The role of extinction and range expansion in shaping the spatial pattern of marine biodiversity

The distribution of biodiversity across the planet is neither even nor constant. Attempts to explain such distributions generally focus on environmental correlations (such as richness vs. temperature), but diversity in any region is ultimately the result of the interplay through time of extinction, origination, invasion and extirpation. Mass extinctions and recoveries represent extreme examples of this interplay, although their lasting influence on the biosphere is debated. Here, I show that evolutionary variables exert a first-order control over the biogeography of taxa throughout geologic time. Following the Late Ordovician mass extinction, for example, unidirectional invasion and high origination rates during the recovery interval created a tropical diversity peak that persisted for over 20 Myr. The deployment of diversity in present-day oceans reflects evolutionary changes that occurred both coincident with, and subsequent to, the end Cretaceous mass extinction, including a) a global increase in origination rates that unfolded in a spatially explicit manner, leaving a signature that persists despite millions of years of evolutionary, tectonic, and environmental change; b) persistent expansion of genera from tropics to poles via speciation, and c) the emergence of divergent, low-diversity polar faunas via phylogenetically structured extinctions. Combining biological and paleontological datasets can capture the long-term interplay of extinction, recovery and expansion through time to a degree inaccessible to either discipline alone.

Speaker: Dr. Andrew Krug, University of Chicago

Room 2040