DIVERSITY IN A CHANGING LANDSCAPE: COUPLING TECTONIC, CLIMATIC, AND BIOTIC PROCESSES IN THE BASIN AND RANGE PROVINCE OVER THE NEOGENE (Invited Presentation)

Today, regions of high topographic relief host elevated species richness and turnover, as well as high ecological and phylogenetic diversity. To evaluate the coupling of landscape and eco-evolutionary processes that generate these biodiversity hotspots requires integration of paleobiological and geological records. Tectonics, climate, and erosion interact to build mountain topography and influence the distribution of environmental gradients and heterogeneous habitats over geologic time. In turn, species dispersal, macroevolutionary dynamics, and community assembly processes influence biodiversity patterns at local to regional scales. To investigate the processes that underlie high diversity in high relief regions, we examined the Neogene fossil record of mammals in the Basin and Range Province in western North America alongside tectonic activity and climate-topography interactions. We used novel regional climate and elevation models to explore biotic turnover in relation to climatic and physiographic gradients across the region. We also ran a series of competing models to test the roles of tectonic extension, paleoelevation, topographic ruggedness, climate, and sediment accumulation on paleodiversity and macroevolutionary processes. We found significant positive relationships between the rate of tectonic extension, species richness, and origination rates during the Neogene, with peak mammal diversity and origination rates coinciding with elevated tectonic extension from 20 to 15 Ma. During this time, topographic ruggedness and regional climate gradients further explained high turnover in faunal composition across the Basin and Range Province. Origination rates were negatively correlated with diversity implying a role for diversity dependent dynamics, while extinction rates were negatively correlated with the global temperature record. Our results support the role of mountains as a species pump over geologic time and help unravel key questions related to mountain building and biological evolution.