Evolution of host resistance: looking for coevolutionary hotspots at small spatial scales.
Natural plant populations are often found to be extremely diverse in their resistance to pathogens. While the potential of pathogens in driving the evolution of resistance in hosts has been widely recognized, empirical evidence linking disease dynamics to host population genetic structure has remained scarce. Here I show that current coevolutionary selection for resistance can be divergent even on a very fine spatial scale. In a natural plant-pathogen metapopulation, disease occurrence patterns were highly aggregated over space and time within host populations. A laboratory inoculation experiment showed higher resistance within areas of the host populations where encounter rates with the pathogen have been high. Higher resistance to sympatric than to allopatric strains of the pathogen suggests that this change has taken place as a response to local selection. These results constitute evidence of adaptive microevolution of resistance resulting from disease epidemics in natural plant-pathogen associations, and highlight the importance of finding the relevant scale at which to address questions of current coevolutionary selection.
Department of Biological and Environmental Sciences, University of Helsinki, Metapopulation Research Group, PO Box 65 (Viikinkaari 1), 00014 Helsinki, Finland. anna-liisa.laine@helsinki.fi
Anna-Liisa
AL
Laine
D001203:Ascomycota / Q000254:growth & development*; D005075:Biological Evolution; D007113:Immunity, Innate / Q000235:genetics; D010935:Plant Diseases / Q000382:microbiology*; D010943:Plantago / Q000235:genetics*; D012641:Selection, Genetic