Biodiversity in microbial communities: system scale patterns and mechanisms

Authors

  • J. JACOB PARNELL,

    1. Department of Biology, 5305 Old Main Hill,
    2. Ecology Center, 5205 Old Main Hill,
    3. Center for Integrated BioSystems, 4700 Old Main Hill, Utah State University, Logan, UT 84322, USA
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  • TODD A. CROWL,

    1. Ecology Center, 5205 Old Main Hill,
    2. Department of Watershed Sciences, 5210 Old Main Hill,
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    • Present address: Division of Environmental Biology, National Science Foundation, Arlington, VA 22230, USA.

  • BART C. WEIMER,

    1. Department of Biology, 5305 Old Main Hill,
    2. Center for Integrated BioSystems, 4700 Old Main Hill, Utah State University, Logan, UT 84322, USA
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    • **

      Present address: School of Veterinary Medicine, Department of Population Health and Reproduction, University of California, Davis, 1 Shields Avenue, 2055 Haring Hall, Davis, CA 95616, USA.

  • MICHAEL E. PFRENDER

    1. Department of Biology, 5305 Old Main Hill,
    2. Center for Integrated BioSystems, 4700 Old Main Hill, Utah State University, Logan, UT 84322, USA
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J. Jacob Parnell, Fax: 435-797-1575; E-mail: jparnell@biology.usu.edu

Abstract

The relationship between anthropogenic impact and the maintenance of biodiversity is a fundamental question in ecology. The emphasis on the organizational level of biodiversity responsible for ecosystem processes is shifting from a species-centred focus to include genotypic diversity. The relationship between biodiversity measures at these two scales remains largely unknown. By stratifying anthropogenic effects between scales of biodiversity of bacterial communities, we show a statistically significant difference in diversity based on taxonomic scale. Communities with intermediate species richness show high genotypic diversity while speciose and species-poor communities do not. We propose that in species-poor communities, generally comprising stable yet harsh conditions, physiological tolerance and competitive trade-offs limit both the number of species that occur and the loss of genotypes due to decreases in already constrained fitness. In species-rich communities, natural environmental conditions result in well-defined community structure and resource partitioning. Disturbance of these communities disrupts niche space, resulting in lower genotypic diversity despite the maintenance of species diversity. Our work provides a model to inform future research about relationships between species and genotypic biodiversity based on determining the biodiversity consequences of changing environmental context.

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