• Open Access

Resource shifts in Malagasy dung beetles: contrasting processes revealed by dissimilar spatial genetic patterns

Authors

  • Ilkka Hanski,

    Corresponding author
    1. Department of Biological and Environmental Sciences, University of Helsinki, Viikinkaari 1, PO Box 65, FI-00014, Helsinki, Finland
      *E-mail: ilkka.hanski@helsinki.fi
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  • Helena Wirta,

    1. Department of Biological and Environmental Sciences, University of Helsinki, Viikinkaari 1, PO Box 65, FI-00014, Helsinki, Finland
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  • Toshka Nyman,

    1. Department of Biological and Environmental Sciences, University of Helsinki, Viikinkaari 1, PO Box 65, FI-00014, Helsinki, Finland
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  • Pierre Rahagalala

    1. Département d’Entomologie, Faculté des Sciences, Université d’Antananarivo, Antananarivo, B.P. 906, Madagascar
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  • Reuse of this article is permitted in accordance with the Creative Commons Deed, Attribution 2.5, which does not permit commercial exploitation.

*E-mail: ilkka.hanski@helsinki.fi

Abstract

The endemic dung beetle subtribe Helictopleurina has 65 species mostly in wet forests in eastern Madagascar. There are no extant native ungulates in Madagascar, but three Helictopleurus species have shifted to the introduced cattle dung in open habitats in the past 1500 years. Helictopleurus neoamplicollis and Helictopleurus marsyas exhibit very limited cytochrome oxidase subunit 1 haplotype diversity and a single haplotype is present across Madagascar, suggesting that these species shifted to cattle dung in a small region followed by rapid range expansion. In contrast, patterns of molecular diversity in Helictopleurus quadripunctatus indicate a gradual diet shift across most of southern Madagascar, consistent with somewhat broader diet in this species. The three cattle dung-using Helictopleurus species have significantly greater geographical ranges than the forest-dwelling species, apparently because the shift to the currently very abundant new resource relaxed interspecific competition that hinders range expansion in the forest species.

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