Figure 3.

Effect of range cohesion on predicted bird species richness for fourth quartile (largest) ranges. Expected richness driven by: (a) NPP in the range scatter model (geographical range cohesion not enforced; r²=0.63); (b) simple geometric constraints (geographical range cohesion enforced, but environment uniform, producing the mid-domain peak expected for such models; r²=0.37); (c) NPP in the range cohesion model (necessarily influenced by geometric constraints; r²=0.74). (d) Spatial distribution of residuals (observed minus expected species richness) for the range scatter NPP model, (a). (e) Observed richness. (f) Residuals for the range cohesion NPP model (c).