Bacteria Balancing Act: Exploring the Association of Social and Sexual Dynamics on the Primate Microbiome in Pan paniscus and Colobus vellerosus




Samartino, Shelby D.

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This dissertation examines the relationship between social and sexual behaviors and microbiota composition in two primates: the bonobo (Pan paniscus) and black-and-white colobus (Colobus vellerosus). I collected behavioral data and vaginal swabs over a 21-day period at Ape Cognition and Conservation Initiative in Des Moines, IA. Vaginal microbiota composition was not predicted by individual ID, but there was a trend of significant effect of swelling size and sexual interactions. I also utilized a dataset of urinary cortisol samples collected during the same study period to examine the association between vaginal microbiota diversity and cortisol. I identified a strong trend towards a positive relationship between alpha diversity and cortisol level for one female when samples were collected on the same day, but this same relationship was not observed in the other female. I investigated whether social instability associated with the immigration of new males could explain differences in the gut microbiota in female colobus across several social groups at Boabeng-Fiema, Ghana. Beta diversity was predicted by year, alpha male stability, group identity, age, and individual ID. I then utilized focal follow data of 19 adult females to create 1-m proximity networks. Yearly 1-m proximity ties predicted female beta-diversity in socially stable groups. An alpha male takeover in the third group was associated with infant mortality and temporal variation in proximity networks. Findings from this dissertation provide evidence for how different external factors are associated with vaginal microbiota composition in bonobos and how the conditions surrounding alpha male instability predict gut microbiota composition in colobus. Overall, my results suggest social and sexual transmission of microbes both shapes and is shaped by behavior, making further investigation vital to understanding their role in the evolution of group living.


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Bonobo, Microbiome, Primate, Sexual behavior, Vaginal microbiome