Microbial community structure across grazing treatments and environmental gradients in the Serengeti
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https://doi.org/10.1007/s42832-020-0065-z
RESEARCH ARTICLE
Microbial community structure across grazing treatments and environmental gradients in the Serengeti Bo Maxwell Stevens1 ,*, Derek Lee Sonderegger2, Nancy Collins Johnson1,3 1 School of Earth and Sustainability, Northern Arizona University, Flagstaff, AZ 86011, USA 2 Department of Mathematics and Statistics, Northern Arizona University, Flagstaff, AZ 86001, USA 3 Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA HIGHLIGHTS
GRAPHICAL
ABSTRACT
• Volcanic inputs and grazing impact the distribution of microbes in Serengeti soil. • Soil texture and phosphorus are important environmental filters structuring soil microbes. • Herbivores impact microbial communities via environmental filtering not stochastic dispersal.
ARTICLE INFO
ABSTRACT
Article history: Received June 1, 2020 Revised September 11, 2020 Accepted September 21, 2020 Keywords: Soil bacteria Community ecology Grazing Serengeti National Park Soil texture Phosphorus
As one of the last remaining naturally grazed ecosystems on Earth, the Serengeti National Park is an ideal location to study the influence of migratory mammals on the structure of microbial communities and the factors that generate biogeography of soil microbes. Furthermore, volcanic inputs generate environmental gradients that may also structure microbial communities. We studied 16S rRNA amplicons in a 13-year herbivore removal experiment to examine the influence of grazing and environmental gradients on the natural distribution of soil microbes. Removal of mammalian herbivores shifted microbial community structure, with 31 taxa that were significant indicator taxa of the ungrazed treatment and three taxa that were indicators of the grazed treatment. The abundance of many taxa were correlated with soil texture, phosphorus, iron, calcium and rainfall, and the evenness of taxa within samples was also correlated with these variables. Bayesian general linear mixed effects models with single predictors of multiple, highly correlated variables of beta diversity were consistent with a significant, but weak (2%), effect of grazing, and stronger effects of phosphorus (14%). Beta diversity of microbial communities was greater in grazed than in ungrazed plots; suggesting that the impacts of grazing on community assembly of microbes results from deterministic environmental filtering caused by the influence of herbivores on plant communities and soil properties rather than stochastic dispersal via herds of large mammals. These herbivore effects are superimposed on deterministic environmental filtering by natural soil and precipitation gradients across the Serengeti. © Higher Education Press 2020
* Corresponding author E-mail address: [email protected] (B.M. Stevens)
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1 Introduction Soil bacteria and archaea serve critical functions in ecosystems but little is known about the factors that control their distribution in natural landscapes. Analyzing the biogeography of bacteria and archaea (hereafter referred to
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