The origin and evolutionary scenario of Percocypris
As shown below, Percocypris offers an excellent system for testing the hypotheses of the morphologies of the paleo-drainage basins of the Southeastern Tibetan Plateau, and the concomitant influences on the speciation of organisms living there.
The results of divergence time and ancestral drainage estimations indicate that Percocypris probably originated in the early Miocene (17.56 Mya; Figure 5) from a single paleo-drainage that included current Upper Yangtze, Mekong, Salween, Upper Pearl, and probably Red rivers; this supports the hypothesis that original Upper Yangtze, Middle Yangtze, Upper Mekong and Upper Salween rivers drained together as major tributaries of the paleo-Red River drainage system [60]. Regarding the origin of Percocypris, it is noteworthy that our results strongly suggest that it may originate from a common ancestor with Schizothorax. This result is compatible with the hypothesis that Percocypris originated from a common ancestor with certain species of the Barbinae (e.g., [4]–[7]). The estimated divergence time of Percocypris and Schizothorax falls within the time range of the second uplift of the Tibetan Plateau (25–17 Mya; [61]–[64]).