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Resolving the native provenance of invasive fireweed (Senecio madagascariensis Poir.) in the Hawaiian Islands as inferred from phylogenetic analysis

Authors

  • Johannes J. Le Roux,

    Corresponding author
    1. Department of Tropical Plant and Soil Sciences, University of Hawaii at Manoa, 3190 Maile Way, St. John 102, Honolulu, Hawaii 96822, USA, and
      *Correspondence: Johannes J. Le Roux, Department of Tropical Plant and Soil Sciences, University of Hawaii at Manoa, 3190 Maile Way, St. John 102, Honolulu, Hawaii 96822, USA. Tel.: (808) 956 0781, Fax: (808) 956 3894; E-mail: roux@hawaii.edu
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  • Ania M. Wieczorek,

    1. Department of Tropical Plant and Soil Sciences, University of Hawaii at Manoa, 3190 Maile Way, St. John 102, Honolulu, Hawaii 96822, USA, and
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  • Mohsen M. Ramadan,

    1. Division of Plant Industry, Hawaii Department of Agriculture, 1428 South King Street, Honolulu, Hawaii 96814, USA
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  • Carol T. Tran

    1. Department of Tropical Plant and Soil Sciences, University of Hawaii at Manoa, 3190 Maile Way, St. John 102, Honolulu, Hawaii 96822, USA, and
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*Correspondence: Johannes J. Le Roux, Department of Tropical Plant and Soil Sciences, University of Hawaii at Manoa, 3190 Maile Way, St. John 102, Honolulu, Hawaii 96822, USA. Tel.: (808) 956 0781, Fax: (808) 956 3894; E-mail: roux@hawaii.edu

ABSTRACT

Accurate identification of weedy species is critical to the success of biological control programs seeking host-specific control agents. Phylogenetic relationships based on internal transcribed spacer region (ITS1, ITS2) DNA sequence data were used to elucidate the most likely origin and taxonomic placement of Senecio madagascariensis Poir. (fireweed; Asteraceae) in the Hawaiian archipelago. Putative S. madagascariensis populations from Madagascar, South Africa, Swaziland, and Hawaii were included in the analysis. Different phylogenetic models (maximum parsimony and maximum likelihood) were congruent in suggesting that Hawaiian fireweed is most closely related to populations from the KwaZulu-Natal region in South Africa. Phylogenetic divergence and morphological data (achene characteristics) suggest that the S. madagascariensis complex is in need of revised alpha-level taxonomy. Taxonomic identity of invasive fireweed in Hawaii is important for finding effective biological control agents as native range populations constitute different biotypic variants across a wide geographical area. Based on our phylogenetic results, research directed at biological control of Hawaiian infestations should focus on areas in the KwaZulu-Natal region in South Africa where host-specific natural enemies are most likely to be found. Our results show that phylogeographical analysis is a potential powerful and efficient tool to address questions relevant to invasion biology of plants.

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