Burrowing facilitated the survival of mammals in harsh and fluctuating climates

Species' ability to cope with climatic instability varies greatly, influenced by factors such as dispersal, physiological adaptations, and phylogenetic conservatism. Here, we investigate how burrowing behavior, a key component of species' endurance strategies and ecosystem functioning, shaped the contemporary patterns of species richness and range size as well as the diversification of mammalian lineages. Analyzing 4,407 terrestrial mammal species, excluding bats, combined with novel trait data on 3,096 species, we reveal contrasting responses to climatic factors between burrowing and non-burrowing species. Burrowing lineages are disproportionately species-rich at lower temperatures and productivity. Both range size and species richness steeply increase with climate seasonality in burrowing species as opposed to non-burrowing species. The proportion of burrowing species increases with latitude, with regions above 20°, especially those exhibiting greater Pleistocene temperature changes, being almost exclusively composed of burrowing species. Trait conservatism, higher net diversification rates, and Eocene peak diversification provide the evolutionary context for these contemporary patterns, underscoring the role of burrowing for mammalian radiations into temperate climates. Moreover, the lower extinction rate of burrowing species and peak diversification at the Cretaceous-Paleogene (K-Pg) boundary support the longstanding hypothesis that burrowing behavior promoted survival during the "impact winter" that marks the replacement of non-avian dinosaurs by mammals. Our study highlights the potential of readily available trait information for understanding the ecological and evolutionary processes that shape species distributions through space and time. The careful integration of divergent environmental constraints bears vast improvements for forecasts of species' responses to climatic changes and global models of biodiversity patterns.