Fitness and extra-group reproduction in male Verreaux's sifaka: An analysis of reproductive success from 1989-1999

• Published in: American journal of physical anthropology Vol. 132; no. 2; pp. 267 - 277
• Main Author: Lawler, Richard R.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.02.2007; Wiley-Liss
• Subjects: Animals; Biological anthropology; Environmental studies; Excavation and methods; Fauna; fitness components; Human paleontology; Interpretation, statistical and computer analysis; Laboratory methods; lemur; Madagascar; Male; Mankind origin and evolution; Mate selection; mating systems; Methodology and general studies; Models, Biological; Physical anthropology; Prehistory and protohistory; Primates; Primatology; Propithecus; Reproduction; Sexual Behavior, Animal; Social organization; Strepsirhini - physiology; Madagascar; Africa; Study; Demography; Sample; Access; mating systems; Source; fitness components; lemur; Reproduction; Propithecus; Analysis; Model; Population; Primate; Coupling; Variation
• ISSN: 0002-9483; 1096-8644
• DOI: 10.1002/ajpa.20507

Adult males in social groups often compete with other male group members for access to adult females. In some primate species, males also seek mating opportunities in neighboring social groups. Such extra‐group fertilizations (EGFs) provide an additional source of variation in male fitness. This additional component of fitness provided by EGFs must be incorporated into analyses that investigate sources of variation in male lifetime reproductive success. In this study, a model is analyzed in which male fitness over a 10‐year sample period is decomposed into additive and multiplicative variance and covariance components. The data come from an ongoing study of a wild population of Verreaux's sifaka (Propithecus verreauxi verreauxi) located at Beza Mahafaly Special Reserve, Southwest Madagascar. Paternity and demographic data for 134 males are used to decompose male fitness into the following three multiplicative components: reproductive lifespan during sample period, fertility, and offspring survival. These multiplicative components are estimated for males reproducing within their resident groups plus (i.e., the additive portion) for males reproducing in neighboring social groups. The analysis shows that variation in fertility makes the largest contribution to variation in total fitness, followed by variation in amount of time spent in sample period (which is a proxy of total reproductive lifespan) and variation in offspring survival. EGFs contribute an important source of variation to male fitness, and numerous factors enhance the opportunities for EGFs in male sifaka. These include female choice, a high degree of home range overlap, and a limited mating season. Am J Phys Anthropol, 2007. © 2006 Wiley‐Liss, Inc.