What is it about?
We looked at extinct mammals in North America during the Cenozoic (36 million years to the present) and showed that there was greater variability in species between regions when mean annual precipitation was lowest. This is consistent with theory, which suggests that when precipitation is (on average) higher communities are more similar to one another as you move north. We then looked at what might be expected from current mammal species under climate change. We used climate models to predict where these species might occur in the future and saw little evidence of the precipitation relationships that we found in the fossil data.
Why is it important?
Much of the work done on biological responses to climate change has focused on temperature, looking at the number of species in each area, and purely ecological responses (i.e. over short time periods). We demonstrate that precipitation can also play an important role in driving responses to global climate. We also show that it isn’t just the number of species that changes in space but the relationship between communities: there is a greater rate of turnover (a greater dissimilarity) in communities as well. Finally, we show that these relationships seem to be present in the evolutionary record but cannot be predicted from the ecological responses of current mammals, suggesting that the patterns we saw in the fossil record are due (at least in part) to evolutionary processes that are not incorporated into climate models.
The following have contributed to this page: Dr Christopher Hassall