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Contrasting spatio-temporal climatic niche dynamics during the eastern and western invasions of spotted knapweed in North America

Authors

  • Olivier Broennimann,

    Corresponding author
    1. Spatial Ecology Laboratory, Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
    • Correspondence: O. Broennimann, Spatial Ecology Laboratory, Department of Ecology and Evolution, University of Lausanne, Biophore Building, CH-1015, Lausanne, Switzerland.

      E-mail: olivier.broennimann@unil.ch

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  • Patrik Mráz,

    1. Unit of Ecology and Evolution, Department of Biology, University of Fribourg, Fribourg, Switzerland
    2. Department of Botany, Charles University in Prague, Prague, Czech Republic
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  • Blaise Petitpierre,

    1. Spatial Ecology Laboratory, Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
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  • Antoine Guisan,

    1. Spatial Ecology Laboratory, Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
    2. Institute of Earth Surface Dynamics, University of Lausanne, Lausanne, Switzerland
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    • Shared last authorship.
  • Heinz Müller-Schärer

    1. Unit of Ecology and Evolution, Department of Biology, University of Fribourg, Fribourg, Switzerland
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    • Shared last authorship.

Abstract

Aim

The spotted knapweed (Centaurea stoebe), a plant native to south-east and central Europe, is highly invasive in North America. We investigated the spatio-temporal climatic niche dynamics of the spotted knapweed in North America along two putative eastern and western invasion routes. We then considered the patterns observed in the light of historical, ecological and evolutionary factors.

Location

Europe and North America.

Methods

The niche characteristics of the east and west invasive populations of spotted knapweed in North America were determined from documented occurrences over 120 consecutive years (1890–2010). For this investigation, the 2.5 and 97.5 percentiles of values along temperature and precipitation gradients, as given by the two first axes of a principal components analysis (PCA), were calculated. We additionally measured the climatic dissimilarity between invaded sites and the native niche using a multivariate environmental similarity surface (MESS) analysis.

Results

Along both invasion routes, the species established in regions with climatic conditions that were similar to those in the native niche. An initial spread in ruderal habitats always preceded spread in (semi-)natural habitats. In the east, the niche gradually increased over time until it reached limits similar to the native niche. Conversely, in the west the niche abruptly expanded after an extended time lag into climates not occupied in the native range; only the native cold niche limit was conserved.

Main conclusions

Our study reveals that different niche dynamics have taken place during the eastern and western invasions. This pattern indicates different combinations of historical, ecological and evolutionary factors in the two ranges. We hypothesize that the lack of a well-developed transportation network in the west at the time of the introduction of spotted knapweed confined the species to a geographically and climatically isolated region. The invasion of dry rangelands may have been favoured during the agricultural transition in the 1930s by release from natural enemies, local adaptation and less competitive vegetation, but further experimental and molecular studies are needed to explain these contrasting niche patterns fully. Our study illustrates the need and benefit of applying large-scale, temporally explicit approaches to understanding biological invasions.

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