华北地区中华蒙潮虫(甲壳动物亚门:等足目)种群遗传多样性研究

中华蒙潮虫Mongoloniscus sinensis(Dollfus,1901)隶属于甲壳动物亚门Crustacea等足目Isopoda潮虫亚目Oniscidea,中国特有种。为了探究中华蒙潮虫的种群遗传分化和系统进化关系,采用PCR对采自华北地区10个地理种群89只个体线粒体2个基因COⅠ和ND5进行联合分析。结果表明:1)中华蒙潮虫COⅠ部分基因长604 bp,ND5部分基因长615 bp,拼接序列长1 219 bp,T、C、A和G含量分别为41.0%、11.2%、30.8%和17.0%,具有显著的A+T偏倚;变异位点503个(占总核苷酸序列的41.3%),序列间的转换/颠换比值为2.8。2)89只个体共45种单倍型,单倍型多样性0.964,核苷酸多样性0.005 6,整体遗传多样性水平中等;单倍型H1、H15、H16、H21、H41为2～3个种群共享单倍型。3)联合基因(COⅠ+ND5)系统发育树表明,最早出现的是华北以北地区(山西大同、河北石家庄),最晚分化出的是华北以南地区(山西临汾、陕西西安未央区、河南新乡),演化路线为从北向南,个别种群单倍型未按地理来源形成明显的簇群。4)平均遗传分化指数为0.513,基因流为0.24;分子变异分析结果表明,种群的变异与分化主要来自种群内部,错配分布呈多峰,结合中性检验(Tajima's D=-1.429;Fu's F_s=6.499),发现中华蒙潮虫近期未经历扩张,但种群内部分化显著,增长平稳。本研究首次基于线粒体多基因联合分析了中华蒙潮虫种群遗传多样性。

Population Genetic Diversity of Mongoloniscus sinensis (Dollfus, 1901) (Crustacea:Isopoda) from North China

Mongoloniscus sinensis (Dollfus, 1901) is an endemic species of China and belongs to suborder Oniscidea, order Isopoda, and subphylum Crustacea. To explore the genetic diversity of different geographical populations of M. sinensis and to determine their phylogenetic relationships, 89 individuals were collected from 10 geographic populations of north China. Mitochondrial COⅠ and ND5 genes fragments were amplified using PCR. The results of sequence analysis showed that:1) partial mitochondrial COⅠ and ND5 genes length of M. sinensis were 604 bp and 615 bp, respectively. The full length (COⅠ+ND5) is 1 219 bp after sequence assembly, and the percentages of T, C, A and G were 41.0%, 11.2%, 30.8% and 17.0% with significantly higher A+T content. A total of 503 variable sites were detected (41.3% in the full sequences) among the sequences and the average conversion value was 2.8.2) A total of 45 haplotypes from the 89 individuals were identified, and 5 haplotypes (H1, H15, H16, H21 and H41) were found to be shared by 2 or 3 populations. The haplotype diversity and the nucleotide diversity were 0.964 and 0.005 6, indicating a medium level of genetic diversity. 3) Phylogenetic analysis of the combined gene (COⅠ+ND5) indicated that, the earliest derived area was the north of north China (Datong, Shijiazhuang), and the last derived area was the south of north China (Linfen, Weiyang district of Xi'an, and Xinxiang). Therefore, it was concluded that M. sinensis might evolve from north to south in north China, although some haplotypes did not form obvious clusters according to geographical origin. 4) The average genetic differentiation coefficient value was 0.513 and the gene flow was 0.24. AMOVA analysis showed that the species variation mainly happened within populations. Mismatch distribution exhibited a multimodal distribution curve, and this finding combined with the neutral test revealed that although M. sinensis did not experience population expansion recently, the interior population differentiation was significant and the population showed a relatively flat growth. To the best of our knowledge, this is the first mitochondrial multi-genes based study to investigate the population genetic diversity of M. sinensis.