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Biogeography of bacteria associated with the marine sponge Cymbastela concentrica

Authors

  • Michael W. Taylor,

    Corresponding author
    1. School of Biological, Earth and Environmental Sciences,
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    • Present address: Lehrstuhl für Mikrobielle Ökologie, Institut für Ökologie und Naturschutz (IECB), Universität Wien, Althanstr. 14, A-1090 Wien, Austria.

  • Peter J. Schupp,

    1. Centre for Marine Biofouling and Bio-Innovation, University of New South Wales, Sydney, NSW 2052, Australia.
    2. University of Guam Marine Laboratory, UOG Station, Mangilao, Guam 96923, USA.
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  • Rocky De Nys,

    1. School of Marine Biology and Aquaculture, James Cook University, Townsville, QLD 4811, Australia.
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  • Staffan Kjelleberg,

    1. Centre for Marine Biofouling and Bio-Innovation, University of New South Wales, Sydney, NSW 2052, Australia.
    2. School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
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  • Peter D. Steinberg

    1. School of Biological, Earth and Environmental Sciences,
    2. Centre for Marine Biofouling and Bio-Innovation, University of New South Wales, Sydney, NSW 2052, Australia.
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*E-mail taylor@microbial-ecology.net; Tel. (+43) 1 4277 54207; Fax (+43) 1 4277 54389.

Summary

Recent debate regarding microbial biogeography has focused largely on free-living microbes, yet those microbes associated with host organisms are also of interest from a biogeographical perspective. Marine eukaryotes and associated bacteria should provide ideal systems in which to consider microbial biogeography, as (i) bacteria in seawater should be able to disperse among individuals of the same host species, yet (ii) potential for adaptation to particular hosts (and thus speciation) also exists. We used 16S rDNA-DGGE (denaturing gradient gel electrophoresis) to examine geographic variability in bacterial community composition in the marine sponge Cymbastela concentrica. Denaturing gradient gel electrophoresis banding patterns (and phylogenetic analysis of excised DGGE bands) indicated different communities in Cymbastela concentrica from tropical versus temperate Australia. In contrast, communities were very similar over a 500-km portion of the sponge's temperate range. Variation in bacterial community composition was also considered with respect to ocean current patterns. We speculate that the divergent communities in different parts of the sponge's range provide evidence of endemism attributed to host association, although variation in environmental factors such as light and temperature could also explain the observed results. Interestingly, bacterial communities in seawater varied much less between tropical and temperate locations than did those in C. concentrica, supporting the concept of widespread dispersal among these free-living microbes.

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