Figure 3: Higher transcriptome similarities among representative pharyngula stages.

(a) Spearman correlation coefficient (ρ) of the expression profiles of 1,573 core orthologues from representative stages of cleavage, blastula/shield, pharyngula (defined here as the stage of onset of pharyngeal arch formation) and late-stage embryos. Numbers or text in the grey spheres indicate the stage of each species. The colours of the lines, which connect each stage, reflect the ρ value, according to the colour gradient shown at the top. (b) Box (quantile) plot of the ρ scores of representative stages, which were evaluated with hierarchical Bayes-based, Kruskal–Wallis analysis of variance tests (P=1.9×10⁻¹²). The asterisk indicates that the ρ scores of the pharyngula stages were significantly higher than that of the cleavage, blastula/shield or late embryo stages (Wilcoxon test corrected α=0.0017).