Figure 1.

Ancestral state reconstruction of nest shape on a DNA-based phylogenetic tree of 281 Australian passerine species [32]. Although cup-shaped nests (red) are more common than domed nests (black) among species today (187 or 66.5% of species on the tree build cup nests), multiple analyses reconstructed domed nests as the ancestral state. The pie chart in the centre shows the probability of a domed nest in the common ancestor (97% likelihood on this phylogeny using Mk1 maximum-likelihood, strongly supported by a likelihood decision threshold of 2.0). Reconstructions using different evolutionary models and alternative trees [31,33] gave nearly identical results (also see electronic supplementary material, figure S1). Asterisks indicate families that are primarily cavity nesters.