Landscape dynamics and diversification of the megadiverse South American freshwater fish fauna.

Landscape dynamics are widely thought to govern the tempo and mode of continental radiations, yet the effects of river network rearrangements on dispersal and lineage diversification remain poorly understood. We integrated an unprecedented occurrence dataset of 4,967 species with a newly compiled, time-calibrated phylogeny of South American freshwater fishes—the most species-rich continental vertebrate fauna on Earth—to track the evolutionary processes associated with hydrogeographic events over 100 Ma. Net lineage diversification was heterogeneous through time, across space, and among clades. Five abrupt shifts in net diversification rates occurred during the Paleogene and Miocene (between 30 and 7 Ma) in association with major landscape evolution events. Net diversification accelerated from the Miocene to the Recent (c. 20 to 0 Ma), with Western Amazonia having the highest rates of in situ diversification, which led to it being an important source of species dispersing to other regions. All regional biotic interchanges were associated with documented hydrogeographic events and the formation of biogeographic corridors, including the Early Miocene (c. 23 to 16 Ma) uplift of the Serra do Mar and Serra da Mantiqueira and the Late Miocene (c. 10 Ma) uplift of the Northern Andes and associated formation of the modern transcontinental Amazon River. The combination of high diversification rates and extensive biotic interchange associated with Western Amazonia yielded its extraordinary contemporary richness and phylogenetic endemism. Our results support the hypothesis that landscape dynamics, which shaped the history of drainage basin connections, strongly affected the assembly and diversification of basin-wide fish faunas.

Project(s)

Priority 2: Trait Diversity and Function

Funder

Funder name	Awards
National Science Foundation, United States	0614334 - 0741450 - 1354511
Conselho Nacional de Desenvolvimento Científico e Tecnológico, Brazil	465610/2014‐5 - 306455/2014-5 - Postgraduate Scholarship 141242/2018-3 - Research Productivity Grant PQ No 305200/2018-6
Horizon Europe, European Research Council, European Union	Grant agreement no. 787638
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Switzerland	SNF no. 197753
Fundação de Amparo à Pesquisa do Estado de Minas Gerais, Brazil	BPD-00201-22 - APQ-03695-22
Swiss Federal Institute for Forest, Snow and Landscape Research, Switzerland	Visiting Fellowship
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Brazil	Postdoctoral Fellowship
Fundação de Amparo à Pesquisa do Estado de Goiás, Brazil	201810267000023
Vetenskapsrådet, Sweden
Stiftelsen för Strategisk Forskning, Sweden
Royal Botanic Gardens, Kew, United Kingdom