Choisy Marc auteur aut IRD de Roode J. C. auteur aut IRD text journalArticle eng text/pdf born digital access Animal medication against parasites can occur either as a genetically fixed (constitutive) or phenotypically plastic (induced) behavior. Taking the tritrophic interaction between the monarch butterfly Danaus plexippus, its protozoan parasite Ophryocystis elektroscirrha, and its food plant Asclepias spp. as a test case, we develop a game-theory model to identify the epidemiological (parasite prevalence and virulence) and environmental (plant toxicity and abundance) conditions that predict the evolution of genetically fixed versus phenotypically plastic forms of medication. Our model shows that the relative benefits (the antiparasitic properties of medicinal food) and costs (side effects of medicine, the costs of searching for medicine, and the costs of plasticity itself) crucially determine whether medication is genetically fixed or phenotypically plastic. Our model suggests that animals evolve phenotypic plasticity when parasite risk (a combination of virulence and prevalence and thus a measure of the strength of parasite-mediated selection) is relatively low to moderately high and genetically fixed medication when parasite risk becomes very high. The latter occurs because at high parasite risk, the costs of plasticity are outweighed by the benefits of medication. Our model provides a simple and general framework to study the conditions that drive the evolution of alternative forms of animal medication. specialized self-medication phenotypic plasticity zoopharmacognosy ecological immunology behavioral immunity disease ecology 080 020 052 076 184 Suppl. 1 S31-S46 2014 0003-0147 https://www.documentation.ird.fr/hor/fdi:010063612 10.1086/676928 0003-0147 [F B010063612] https://www.documentation.ird.fr/hor/fdi:010063612 https://www.documentation.ird.fr/intranet/publi/2015/01/010063612.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2015-02-02 2017-08-23 fdi:010063612 fre