Résumé
Ecological theory predicts that disease incidence increases with
increasing density of host networks, yet evolutionary theory suggests that
host resistance increases accordingly. To test the combined effects of
ecological and evolutionary forces on host-pathogen systems, we analyzed
the spatiotemporal dynamics of a plant (Plantago lanceolata)–fungal
pathogen (Podosphaera plantaginis)relationship for 12 years in over 4000
host populations. Disease prevalence at the metapopulation level was low,
with high annual pathogen extinction rates balanced by frequent
(re-)colonizations. Highly connected host populations experienced less
pathogen colonization and higher pathogen extinction rates than expected;
a laboratory assay confirmed that this phenomenon was caused by higher
levels of disease resistance in highly connected host populations.