Fig. 2.

Phylogenetic relationships between 58 species of birds with four categories of age-related eye color changes (brown to red, brown to yellow, yellow to red and dark to light; depicted in the insert legend). The phylogenetic tree is the least-squares consensus tree calculated from the mean patristic distance matrix of a set of 1000 probable phylogenies from Jetz et al. 2012 (Nature 491: 444–448). The reconstruction of ancestral states was made by stochastic character mapping using an empirical Bayesian Monte Carlo Markov Chains (MCMC) approach (Huelsenbeck et al. 2003, Systematic Biology 52: 131–158) as implemented in phytools (Revell 2012, Methods in Ecology and Evolution 3: 217–223)