Abstract # 58:

Scheduled for Thursday, June 19, 2008 05:00 PM-07:00 PM: Session 4 (Ball Rooms A and B) Poster Presentation

Battle of the sexes: cost assymetry explains female dominance in lemurs

A. E. Dunham
Rice University, Department of Ecology and Evolutionary Biology, Houston, TX, USA
     The occurrence of female social dominance in lemurs (Lemur sp.) has been an unsolved enigma in primatology for almost 25 years. The two predominant explanations in the current literature are that it has evolved as an adaptation to a harsh island environment to favor female reproduction or that it may be a result of evolutionary disequilibrium following the extinction of large predatory eagles and large-bodied lemur species in Madagascar's recent history. However, these explanations have been controversial and/or fail to adequately explain the discrepancy with other mammalian taxa that display typical male dominance patterns and live in environments that are substantially poorer in resources and more extreme in seasonality. I show through a game theoretical approach how female dominance can be explained simply by a cost asymmetry in inter-sexual contests over resources and the unusual size monomorphism of the sexes. The model is based on previously developed game theoretical explanations that are generally accepted in the field of animal behavior but so far missing from discussions of lemur life history. The model that is developed shows that the conditional strategy of males deferring to females in this case is an evolutionarily stable strategy. These results have important implications for understanding social evolution in primates and other taxa. I suggest that we should rethink our current focus on the question of female dominance in lemurs and other monomorphic taxa and redirect it towards understanding the evolution of monomorphic size in species with male-biased operational sex ratios.