title: Variance in male lifetime reproductive success and estimation of the degree of polygyny in a primate.
abstract: The degree of polygyny is predicted to influence the strength of direct male-male competition, leading to a high variance in male lifetime reproductive success and to reproduction limited to the prime period of adulthood. Here, we explore the variance in male lifetime reproductive success and reproductive time in an anthropoid primate forming multimale-multifemale groups. Males of this species form dominance hierarchies, which are expected to skew reproduction toward few high-ranking males. At the same time, however, females mate with multiple males (polygynandry), which should limit the degree of polygyny. Using 20 years of genetic and demographic data, we calculated lifetime reproductive success for the free-ranging rhesus macaque (Macaca mulatta) population of Cayo Santiago for subjects that died naturally or reached senescence. Our results show that 1) male lifetime reproductive success was significantly skewed (range: 0-47 offspring; males reproducing below average: 62.8%; nonbreeders: 17.4%), 2) variance in male lifetime reproductive success was 5 times larger than in females, and 3) male lifetime reproductive success was more influenced by variation in fecundity (60%) than longevity (25%), suggesting that some direct male-male competition takes place. However, the opportunity for selection (i.e., standardized variance in male lifetime reproductive success) is low compared with that in other large mammal species characterized by a high degree of polygyny. Moreover, male reproductive life extended much beyond the prime period, showing that physical strength was not required to acquire mates. We conclude that rhesus macaques exhibit a moderate degree of polygyny and, therefore, low levels of direct male-male competition for fertile females, despite the fact that males form linear dominance hierarchies.
authors.affiliation: Junior Research Group of Primate Kin Selection, Department of Primatology, Max-Planck Institute for Evolutionary Anthropology , Deutscher Platz 6, 04103 Leipzig , Germany , ; Center for the Study of Human Origins, Department of Anthropology, New York University , 25 Waverly Place, New York, NY 10003 , USA .
authors.forename: Constance
authors.initials: C
authors.lastname: Dubuc
authors.affiliation: Junior Research Group of Primate Kin Selection, Department of Primatology, Max-Planck Institute for Evolutionary Anthropology , Deutscher Platz 6, 04103 Leipzig , Germany , ; Cayo Santiago, Caribbean Primate Research Center, University of Puerto Rico , PO Box 306, Punta Santiago, PR 00741 , USA , and.
authors.forename: Angelina
authors.initials: A
authors.lastname: Ruiz-Lambides
authors.affiliation: Junior Research Group of Primate Kin Selection, Department of Primatology, Max-Planck Institute for Evolutionary Anthropology , Deutscher Platz 6, 04103 Leipzig , Germany , ; Research Group of Behavioural Ecology, Institute of Biology, Faculty of Bioscience, Pharmacy and Psychology, University of Leipzig , Talstrasse 33, 04103 Leipzig , Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Widdig
keywords: lifetime reproductive success; male–male competition; mammals; opportunity for selection; reproductive skew; reproductive timing; rhesus macaques.