A hotspot revisited – a biogeographical analysis of West African amphibians

Authors

  • Johannes Penner,

    Corresponding author
    1. Museum für Naturkunde, Leibniz Institute for Research on Evolution and Biodiversity at the Humboldt University Berlin, Invalidenstrasse 43, 10115 Berlin, Germany
      Johannes Penner, Museum für Naturkunde, Leibniz Institute for Research on Evolution and Biodiversity at the Humboldt University Berlin, Invalidenstrasse 43, 10115 Berlin, Germany.
      E-mail: johannes.penner@mfn-berlin.de
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  • Martin Wegmann,

    1. Department of Remote Sensing, Remote Sensing and Biodiversity Unit, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
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  • Annika Hillers,

    1. Royal Society for the Protection of Birds, Across the River – A Transboundary Peace Park for Sierra Leone and Liberia, 38 Maxwell Khobe Street, Kenema, Serra Leone
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  • Michael Schmidt,

    1. Comision Nacional para el Conocimiento y Uso de la Biodiversidad, Liga Periférico – Insurgentes Sur, Núm. 4903, Col. Parques del Pedregal, Delegación Tlalpan, 14010 México, D.F., México
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  • Mark-Oliver Rödel

    1. Museum für Naturkunde, Leibniz Institute for Research on Evolution and Biodiversity at the Humboldt University Berlin, Invalidenstrasse 43, 10115 Berlin, Germany
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Johannes Penner, Museum für Naturkunde, Leibniz Institute for Research on Evolution and Biodiversity at the Humboldt University Berlin, Invalidenstrasse 43, 10115 Berlin, Germany.
E-mail: johannes.penner@mfn-berlin.de

Abstract

Aim  The study was aimed at testing whether West Africa can be regarded as a distinct biogeographic region based on amphibian assemblages. If so, we asked what were the relationships of these assemblages with those in Central Africa, and whether West African amphibian distributions showed biogeographic substructure. We further investigated what events or processes may explain the observed patterns.

Location  Sub-Saharan Africa.

Methods  Presence–absence data of amphibian assemblages derived from field surveys and the literature were statistically analysed using three different multivariate techniques (consensus clustering, Monmonier analysis and nonmetric multidimensional scaling) to emphasize consistent results.

Results  We showed that West Africa has unique amphibian assemblages, which could be clearly demarcated from Central African assemblages, particularly by the geographic barrier of the Cross River. Further biogeographic subdivisions were detected to the west of this barrier. Habitat, mainly forest, was the best factor explaining our observed pattern. Overall, intra-regional similarity (e.g. within West Africa) was higher than intra-habitat similarity (e.g. within forest) across regions.

Main conclusions  Our results are compared with previous works and interpreted in the light of the known evolutionary history of West and Central Africa. The observed pattern may be explained by postulated differences in river continuity through time, with West African rivers serving as more or less constant barriers in contrast to those in Central Africa. Our results demonstrate the uniqueness of West African amphibian assemblages, highlighting the need for their conservation as many are under acute anthropogenic pressure.

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