Within- and among-population variation in infectivity, latency and spore production in a host–pathogen system

Authors

  • O. Kaltz,

    1. Laboratoire d'Evolution et Systématique, CNRS URA 2154, Université de Paris-Sud (XI), Bâtiment 362, 91405 Orsay Cedex, France
    2. Experimentelle Ökologie, Eidgenössische Technische Hochschule Zürich, ETHZ – NW, 8092 Zürich, Switzerland
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  • J. A. Shykoff

    1. Laboratoire d'Evolution et Systématique, CNRS URA 2154, Université de Paris-Sud (XI), Bâtiment 362, 91405 Orsay Cedex, France
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 Oliver Kaltz, Laboratoire de Parasitologie Evolutive CNRS-UMR 7103, Université Pierre et Marie Curie, CC 237, 7, quai Saint Bernard, F-75252 Paris Cedex, France.
Tel.: +33 1 44273823; fax: +33 1 44273516; e-mail: okaltz@snv.jussieu.fr

Abstract

In spatially structured populations, host–parasite coevolutionary potential depends on the distribution of genetic variation within and among populations. Inoculation experiments using the plant, Silene latifolia, and its fungal pathogen, Microbotryum violaceum, revealed little overall differentiation in infectivity/resistance, latency or spore production among host or pathogen populations. Within populations, fungal strains had similar means, but varied in performance across plant populations. Variation in resistance among seed families indicates the potential for parasite-mediated selection, whereas there was little evidence for local pathogen genotype × plant genotype interactions assumed by most theoretical coevolution models. Lower spore production on sympatric than allopatric hosts confirmed local fungal maladaptation already observed for infectivity. Correlations between infectivity and latency or spore production suggest a common mechanism for variation in these traits. Our results suggest low variation available to this pathogen for tracking its coevolving host. This may be caused by random drift, breeding system or migration characteristic of metapopulation dynamics.

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