Dernière mise à jour : mardi 1er décembre 2015, par
Par : Andrew MACINTOSH, Kyoto University
Date : Lundi 7 décembre 2015 à 14h00
Lieu : IPHC, Amphithéâtre Grünewald, bâtiment 25
The hypothesis that parasites have influenced primate social evolution appeared four decades ago in a seminal paper by W. J. Freeland in 1976, but empirical support remains scarce. For parasites to select for primate social characteristics, natural selection requires that parasites (1) differentially infect individuals with certain social characteristics and (2) constrain the reproductive success of differentially infected individuals. Recently, studies have begun to link certain elements of primate social structure (e.g. social network topology) to infection, but few have attempted to ground-truth the models using empirical systems and none have yet linked parasite infection to the reproductive success of individual primates. Here, I synthesize work from a Japanese macaque (Macaca fuscata) – gastrointestinal helminth model system, providing multiple lines of evidence supporting this hypothesis. First, naturalistic observation of social interactions and parasite infection suggests that parasites, particularly nodular worm (Oesophagostomum aculeatum), differentially infect macaques according to social interaction networks. Second, parasite removal experiments across 3 breeding seasons suggest that the same parasite constrains female macaque fitness by impairing body mass maintenance and reproductive output. Establishing one-to-one links in complex ecological interactions is difficult and may not reflect the whole story, but this work is consistent with the possibility that nodular worm – like the strongyle nematodes that regulate other vertebrate hosts – can regulate primate populations and sociality at both ecological and evolutionary scales.