Origin and evolution of the Yangtze River reconstructed from the largest molecular phylogeny of Cyprinidae

Abstract The Yangtze River is the longest river in Asia, but its evolutionary history has long been debated. So far no robust biological evidences can be found to crack this mystery. Here we reconstruct spatiotemporal and diversification dynamics of endemic East Asian cyprinids based on a largest molecular phylogeny of Cyprinidae, including 1420 species, and show that their ancestors laying adhesive eggs were distributed in southern East Asia before ~24 Ma, subsequently dispersed to the Yangtze River to spawn semi-buoyant eggs at ~19 Ma. This indicates that the Yangtze River diverted eastward around the Oligocene-Miocene boundary. Some of these cyprinids evolved again into fishes producing adhesive eggs at ~13 Ma, together with a peaked net diversification rate, indicating that the river formed a potamo-lacustrine ecosystem during the Mid-Miocene. Our reconstruction of the history of the Yangtze River has higher time resolution and much better continuity than those deriving from geological studies.