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Susan Perry


Speaker: Susan Perry
Title: Male life history strategies in wild white-faced capuchin monkeys, Cebus capucinus
Affiliation: University of California, Los Angeles
Date: Friday, February 17, 2012
Place and Time: Room 101, Love Building, 3:35-4:30 pm
Refreshments: Room 204, Love Building, 3:00 pm

Abstract. The efforts of mathematical modelers of social strategies are often hampered by lack of access to long-term data sets that include variables of interest such as demography of multiple groups in a population, genetic relatedness of individuals, life history parameters, and detailed nuances of social interactions of interest (e.g. cooperative behaviors, dominance interactions, and aggression) collected over the lifetimes of individuals. The Lomas Barbudal Monkey Project is a 21-year study of wild white-faced capuchin monkeys that has demographic data, including genetic parentage data, for 445 individual monkeys in 10 social groups, and 79,000 hours of detailed behavioral data on the social and foraging behavior of these individuals. This data set yields a rich source of data for mathematical models of alliance formation, life history strategies, and the emergence of social structures.

White-faced capuchins are characterized by strong long-term bonds in both sexes, and frequent coalitionary behavior. Although females are the philopatric sex, males also maintain long-term relationships with kin, by co-migrating with close male relatives. High male reproductive skew, frequent coalitionary lethal aggression and infanticide put selective pressures on both males and females to engage in coalition formation. Males need male allies to take over groups with mature females. The alpha male sires virtually all offspring born to females who are not his direct descendants. Thus, the males who assist the alpha male in gaining and preserving access to breeding females typically must delay breeding until the alpha male's daughters have matured. Infanticide by new alpha males is the primary cause of infant death, and therefore females tend to support the current alpha male. Some alpha males maintain their position for up to 18 years; under such stable demographic conditions, survival rates and the average degree of relatedness within a group are high.