Doctoral Dissertation Research: Sources of of Conflict and Power Variation in Male-Female Relationship in White Sifaka (Propithecus Verreauxi Verreauxi)

Duke University, Durham NC

Investigators

Abstract

Power in animal societies is typically studied in terms of differences in fighting abilities, or dominance. However, other more economic forms of power, or leverage, may influence an individual's power. Relationships between the sexes are particularly interesting for studying power because mating opportunities and protection services may be exchanged between males and females and often cannot be taken by force. The objective of this research is to examine some power-related factors that can lead to variation in male-female relationships. This study will examine the effects of leverage (based upon female reproductive status and the ratio of males to females) and dominance (based upon fighting ability) on male-female relationships in white sifaka. The white sifaka is an ideal species for studying male-female relationships. First, males and females are not expected to differ in their fighting abilities because they are the same size. Nevertheless, female sifaka have priority of access to resources and often are aggressive towards males. Second, the effects of reproductive status on male-female relationships can be determined without depending upon hormone analysis because sifaka have a very short mating season. Third, services such as watching for predators, alarm calling, and defense against predators may be an important currency for exchange for sifaka. Finally, these lemurs live in social groups where the ratio of males to females varies across groups. These characteristics suggest that the effects of dominance will be reduced and that leverage effects will more easily be observed in this species. Sex ratio, behavioral, and body size data will be collected by 4 observers on 6 focal groups with different sex ratios at Kirindy forest in Madagascar from October 2000-March 2002. Neighborhoods will be censused monthly. To estimate each individual's ability to use force, body size and condition data will be collected 4 times during the study and combined with canine size data. The broader implications of this research include a better understanding of male-female relationships in all mammals, where a broad theoretical framework is lacking outside of mating systems. Moreover, male-female relationships have played a prominent role in hypotheses about human social evolution. The exchange of services, such as parental care and infanticide protection, may have led to some sort of bonding between the sexes. Using economic and political theory, this interdisciplinary project attempts to better understand human social evolution by testing these theories in a species where males and females are the same size, and hence, non-dominance power can best be studied.