Figure 1. A, per-lineage rates of speciation across a time-calibrated phylogenetic tree of 6670 species of extant birds (67% of the total diversity) as inferred using a statistical model that simultaneously estimates the magnitude of rate variation through time and across lineages. Colours correspond to the instantaneous rate of speciation at each point in the tree. The fastest 5% of rates exceed 0.4 species Myr –1 (dark red). Analysis of evolutionary rates explicitly accounts for extinction, although only speciation rates are shown. B, estimated present-day speciation rates for all 6670 species; these are simply the best estimate of the instantaneous rate of speciation for each tip in the phylogeny. Inset images depict representative birds with fast (western gull, Larus occidentalis) and slow (go-away-bird, Corythaixoides leucogaster) rates of speciation. The phylogenetic dataset is from Jetz et al. (2012) and speciation rate analysis is described in Rabosky & Matute (2013).