Figure 2.

Relationship between conductance of whole eggs and ecological variables for 364 bird species. (a) Phylogenetic tree of residual water vapour conductance (RG_H2O). Bar plots and rings around the phylogeny represent significant predictors of RG_H2O in conditionally averaged models. Conditional model averaging was used to obtain a single average model when more than one PGLS model was best ranked (i.e. more than one model with ΔAICc < 2 from the top-ranked model). Branch colours show the diversification in RG_H2O across the phylogeny and ancestral trait estimates. RG_H2O is plotted as a function of (b) temperature seasonality within each avian group and (c) whether both parents incubate the eggs. In the hybrid box plot, species RG_H2O are shown as filled circles, vertical lines indicate the median, box shows the interquartile range (IQR) and the whiskers are 1.5 × IQR (distribution is shown as histograms). p-values are given in asterisks, with *less than 0.05, **less than 0.01 and ***less than 0.001. Silhouette illustrations came from PhyloPic (http://phylopic.org), contributed by various authors under public domain license. (Online version in colour.)