCR technology was used for the amplification of mitochdrial Cytb gene of five groups of Trematomus bernacchii(Great Wall Station,Ross Sea,Casey Station,Davies station,Zhongshan Station)to analyze the population diversity,genetic structure,and population evolution history.A total of 98 specimens from five sampling sites were collected and analyzed to find 27 different haplotypes.In most cases,the haplotype diversity(h=0.685 9±0.002 36)level was high,while the nucleotide diversity was relatively low(P i=0.002 59±0.0134 3).The base content of A+T(53%)was higher than that of G+C(47%).The average intra-specific genetic distance was 0.39%.The distance between each sampling sites ranged 0.173 3%~0.714%.The results of AMOVA analysis showed that the variation among the groups was 4.42%(P<0.05)and 95.58%(P<0.05)in the group.Cluster analysis method was used to build phylogenetic trees and determine the evolutionary relationship between the sequences.Neutral evolutionary analysis showed that the groups of Trematomus bernacchii experienced a period of rapid expansion about one hundred thousand years ago(about the Middle Pleistocene).Both molecular variance analysis and F st analysis showed that the genetic variation of Trematomus bernacchii mainly came from individuals in the specimens,and few came from the populations.The results show that there are certain genetic exchanges among five sampling points in the Antarctic,which is a random mating group.