Genetic and geographic structure of an insect resistant and a susceptible type of Barbarea vulgaris in western Europe

Thure Pavlo Hauser, Fiorello Toneatto, Jens Kvist Nielsen

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    Abstract

    Abstract Interactions between herbivores and plants are believed to have been important
    drivers of biodiversity. However, to drive an initial resistance divergence into different
    evolutionary lineages and taxa, these interactions have probably been embedded in other
    processes of divergence, like allopatric isolation. The cruciferous plant Barbarea vulgaris
    ssp. arcuata occurs in Denmark in two types: one (G) is resistant to most genotypes of the
    flea beetle Phyllotreta nemorum, the other (P) is susceptible. The two types additionally
    differ in hairiness and glucosinolates, they are genetically strongly divergent, and reproduction
    between them is reduced. To determine whether the two plant types and their
    resistance polymorphisms are also present outside Denmark, and to understand how they
    have evolved, we analysed 33 European populations of B. vulgaris for resistance, hairiness,
    glucosinolates, and microsatellite markers. Most populations had traits indicative of the G
    type, including the already characterized Danish G populations. In contrast, only two
    populations outside Denmark were of the P type; one from northern Sweden and one from
    Estonia. Genetically, the G populations formed two genetic clusters that were strongly
    divergent from a genetic cluster containing P populations. A fourth genetic cluster, which
    contained only a single population and no Danish plants, belonged morphologically to the
    subspecies ssp. vulgaris. The divergence found in Denmark between a resistant G and a
    susceptible P type is thus part of a larger divergence in Europe. Judging from the trait
    correlations, genetic divergence, and partial reproductive incompatibility, the plant types
    must have been isolated from each other for quite some time. The two P populations
    outside Denmark came from the north and east, suggesting a more eastern distribution. If
    so, resistant and susceptible types could have diverged during the ice age and later met in
    Scandinavia. However, more samples from Eastern Europe are needed to clarify this.
    Original languageEnglish
    JournalEvolutionary Ecology
    Volume26
    Issue number3
    Pages (from-to)611-624
    Number of pages14
    ISSN0269-7653
    DOIs
    Publication statusPublished - 2012

    Keywords

    • ???Modstandsdygtighed mod sygdomme???

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