Dispersal limitation and thermodynamic constraints govern spatial structure of permafrost microbial communities

Journal Article · Thu Jun 14 00:00:00 EDT 2018 · FEMS Microbiology Ecology (Online)

DOI:https://doi.org/10.1093/femsec/fiy110· OSTI ID:1503495

Bottos, Eric M. ^[1]; Kennedy, David W. ^[2]; Romero, Elvira B. ^[2]; Fansler, Sarah J. ^[2]; Brown, Joseph M. ^[3]; Bramer, Lisa M. ^[4]; Chu, Rosalie K. ^[5]; Tfaily, Malak M. ^[5]; Jansson, Janet K. ^[2]; Stegen, James C. ^[2]

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1. Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA, 99352, USA; Department of Biological Sciences, Thompson Rivers University, 805 TRU Way, Kamloops, BC, V2C 0C8, Canada
2. Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA, 99352, USA
3. Computational Biology, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA, 99352, USA
4. National Security Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA, 99352, USA
5. Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA, 99352, USA

Understanding drivers of permafrost microbial community composition is critical for understanding permafrost microbiology and predicting ecosystem responses to thaw, however studies describing ecological controls on these communities are lacking. We hypothesize that permafrost communities are uniquely shaped by constraints imposed by prolonged freezing, and decoupled from factors that influence non-permafrost soil communities. To test this hypothesis, we characterized patterns of environmental variation and microbial community composition in permafrost across an Alaskan boreal forest landscape. We used null modeling to estimate the relative importance of selective and neutral assembly processes on community composition, and identified environmental factors influencing ecological selection through regression and structural equation modeling (SEM). Proportionally, the strongest process influencing community composition was dispersal limitation (0.36), exceeding the influence of homogenous selection (0.21), variable selection (0.16), and homogenizing dispersal (0.05). Fe(II) content was the most important factor explaining variable selection, and was significantly associated with total selection by univariate regression (R2=0.14, 41 p=0.003). SEM supported a model in which Fe(II) content mediated influences of the Gibbs free energy of the organic matter pool and organic acid concentration on total selection. These findings reveal that the processes shaping microbial communities in permafrost are distinct from those in non-permafrost soils, as the stability of the permafrost environment imposes dispersal and thermodynamic constraints on permafrost communities. Models of permafrost community composition will need to account for these unique drivers in order to predict community characteristics across permafrost landscapes, and in efforts to understand how pre-thaw conditions will influence post-thaw ecological and biogeochemical processes.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1503495
• Report Number(s): PNNL-SA-130968
• Journal Information: FEMS Microbiology Ecology (Online), Vol. 94, Issue 8; ISSN 1574-6941
• Publisher: Federation of European Microbiological Societies
• Country of Publication: United States
• Language: English

Related Subjects

permafrost