Fig. 4.
Global variation in orchidoid biodiversity. Species richness (A) and species richness by latitude (B) are calculated, respectively, from the number of orchidoid species represented in octagonal 200 m2 grid cells spanning the Earth and the average number of species in occupied grid cells by latitude fit to a generalized additive model. Speciation rate (C) and speciation rate by latitude (D) were modeled by BAMM, respectively, within each grid cell and averaged across occupied grid cells by latitude fit to a generalized additive model.