Classification And Evolution Of Sisoridae In Yortong And Zayul Sections

The Qinghai Tibet Plateau is the highest area on earth and is the birthplace of 10 rivers in Asia.The geological history and special landform,climate end environmental of the Qinghai Tibet Plateau have bred its unique fish resources.Yortong and Zayul sections are located in the southeast of the Tibet Autonomous Region and in the lower reaches of the Yarlung Zangbo River.There are high biodiversity and distinctive flora and fauna,which are breed and support by low latitudes,abundant rainfall and huge altitude differences.Sisoridae belongs to Osteichthyes,Actinopterygii and Siluriformes,mainly distributed in southeast of the Qinghai Tibet Plateau and its surrounding areas,which is one of the three major components of fish in the Qinghai Tibet Plateau.At present,great progress has been made in the investigation and research of fish resources in the Qinghai Tibet Plateau and adjacent mountainous areas,but there is still lack of systematic and in-depth investigations and researches on fish diversity in some diversity hotspots and key areas,such as Yortong and Zayul sections,especially lacks the taxonomic research of catfish.Based on the systematic measurement and description of morphology,combined with mitochondrial Cyt b gene,COI gene and mitochondrial complete genome sequence,this study added the species of Parachiloglanis to the phylogeny analysis of Sisoridae for studied the classification and evolution of Sisoridae.(1)According to morphological taxonomy and molecular identification,11 species of catfish belonging to 6 genera are found in Yortong and Zayul sections in the lower reaches of the Yarlung Zangbo River,viz,Creteuchiloglanis,Parachiloglanis,Glyphothorax,Exotoma,Glaridoglanis and Pseudecheneis.There are 1 species of the genus Parachiloglanis,2 species of the genus Glyphothorax,4 species of the genus Exotoma,2 species of the genus Creteuchiloglanis,1 species of the genus Glaridoglanis and 1 species of the genus Pseudecheneis.(2)According to the morphological characteristics and genetic differences,three new species were found in this study: the new species of Glyphothorax is not described temporarily cause its small sample size,the other two new species are Creteuchiloglanis zayulinsis sp.nov.and Exostoma microadiposa sp.nov.;and two new record species: Pseudecheneis sirenica and Parachiloglanis dangmechhuensis;also found an undetermined species of Glyphothorax.(3)We have performed the phylogenetic analysis of Sisoridae based on Cyt b gene,COI gene and the mitochondrial complete genome by Maximum Likelihood(ML)and Bayesian Inferences(BI)methods.The results of three genetic marker sequences showed that the genus Pseudecheneis located in the tree base;and the genus Pareuchiloglanis is not a monophy,but formed a monophyletic clade with Creteuchiloglanis,Oreoglanis,Pseudexostoma and Euchiloglanis.The phylogenetic trees based on mitochondrial complete genome and COI gene showed that Glaridoglanis and Glyptosternon formed a sister group;the Glyptosternoid fishes did not form a monophy.While the results based on Cyt b showed that the Glyptosternoid fishes formed a monophyletic group with low support(BI = 0.55,ML = 0.33).The different results may be caused by the difference of gene length,species composition and the influence of "Long-branch Attraction".(4)The results of molecular clock showed that the fish of Sisoridae originated in the late Miocene,about 8.71 Mya,and the differentiation time of the Glyptosternoid fishes except the genus Parachiloglanis was about 6.78 Mya;from the late Pliocene to the Pleistocene,about 0.2～ 4.0 Mya,Pareuchiloglanis,Creteuchiloglanis,Pseudexostoma,Euchiloglanis and Glyptothorax are occurred by explosive speciation.Since 5.3 Mya,the Qinghai Tibet Plateau has entered a short-term rapid uplift stage,and gradually peaked after 3.0 Mya.During the uplift of the Qinghai Tibet Plateau,the Jinsha River,Irrawaddy River,Nujiang River and other water systems also took shape one after another.This study speculates that under the influence of the uplift of the Qinghai Tibet Plateau,the species of Sisoridae showed an explosive species formation process,and with the formation of various water systems,the species of Sisoridae spread and distributed,forming the current distribution pattern of Sisoridae.