Reconstruction of ancestral histone H3 states. The ancestral state reconstruction of histone H3 variants from various clades (corresponding nodes are highlighted in the group-specific phylogenetic trees by red rhombs in Figure 2B) and H3 variant(s) of LECA confirms a high degree of sequence identity or similarity, respectively (shaded columns). Variable sites are highlighted (*); color scheme: basic amino acids (blue), acidic amino acids (red), aromatic amino acids (orange), putative phosphorylation sites (green). Nuclearia simplex H3 was used as outgroup for all group-specific trees. A detailed overview about the most frequent residues observed at such variable site is given in Additional file 4.