THE LATITUDINAL BIODIVERSITY GRADIENT FOR PLANKTONIC FORAMINIFERA OVER THE CENOZOIC

The latitudinal biodiversity gradient (LBG), in which the number of species increases from the poles to the equator, is one of the largest scale and longest known patterns in ecology. Although the pattern is prevalent today in both marine and terrestrial systems, evidence suggests that biodiversity gradients have varied in strength and shape in the geological past. Here we use a new database for planktonic foraminifera, Triton, to examine changes in the LBG at 5 million-year intervals over the Cenozoic. Triton is the most complete database of any fossil group, allowing us to test for changes in the LDG at unprecedented temporal resolution. We find a shallow LBG during the Eocene warm period, which steepens as the climate cools towards an Icehouse Earth about 33 million years ago. LBGs are combined with climate variables to understand putative drivers, with preliminary analyses suggesting that warm temperatures and high climate heterogeneity elevate planktonic foraminifera diversity.