【摘要】 测定了连云港、舟山、防城群体34 ind军曹鱼(Rachycentron canadum)线粒体细胞色素b基因883 bp序列,共检测到5个变异位点,发现6个单倍型,平均单倍型多样性(h)和核苷酸多样性(π)分别为0.324和0.000 4,总体表现出较低的遗传多样性;其中连云港群体遗传多样性最高,单倍型多样性和核苷酸遗传多样性分别为0.473±0.162和0.000 57±0.005 93;而舟山群体没有任何变异。连云港与舟山、防城群体间的FST值分别为0.029(P=0.00)与0.042(P=0.00),舟山与防城群体间的FST为-0.048 03(P=0.00),表明连云港与其它两个群体间仅有较低的分化而舟山与防城群体间无明显分化。分子方差分析(AMOVA)表明,3个群体的遗传变异大部分来自于群体内(74.45%,P=0.000)。军曹鱼单倍型拓扑结构呈星状排列,将3个群体作为一个整体进行Tajimas D和Fu’s Fs分析,二者均为显著负值(FST=-1.922 40,P﹤0.00;FST=-5.735,P﹤0.00),表明军曹鱼在历史上经历了种群的扩张,根据τ的观察值0.364,估算出军曹鱼种群扩张时间约为3.1~1.2万年,即末次冰盛期。更多还原

【Abstract】 Rachycentron canadum is a species widely distributed in warm waters of the bottom of the Atlantic,Indian and western Pacific. It is also a kind of important economic fish. For a long time,affected by natural and human factors,the number of wild Rachycentron canadum has decreased sharply. In order to provide valuable and referable data for the making of Rachycentron canadum conservation policy and for management of the shrinking population,researches on genetic diversity needs to be started.In this study,883 bp mtDNA cytochrome b sequences from 34 individuals collected from Lianyungang( LYG,n =11),Zhoushan( ZS,n =8),Fangcheng( FC,n =15) were sequenced. Results were as follows:1. Genetic diversity: Five variable sites detected in aligned sequences defined six haplotypes,the average haplotypes( h) and nucleotide diversity( π) were 0. 324 and 0. 0004 respectively,indicating a low genetic diversity. LYG contained the highest values of genetic diversity,the haplotype and nucleotide diversity were0. 473 ± 0. 162 and 0. 00057 ± 0. 00593 respectively,whereas ZS showed no genetic variation. 2. Genetic differentiation: Pairwise FSTfrom LYG to ZS and FC were 0. 029( P = 0. 00) and 0. 042( P = 0. 00)respectively,and FSTbetween ZS and FC was- 0. 048 03( P = 0. 00),indicating that there was only relatively low differentiation between LYG and the other two populations,and no obvious differentiation was found in ZS and FC. Analysis of Molecular Variance( AMOVA) showed that most of genetic variation in three populations distributed within populations. This may be due to the fact that the East China Sea,South China Sea and the Yellow Sea have continuity,which promotes groups of communication between genes. Chinese offore Rachycentron canadum showed low genetic diversity( Hd = 0. 324 ± 0. 103,Pi = 0. 0004),and FST,AMOVA and TCS network showed no genetic variation and no obvious geographical pattern system within populations. 3. Population expanding: The haplotype network was star-like,Tajima’s D and Fu’s Fs values in three populations of combined neutrality tests were significantly negative( FST=- 1. 92240,P ﹤ 0. 00; FST=- 5. 735,P ﹤ 0. 00),indicating that cobia in coastal waters of China had experienced populations expansion in history. According to observed τ value( 0. 364),the deduced population expansion of Cobia occurred about 3. 1- 1. 2 million years ago,in last glacial of the maximum. 4. We can speculate that these three groups maybe belong to the same population,for their geographic genetic differention was not obvious. It should be noted that these results do not exclude the possibility of difference in other regions for the number of geographic populations and samples is small. In order to understand and assess the genetic diversity of Rachycentron canadum,we need to use AFLP fingerprinting,microsatellite DNA and relevant techniques,which can understand the genetic differentiation of Rachycentron canadum and provide a theoretical basis for the protection of wild germplasm.更多还原