Differentiation of reproductive and competitive ability in the invaded range of Senecio inaequidens: the role of genetic Allee effects, adaptive and nonadaptive evolution

Authors

  • Susanne Lachmuth,

    1. Plant Ecology and Nature Conservation, University of Potsdam, Maulbeerallee 2, 14469 Potsdam, Germany
    2. Plant Ecology, Martin-Luther-University Halle-Wittenberg, Am Kirchtor 1, 06099 Halle, Germany
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  • Walter Durka,

    1. Helmholtz-Centre for Environmental Research – UFZ, Department Community Ecology (BZF), Theodor-Lieser-Str. 4, 06120 Halle, Germany
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  • Frank M. Schurr

    1. Plant Ecology and Nature Conservation, University of Potsdam, Maulbeerallee 2, 14469 Potsdam, Germany
    2. Institute for Physical Geography, Goethe-University Frankfurt am Main, Altenhoeferallee 1, 60438 Frankfurt am Main, Germany
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Author for correspondence:
Susanne Lachmuth
Fax: +49 345 5527228
Email: susanne.lachmuth@botanik.uni-halle.de

Summary

  • Genetic differentiation in the competitive and reproductive ability of invading populations can result from genetic Allee effects or r/K selection at the local or range-wide scale. However, the neutral relatedness of populations may either mask or falsely suggest adaptation and genetic Allee effects.
  • In a common-garden experiment, we investigated the competitive and reproductive ability of invasive Senecio inaequidens populations that vary in neutral genetic diversity, population age and field vegetation cover. To account for population relatedness, we analysed the experimental results with ‘animal models’ adopted from quantitative genetics.
  • Consistent with adaptive r/K differentiation at local scales, we found that genotypes from low-competition environments invest more in reproduction and are more sensitive to competition. By contrast, apparent effects of large-scale r/K differentiation and apparent genetic Allee effects can largely be explained by neutral population relatedness.
  • Invading populations should not be treated as homogeneous groups, as they may adapt quickly to small-scale environmental variation in the invaded range. Furthermore, neutral population differentiation may strongly influence invasion dynamics and should be accounted for in analyses of common-garden experiments.

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