Strategies of host resistance to pathogens in spatially structured populations: An agent-based evaluation.

Abstract

There is growing theoretical evidence that spatial structure can affect the ecological and evolutionary outcomes of host-parasite interactions. Locally restricted interactions have been shown in particular to affect host resistance and tolerance. In this study we investigate the evolution of several types of host disease resistance strategies, alone or in combination, in spatially structured populations. We construct a spatially explicit, individual-based stochastic model where hosts and parasites interact with each other in a spatial lattice, and interactions are restricted to a given neighbourhood of varying size. We investigate several host resistance strategies, including constitutive (expressed in all resistant hosts), induced (expressed only upon infection), and combinations thereof. We show that the specific resistance mechanism against a pathogen as well as the size of the neighbourhood both affect resistance spread and parasite dynamics, an effect modulated by the level of the cost of resistance. Our results shed new light on the dynamics of disease resistance in a spatially-structured host-pathogen system, and illustrate the conditions in which a variety of resistance mechanisms can be maintained, including when they are costly. Overall these results advance our theoretical understanding of the evolutionary dynamics of disease resistance, a necessary step to elaborate more efficient and sustainable strategies for disease management.