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

Egalitarian female relationships in Colobus vellerosus (ursine colobus): individualistic hierarchies with high linearity and stability, moderate bidirectionality, and low expression


1Department of Anthropology, University of Calgary, 2Department of Anthropology, McGill University, 3Department of Anthropology, University of Toronto

Thursday 9:00-9:15, Galleria South Add to calendar

Females that do not experience strong and consistent contest competition for food are presumed to lack decided dominance relationships. However, recent studies have documented stable dominance relationships between females that only occasionally experience contest competition. It is unclear where females in these populations lie on the egalitarian to despotic dominance continuum. It is therefore important to compare the characteristics of their dominance relationships with other populations. We investigated the linearity, expression, bidirectionality and stability of the female hierarchies in a folivorous primate, Colobus vellerosus. During 2004 to 2011, we collected data via ad libitum and focal sampling on sixty-four females in eight groups at Boabeng-Fiema, Ghana. In four groups with few unknown submissive relationships, females formed individualistic hierarchies with high linearity indices ranging from 0.9 to 1. The hierarchical expression was low based on submission rates, although there was considerable between-group variation in the latency to detect a linear hierarchy. Females in most groups formed unidirectional and stable relationships. However, maturing females challenged older females in some groups, and these groups had more bidirectional relationships and higher rates of individual rank change (ranging up to 0.83 positions per year). This between-group variation highlights the importance of using longitudinal data. Apart from higher stability, the dominance relationships were similar to those in other folivorous primates that may experience occasional contest competition. Female C. vellerosus did not show as unidirectional or well-expressed submissive relationships as despotic cercopithecines. Therefore, female C. vellerosus lie on the egalitarian end of the dominance continuum.

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