| The fish genus Sinocyclocheilus is endemic to China and belongs to subfamliy Barbinae,famliy Cypriniade,and order Cypriniformes.The Sinocyclocheilus fishes are only distributed in the karst landforms of Yunnan province,Guizhou province and Guangxi Zhuang Autonomous Region and are mainly found in the tributaries of the Xijiang River system and are rarely found in the Jinsha River system and the Red River system.There are so far several studies working on phylogenetic relationships among Sinocyclocheilus species.However,due to continuous discovery of new species,inconsistent phylogenetic relationships between morphological characteristics and molecular data,and a limited number of genetic markers used in previous studies,phylogenetic relationships among Sinocyclocheilus species remains not fully resolved.For that reason,to address these issues at genome scale,this study applied RAD-seq(Restriction-site associated DNA sequencing)technology to further investigating phylogenetic relationships among of Sinocyclocheilus fishes and thus expected to provide scientific evidence for conservation and management of Sinocyclocheilus fish resources.This study first applied RAD-seq technology to conducting next-generation sequencing of 30 Sinocyclocheilus species and obtained a total amount of 472.1 Gb clean data.The average number of high-quality reads was 20.01(Mreads)and the average Q30 is 94.61%.A total of 64,040,060 Single nucleotide variants(SNVs)were detected after bioinformatic analyses.Based on these SNVs,phylogenetic analyses were conducted and the main findings were obtained as the followings:First,phylogenetic results from Bayesian tree,neighbor-joining(NJ)tree and maximum likelihood(ML)tree showed that: The Sinocyclocheilus species formed a monophyletic group;Sinocyclocheilus jii was located at the basal position of phylogenetic trees;the Sinocyclocheilus species that are distributed in Guangxi and Guizhou are at the bottom of phylogenetic trees,while most Sinocyclocheilus species that are found in Yunnan are located at the top of phylogenetic trees,indicating that most Sinocyclocheilus species in Yunnan were more recently differentiated that those in Guangxi and Guizhou.Second,this study reveals phylogenetic positions of 10 Sinocyclocheilus species that are not yet studied: Sinocyclocheilus jinxiensis,Sinocyclocheilus aquihornes and Sinocyclocheilus convexifreheadus form the Clade II;Sinocyclocheilus broadihornes,Sinocyclocheilus angularis,Sinocyclocheilus mashanensis and other previously studied species form the Clade III;Sinocyclocheilus aluensis,Sinocyclocheilus wenshanensis,Sinocyclocheilus wumengshanensis,Sinocyclocheilus xichouensis and other previously studied species that are distributed in Yunnan form the Clade VI at the top of phylogenetic trees.Third,this study supports the hypothesis that distribution pattern of Sinocyclocheilus species is shaped by “dispersal – geographic isolation – allopatric speciation – dispersal – sympatric distribution” model,in which dispersal plays a major role.Fouth,this study does not support the separation of Sinocyclocheilus jinxiensis as new genus Pseudosinocyclocheilus from Sinocyclocheilus.The genus Pseudosinocyclocheilus should be merged into the genus Sinocyclocheilus and the Pseudosinocyclocheilus jinxiensis should be changed back to its original species name Sinocyclocheilus jinxiensis.Finally,Sinocyclocheilus grahami and Sinocyclocheilus xichouensis which are distributed in different river systems with far distance apart from each other are closely related in our phylogenetic trees. |
