基于cyt b基因的长江中上游大鳞马口鱼遗传多样性及谱系生物地理学过程分析

Genetic Diversity and Phylogeography of Opsariichthys macrolepis from the Upper and Middle Yangtze River Based on Cytochrome b Sequences

以线粒体cyt b基因为分子标记,对长江上游干流及汉江等9条支流13个地理种群的大鳞马口鱼Opsariichthys macrolepis Yang et Huang进行遗传多样性及种群历史动态分析,并探讨其谱系生物地理学过程。结果显示,414尾大鳞马口鱼样本中共检测到79个单倍型,整体的单倍型多样性(h=0.9301)和核苷酸多样性(π=0.129421)均较高。基于单倍型构建的最大似然树和贝叶斯树显示,所有单倍型分为2个谱系(A和B),谱系A分布于中游支流汉江、清江,谱系B分布于长江上游干支流及沅江,表现出东-西方向的空间差异。分子钟估算显示,2个谱系于早更新世(~1.34 Ma)分化。不同地理种群间的遗传分化指数为-0.01624~0.99827,除个别种群外,多数地理种群呈现高度分化,说明种群间存在显著的遗传隔离。空间分子方差分析显示,大鳞马口鱼种群具有一定的遗传结构,特别是老鹤河、任河、清江地理种群分化显著。贝叶斯天际线分析显示,大鳞马口鱼各地理种群的扩张和收缩时间为0.01~0.04 Ma,可能与冰期-间冰期旋回有一定关联。推测青藏高原的隆升以及更新世冰期的更迭对长江中上游大鳞马口鱼的遗传分化以及种群动态产生了重大影响。

In the present study,the genetic diversity,population demography and phylogeography of 13 Opsariichthys macrolepis Yang et Huang populations from the upper Yangtze River and 9 tributaries were investigated based on mitochondrial DNA cytochrome b gene sequences.A total of 79 haplotypes were identified from 414 individuals with relatively high haplotype and nucleotide diversity(h=0.9301,π=0.129421).The results of haplotype-based phylogenetic analysis using Maximum Likelihood and Bayesian trees revealed 2 major lineages(Lineage A and Lineage B),representing a significant west-east split.Lineage A was consisted exclusively of populations from 2 tributaries(Hanjiang River and Qingjiang River)of the middle Yangtze River,while Lineage B mainly from the upper Yangtze River and Yuanjiang River.According to the molecular clock,these 2 lineages began to diverge in the early Pleistocene(around 1.34 Ma).Pairwise comparison of genetic differentiation index(FST)among populations ranged from-0.01624 to 0.99827,and most pairs showed a high degree of differentiation,indicating significant genetic isolation among populations.In addition,some population structures could be identified based on spatial analysis of molecular variance.For example,populations from Laohe River,Renhe River and Qingjiang River showed significant differentiation from other populations.The result of Bayesian skyline plot showed that most populations experienced demographic expansion or contraction during 0.01-0.04 Ma,and this was probably correlated with the glacial-interglacial cycle.This study suggests that the uplift of Qinghai-Tibetan Plateau and Pleistocene glacial cycles may have played vital roles in shaping the genetic patterns and demographic history of O.macrolepis from the upper and middle Yangtze River.