Mate choice by lineage in three captive groups of rhesus macaques (Macaca mulatta).

The hypothesis that the matrilineal affiliation of 410 infants born in three captive groups of rhesus macaques is independent of the patrilineal affiliation of these infants was tested. Preferential mating with particular patrilines was observed for matrilineal members. We conclude that lineage affiliation does influence mate choice of rhesus macaques, at least when a large number of matrilines and relatively few patrilines which include natal males are represented in the group. Such nonrandom mating might explain high levels of genetic heterogeneity reported among matrilines within rhesus groups, despite high rates of male emigration, and is consistent with the maintenance of high levels of within-matriline kinship which might promote cooperative behavior among matriline members.