基于线粒体COⅠ基因序列的梭鲈野生群体遗传结构

Genetic structure of wild Sander lucioperca populations based on COⅠ gene

摘要:

为了解梭鲈种群的遗传结构，实验利用线粒体细胞色素c氧化酶Ⅰ亚基(COⅠ)基因部分序列分析了中国6个和中亚2个群体的遗传差异，并与欧洲群体的单倍型序列进行了比较。结果在640 bp的COⅠ基因序列中检测到5个变异位点，定义了7种单倍型，发现Hap1为8个梭鲈群体的共享单倍型，且与欧洲群体的HapA相同，在中国群体所占比例(93.36%)高于中亚群体(72.58%)和欧洲群体(53.85%)；Hap2和Hap3是中国群体的特异单倍型，而Hap4~Hap7为中亚群体的特异单倍型。单倍型序列的聚类图和网络图均显示Hap1/A为梭鲈群体的原始单倍型，中国和中亚群体的特异单倍型相对于原始单倍型仅有1~2个位点的变异，属于Hap1/A的亚型，与欧洲群体的特异单倍型具有较大的差异。每个群体检测到1~4种单倍型，斋桑湖(ZS)群体单倍型最多，而中国的腾格里湖(NX)、兴凯湖(XK)和鸭绿江(YJ)群体仅有1个单倍型(Hap1)；塔什干(TS)群体的单倍型多样性(H_d)和核苷酸多样性(π)最高(H_d=0.514±0.069; π=0.000 79±0.000 11)，其次是ZS群体，而中国梭鲈群体的多样性参数较低。AMOVA分析结果显示，梭鲈群体间遗传变异占20.74%，群体间遗传分化程度较高(0.15≤F_st=0.207 36<0.25)，TS群体与ZS群体和中国群体间的遗传分化极大(F_st>0.25)，中国群体中仅黑河(HH)群体与其他群体的遗传分化较大，而中国其他5个群体间无遗传分化。基于群体间遗传距离的系统进化树显示，来自中国的6个梭鲈群体与哈萨克斯坦的ZS群体聚为一支，而乌兹别克斯坦的TS群体独立为一支。研究结果为梭鲈群体的繁殖及放流管理提供了参考。

关键词:梭鲈;线粒体COⅠ基因;野生群体;遗传结构

Abstract:

The pike-perch (Sander lucioperca) is a native fish species in European and Asian river basins. Owing to its fast growth rate, strong adaptability, and high nutritional value, it has become a promising candidate species for aquaculture. In China, artificial reproduction of pike-perch has been realized, and most of its parents are caught from wild populations. However, the genetic background and diversity information of wild populations are still limited, which is not conducive to the establishment of genetic breeding management strategies. In order to investigate the genetic structure of S. lucioperca wild populations, we analyzed the genetic differences of six populations in China and two populations in Central Asia using partial mitochondrial COⅠ gene sequences, and compared them with the haplotype sequences of European populations. As a result, 5 variable sites were detected in the 640 bp COⅠ gene sequence, and 7 haplotypes were defined, among which Hap1 was the shared haplotype between eight populations, and was identical to HapA of European groups. The proportion of Hap1 in Chinese populations (93.36%) was higher than that in Central Asian populations (72.58%) and European population (55.56%). Hap2 and Hap3 were specific haplotypes of Chinese populations, while Hap4, Hap5, Hap6, and Hap7 were specific haplotypes of Central Asian populations. The cluster and network analysis of haplotype sequences showed that Hap1/A was the ancestral haplotype in Sander lucioperca populations. The specific haplotype of Chinese and Central Asian populations belonged to Hap1/A subtype with only 1-2 loci variation compared with the ancestral haplotype, which was quite different from the specific haplotype of European populations. The number of haplotypes per population ranged from one to four, with the largest number of haplotypes in the Zaysan Lake (ZS) population, while there was only one haplotype (Hap1) in Tengger Lake (NX), Xingkai Lake (XK) and Yalu River (YJ) populations in China. The haplotype diversity (H_d) and nucleotide diversity (π) of TS population were the highest (H_d=0.514±0.069; P_i=0.000 80±0.000 11), followed by ZS population, while the diversity parameters of six populations in China were lower. The AMOVA analysis showed that the genetic variation among S. lucioperca populations accounted for 20.74%, and the degree of genetic differentiation (F_st) among populations was relatively high (0.15≤F_st=0.207 36<0.25). The genetic differentiation of the TS and the ZS, the TS and the six Chinese populations all were great (F_st>0.25). Among Chinese populations, Heihe (HH) population had great genetic differentiation against other populations, while there was no genetic differentiation between the other five populations. The phylogenetic tree based on genetic distance showed that six populations from China and ZS population from Kazakhstan were clustered into one branch, while TS population from Uzbekistan was a separate branch. The results of this study provide a reference for the breeding and releasing management of S. lucioperca populations.

Key words:Sander lucioperca;mitochondrial cytochrome c oxidase subunit Ⅰ (COⅠ) gene;wild population;genetic structure