根据mtDNA控制区序列分析野生唇的种群遗传结构

Population structure of Hemibarbus labeo as inferred from mtDNA control region sequence

为了掌握不同地理种群唇(Hemibarbu labeo)的遗传多样性和遗传结构,探讨其亲缘地理演化过程,研究分析了乌苏里江、长江、黑龙江、鸭绿江和牡丹江5大水系,8个地理群体(n=42)的mtDNA控制区404 bp片段的变异,该片段共有26个变异位点,变异率为6.43%,平均核苷酸多样性为0.011 5。42尾样本共检测到18个单倍型,这8个地理群体是以HT1和HT2单倍型为中心向外辐射演化的。AMOVA分析结果表明,群体内变异为59.29%,同一水系群体间变异为23.50%,不同水系群体间变异为17.20%,以上变异均达到显著水平(P<0.05),群体间配对FST分析结果表明,同一水系内有些群体间差异也达到了显著水平。聚类分析发现,最大简约法(MP)和最大似然率法(ML)结果基本一致,嘉荫群体(HRJY)和四川群体(YRSC)绝大部分个体被聚在一支,鸭绿江群体(YRLJ)聚在一支,这与单倍型网络的分析结果一致,以上结果表明唇的遗传多样较为丰富,黑龙江流域的唇保持了祖先单倍型,其他地理群体为黑龙江流域内群体向不同方向演化的结果,并且部分地理群体已经形成了特有的单倍型。

Genetic diversity and structure were investigated to explore the phylogeography and evolution of Hemibarbus labeo from five different river systems, including Wusuli River, Yangtze Rive, Heilongjiang River, Yalu River and Mudan River. The mtDNA control region was used to analyze genetic differentiation of eight geographical populations （n=42） in this study. Results showed that 26 variation sites existed in a 404 bp sequence with variation rate of 6.43% and average nucleotide diversity of 0.011 5. The sequence information identified 18 haplotypes in the control region gene. Eight geographical populations were evolved through a mode of center outward radiation based on DWRHT1 and DWRHT2 haplotype. AMOVA analysis showed that the variation rate was 59.29% within populations, 23.50% among populations from the same river system and 17.20% among populations from the different river system. There was significant difference within different populations, among popula- tions from the same river system and populations from different river systems （P〈0.05）. Pairwise FST of control region sequence analysis among populations showed that there was significant difference among several popula- tions from the same river system. Cluster analysis showed that maximum-parsimony method （MP） and maximum likelihood ratio method （ML） results were basically consistent, which suggested that most individuals from HRJY and YRSC population clustered together and individuals from YRLJ population clustered into a single branch. Meanwhile, cluster analysis results were found to be consistent with haplotype parsimony network analysis. These results suggested abundant genetic diversity existed among hemibarbus labeo populations. However, the population size was decreased due to environmental pollution and overexploitation in recent years. In addition, H. labeo from Heilongjiang River kept ancestral haplotypes, while If. labeo from other river systems had evolved to dif- ferent directions based on haplotypes from Heilongjiang River and formed their unique haplotypes during the long-term evolution and geographical isolation.