Abstract
Aim: The Neotropics currently host outstanding levels of species richness, with onethirdof the global tetrapod species. The underlying causes of these extraordinarylevels of biodiversity are a topic debated in evolutionary ecology, but the main processesat work remain elusive.Location: Neotropics.Time period: Cenozoic and Mesozoic.Major taxa studied: Tetrapods.Methods: Using global phylogenies for amphibians, birds, lepidosaurs and mammals,biogeographical and time-variable (trait-dependent and trait-independent) diversificationmodels, we examined changes in speciation and extinction rates through timein the Neotropics in relationship to other areas of the world, and estimated the timeof Neotropical colonizations.Results: We found that from the origin of lepidosaurs and mammals until the Pliocene(the Miocene for birds), diversification rates within the Neotropics were lower thanrates in other regions (i.e., turnover was high). Afterwards, extinction decreasedrelative to speciation, and Neotropical diversification outpaced diversification inother regions. Dispersal out of the Neotropics also increased after the Pliocene (theMiocene for birds), exceeding into-the-Neotropics migrations. For amphibians, diversificationrates in the Neotropics have been higher than in other areas through time,and dispersal out of the Neotropics decreased in the Cenozoic.Main conclusions: The common view that the Neotropics are an ancient source ofworld species diversity, with high in situ speciation, dispersal to other areas and lowextinction, might be true only for amphibians. For mammals, birds and lepidosaurs,the Neotropics acted as a diversity sink from their origin until the Miocene–Pliocene(i.e., diversification rates were lower and turnover higher than in other areas). Onlyafterwards did the region turn into a diversity source. Our study highlights that modelsaccounting for rates of diversification that vary through time could improve ourcapacity to assess evolutionary dynamics over long time-scales.