Evolutionary hotspot of Cenozoic fish: Paleogene ichthyofauna from the onshore basins around Beibu Gulf

et al. 2021

Preprint

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.

Section: Resultssupporting

confidence: 90%

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

et al. 2021

Preprint

“…The cyprinid fossils Nanningocyprinus wui and Huashancyprinus robustispinus found in Oligocene formations of the Nanning and Ningming Basins are also consistent with our results (29). Other biological and geological evidence suggests that the palaeo-Jinshajiang once owed southward and probably connected through the palaeo-Red River into the South China Sea (SI Appendix, Table S1).…”

Section: Resultssupporting

confidence: 90%

Evolution of the Yangtze River reconstructed from the largest molecular phylogeny of Cyprinidae

et al. 2021

Preprint

The Yangtze River is the longest river in Asia, but its evolutionary history has long been debated, in particular the origin of the First Bend and formation of the Three Gorges. Diverse groups of endemic freshwater fishes have evolved in this river. Here we present the historical, spatiotemporal pattern of the endemic East Asian cyprinid clade based on the largest molecular phylogeny of Cyprinidae, including 1420 species and fossil records. Based on the evolution of egg types adapting to different hydrological conditions, we show that the ancestors of this endemic clade (laying adhesive eggs) were distributed in southern East Asia before ~24 Ma and subsequently dispersed to the Yangtze River basin to spawn semi-buoyant eggs at ~19 Ma. These results are consistent with the Yangtze River reversing its flow direction from southward to eastward to form the present river system around the Oligocene-Miocene boundary (~24–19 Ma). Some East Asian cyprinids evolved into fishes producing adhesive eggs again at ~13 Ma. This together with an increased net diversification rate, indicates that the river formed a potamo-lacustrine system during the Mid-Miocene. This new reconstruction of the history of the Yangtze River system through Cyprinidae phylogeny, together with the evolution of egg types in endemic East Asia cyprinids, improves the time resolution derived from geological studies.

“…The cyprinid fossils Nanningocyprinus wui and Huashancyprinus robustispinus found in the Oligocene Formation of the Nanning and Ningming Basins are also in agreement with our results (30). Other biological and geological evidence also suggests that the palaeo-Jinshajiang once owed southward and probably owed through the palaeo-Red River into the South China Sea (Supplementary Table 1).…”

Section: The Palaeo-jinshajiang Owing Southward In the Oligocenesupporting

confidence: 91%

Evolution of the Yangtze River reconstructed by the largest molecular phylogeny of Cyprinidae

et al. 2021

Preprint

The Yangtze River is the largest river in Asia, but its evolutionary history has long been debated. Diverse groups of endemic freshwater fishes have evolved in this river. Here we represent the historical spatiotemporal pattern of the endemic East Asian cyprinid clade based on the largest molecular phylogeny of Cyprinidae, including 1420 species and fossil records. Based on the evolution of egg types adapting to different hydrological conditions, we show that the ancestors of this endemic clade (laying adhesive eggs) were distributed in southern East Asia before ~24 Ma and subsequently dispersed to the Yangtze River basin to spawn semi-buoyant eggs at ~19 Ma. These results indicate that the Yangtze River reversed its flow direction from southward to eastward to form the present river system within the Oligocene-Miocene boundary (~24-19 Ma). Some East Asian cyprinids evolved into fishes producing adhesive eggs again at ~13 Ma, together with an increased net diversification rate, indicating that the river began to form a potamo-lacustrine system during the Mid-Miocene. The new sketch of the formation history of the Yangtze River system through Cyprinidae phylogeny, together with the evolution of egg types in endemic East Asia cyprinids, has better spatiotemporal integrity than traditional geological studies.