Diversity dynamics of the Late Cenozoic rodent community from south‐western Kansas: the influence of historical processes on community structure

Abstract

ABSTRACTThis study used the dense late Cenozoic rodent record of south‐western Kansas to test for an equilibrium in species richness through millions of years, identify and clarify historical influences on species richness, determine the relative contribution of immigration, speciation and local extinction to species originations at the community level, and calculate background extinction rates to compare with modern species losses due to anthropogenic activities. The Meade Basin rodent community has been in equilibrium, with an average of about 17 species, for almost 5 million years. No speciation events were identified in the Meade Basin rodent record; although speciation ultimately contributes to the regional species pool, local speciation events contributed little to community structure. Extinctions and immigrations continued through the study period, with elevated bouts of turnover correlated with global cooling events and lowered sea level associated with the Beringian land bridge. Turnover was generated primarily by stochastic climatic agents at several temporal scales, possibly including rapid and devastating regional volcanic ashfalls. None of the extinction rates recorded in the Meade Basin system rivals extinction levels in modern species due to anthropogenic activities.