Abstract

Spatial dynamics are physical representations of decisions based on balancing ecological requirements with social dynamics. Socioecological factors are not static, and whether a species can navigate a landscape with greater ecological and social organizational complexity is dependent upon having sufficient abilities for behavioral variability and flexibility. Although the importance and demand for more investigation into intraspecific variation from a species, population, and individual level is recognized, research directly addressing variation is relatively rare in behavioral studies. As such, in this research, we investigated the degree of intraspecific variation in space use behaviors of habituated western lowland gorillas (Gorilla gorilla gorilla) in the Ndoki forest. Specifically, we drew upon a nine-year longitudinal dataset to asses the presence and possible drivers of intraspecific variation in space use behaviors of five habituated western lowland gorilla groups. We investigated the home range size, fidelity, and intergroup overlap, investigating the best predictors of monthly range size, tested whether resource access and dietary profiles were comparable across groups, and evaluated decision-making modalities and influential individuals within given contexts. We found that home ranges were smaller than previous investigations, although they were stable over years. Monthly ranging expanded with fruit availability and group size, but annual differences in range size with seasonality were not pronounced, with annual range as well variable with group size. The greatest degree of variation was with intergroup overlap, which remained consistent over years and seasons. We did not find a difference in gorilla-specific resource access across the groups, with minimal differences in resource access across the home range. The diet profiles of the groups were distinct, but differences in resource access were not the best explanation for differences in diet across groups. Although all individuals demonstrated a high success rate in recruiting followers, females were more successful initiators in the groups. Initiation success similarly differed with context and with the type of initiation. Silverbacks were attempted initiations the most and were generally the most influential individual in group decision-making, but silverback influence was not universal and could change with spatial context and group composition changes. These findings suggest that western lowland gorillas demonstrate a high degree of populational intraspecific variation and flexibility, both in response to ecological and social factors. Further research is necessary to evaluate how space use similarities and differences correspond to differences in resource targeting, whether differences in age and sex class initiation success connects to differences in initiation success with context, and how intergroup social dynamics may connect to differences in ranging dynamics and space use decisions. Based on these findings, I conclude that enhanced cognitive capabilities facilitate behavioral variation and flexibility in western lowland gorillas, and selection for cognitive enhancements that facilitate behavioral variation to multiple socioecological contexts was important within not just human evolution but throughout primate evolution.

Committee Chair

Crickette Sanz

Committee Members

Linda Schilling; Miguel Faria-e-Castro; Philippe Andrade; Rodolfo Manuelli

Degree

Doctor of Philosophy (PhD)

Author's Department

Anthropology

Author's School

Graduate School of Arts and Sciences

Document Type

Dissertation

Date of Award

5-6-2025

Language

English (en)

Author's ORCID

https://orcid.org/0000-0003-4641-6450

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Available for download on Wednesday, May 05, 2027

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Anthropology Commons

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