Unstandardized and standardized Y–chromosomal genetic differentiation (with 95% confidence interval) in bonobo and chimpanzee groups.

*We examined genetic differentiation for a more locally restricted subset of chimpanzee social groups (Central Region, Figure 1) which was comparable to the bonobo sample, and for the entire chimpanzee sample. Results, however, did not qualitatively change. **Eastern chimpanzee data taken from Langergraber and colleagues [62]. To minimize stochasticity, for all analyses of genetic differentiation between communities we excluded social groups with fewer than four individuals genotyped at the respective marker (autosomal/Y-chromosomal). Therefore, the number of pairwise comparisons differs between the Y-chromosomal and autosomal data (Table 1).