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

Abstract

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.

Table of Contents

Table of Contents
CHAPTER 1 1
INTRODUCTION 1
CHAPTER 2: 8
LOMAKO FOREST AND THE IYEMA STUDY SITE 8
CHAPTER 2 ABSTRACT 9
2.1 LOMAKO FOREST 10
2.2 FOREST COMPOSITION AT IYEMA 15
2.2.1 RESOURCE DENSITY AND DISTRIBUTION 17
2.3 COMMUNITY STRUCTURE 19
CHAPTER 3: 21
SEASONALITY AND DIET OF THE IYEMA FOREST AND BONOBO COMMUNITY 21
CHAPTER 3 ABSTRACT 22
SEASONALITY AND DIET OF THE IYEMA FOREST AND BONOBO COMMUNITY 23
3.1 BACKGROUND: 23
3.1.1 ABUNDANCE AND DIVERSITY 24
3.1.2 DIFFERENCES IN PAN SOCIAL STRUCTURE 24
3.2 ORGANIZING QUESTIONS: 27
3.3 METHODS 27
3.3.1 RAINFALL AND TEMPERATURE 27
3.3.2 PHENOLOGICAL TRANSECTS 30
3.3.3 COLLECTION AND ASSESSMENT OF FECES 33
3.4 RESULTS 34
3.4.1 DOES THE IYEMA BONOBO COMMUNITY LIVE IN A SEASONAL ENVIRONMENT? 34
3.4.2 ARE SEASONAL FLUCTUATIONS IN THE ENVIRONMENT REFLECTED IN THE IYEMA BONOBOS' DIET? 45
3.4.2.1 DOES DIETARY DIVERSITY (MEASURED THROUGH THE NUMBER OF SPECIES FOUND IN BONOBO FECES) REFLECT ENVIRONMENTAL DIVERSITY OF AVAILABLE RIPE FRUIT? 45
3.5 DISCUSSION 47
CHAPTER 4: 48
TERRESTRIAL HERBACEOUS VEGETATION AND THE IYEMA BONOBO DIET 48
CHAPTER 4 ABSTRACT 49
TERRESTRIAL HERBACEOUS VEGETATION: CONSUMPTION PATTERNS BY THE IYEMA BONOBOS AND IMPLICATIONS FOR DIET AND SOCIALITY 50
4.1 BACKGROUND/LINEAGE 50
4.1.2 THV CONSUMPTION PATTERNS ACROSS PAN 50
4.1.2 PREFERENCES FOR THV 51
4.1.3 NUTRITIONAL CONTENT OF THV 52
4.2 ORGANIZING QUESTIONS 54
4.3 METHODS 54
4.3.1 DISTRIBUTION ACROSS THE STUDY SITE 54
4.3.2 FECAL ANALYSIS 54
4.4 RESULTS 55
4.4.1 DO BONOBOS EAT MORE THV WHEN DIETARY RESOURCES ARE LOW? 56
4.4.2 IS THE CONSUMPTION OF THV CORRELATED WITH LARGER PARTY SIZES? 63
4.5 DISCUSSION 65
CHAPTER 5: 67
NEST PARTIES AND THEIR ECOLOGICAL CORRELATES AT IYEMA 67
CHAPTER 5 ABSTRACT 68
NEST PARTIES AT IYEMA: BASIC PATTERNS OF SEASONAL SOCIALITY AND THEIR ECOLOGICAL CORRELATES 69
5.1 BACKGROUND 69
5.1.1 FACTORS THAT AFFECT PRIMATE SOCIAL DYNAMICS 69
5.1.2 FEEDING PARTIES IN BONOBOS AND CHIMPS: 72
5.2 ORGANIZING QUESTIONS 75
5.3 METHODS 75
5.3.1 NEST PARTIES 75
5.4 RESULTS 76
5.4.1 DO PARTY SIZES SHIFT SEASONALLY? 76
5.4.2 DO SEASONAL SHIFTS IN RESOURCE AVAILABILITY, MEASURED THROUGH ABUNDANCE AND DIVERSITY AFFECT PARTY SIZE? 79
5.5 DISCUSSION 82
CHAPTER 6: 84
HORMONAL CORRELATES OF SEASONALITY, SOCIALITY AND DIET IN THE IYEMA BONOBO COMMUNITY 84
CHAPTER 6 ABSTRACT 85
HORMONAL CORRELATES OF SEASONALITY, SOCIALITY AND DIET IN THE IYEMA BONOBO COMMUNITY 86
6.1 INTRODUCTION: 86
6.1.1 BONOBO (AND CHIMPANZEE) BEHAVIOR, ECOLOGY, SOCIAL STRUCTURE AND THEIR HORMONAL CORRELATES 89
6.2 RESEARCH GOALS AND ORGANIZING QUESTIONS 94
6.3 METHODS 97
6.3.1 COLLECTION 97
6.3.2 PRESERVATION AND FIELD PROCESSING 97
6.3.3 EXTRACTION 101
6.3.4 ANALYSIS AND VALIDATION 109
6.3.5 KETONES: PROBLEMS WITH COLOR AND RELIABILITY 120
6.4 RESULTS 122
6.4.1 HORMONES AND SEASONALITY 124
6.4.2 HORMONES AND TERRESTRIAL HERBACEOUS VEGETATION (THV) 143
6.4.3 HORMONES AND NEST PARTIES 148
6.5 DISCUSSION: 151
6.5.1 DISCUSSION OF METHODS: 151
6.5.2 SUMMARY OF RESULTS: 155
CHAPTER 7 CONCLUSION 158
REFERENCES 166

About this Dissertation

Rights statement

• Permission granted by the author to include this thesis or dissertation in this repository. All rights reserved by the author. Please contact the author for information regarding the reproduction and use of this thesis or dissertation.

School	Laney Graduate School
Department	Anthropology
Degree	PhD
Submission	Dissertation
Language	English
Research Field	Anthropology, Physical
Keyword	stress non-invasive bonobos wild seasonality endocrinology
Committee Chair / Thesis Advisor	Gouzoules, Sarah, Emory University Hadley, Craig, Emory University
Committee Members	Wallen, Kim, Emory University De Waal, Frans B M, Emory University

Last modified

Primary PDF

Thumbnail	Title	Date Uploaded	Actions
	Party Animals: Food, Sociality and Stress in Wild Bonobos (Pan paniscus) of Iyema, Lomako Forest, Democratic Republic of Congo ()	2018-08-28 10:25:55 -0400	Press to Select an action Download

Supplemental Files

Thumbnail	Title	Date Uploaded	Actions