Stochastic and deterministic assembly processes in subsurface microbial communities

• Published in: The ISME Journal Vol. 6; no. 9; pp. 1653 - 1664
• Main Authors: Stegen, James C, Lin, Xueju, Konopka, Allan E, Fredrickson, James K
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.09.2012; Oxford University Press; Nature Publishing Group
• Subjects: 631/158/1745; 631/158/2451; 631/158/853; 631/181/757; Bacteria - classification; Bacteria - genetics; Bacterial Physiological Phenomena; Biodiversity; Biomedical and Life Sciences; Community composition; Community ecology; Data processing; Ecology; Ecosystem; Environmental factors; Evolutionary Biology; Habitat; Life Sciences; Metagenome - genetics; Metagenome - physiology; Microbial activity; Microbial Ecology; Microbial Genetics and Genomics; Microbiology; Niches; Original; original-article; Phylogeny; Stochastic Processes; Stochasticity; Water Microbiology; distance decay; evolutionary niche conservatism; phylogenetic beta diversity; neutral theory; community assembly; niche theory
• ISSN: 1751-7362; 1751-7370; 1751-7370
• DOI: 10.1038/ismej.2012.22

A major goal of microbial community ecology is to understand the forces that structure community composition. Deterministic selection by specific environmental factors is sometimes important, but in other cases stochastic or ecologically neutral processes dominate. Lacking is a unified conceptual framework aiming to understand why deterministic processes dominate in some contexts but not others. Here we work toward such a framework. By testing predictions derived from general ecological theory we aim to uncover factors that govern the relative influences of deterministic and stochastic processes. We couple spatiotemporal data on subsurface microbial communities and environmental parameters with metrics and null models of within and between community phylogenetic composition. Testing for phylogenetic signal in organismal niches showed that more closely related taxa have more similar habitat associations. Community phylogenetic analyses further showed that ecologically similar taxa coexist to a greater degree than expected by chance. Environmental filtering thus deterministically governs subsurface microbial community composition. More importantly, the influence of deterministic environmental filtering relative to stochastic factors was maximized at both ends of an environmental variation gradient. A stronger role of stochastic factors was, however, supported through analyses of phylogenetic temporal turnover. Although phylogenetic turnover was on average faster than expected, most pairwise comparisons were not themselves significantly non-random. The relative influence of deterministic environmental filtering over community dynamics was elevated, however, in the most temporally and spatially variable environments. Our results point to general rules governing the relative influences of stochastic and deterministic processes across micro- and macro-organisms.