Résumé
The Great American Biotic Interchange (GABI) refers to the admixture of North and South American faunas promoted by the closure of the isthmus of Panama. Among land mammals, this faunal exchange was asymmetric because it witnessed a greater ability of North American lineages to establish southwards, meanwhile many South Americans went extinct. Here, coupling a mechanistic eco-evolutionary simulator with palaeoclimatic reconstructions for the last 5 million years, we explore the extent to which palaeoclimate, alone, may have shaped such a biogeographic asymmetry. When climatic variables are the only constraints to virtual species' dispersal, our results indicate that (1) successful interchanges are more frequently achieved when simulations start from South America than from North America, contrasting with empirical observations. In addition, (2) our models fail at explaining the higher representation of temperate-adapted mammals in the fossil record of successfully exchanged mammals, particularly of North American origin, but (3) suggest that successful colonisers from North America occupy larger areas in South America than the other way around. Hence, our findings stress that spatio-temporal palaeoclimate dynamics are not sufficient to explain the imbalanced success of North American migrants in South America following the GABI, suggesting the implication of additional biogeographic and ecological filters.