新疆塔里木河叶尔羌高原鳅遗传多样性研究

GENETIC DIVERSITY OF TRIPLOPHYSA YARKANDENSIS POPULATIONS IN TARIM RIVER BASIN IN XINJIANG

为探究新疆塔里木河叶尔羌高原鳅(Triplophysa yarkandensis)遗传多样性现状,研究基于线粒体Cytb和D-loop序列对塔里木河两条支流(车尔臣河和渭干河)的8个地理群体进行了遗传学多样性和遗传结构分析。结果显示,基于Cytb和D-loop序列分别获得了41和51个单倍型,单倍型多样性指数/核苷酸多样性指数分别为0.9247±0.0124/0.9776±0.0032和0.0065±0.0034/0.0115±0.0058,表明各群体的遗传多样性水平均较高。AMOVA结果显示,遗传变异主要来自群体内部(Cytb F_(st)=96.57%;D-loop F_(st)=95.25%),仅有3.43%(Cytb)和4.75%(D-loop)来自群体间;各群体间的遗传距离值小,遗传分化指数F_(st)值低,属于弱分化水平。基于样本构建的系统发育树和单倍型构建的网络进化图均显示,各群体的样本没能形成明显的地理聚群和谱系结构。虽然两支流群体间存在潜在的遗传障碍,并发生了一定的遗传分化,但其遗传距离值只在0.05附近(Cytb,F_(ct)=0.0540;D-loop,F_(ct)=0.0471)。种群历史动态分析结果表明,叶尔羌高原鳅种群相对稳定,未经历过明显的扩张。综合上述结果,塔里木河叶尔羌高原鳅群体遗传多样性水平较高,但是遗传分化主要来源于群体内部,群体间有明显的基因交流,建议将其作为一个保护管理单元进行保护。研究为叶尔羌高原鳅种质资源开发利用、制定合理的保护措施提供了基础数据。

The distribution of Triplophysa yarkandensis is restricted in the Tarim River basin.Due to the gradual depletion of water resources,together with alien invasion and agricultural cultivation in Tarim River,the population size of T.yarkandensis has been diminishing and critically endangered.Changing this trajectory will require coordinated researches and conservation strategies to provide a better understanding of population genetics at large spatial scales.To accomplish it,eight populations of T.yarkandensis were collected from Qarqan River and Weigan River,and the genetic diversity,population structure and population dynamics were analyzed by sequencing the mitochondrial cytochrome b(Cytb)gene and control region(D-loop).Based on the Cytb and D-loop sequences,41 and 51 haplotypes were detected,and the haplotype diversity/nucleotide diversity were 0.9247±0.0124/0.9776±0.0032 and 0.0065±0.0034/0.0115±0.0058,respectively,indicating a high genetic diversity.The AMOVA results showed that,the genetic variations mainly derived from intrapopulation(Cytb F_(st)=96.57%;D-loop F_(st)=95.25%),with only 3.43%(Cytb)and 4.75%(D-loop)from inter-populations.In addition,the low genetic distance and genetic differentiation index F_(st) between populations and no obvious geographical clustering and pedigree structure formatting according to the phylogenetic tree and network evolution diagram of haplotypes analyzing revealed a small degree of genetic differentiation among populations.Although there were potential genetic barriers and genetic differentiation between populations from Weigan River and Qarqan River,the genetic distance value was only around 0.05(Cytb,F_(ct)=0.0540;D-loop,F_(ct)=0.0471).The results of neutrality test and nucleotide mismatch distribution plotting indicated that T.yarkandensis populations in Tarim River basin were relatively stable and no obvious population expansion occurred recently.To sum up,the genetic diversity of T.yarkandensis populations in Tarim River relative higher,but the genetic divergence was mainly from intrapopulation,and obvious gene flow between populations in the studied area was supported by our results.Thus,we suggest protecting it as one protection unit.These results provide valuable genetic data for developing scientific management strategies and directing future monitoring and utilization of the wild resource of T.yarkandensis in Tarim River basin.