陕西省林麝mtDNA D-loop区序列结构和种群遗传多样性

林麝(Moschus berezovskii)曾广泛分布于中国,由于盗猎和栖息地缩小,秦岭地区野生种群数量迅速下降,圈养繁殖种群已成立了几十年,但大多数圈养种群的遗传背景不清,种群规模增长非常缓慢。为了给这一物种的保护和管理提供有用的信息,调查了陕西省林麝1个圈养种群3个野生种群线粒体DNA(mt DNA)D-Loop 632 bp片段的遗传多样性和种群结构。在69个个体中其碱基组成为A+T的平均含量63.2%高于G+C含量36.8%,共检测到变异位点171个(约占总位点数的27.05%)。核苷酸多样性(Pi)为0.04424,平均核苷酸差异数(K)为19.908。69个个体分属32个单倍型,单倍型间的平均遗传距离(P)为0.070。32个单倍型构建的NJ系统树聚为3个分支,4个林麝群体中的单倍型是随机分布的。4个群体的平均遗传距离为0.043(标准误SE为0.005),凤县养殖场群体与留坝和陇县群体的亲缘关系较远。单倍型间的平均遗传距离为0.043,可见其遗传分化尚未达到种群分化的水平。结果表明,陕西省林麝群体mt DNA D-loop区序列存在着较丰富的变异和遗传多样性,凤县野生群体和凤县养殖场群体的核苷酸多样性和单倍型多样较高,养殖场种群没有出现近亲繁殖及遗传多样性下降的情况。凤县野生群体和凤县养殖场群体两者遗传分化较小,存在着较高的基因流水平。

Structure of the mitochondrial DNA D-Loop region and genetic diversity of Moschus berezovskii in Shaanxi Province

Forest musk deer (Moschus berezovskii) were once distributed widely in China. However, wild populations in the Qinling Mountains have declined dramatically because of poaching and habitat loss. Captive breeding populations have been established for several decades, but the genetic background of most captive populations has been unclear and the populations have increased very slowly. In order to gather useful information for the conservation and management of this species, we investigated the genetic diversity and population structure of forest musk deer by analyzing a 632-bp fragment of the mitochondrial DNA (mtDNA) D-loop region in one captive breeding population and three wild populations in Shaanxi Province, China. The captive breeding population was from the Fengxian musk deer plant; the three wild populations were from Fengxian, Liuba and Longxian Counties. The mtDNA was extracted from two samples: hair and muscle. The average contents of A+T (63.2%) were higher than those of G+C (36.8%) in the mtDNA D-loop region. A total of 171 variable sites (about 27.05% of the total nucleotides in the sequence) were detected in 69 individuals. The nucleotide diversity (Pi) of the 69 individuals was 0.04424, and the average number of nucleotide differences (K) between them was 19.908. The 69 individuals belonged to 32 haplotypes, according to the determined sequences. The average genetic distance (P) among the haplotypes of the species was 0.070. Analysis of the phylogenetic tree using the neighbour-joining method showed that the 32 haplotypes were clustered into three groups. The 32 haplotypes were randomly distributed between the four forest musk deer populations. By means of the median-joining method, we found that haplotype 3 was located in the center of the star graph, and that the other haplotypes were associated with haplotype 3 by 1-38 steps. The average genetic distance of the four groups was 0.0434 (standard error 0.005). The genetic relationship between the Fengxian musk deer plant and Liuba populations was distant. The average genetic distance among the haplotypes was 0.043, so the genetic differentiation had not yet reached the level of population differentiation. Our data indicated that the variation and genetic diversity were high in the four populations of Moschus berezovskii. The captive breeding population and the wild population in Fengxian both had a higher nucleotide diversity and haplotype diversity. There was no inbreeding or genetic diversity reduction in the captive breeding population. The analysis of molecular variance demonstrated that most variation occurred within samples and that there was significant differentiation between the four populations. The genetic differentiation between the farm populations and the wild populations in Fengxian was small, with a high degree of gene flow. Estimates of the gene flow indicated that there were few genetic exchanges among the four populations. Building pedigree records and increasing the gene flow between populations will help to conserve these populations and this species.