Résumé
Simultaneous investigation of the effects of abiotic and biotic factors over diversity dynamics is now essential to understand the evolutionary history of clades. The Grande Coupure (GC) corresponds to a major faunal turnover during the severe biological and climatic crisis of the Eocene–Oligocene transition (EOT), and is defined in western Europe as a dramatic extinction of insular European mammals coupled with a massive arrival of modern Asian clades. Here, we focused on the species-rich group of endemic European artiodactyls (EEA) to determine the proximal drivers of the GC. Using Bayesian birth-death models, we analyzed an original high-resolution fossil dataset (90 species, >2,100 occurrences) from South-West France (Quercy area) and estimated the regional diversification and diversity dynamics of EEA and immigrant artiodactyls (IA). We show that the EEA radiation is mainly related to the favorable Eocene tropical conditions, and that the major climatic changes at the EOT are responsible for their spectacular extinction, with the disappearance of 77% of species. We further highlight that the concurrent increase in seasonality in Europe during the Oligocene is likely one of the main drivers of their decline. Surprisingly, we do not support the widely-held hypothesis of active competition between EEA and IA, but rather suggest a passive or opportunistic replacement by IA, which is further supported by morphological clustering of specific ecological traits across the EOT. Our work thus provides insights into the evolutionary and ecological processes driving the diversification and decline of mammalian clades during a major biological and climatic crisis.