High incidence of the maternally inherited bacterium Cardinium in spiders

Authors

  • OLIVIER DURON,

    1. Department of Biology, University College London, 4 Stephenson Way, London NW1 2HE, UK,
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  • GREGORY D. D. HURST,

    1. Department of Biology, University College London, 4 Stephenson Way, London NW1 2HE, UK,
    2. School of Biological Sciences, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK,
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  • EMILY A. HORNETT,

    1. Department of Biology, University College London, 4 Stephenson Way, London NW1 2HE, UK,
    2. School of Biological Sciences, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK,
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  • JAMES A. JOSLING,

    1. Department of Biology, University College London, 4 Stephenson Way, London NW1 2HE, UK,
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  • JAN ENGELSTÄDTER

    1. Department of Biology, University College London, 4 Stephenson Way, London NW1 2HE, UK,
    2. Institute of Integrative Biology (IBZ), ETH Zurich, Universitätsstrasse 16, ETH Zentrum, CHN K12.1, CH-8092 Zurich, Switzerland
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Olivier Duron, Fax: +44 20 7679 5052; E-mail: o.duron@ucl.ac.uk

Abstract

Inherited bacteria are now recognized as important players in arthropod evolution and ecology. Here, we test spiders, a group recently identified as possessing inherited bacteria commonly, for the presence of two reproductive parasites, Cardinium hertigii (Bacteroidetes group) and Wolbachia (α-proteobacteria), estimating incidence, prevalence, any sex bias in infection, and infection diversity, for a panel of field-collected specimens. We identify spiders as a hotspot for Cardinium. Present in 22% of the sampled species, incidence was significantly higher than that previously recorded in insects. Where present, Cardinium infection occurred at medium prevalence without evidence of sex bias in prevalence that would indicate sex-ratio distortion activity. Wolbachia was present in 37% of species, but revealed a gradation from being rare to very common. In one case, Wolbachia was found significantly more commonly in females than males, indicating it may act as a sex-ratio distorter in some species. Breeding work conducted on two species confirmed that Wolbachia and Cardinium were transmitted maternally, which represents the first proof of inheritance of these symbionts in spiders. Overall, this study demonstrates that the majority of spider species are infected with inherited bacteria, and their role in host biology clearly requires determination.

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