Fig. 5

Differences in within-group Bray-Curtis distances (a), Shannon entropy (b), and OTU richness (c) among primate samples. a Inter-individual variation in geladas was significantly lower than in Bale monkeys and human adults and infants (p < 0.001, unpaired t test) and marginally lower than in vervets and grivets (p = 0.087 and 0.072, respectively). Infants had significantly higher variation than all other groups (p < 0.001 for all comparisons). b Shannon entropy was significantly lower in geladas than in Bale monkeys and grivets, and higher than in human adults and infants (p < 0.001 for all comparisons). c OTU richness was significantly lower in geladas than in Bale monkeys and grivets (p < 0.05 for both comparisons), and higher than in human adults and infants (p < 0.001 for both comparisons). Each box represents the interquartile range, with the horizontal lines representing the medians and the whiskers representing 1.5 times the interquartile range. Points outside the whiskers represent outliers. Gel, gelada (n = 39); BM, Bale monkey (n = 29); HA, human adult (n = 11); HI, human infant (n = 10); Ver, vervet (n = 11); Gri, grivet (n = 13)