Cenozoic palaeoecology, phylogeography and ecosystem dynamics of South American mammals (Sparassodonta and Chiroptera)

摘要

Biogeographic studies of South American mammals have typically shown a mismatch between latitudinal trends of extant and extinct mammal richness. South America shows modern mammal biodiversity increasing towards the Equator, whereas evidence of extinct South American mammals is concentrated at higher latitudes. Consequently, most studies focusing on the ecology and evolution of the South American mammal fauna have been limited temporally (to either extinct or extant taxa) or spatially (specific localities or ecosystems only). In this study, new methodologies were implemented to include both extinct and extant taxa in analyses of two orders of South American mammals: the Sparassodonta and the Chiroptera. A novel multivariate statistical approach was used to study the endemic metatherian order Sparassodonta and to test several competing hypotheses about the extinction of this group. Non-competitive ecological interactions within the South American mammal assemblage appear to have been the main drivers for sparassodontan extinction rather than, as commonly assumed, the result of competition and/or abiotic fluctuations. Diversity loss and eventual demise of the sparassodontans was a gradual process that followed family-specific patterns which changed over time. New statistical tools were also developed to examine phylogenetic diversity and phylogenetic endemism spatially and temporally in New World chiroptera. Trans-continental migrations proved to be most significant in the evolution of the South American bat fauna. Multiple centres of significant endemism were found across the New World for most bat families, extending the hypothesis of dual centres of diversification, previously proposed for Emballonuridae, Phyllostomidae and Mormoopidae, to Molossidae and Vespertilionidae. Central America and southern North America played particularly important roles in the diversification of New World bats, as did the Andes in South America.