Print PageForecasting how species will respond to ongoing environmental change requires knowledge of the processes that have shaped biodiversity in the past. In general, we expect species to track warming conditions by shifting their geographic ranges poleward. At a given locality this should be reflected by an increased dominance in the identity and abundance of more equatorial species. Here we test this hypothesis using time series data from the Holocene small mammal fossil record. More specifically, we evaluate how community dynamics over the last 7,000 years have been shaped by contrasting and variable local paleoclimates at two replicate caves in the Great Basin from the same latitude.
Results/Conclusions
Consistent with expectation, both records exhibit an increase in the presence and dominance of communities by species with a southern geographic affinity during periods of relative warmth. These strong correlations are robust to temporal autocorrelation and time-averaging.
Despite the predictability of community-scale dynamics, species-specific abundance-climate relationships were variable and poorly explained by a species’ geographic affinity. Nevertheless, species present at both sites exhibited the same response to climate at one site as at the other. Species life histories therefore play important roles in determining their responses to climatic warming. These results are corroborated by a regression-tree analysis of functional groups: while the abundance of granivores shows a significant and positive relationship with warming, omnivores and herbivores show significant negative relationships.
In summary, while community-level dynamics are consistent with expectations of species responses to climatic warming, species-level dynamics are less predictable. Although a species’ current geographic range may reflect many ecological and evolutionary factors, intrinsic biology and interspecific interactions may be more important for predicting responses to future warming.
