The role of spatial heterogeneity in shaping pathogen populations in agricultural landscapes
Résumé
Which pathogen genotypes will develop on which crop cultivar? This is a crucial question in plant epidemiology for understanding the link between the host population structure and its susceptibility to disease. In the present work, we develop a theoretical approach to investigate the conditions of emergence and establishment of a mutant pathogen with generalist features in an agricultural landscape, then we determine the conditions of co-existence between genotypes with specialist and generalist features. We found that the spatial structure of landscape heterogeneity had a strong effect on the genetic structure of the pathogen population. In particular, the geometry and size of the host genotype aggregates interacted with the initial position of inoculums to determine the ability of the generalist pathogen to establish locally. In addition, coexistence among generalist and specialist pathogen genotypes occurred rather easily while only two hosts are cultivated. We finally discuss the implication of ours findings in a management perspective.
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