Fig. 4
Overview of 83 genes with gene substitution rates correlating with bone microstructures. a. Protein–protein interaction network generated using STRING [42]. Nodes represent protein-coding genes correlating with bone variables (regression analysis, vs. ‘root-to-tip’ dN/dS). Lines between nodes indicate inferred or experimentally demonstrated biological associations. Humerus, rib, and vertebrae are indicated in yellow, beige, and brown respectively. Genes also under positive or divergent selection are indicated in maroon and purple, respectively. b. Heat map of genes correlating (green, positive; red, negative) with bone variables (regression analysis, vs. ‘root-to-tip’ dN/dS). Genes in the osteoclast differentiation pathway are highlighted in pink. For selected genes, a plot of bone variable (vertical axis; please see main text for details) and substitution rate (‘root-to-tip’ dN/dS) is shown; with salmon, blue, and green indicating species in an aquatic, flying, and terrestrial habitat, respectively