抄録
Mammals are exposed to a large array of parasites that may dramatically affect host fitness. Species living in large groups are especially exposed. An increased exposure to parasites has been proposed to be one of the major costs of sociality. Parasites are thought, however, to represent a selection force driving the evolution of host social system, possibly shaping specific host behavioral patterns. Here, we studied the influence of intestinal parasitism on social behavior in a wild mandrill population as well as a proximate mechanism responsible for the detection and the avoidance of parasitized individuals. By coupling chemical, behavioral and parasitological analyses, we showed that some intestinal parasites, transmitted by physical contacts between hosts, involve a decrease in sociality of infected individuals. Besides, some of these parasites appeared to modify the fecal odorants of infected animals. These results suggest that parasitism may represent a selection force acting directly on social behavior: individuals could adapt to important parasitic pressures by elaborating recognition mechanisms based on odorants, allowing behavioral avoidance of infected individuals.
