A re-examination of the molecular phylogeny and biogeography of the genus Schizothorax (Teleostei: Cyprinidae) through enhanced sampling, with emphasis on the species in the Yunnan-Guizhou Plateau, China

Abstract

The mitochondrial DNA cytochrome b sequences of 36 Schizothorax species from 51 localities in the Yunnan–Guizhou Plateau (YGP) and its adjacent areas were analysed. Maximum parsimony, Maximum likelihood and Bayesian phylogenetic analyses were performed to examine the relationships of Schizothorax species. A hypothesis of the phylogenetic relationships of the species is given. A relaxed molecular clock based on Bayesian evolutionary analysis was used to tentatively calculate the divergence times of Schizothorax. Samples from the YGP were tentatively grouped into three geographically distributed clades: the Tsangpo-Irrawaddy, the Mekong-Salween and the Trans-Jinsha River (including Jinsha, Red, Nanpan and Beipan Rivers). Calibration of the molecular clock revealed that two geological periods, the late Miocene about 10 million years before present (Myr BP) and the Pliocene (4.0 Myr BP), were important times in the vicariant speciation of Schizothorax. The phylogenetic history of the species is congruent with events caused by the uplift of the Tibetan Plateau and the YGP. The divergence of Schizothorax species in YGP began in the Pliocene. Our phylogenetic trees did not support the hypothesis that the paleo Jinsha River was drained through the Yangtze River-Jianchuan Lake-Erhai Lake to the Red River. Schizothorax in the Beipan River were derived from the Jinsha River.