The 81st Annual Meeting of the American Association of Physical Anthropologists (2012)

Ecological and behavioral analyses of the Cercopithecus hybrid population at Gombe National Park, Tanzania


Anthropology, Florida Atlantic University

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Hybridization events that produce viable and fertile hybrids have the potential to alter the evolutionary trajectories of the parental species, as well as lead to the formation of new recombinant lineages. Among extant primates, sympatric hybridization is rare, and the best-known cases occur among the arboreal Cercopithecus monkeys of the guenon radiation. Gombe National Park in Tanzania is the only known persistent hybrid zone between two well-differentiated and ecologically distinct primate species. The Gombe guenon population (Cercopithecus mitis, C. ascanius and their hybrids) thus provides a rare opportunity to study ecological and behavioral dynamics of a hybrid primate population.

I conducted a 12-month field study of Gombe’s guenon population. I used a combination of line-transect survey methods and focal group follows to estimate abundance of hybrid monkeys and the two parental populations. I recorded GPS positions of all sightings to examine distribution patterns within the entire park. I recorded group composition data and all reproductive behaviors observed. Survey results indicate 15.2% of the monkeys counted were hybrid, 30.4% were C. mitis, and 54.5% were C. ascanius. Hybrid monkey density was highest in the southern half of the park. Females and males of each phenotype mated with conspecifics, heterospecifics and hybrids. Heterospecific and hybrid monkeys engaged in affiliative, contact calling, and intergroup territorial behaviors typical of conspecific members of the same social group. These behavioral observations confirmed that mixed-phenotype groups (groups having blue, red-tailed and hybrid adult females) are a behaviorally defined social group type occurring at Gombe.

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