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The contribution of temperature and continental fragmentation to amphibian diversification
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International audience. Aim: Abiotic factors such as global temperature or continental fragmentation mayfavour speciation through the ecological and geographical isolation of lineages, butmacroevolutionary quantifications of such effect with both fossil and phylogeneticdata are rarely performed. Here, we propose to use biogeographical estimations andpalaeo‐environmental diversification models to estimate whether and how palaeotemperatureand the sequential break‐ups of Pangaea, Gondwana and Laurasiahave affected the diversification of amphibians through time.Location: Global.Methods: Using a time‐calibrated phylogeny for 3,309 amphibian species and agenus‐level fossil record, we estimated the diversification rates of the group withbirth–death models allowing rates to depend on the temporal variations of the environment.We used estimates of global palaeotemperature and an index of continentalfragmentation through time to test the association between speciation and/or extinctionrates and past temperature and fragmentation. We also estimated the biogeographicalhistory based on a time‐stratified parametric model informed by theglobal palaeogeography. We inferred whether vicariance or dispersal events explainedthe ancient and current geographical distribution of amphibians.Results: The diversification analyses on the whole amphibians showed that temperature‐dependent models are better supported than tectonic‐dependent, time‐dependentand constant‐rate models for both the fossil and phylogenetic data. Thebest‐fitting temperature‐dependent model indicated a positive dependence of bothspeciation and extinction rates with the temperature through time. Biogeographicalanalyses indicated a Pangaean origin for amphibians and also showed that allopatricspeciation (vicariance) explained important phases of the evolution of geographicalranges in the Mesozoic.Main conclusions: Our results support that palaeotemperatures have positively impactedamphibian diversification. Our study provides additional insights into how toquantify the effect of the landmass fragmentation on the diversification processesand shows with biogeographical reconstruction that continental fragmentation islinked to allopatric speciation in the early history of the clade.
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