title: Coupling Spatiotemporal Community Assembly Processes to Changes in Microbial Metabolism.
abstract: Community assembly processes generate shifts in species abundances that influence ecosystem cycling of carbon and nutrients, yet our understanding of assembly remains largely separate from ecosystem-level functioning. Here, we investigate relationships between assembly and changes in microbial metabolism across space and time in hyporheic microbial communities. We pair sampling of two habitat types (i.e., attached and planktonic) through seasonal and sub-hourly hydrologic fluctuation with null modeling and temporally explicit multivariate statistics. We demonstrate that multiple selective pressures-imposed by sediment and porewater physicochemistry-integrate to generate changes in microbial community composition at distinct timescales among habitat types. These changes in composition are reflective of contrasting associations ofBetaproteobacteriaandThaumarchaeotawith ecological selection and with seasonal changes in microbial metabolism. We present a conceptual model based on our results in which metabolism increases when oscillating selective pressures oppose temporally stable selective pressures. Our conceptual model is pertinent to both macrobial and microbial systems experiencing multiple selective pressures and presents an avenue for assimilating community assembly processes into predictions of ecosystem-level functioning.
authors.affiliation: Biological Sciences Division, Pacific Northwest National Laboratory Richland, WA, USA.
authors.forename: Emily B
authors.initials: EB
authors.lastname: Graham
authors.affiliation: Biological Sciences Division, Pacific Northwest National Laboratory Richland, WA, USA.
authors.forename: Alex R
authors.initials: AR
authors.lastname: Crump
authors.affiliation: Biological Sciences Division, Pacific Northwest National Laboratory Richland, WA, USA.
authors.forename: Charles T
authors.initials: CT
authors.lastname: Resch
authors.affiliation: Biological Sciences Division, Pacific Northwest National Laboratory Richland, WA, USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Fansler
authors.affiliation: Biological Sciences Division, Pacific Northwest National Laboratory Richland, WA, USA.
authors.forename: Evan
authors.initials: E
authors.lastname: Arntzen
authors.affiliation: Biological Sciences Division, Pacific Northwest National Laboratory Richland, WA, USA.
authors.forename: David W
authors.initials: DW
authors.lastname: Kennedy
authors.affiliation: Biological Sciences Division, Pacific Northwest National Laboratory Richland, WA, USA.
authors.forename: Jim K
authors.initials: JK
authors.lastname: Fredrickson
authors.affiliation: Biological Sciences Division, Pacific Northwest National Laboratory Richland, WA, USA.
authors.forename: James C
authors.initials: JC
authors.lastname: Stegen
keywords: Hanford; aerobic respiration; ammonia oxidation; dispersal; hyporheic; microbial community structure; niche; selection