A 21-YEAR STUDY OF MATERNAL DOMINANCE AND SECONDARY SEX-RATIO IN A COLONY GROUP OF STUMPTAILED MACAQUES (MACACA-ARCTOIDES)

Trivers and Willard's theory of sex-ratio adjustment, as applied to ce rcopithecines, predicts that the ratio of male to female offspring wil l be greater for dominant than for subordinate mothers. A local-resour ce-competition hypothesis predicts the reverse. To date, results from several species of macaque are inconsistent and often not statisticall y significant. In this 21 year study, a colony group of stumptailed ma caques is added to the species previously studied. Seventy-five offspr ing were born to eight mothers for whom long-term dominance was establ ished. Chi-square analyses of data from these 75 offspring failed to y ield a significant relationship between sex-ratio and mother's dominan ce; consequently, consistent with a growing body of cercopithecine lit erature, neither of the competing theories was supported, (C) 1994 Wil ey-Liss, Inc.