Host-related genetic differentiation in the anther smut fungus Microbotryum violaceum in sympatric, parapatric and allopatric populations of two host species Silene latifolia and S. dioica

Authors

  • W. F. Van Putten,

    1. Department of Plant Population Biology, Netherlands Institute of Ecology, NIOO-KNAW, NL-6666 ZG Heteren, The Netherlands
    2. Department of Evolutionary Genetics, University of Groningen, Kerklaan, The Netherlands
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  • A. Biere,

    1. Department of Plant Population Biology, Netherlands Institute of Ecology, NIOO-KNAW, NL-6666 ZG Heteren, The Netherlands
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  • J. M. M. Van Damme

    1. Department of Plant Population Biology, Netherlands Institute of Ecology, NIOO-KNAW, NL-6666 ZG Heteren, The Netherlands
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W. F. Van Putten, Department of Evolutionary Genetics, University of Groningen, Kerklaan 30, NL-9751 NN Haren, The Netherlands.
Tel.: +31 50 363 2119; fax: +31 50 363 2348;
e-mail: w.f.van.putten@biol.rug.nl

Abstract

We investigated genetic diversity in West European populations of the fungal pathogen Microbotryum violaceum in sympatric, parapatric and allopatric populations of the host species Silene latifolia and S. dioica, using four polymorphic microsatellite loci. In allopatric host populations, the fungus was highly differentiated by host species, exhibiting high values of FST and RST, and revealed clear and distinct host races. In sympatric and parapatric populations we found significant population differentiation as well, except for one sympatric population in which the two host species grew truly intermingled. The mean number of alleles per locus for isolates from each of the host species was significantly higher in sympatric/parapatric than in allopatric populations. This suggests that either gene flow between host races in sympatry, or in case of less neutral loci, selection in a more heterogeneous host environment can increase the level of genetic variation in each of the demes. The observed pattern of host-related genetic differentiation among these geographically spread populations suggest a long-term divergence between these host races. In sympatric host populations, both host races presumably come in secondary contact, and host-specific alleles are exchanged depending on the amount of fungal gene flow.

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