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Party Animals: Food, Sociality and Stress in Wild Bonobos (Pan paniscus) of Iyema, Lomako Forest, Democratic Republic of Congo

Cobden, Amy Kathleen (2014)
Dissertation (196 pages)
Committee Chair / Thesis Advisers: Gouzoules, Sarah; Hadley, Craig
Committee Members: Wallen, Kim ; De Waal, Frans B M
Research Fields: Anthropology, Physical
Keywords: bonobos; endocrinology; stress; wild; seasonality; non-invasive
Program: Laney Graduate School, Anthropology
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Bonobos (Pan paniscus) and Chimpanzees (Pan troglodytes) are the two closest primate relatives to humans, sharing over 98% of our genetic blueprint and more than 99% with one another. However, behaviorally they are remarkably different. Chimpanzees are hierarchical, male-dominant and use aggression to resolve conflicts. Bonobos are egalitarian, female-biased and use a wide array of sexual behaviors to resolve conflict. Their diverse sexual repertoires are pronounced when food is present, suggesting that food-related pressures fostered this notable behavioral adaptation, raising the question: Do bonobos experience food stress, and if so, how do they respond? Popular theories attempting to explain differences in social behaviors between both species of Pan often include the hypothesis that terrestrial herbaceous vegetation (THV) is a key factor in maintaining large party sizes seen in bonobos. Although this theory has been negated repeatedly over the years and across sites, there are still gaps in our understanding about its role in wild bonobo diets. Using a year's worth of behavioral and ecological data from a community of wild bonobos and their environment, I examined seasonal patterns in resource availability and diet in the Iyema community, corresponding seasonal patterns in nest party sizes and energetic hormonal profiles that accompanied these changes to see if shifts in resource availability and sociality were reflected in three key hormonal metabolites associated with different kinds of stress. The Iyema forest displayed seasonal patterns in both fruit abundance and diversity, and both these factors proved significant in predicting nest party sizes, using a generalized linear mixed model. THV was the third most frequently consumed food item in the Iyema bonobo diet, but its consumption was significantly negatively correlated with an increase in party size. THV consumption showed distinctly seasonal patterns, suggesting that its nutritional properties should be reexamined on a seasonal scale. Urinary C-peptide and urinary cortisol were predictably inversely correlated in the context of diet, environmental diversity and shifts in party sizes, showing that bonobos experience periods of environmentally-related energetic stress that affect their sociality and long-term use of non-invasively collected hormonal metabolites effectively demonstrate complex social and energetic relationships in wild primates.

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Access restricted until 2020-06-01


Access restricted until 2020-06-01

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