Parasite-mediated sexual selection in primates? The effect of intestinal parasites on the reproductive success of wild lemurs (Eulemur fulvus rufus)

Abstract

Parasites are a driving force in sexual selection, but they can have negative impacts on their hosts. Hence, females should choose mates displaying good health and an ability to resist para-site infections. Assuming a genetic basis for parasite resistance, partners with low parasite infections should be preferred over others in order to obtain resistance genes for their offspring (parasite-mediated sexual selection). With our interdisciplinary approach we will contribute to understanding both determinants of individual parasite infections and mechanisms of para-site-mediated sexual selection in primates. Specifically, we analyze faecal samples of free-ranging red-fronted lemurs (Eulemur fulvus rufus)to characterize their intestinal parasite fauna by means of the formalin-ethyl-acetate sedimentation technique. Parasite infections are being cor-related with (1) genetic correlates at the interleukin-4 locus, which is involved in parasite resistance, (2) proximate endocrine factors (testosterone and cortisol) that co-vary with the functioning of the immune system, and (3) socio-demographic data, such as sex, age and population group size of the hosts that may influence parasite infestations. Moreover, we examine whether primates use honest signals, such as conspicuous coloration, in order to assess their mate’s genetic quality. Using data from paternity analyses of the study population, we will be able to link parasite infection with reproductive success of males with different genetic and endocrine constitutions. As data collection was just about finished at the start of this conference, the presentation will give an overview of the project and present preliminary data.