Molecular Phylogeny and Biogeography of Percocypris (Cyprinidae, Teleostei)

Citation: Wang M, Yang J-X, Chen X-Y ( Molecular Phylogeny and Biogeography of Percocypris (Cyprinidae, Teleostei) Mo Wang 0 Jun-Xing Yang 0 Xiao-Yong Chen 0 Walter Salzburger, University of Basel, Switzerland 0 1 State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences , Kunming, Yunnan , China , 2 University of Chinese Academy of Sciences , Beijing , China Fierce predatory freshwater fishes, the species of Percocypris (Cyprinidae, Teleostei) inhabit large rivers or lakes, and have a specific distribution pattern. Only a single species or subspecies occurs in each large-scale drainage basin of the Southeastern Tibetan Plateau. In this study, the molecular phylogenetic relationships for all but one of the described subspecies/species of Percocypris were investigated based on three mitochondrial genes (16S; COI; Cyt b) and one nuclear marker (Rag2). The results of Maximum Likelihood and Bayesian Inference analyses show that Percocypris is a strongly supported monophyletic group and that it is the sister group of Schizothorax. Combined with analyses of morphological characters, our results suggest that Percocypris needs to be reclassified, and we propose that six species be recognized, with corresponding distributions in five main drainages (including one lake). In addition, based on the results of the estimation of divergence times and ancestral drainages, we hypothesize that Percocypris likely originated in the early Miocene from a paleo-connected drainage system containing the contemporary main drainages of the Southeastern Tibetan Plateau. This study suggests that vicariance (due to the uplift of the Tibetan Plateau modifying the large-scale morphologies of drainage basins in the Southeastern Tibetan Plateau) has played an important role in the speciation of the genus. Furthermore, external morphological characters (such as the length of the fins) and an internal trait (the position of pterygiophore) appear to be correlated with different habitats in rivers and the lake. - Funding: This research was supported by grants from the National Natural Science Foundation of China (No. 30870288, No. 30730017). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. The species of Percocypris (Cyprinidae, Teleostei) are fierce predatory freshwater fishes inhabiting large rivers or lakes, in southwestern China and northern Vietnam. Members of the genus have a specific distribution pattern, that is, there is only one species or subspecies in each drainage as follows (Chinese names in brackets): Upper Yangtze River (Jinsha Jiang), Mekong River (Lancang Jiang), Salween River (Nu Jiang), Upper Pearl River (Nanpan Jiang), Red River (Yuan Jiang). The genus thus appears to be an ideal system to study how historical geologic or geographic events of the relevant drainages including the famous Three Parallel Rivers of Yunnan Protected Areas (Salween, Mekong and Upper Yangtze rivers) influenced the biogeography of freshwater fishes. However, even the basic taxonomy of how many species of Percocypris exist has not been resolved. Chu [1] erected Percocypris for Leptobarbus pingi Tchang (1930) [2]. In the same year, Tchang [3] described Barbus regani (subsequently treated as P. pingi regani; [47]) from Fuxian Lake. Cui & Chu [6] described P. pingi retrodorslis from Mekong and Salween rivers, and presented a classification system of one species with three subspecies that was adopted by other Chinese researchers (e.g., [7]). Nevertheless, Kottelat [8] regarded the three subspecies as three species with the scientific names of P. pingi, P. regani and P. tchangi (P. pingi retrodorslis treated as a synonym of P. tchang), and pointed out that the species P. tchangi Pellegrin & Chevey 1936 [9] (described from Red River) was apparently overlooked. The basic disagreement over the classification of Percocypris of whether it consists of one species with three subspecies (P. pingi pingi, P. pingi regani and P. pingi retrodorslis; [6]) or three species (P. pingi, P. regani and P. tchangi; [8]) needs to be resolved. In this study, we provisionally follow the classification system of Cui & Chu [6], that is, P. pingi pingi (Upper Yangtze River), P. pingi regani (Fuxian Lake, Upper Pearl River) and P. pingi retrodorslis (Mekong and Salween rivers). The studies cited above on the taxonomy of Percocypris relied entirely on morphological characters. However, molecular studies on Percocypris to date have utilized only collections of P. pingi pingi from one locality (Hejiang, Sichuan Prov.) and P. pingi retrodorslis from one locality (Baoshan, Yunnan Prov.). The sample of P. pingi pingi was used in the molecular phylogenetic analyses of Wang et al. [10], Kong et al. [11] and Li et al. [12], which were based on the Rag2 [recombinant activation gene 2], S6K1 [ribosomal protein S6 kinase 1] and 16S [16S ribosomal small subunit] genes, respectively. In addition to P. pingi pingi, one sample of P. pingi retrodorslis (IHBCY0505008; Baoshan, Yunnan Prov.) was also included in the study of Li et al. [12]. The results of all the three studies suggested that Schizothorax may be the sister group of Percocypris. In addition, the monophyly of Percocypris was not firmly established by Li et al. [12], due to the particularly weak nodal supports of the clade of P. pingi pingi and P. pingi retrodorslis (Maximum parsimony bootstrap values = 56; Bayesian posterior probability = 0.80/0.82). These studies suffered from incomplete taxon sampling, with only two samples, at most, included. Moreover, only a single gene was used in these analyses; no combined molecular data set was compiled. Thus, there are ambiguities regarding the relationships within this genus, and the monophyly of Percocypris has not been convincingly demonstrated. The potential impact of paleo-drainage basin morphologies on biogeographic patterns of the Tibetan Plateau and East Himalayas has been attracting increasing attention in recent studies (e.g., [13 18]). Although Percocypris is likely an ideal system for testing the biogeographical hypotheses, the evolutionary history and even the classification of this group were not well understood because of the difficulty of collecting relevant specimens. To the best of our knowledge, there have been few, if any, studies using a fish genus with the particular distribution pattern found in Percocypris to investigate biogeographic issues of the Southeastern Tibetan Plateau. In this paper, a molecular phylogeny was reconstructed including all but one of the putative species of Percocypris, based on a combined dataset of three mitochondrial DNA genes and one nuclear gene. The divergence times and ancestral drainage of this group were also inferred using the Bayesian relaxed molecular clock and primary B (...truncated)