(A) Biome-specific spatially auto-correlated regressions (MRSAR) of passerine species richness against elevational range in the grid cells (Topo HT; left blank if not selected in the final model), water availability (ETR increases with water availability; left blank if not selected in the final model), and primary productivity (NDVI increases with primary productivity).

* For the Forest and Desert Biomes, regressions were computed across all grid cells where the biome occurred. For other biomes, regressions were implemented for the grid cells with >75% coverage by the biomes.
σ and λ respectively estimate the remaining variance and the autocorrelation coefficient. All variables were standardized to a mean of 0 and standard deviation of 1 before analysis. (B) Average and standard deviation of biodiversity metrics (estimated and observed species richness, taxonomic dispersion under the two null models) for each biome.