Schematic representation of PRDM9 domains and allelic variation in Pan.

The top block depicts alleles identified in this study. The second block shows the additional alleles characterized by Auton et al. [36]. The four alleles common to both studies are shown in the top block, with the number of occurrences and the corresponding (sub-)species given in square brackets. Pp  =  Pan paniscus, Ptv  =  P. troglodytes verus, Ptt  =  P. t. troglodytes, Pts  =  P. t. schweinfurthii. Different ZnF repeats are coded by letters and repeats marked with a * differ from those with the same letter code by one, two, or three synonymous substitutions. The underlying nucleotide sequence, as shown in Figure 2, of O* is n or zg, D* represents q, A* is zf and U* represents w. Colors correspond to the AA residue combination at positions −1, 3 and 6 of the ZnFs, as given in the legend. Residue position 2, which also plays a role in DNA binding is fixed (serine) and therefore not shown. Human allele A is depicted for reference.