基于MHCⅡ类B基因的凹耳臭蛙(Odorrana tormota)种群遗传分化模式  

Genetic Differentiation Patterns of Odorrana Tormota in South Anhui Province Based on MHC Class Ⅱ B Gene

作　　者：张继辉[1,2] 疏义林[1] 张巨杨 吴海龙[1] 

机构地区：[1]安徽师范大学生命科学学院,安徽省重要生物资源保护与利用重点实验室,安徽芜湖241000 [2]黄山职业技术学院,安徽黄山245041

出　　处：《安徽师范大学学报（自然科学版）》2017年第4期359-364,共6页Journal of Anhui Normal University(Natural Science)

基　　金：国家自然科学基金项目(31370537);高等学校博士学科点专项科研基金(20133424110006)

摘　　要：利用II类MHC基因单基因座位Odto-A作为分子标记,对皖南山区凹耳臭蛙6个种群的遗传多样性和遗传分化进行研究.结果显示,皖南凹耳臭蛙总的基因多样性为0.812,核苷酸多样性为0.018.局域种群单倍型多样性变化范围为0.531-0.864,香溪种群单倍型多样性最高,最低的是漳河种群.与线粒体cyt b基因所揭示的单倍型多样性差别不大,但B基因的核苷酸多样性较之线粒体cyt b基因的高达一个数量级.暗示MHC基因丰富的核苷酸多态性可能与其病原体抗性多样性密切相关.分子变异分析结果显示,皖南山区凹耳臭蛙种群MHC II类B基因遗传变异主要来源于种群内,种群间发生了显著的遗传分化(Fst=0.05644,P=0.00391).成对种群间的遗传分化分析结果显示,直线距离最近的浮溪和香溪种群间也发生了显著的遗传分化,暗示这两个种群经历了不同的选择压力.受平衡选择的作用,MHC基因与基于中性分子标记所揭示的遗传格局不同,基于MHC基因的种群遗传分化与水系和直线地理距离均没有明显的相关性,而与种群所经历的选择压力密切相关.结果表明皖南凹耳臭蛙不同局域种群所经历的环境病原体的选择压力存在时空变异.Being affected by pathogen-mediated balancing selection, genetic differentiations among populations based on MHC genes were usually subject to the influences of environmental pathogens dynamic. Therefore, population genetic structure patterns are usually different revealed by different molecular markers. In this study, exon 2 sequence of a single locus, Odto -A, of MHC class Ⅱ B gene was used as molecular marker to detect genetic structure among six populations of Odorrana tormota in south Anhui province. The total haplotype diversity and nucleotide diversity of the six populations is 0.812 and 0.01790, respectively. Haplotype diversity of the six local populations ranged from 0.531 to 0.864 with Xiangxi population being the highest and Zhanghe population the lowest. Compared with the results of mitochondrial cyt b , MHC B gene has an order of magnitude higher genetic variation indicating that MHC genes possess a faster evolution rate. A rich MHC genes nucleotide polymorphism may be closely associated with a broader pathogen resistance. Analysis of molecular variance （AMOVA） indicated that most of the genetic variation mainly occurred among six populations of the species, and significant genetic structure was detected among populations （ Fst = 0.05644, P =0.00391）. Pairawise analysis showed that significant differentiation was found between Fuxi and Xiangxi suggesting the two populations experienced different selective pressures. Duing to the role of balancing selection, population genetic differentiation pattern based on MHC B gene was distinct from that of microsatellites and mitochondrial DNA. No significant correlation between genetic differentiation and geographic distance and/or river systems of the species in south Anhui province.

关 键 词：凹耳臭蛙 MHC B基因 基因多样性 遗传分化 

分 类 号：Q953[生物学—动物学]