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Genetic equilibrium despite habitat fragmentation in an Afrotropical bird

Authors

  • Peter Galbusera,

    Corresponding author
    1. Laboratory of Animal Ecology, Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium;
      Peter Galbusera. Tel.: +32 3820 2262; Fax: +32 3820 2271; E-mail: peter.galbusera@ua.ac.be
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  • Mwangi Githiru,

    1. Department of Ornithology, National Museums of Kenya, Nairobi, Kenya;
    2. Department of Zoology, University of Oxford, Edward Grey Institute of Field Ornithology, Oxford, UK;
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  • Luc Lens,

    1. Laboratory of Terrestrial Ecology, Department of Biology, Ghent University, Ghent, Belgium
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  • Erik Matthysen

    1. Laboratory of Animal Ecology, Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium;
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Peter Galbusera. Tel.: +32 3820 2262; Fax: +32 3820 2271; E-mail: peter.galbusera@ua.ac.be

Abstract

We examined the effects of habitat fragmentation of the white-starred robin Pogonocichla stellata metapopulation in the Taita Hills archipelago, a hotspot for biodiversity which was fragmented ~40 years ago. Using seven microsatellite markers, we analysed the robin's genetic structure and tested for equilibrium between migration and drift (testing the probability of decreased dispersal) as well as between mutation and drift (test for recent reduction in effective population size, i.e. bottlenecks). This metapopulation was found to retain relatively high levels of genetic variability (HE between 0.63 and 0.71) and to be in migration–drift equilibrium, suggesting that increased isolation between fragments did not have much effect on the dispersal between them. Furthermore, this equilibrium test greatly enhanced the interpretation of parameters (e.g. FST) assumed to have reached an equilibrium value. In contrast to previous findings on the related and sympatric Taita thrush Turdus helleri (which is critically endangered), there were no indications for recent bottlenecks in any of the robin subpopulations. This difference can be attributed to the higher dispersal capacity of the robin compared with the thrush (deduced from both the genetic and capture–recapture data). Our results stress the importance of sustained dispersal for species conservation.

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