基于线粒体DNA控制区序列的6个凡纳滨对虾(Litopenaeus vannamei)养殖群体的遗传多样性分析

Analysis of the Genetic Diversity of Six Populations of Cultured Litopenaeus vannamei Based on the Mitochondrial DNA Control Region

关键词:  凡纳滨对虾  mtDNA控制区序列  遗传多样性  遗传分化  雌雄群体差异  生长差异

Key words:  Litopenaeus vannamei  Control-region of mtDNA  Genetic diversity  Genetic differentiation  Male and female populations differences  Growth differences

摘要:

运用线粒体DNA(mtDNA)控制区部分基因序列测序技术对6个凡纳滨对虾养殖群体(S1、S2、G1、G2、K1和Sg)的遗传多样性和系统进化关系进行了分析。结果显示，在检测到的146个单倍型中，144个为单群体特有，其余两个为群体S1和S2共享。6个群体的单倍型多样性(Hd)为0.42–0.99，核苷酸多样性(π)为0.00–0.08，其中，单倍型多样性最高的是群体K1 (Hd=0.99±0.01)，核苷酸多样性最高的是群体S2 (π=0.08±0.04)。综合考虑，遗传多样性最低的为群体S1 (Hd=0.42±0.08, π=0.00)，遗传多样性最高的是群体S2 (Hd=0.88±0.02, π=0.08±0.04)。AMOVA分析结果显示，来自群体间的遗传差异(46.98%)略低于来自群体内的遗传差异(53.02%)。各群体间的遗传分化Fst值均为正值(0.173–0.974)，表明6个群体间存在较大程度的遗传分化差异。基于遗传距离的构建的UPGMA系统进化树和基于单倍型结果构建的NJ聚类图显示，系统进化树主要分为两支：S1和S2群体聚在一起成为一支；G1和G2群体首先聚在一起，再与Sg群体聚在一起，随后与K1群体聚成另一支，6个群体单倍型的聚类关系与遗传距离的进化关系类似。进一步对群体内雌雄群体间遗传差异进行分析发现，同一群体的雌雄群体间遗传多样性水平相近，雌雄群体间基本出现轻微到明显的遗传分化；比较相同群体不同生长速率的个体的遗传参数发现，生长较快群体与生长较慢群体间可能出现一定程度的遗传分化差异；对同一公司不同时间购买的群体分析发现，购买间隔较长(7–9个月)的群体之间的遗传分化值可能会大于不同种虾公司间群体的遗传分化值。

Abstract:

In this study we analyzed the genetic diversity and phylogenetic relationships of six populations of cultured Litopenaeus vannamei (S1, S2, G1, K1, G2, and Sg) by sequencing their partial DNA sequence of the mitochondrial (mtDNA) control region. The results showed that 144 out of 146 haplotypes were unique for different populations, and the other 2 haplotypes were shared by S1 and S2. The haplotype diversity (Hd) was 0.42−0.99 in the 6 populations, and the nucleotide diversity (π) was 0−0.08. The population with the highest haplotype diversity was K1 (Hd=0.99±0.01), and the population with the highest nucleotide diversity was S2 (π=0.08±0.04). S1 had the lowest genetic diversity (Hd= 0.42±0.08, π=0.00), while S2 showed the highest genetic diversity (Hd=0.88±0.02, π=0.08±0.04). The AMOVE analysis suggested that the genetic difference between different populations (46.98%) was slightly lower than that within the population (53.02%). Fst values of genetic differentiation between populations were all positive (0.173−0.974), which indicated remarkable genetic differentiation between the 6 populations. The UPGMA phylogenetic tree (based on the genetic distance) and the NJ dendrogram (based on haplotype clustering) showed that the evolutionary tree was divided into two branches: S1 and S2 belonged to one branch. G1, G2 and Sg clustered first, and then converged with K1 to form another branch. For the 6 populations the clustering relationship based on haplotype was similar to that based on the genetic distance. The genetic differences between males and females within a population was minimum, but the degrees of inter-population genetic differences varied slightly or significantly. We compared the genetic parameters of individuals with different growth rates in the same population and found that there might be a certain degree of genetic differentiation between the fast-growing and slow-growing groups. We also analyzed the genetic differentiation between populations purchased at different time from the same company. It showed that the Fst value between populations purchased with longer interval (7 to 9 months) from the same company might be greater than that between populations purchased from different companies.