Meeting Abstract
Resource availability is a key environmental constraint affecting the ecology and evolution of species. Resources have strong effects on disease resistance, but they can also affect the other main parasite defense strategy, tolerance. Plant researchers and a growing number of animal disease ecologists have investigated the effects of resources on tolerance phenotypes. Surprisingly, both resource limitation and supplementation can increase tolerance in particular host-parasite systems, but a theoretical framework to understand and predict these outcomes is lacking for macroparasites. We adapted the Anderson and May macroparasite model to explore the conditions under which a tolerance strategy to parasite infection is more adaptive than resisting. Hosts must allocate a finite amount of resources among reproduction, resistance or tolerance. Across a range of resource availability, we find the evolutionary stable strategy varies with both host traits (e.g. lifespan) and parasite traits (e.g. virulence). Optimal investment in tolerance also depends upon whether parasite virulence affects mortality or fecundity, as well as the nature and cost of resistance. Our model provides a framework for interpreting previous resource-tolerance experiments and hypotheses that warrant testing in future empirical studies.
