Examining Foraging models Using Dietary Diversity and Gut Microbiota in Bonobos (Pan paniscus)

Optimal diet and functional response models are used to understand the evolution of primate foraging strategies. The predictions of these models can be tested by examining the changes in dietary diversity. Primate gut microbiome communities are of increasing interest due to their important role in nutrition, development, health, and disease. Recent evidence from gorillas suggests fecal glucocorticoid metabolite concentration (FGMC) has no significant role in structuring gorilla gut microbiomes. We investigated dietary diversity and the gut microbiota in bonobos (Pan paniscus) at two research camps within the same protected area (N’dele and Iyema) in Lomako Forest, Democratic Republic of Congo (DRC). We compared dietary diversity results from behavioral observation (1984/1985, 1991, 1995, 2014, & 2017) and fecal washing analysis (2007 & 2009) between seasons and study period using three diversity indices (Shannon’s, Simpson’s, and SW evenness). W¬¬e describe gut microbiome, δ13C, δ15N data, and FGMC for eighteen bonobo fecal samples from separate individuals, collected in June 2014 at Iyema, Lomako Forest, DRC. The average yearly dietary diversity indices at N'dele were Shannon H’ = 2.04, Simpson’s D = 0.18, and SW evenness = 0.88 while at Iyema, the indices were Shannon H’ = 2.02, Simpson’s D = 0.18, and SW evenness = 0.88. Shannon's index was lower during when fewer bonobo dietary items were available for consumption. The results of the gut microbiome analyses found that δ13C were significant [PERMANOVA F1,17 =0.17261, p = 0.023] in explaining beta diversity in gut microbiota but only when sex was a predictor in the model. Females had slightly higher δ13C values than males perhaps due to lower consumption of C4 plants by females. We found FGMC did not significantly explain the variation in bonobo gut microbiota beta diversity. We ran linear regressions on the abundance of the microbial genera and found eighty genera were significantly explained by FGMC. Overall, this research suggests that optimal diet models best explained bonobo foraging strategies and patterns in bonobo gut microbiota, diet, and stress may need to center around the differential consumption of C4 plants like Ficus spp. and terrestrial herbaceous vegetation (THV) by males and females