From introduction to equilibrium: reconstructing the invasive pathways of the Argentine ant in a Mediterranean region

Authors

  • NÚRIA ROURA-PASCUAL,

    1. Departament de Ciències Ambientals, Universitat de Girona, Campus de Montilivi, 17071 Girona, Catalonia,
    2. Department of Botany and Zoology, Centre for Invasion Biology, Stellenbosch University, Private Bag X1, Matieland 7600, South Africa,
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  • JOSEP M. BAS,

    1. Departament de Ciències Ambientals, Universitat de Girona, Campus de Montilivi, 17071 Girona, Catalonia,
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  • WILFRIED THUILLER,

    1. Laboratoire d'Ecologie Alpine, UMR-CNRS 5553, Université J. Fourier, BP 53, 38041 Grenoble Cedex 9, France,
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  • CANG HUI,

    1. Department of Botany and Zoology, Centre for Invasion Biology, Stellenbosch University, Private Bag X1, Matieland 7600, South Africa,
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  • RAINER M. KRUG,

    1. Department of Botany and Zoology, Centre for Invasion Biology, Stellenbosch University, Private Bag X1, Matieland 7600, South Africa,
    2. Plant Conservation Unit, Department of Botany, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa,
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  • LLUÍS BROTONS

    1. Centre Tecnolgic Forestal de Catalunya, Àrea de Biodiversitat, Pujada del Seminari s/n, 25280 Solsona, Spain
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Núria Roura-Pascual, Departament de Ciències Ambientals, Universitat de Girona, Campus de Montilivi, 17071 Girona, Catalonia, tel. +27 218 083 974, fax +27 218 082 995, e-mail: nrourapascual@gmail.com

Abstract

Determining the geographical range of invasive species is an important component of formulating effective management strategies. In the absence of detailed distributional data, species distribution models can provide estimates of an invasion range and increase our understanding of the ecological processes acting at various spatial scales. We used two complementary approaches to evaluate the influence of historical and environmental factors in shaping the distribution of the Argentine ant (Linepithema humile), a widespread, highly invasive species native to South America. Occurrence data were combined with environmental data at incremental spatial scales (extent and resolution) to predict the suitable range of the ant invasion using ecological niche models. In addition, we also used a spread model that simulated the jump dispersal of the species to identify the most plausible scenarios of arrival of L. humile in the NE Iberian Peninsula at local scales. Based on the results of both modelling practices, we suggest that L. humile might have reached its maximum geographic range at regional scales in the NE Iberian Peninsula. However, the species does not appear in equilibrium with the environment at small spatial scales, and further expansions are expected along coastal and inland localities of the Costa Brava. Long-distance jumps are ultimately responsible for the spread of the Argentine ant in the area. Overall, our study shows the utility of combining niche based models with spread models to understand the dynamics of species' invasions.

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