title: Phylogenetic Signals of Salinity and Season in Bacterial Community Composition Across the Salinity Gradient of the Baltic Sea.
abstract: Understanding the key processes that control bacterial community composition has enabled predictions of bacterial distribution and function within ecosystems. In this study, we used the Baltic Sea as a model system to quantify the phylogenetic signal of salinity and season with respect to bacterioplankton community composition. The abundances of 16S rRNA gene amplicon sequencing reads were analyzed from samples obtained from similar geographic locations in July and February along a brackish to marine salinity gradient in the Baltic Sea. While there was no distinct pattern of bacterial richness at different salinities, the number of bacterial phylotypes in winter was significantly higher than in summer. Bacterial community composition in brackish vs. marine conditions, and in July vs. February was significantly different. Non-metric multidimensional scaling showed that bacterial community composition was primarily separated according to salinity and secondly according to seasonal differences at all taxonomic ranks tested. Similarly, quantitative phylogenetic clustering implicated a phylogenetic signal for both salinity and seasonality. Our results suggest that global patterns of bacterial community composition with respect to salinity and season are the result of phylogenetically clustered ecological preferences with stronger imprints from salinity.
authors.affiliation: Leibniz Institute for Baltic Sea Research Warnemünde, Germany.
authors.forename: Daniel P R
authors.initials: DP
authors.lastname: Herlemann
authors.affiliation: Centre for Ecology and Evolution in Microbial Model Systems, Linnaeus University Kalmar, Sweden.
authors.forename: Daniel
authors.initials: D
authors.lastname: Lundin
authors.affiliation: Science for Life Laboratory, Division of Gene Technology, School of Biotechnology, KTH Royal Institute of Technology Stockholm, Sweden.
authors.forename: Anders F
authors.initials: AF
authors.lastname: Andersson
authors.affiliation: Leibniz Institute for Baltic Sea Research Warnemünde, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Labrenz
authors.affiliation: Leibniz Institute for Baltic Sea Research Warnemünde, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Jürgens
keywords: SAR11; Verrucomicrobia; brackish microbiology; ecological coherence; estuarine ecology; microbial ecology