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Phylogeography and conservation genetics of a giant lobelia (Lobelia giberroa) in Ethiopian and Tropical East African mountains

Authors

  • MULUGETA KEBEDE,

    1. Department of Biology, Addis Ababa University, P.O. Box 3434, Addis Ababa, Ethiopia,
    2. National Centre for Biosystematics, Natural History Museum, University of Oslo, P.O. Box 1172, Blindern, NO-0318 Oslo, Norway,
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  • DOROTHEE EHRICH,

    1. National Centre for Biosystematics, Natural History Museum, University of Oslo, P.O. Box 1172, Blindern, NO-0318 Oslo, Norway,
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  • PIERRE TABERLET,

    1. Laboratoire d’Ecologie Alpine, CNRS UMR 5553, Université Joseph Fourier, BP 53, F-38041 Grenoble Cedex 09, France
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  • SILESHI NEMOMISSA,

    1. Department of Biology, Addis Ababa University, P.O. Box 3434, Addis Ababa, Ethiopia,
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  • CHRISTIAN BROCHMANN

    1. National Centre for Biosystematics, Natural History Museum, University of Oslo, P.O. Box 1172, Blindern, NO-0318 Oslo, Norway,
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Mulugeta Kebede. Fax: +251 11 155 2350; E-mail: kmulugetak@yahoo.com

Abstract

Lobelia giberroa is a giant rosette plant growing in the afro-montane belt of the afro-alpine environment, a unique and little-studied ecosystem occupying the high mountains of eastern Africa. We analysed amplified fragment length polymorphisms (AFLPs) from 11 mountain systems in Ethiopia and Tropical East Africa to infer the phylogeographical history of the species. A total of 191 individuals were investigated from 25 populations. Principal coordinate analysis and population structure analyses revealed three major phylogeographical groups: the Ethiopian mountains and one group on each side of the Rift Valley in Tropical East Africa, respectively: Elgon–Cherangani and Kenya–Aberdare–Kilimanjaro–Meru. Analysis of Molecular Variance showed 55.7% variance among the three groups, suggesting an old divergence. Together with a clear geographical substructure within the main groups, this pattern indicates gradual expansion and supports the montane forest bridge hypothesis, stating that the area occupied by forest was larger and more continuous in previous interglacials and earlier in the present interglacial. Genetic diversity was lower in Ethiopia than in the other two main groups, possibly due to an ancient founder effect when Ethiopia was colonized from the south.

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