Two girls for every boy

The effects of group size and composition on the reproductive success of male and female white‐faced capuchins

Bibliographic Data

ID8317365
AuthorsLinda Marie Fedigan (0000-0001-9343-629X, University of Calgary, corresponding author), Katharine M Jack (0000-0003-3569-8544, Tulane University)
Year2011
Volume144
Issue2
Pages317-326
Publication date2011-02-01
Peer ReviewedYes
Open AccessYes
TypeARTICLE
VenueAmerican Journal of Physical Anthropology (JOURNAL)
Journal identifiersISSN: 0002-9483 • E-ISSN: 1096-8644
PublisherWiley (PUBLISHER • GB)
DOI10.1002/ajpa.21414
PMID20979204
OpenAlexW2096511562
LanguageEN
Citations received13
References cited77

Many factors have been hypothesized to affect the size and adult sex ratios of primate groups and these, in turn, have been argued to influence birth rates. Using park‐wide census data collected on a population of capuchins over a 25‐year period, we examined whether group size and adult sex ratio affect the per capita reproductive success of male and female white‐faced capuchins ( Cebus capucinus ) in Santa Rosa National Park, Costa Rica. We found that the reproductive success of females (measured as the observed minus the expected ratio of immatures to adult females in the group) decreased with increasing group size, whereas that of males was independent of group size. The proportion of adult males residing in groups had significant, yet contrasting effects on males and females. Male reproductive success was negatively associated with the proportion of males residing in groups whereas female reproductive success increased with the proportion of males. The latter finding supports the intersexual conflict hypothesis, which suggests that a conflict of interest occurs between males and females over adult sex ratios. The effects of group size and composition on the reproductive success of capuchins, a male‐dispersed omnivorous species, are similar to those reported for howlers, a bisexually‐dispersed folivorous species. One common factor between these taxa is that groups with low ratios of males to females are at greater risk of takeovers and resultant infanticide. Our results suggest that regardless of dietary preference and dispersal pattern, the threat of infanticide can constrain primate group size and composition. Am J Phys Anthropol, 2011. © 2010 Wiley‐Liss, Inc

Affect (linguistics) · Biology · Population · Primate · Reproductive success · Sex ratio · Zoology · Animal Behavior and Reproduction · Animal Vocal Communication and Behavior · Demography · Ecology · Primate Behavior and Ecology · Psychology