Fig. 2

Bird latitudinal gradient results - despite differences in the underlying model for generating diversity, similar levels of species richness and gradient patterns were achieved. Left: species richness after 6 million years of protracted speciation for the tropical regions, temperate scenario 1 (high population splitting and conversion), and temperate scenario 2 (higher splitting and low conversion). Right: Mean cophenetic distances between sister species (i.e., sister species divergence time) for the same simulations