| The origin and divergence of Triplophysa（Nemacheilidae,Cypriniformes）are generally considered to be closely associated with the rapid and persistent rise of the Qinghai-Tibet Plateau（QTP）.Therefore,species of Triplophysa are widely distributed in the QTP and adjacent regions because of their adaptations to the extreme environment of the QTP.In recent years,the investigation of fish resources in Henan Province has found that there is a wide distribution of Triplophysa in the mountainous areas of Henan Province,However,the dispersal route and phylogeographic pattern and genetic diversity of Triplophysa in the Central Mountain area remain unknown.In this study,A total of 267 individuals from 29 sites were collected from the Central Mountain area（within Henan Province）,and three mt DNA（COI、Cytb、D-Loop）fragments were used.By constructing the species tree and phylogenetic tree of the plateau sturgeon species,estimating the divergence time of the population,and analyzing the genetic diversity and population history dynamics,we investigated the formation of phylogeographical pattern for Triplophysa in Henan Province and discussed how paleoclimate and geological events affect the current biodiversity of this genus.The main findings were as follows:（1）Phylogenetic analysis revealed seven distinct Triplophysa lineages in the Central Mountain area（within Henan Province）（A-G）,among which lineage A,C,D,F and G were distributed in the Qinling Mountains,lineage B and E were distributed in the South Taihang Mountains.In addition,lineage A,C,D and F belonged to the Yellow River system,lineage B and E belonged to Haihe River system,and lineage G belonged to the Yangtze River system.The results showed that the genetic diversity of each lineage was very low.The low historical gene flow and vicariance events could explain the deep divergence among lineages inhabiting in these mountain streams.（2）Molecular dating suggested that the origin time of the common ancestor of the Triplophysa was about 21.18 Ma,coincided with the uplift time of the QTP in the early Miocene.Lineage A was separated from lineages B and C at 7.78 Ma,lineage B was separated from lineage C at 2.28 Ma;lineage F was separated from lineages D,E,and G at 10.97 Ma,lineage D was separated from lineages E and G at 8.58 Ma,lineage G separated from lineage E at 5.28 Ma.The dispersal events after the evolution of the drainage system in the middle Yellow River in Ealy Pleistocene,as well as the vicariance events caused by the rapid uplifting of the Qinling Mountains and Taihang Mountains,were primarily responsible for the extant phylogeographic pattern of Triplophysa in the Central Mountain area（within Henan Province）.（3）Gene tree and species tree,and the results of species delimitation showed that among the seven existing lineages,there may be more than 6 species,respectively,the Triplophysa siluroides（lineage A）and the Triplophysa robusta（lineage B）,Triplophysa dalaica（lineage E）and Triplophysa sellaefer（lineage F）,while two genetically distinct lineages D and G and the depauperate lineage C should be further studied to detect the existence of cryptic species in Triplophysa.（4）The results of genetic diversity showed that the haplotype diversity（Hd）and nucleotide diversity（π）varied from 0 to 1.000 ± 0.126 and from 0 to 0.00540 ± 0.00167,respectively.Most populations showed higher haplotype diversity but lower nucleotide diversity.（5）The results of phylogenetic tree,AMOVA,haplotype network,gene flow and population historical dynamic analysis showed that there were four different genetic sub-lineages with distinct genetic structure and phylogeographical pattern in Qinling Mountains and South Taihang Mountain（within Henan Province）.IBD analysis showed that there was obvious geographical isolation between populations.Neutrality tests showed that two sub-lineages in the Qinling Mountains may have experienced a recent demographic expansion.The formation of Triplophysa robusta phylogeographical pattern in the Central Mountainous area（within Henan Province）is related to vicariance events,as well as affected by Pleistocene ice age.The very low population genetic diversity should be paid attention to strengthen the protection of the genus Triplophysa in the special habitat in the Central Mountainous area. |
