Temperature changes affected mammal dispersal during the Great American Biotic Interchange

The Great American Biotic Interchange (GABI) was a remarkable biogeographic event of biodiversity exchange between North and South America. Climate change has been pointed to as one of the main factors driving species dispersal across the continent, although this hypothesis has not been tested thus far. Here, we use paleontological ecological niche models (PaleoENMs) throughout the last five million years to test if climate change triggered the dispersal of mammalian species and/or caused the extinction of dispersing species during the GABI. We used extant and fossil occurrences for 189 mammalian species related to the GABI along with paleoclimate data to obtain species distributions from PaleoENMs. We calculated dispersal and extinction rates between North, Central, and South America and applied quantile regression models to test the effect of climatic anomalies in these rates. Our results indicate that temperature change, particularly cooling, triggered mammal dispersals during the GABI. On the other hand, we found the extinction rate in South America to be caused by warming. We recognize that the GABI is a complex event and that several factors likely affected it. Nonetheless, our results indicate that climate was one of these factors.