达里湖高原鳅不同地理群体遗传多样性与遗传分化

Genetic Diversity and Genetic Differentiation of Different Geographic Populations of Triplophysa dalaica

了解达里湖高原鳅(Triplophysa dalaica)不同群体遗传变异现状,为制定适宜的物种保护及水域生态系统管理策略提供基础。选择线粒体Cyt b基因作为分子标记,分析了2021年4月和7-8月采集于黄河流域的红碱淖、大黑河和查干诺尔湖流域的辉腾河等3个地理群体,以及文献记载海河流域的漳河群体的遗传多样性、遗传分化及种群历史动态。结果表明,70尾个体中共检测到16个变异位点和13个单倍型;不同群体的单倍型多样性范围为0.233~0.791,核苷酸多样性范围为0.00020~0.00209。其中,辉腾河群体遗传多样性水平最高;红碱淖与大黑河群体单倍型多样性水平较高,核苷酸多样性水平较低;漳河群体单倍型多样性与核苷酸多样性均较低。单倍型系统发育树和进化网络图显示,13个单倍型未聚类形成明显的谱系结构,多数单倍型为单一群体独有;除漳河群体外,其余群体的单倍型混杂连接,未遵循各自的地理分布格局。遗传分化分析结果显示,群体间遗传分化指数为0.233~0.867,多为高度分化;分子方差分析表明遗传变异主要来源于群体间(64.86%)。种群历史动态分析未检测到达里湖高原鳅各地理群体及总体在近期经历过种群扩张。鉴于达里湖高原鳅已成为雅鲁藏布江外来鱼类,建议将达里湖高原鳅自然分布区内的各群体划定为不同保护单元并跟踪监测栖息地质量,同时加强对物种交易与放生活动的管控。

Triplophysa dalaica,a small loach in the Cobitidae family,primarily inhabits the mainstem and tributaries below the Lanzhou section of the Yellow River and some inland water bodies in central and eastern Inner Mongolia.To date,only a few studies have been carried out on the population genetics of T.dalaica.Thus,examination of the genetic diversity,genetic differences among geographically separated populations,and the population history of T.dalaica is needed for species conservation and management.In this study,we explored the genetic diversity and genetic differentiation of four geographic T.dalaica populations(Hongjiannao and Dahei Lakes in the Yellow River basin,Huiteng Lake in the Chagannuoer Lake basin and Zhanghe River in the Haihe Lake basin)by analyzing the mitochondrial Cyt b gene sequences of 70 specimens from the four locations.A total of 16 polymorphic loci and 13 haplotypes were identified in the four populations.The haplotype diversity index(Hd)and nucleotide diversity index(Pi)of the four populations ranged from 0.233 to 0.791 and from 0.00020 to 0.00209,respectively.The genetic diversity of the T.dalaica populations in Huiteng River was the highest.Although the haplotype diversity of the Hongjiannao and Dahei Lake populations was higher,the nucleotide diversity was lower.The haplotype diversity and nucleotide diversity of the Zhanghe population were both lower than those in the other two basins.The phylogenetic tree and evolutionary network of the 13 haplotypes did not cluster into a distinct clade structure,and most haplotypes were unique to a single population.Except for two basal haplotypes in the Zhanghe population,the haplotypes were interconnected in a mixed manner,rather than following their respective geographical distribution patterns.Genetic differentiation analysis shows that the range of genetic differentiation index(Fst)among populations was 0.233 to 0.867,indicating high degrees of differentiation.Analysis of molecular variance(AMOVA)demonstrates that a high proportion of the total genetic variance was attributable to variations between populations(64.86%).The population history shows no recent population expansion of T.dalaica within the various geographical groups or in the overall population.During an ichthyological survey,a specimen of T.dalaica was collected in the Shannan reach of the Yarlung Tsangpo River and recorded as an alien species.In conclusion,the genetic diversity of T.dalaica varied in geographically separated populations,and the genetic differentiation among the populations were generally very high.Based on these findings,we recommend that the different populations of T.dalaica be treated as separate protection units,with monitoring of habitat quality,and that regulation of species trade and release should be strengthened.