Relative performance of integrated single- and two-predictor models of bioregion species richness.

Endemic species are those restricted to a single bioregion and Resident counts species with the largest portion of their range in a given bioregion. Endotherms combine mammals and birds, ectotherms combine reptiles and amphibians. Best models (ΔAICr2 refers to pseudo-r2 values based on fitting model-predicted versus observed. Note that the results for both richness values are unaffected by the pseudo-replication that hampers the results of typical gridded analyses of species richness. Predictor variables: Temperature, average temperature of bioregion; Area, current-day extent of a bioregion; Productivity, average bioregion productivity; AreaProductivity, total bioregion productivity, that is, the product of Productivity and bioregion Area. TimeArea, time-integrated area, that is, the integrated areal extent of a bioregion over 55 million years; TimeAreaProductivity, time-integrated productivity, that is, the product of Productivity and TimeArea. For further details and results by taxon, see Methods and Tables S1, S2, S3, S4, S6, S7, S8, S9, S10.