The ecological consequences of megafaunal loss: giant tortoises and wetland biodiversity

Authors

  • Cynthia A. Froyd,

    Corresponding author
    1. Department of Geography, Swansea University, Swansea, UK
    2. Department of Zoology, Long-Term Ecology Laboratory, Biodiversity Institute, Oxford Martin School, University of Oxford, Oxford, UK
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  • Emily E. D. Coffey,

    1. Department of Zoology, Long-Term Ecology Laboratory, Biodiversity Institute, Oxford Martin School, University of Oxford, Oxford, UK
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  • Willem O. van der Knaap,

    1. Institute of Plant Sciences and Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
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  • Jacqueline F. N. van Leeuwen,

    1. Institute of Plant Sciences and Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
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  • Alan Tye,

    1. Charles Darwin Research Station, Puerto Ayora, Galápagos, Ecuador
    Current affiliation:
    1. Kalo Chorio Oreinis, Nicosia, Cyprus
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  • Katherine J. Willis

    1. Department of Zoology, Long-Term Ecology Laboratory, Biodiversity Institute, Oxford Martin School, University of Oxford, Oxford, UK
    2. Department of Biology, University of Bergen, Bergen, Norway
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  • [Copyright line has been changed on 21 March 2014, after first online publication.]

Abstract

The giant tortoises of the Galápagos have become greatly depleted since European discovery of the islands in the 16th Century, with populations declining from an estimated 250 000 to between 8000 and 14 000 in the 1970s. Successful tortoise conservation efforts have focused on species recovery, but ecosystem conservation and restoration requires a better understanding of the wider ecological consequences of this drastic reduction in the archipelago's only large native herbivore. We report the first evidence from palaeoecological records of coprophilous fungal spores of the formerly more extensive geographical range of giant tortoises in the highlands of Santa Cruz Island. Upland tortoise populations on Santa Cruz declined 500–700 years ago, likely the result of human impact or possible climatic change. Former freshwater wetlands, a now limited habitat-type, were found to have converted to Sphagnum bogs concomitant with tortoise loss, subsequently leading to the decline of several now-rare or extinct plant species.

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