Long-distance dispersal maximizes evolutionary potential during rapid geographic range expansion

Authors

  • Cécile Berthouly-Salazar,

    1. Centre for Invasion Biology, Department of Botany & Zoology, Stellenbosch University, Stellenbosch, South Africa
    Current affiliation:
    1. Institut de Recherche pour le Développement, UMR Diversité, Adaptation et Développement des Plantes (DIADE), Montpellier Cedex 5, France
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  • Cang Hui,

    1. Centre for Invasion Biology, Department of Botany & Zoology, Stellenbosch University, Stellenbosch, South Africa
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  • Tim M. Blackburn,

    1. Institute of Zoology, Zoological Society of London, London, UK
    2. Distinguished Scientist Fellowship Program, King Saud University, Riyadh, Saudi Arabia
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  • Coline Gaboriaud,

    1. Centre for Invasion Biology, Department of Botany & Zoology, Stellenbosch University, Stellenbosch, South Africa
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  • Berndt J. van Rensburg,

    1. Department of Zoology and Entomology, Centre for Invasion Biology, University of Pretoria, Hatfield, South Africa
    Current affiliation:
    1. School of Biological Sciences, University of Queensland, Bribane, Qld, Australia
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  • Bettine Jansen van Vuuren,

    1. Centre for Invasion Biology, Department of Zoology, University of Johannesburg, Auckland Park, South Africa
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  • Johannes J. Le Roux

    Corresponding author
    1. Centre for Invasion Biology, Department of Botany & Zoology, Stellenbosch University, Stellenbosch, South Africa
    • Correspondence: Johannes J. Le Roux, Fax: +27 21 808 2995; E-mail: jleroux@sun.ac.za

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Abstract

Conventional wisdom predicts that sequential founder events will cause genetic diversity to erode in species with expanding geographic ranges, limiting evolutionary potential at the range margin. Here, we show that invasive European starlings (Sturnus vulgaris) in South Africa preserve genetic diversity during range expansion, possibly as a result of frequent long-distance dispersal events. We further show that unfavourable environmental conditions trigger enhanced dispersal, as indicated by signatures of selection detected across the expanding range. This brings genetic variation to the expansion front, counterbalancing the cumulative effects of sequential founding events and optimizing standing genetic diversity and thus evolutionary potential at range margins during spread. Therefore, dispersal strategies should be highlighted as key determinants of the ecological and evolutionary performances of species in novel environments and in response to global environmental change.

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