Figure 2.

Schematic showing major evolutionary transitions to cup-shaped nests (red) from domed nests (black) among passerine families worldwide (grey indicates ambiguous reconstructions). Major evolutionary radiations of the New World (NW) suboscines, core Corvoidea, and Passerida are condensed and shown as triangles (all with more than 93% RAxML bootstrap support [32]). Boxes and bars on the right show approximate proportions of species with cup-shaped nests (red) and domed nests (black) in each group, as well as the proportions of taxa located within (blue) or outside (white) Australasia. Multiple evolutionary transitions between cup-shaped and domed nests have occurred in the NW suboscines and the Passerida (see electronic supplementary material, figure S2), so continuity of red or black triangles and bars in these groups should not imply monophyly of cup- or dome-nesting taxa. Numbers of species in each group are given in parentheses (based on IOC 6.1 [24]), and asterisks indicate families that are primarily cavity nesters. Pie charts show lowest Mk1 maximum-likelihood values for cup-shaped and domed nests at two nodes on this tree [32], with a minimum 73% likelihood that the ancestor of all passerines had an enclosed dome nest and a minimum 96% likelihood that the Corvoidea-Passerida ancestor had a cup-shaped nest.