Fig. 6

High-confidence pedigrees of C2H2-ZFs reveal the role of functional robustness in evolution of diversity. a The species tree of eukaryotic organisms, with the number of high-confidence C2H2-ZF pedigrees that map to each extant or ancestral organism shown by node size. b Three example high-confidence pedigrees, each with five extant C2H2-ZFs, with various degrees of binding diversity. The recognition diversity (RD) of each pedigree is shown on the right (see “Methods” for details). All three pedigrees map to the base of higher primates (Simiiformes). c Proportion of C2H2-ZFs with high-DBF base-contacting (blue) or non-base-contacting (red) residues (i.e. DBF difference between base-contacting and non-base-contacting residues > 0.1) within pedigrees of varying recognition diversity, with pedigree selections shown on the top of each panel. P values (Mann–Whitney U test) correspond to the difference in the recognition diversities of C2H2-ZFs with high-DBF base-contacting or high-DBF non-base-contacting residues (DBF difference > 0.1) relative to C2H2-ZFs with equally strong base-contacting and non-base-contacting residues (DBF difference < 0.1)