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Phylogenetic Signals of Salinity and Season in Bacterial Community Composition Across the Salinity Gradient of the Baltic Sea

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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.

No MeSH data available.


Between-OTU niche difference as a function of between-OTU phylogenetic distance. The data points represent means of OTU niche differences within phylogenetic distance bins. Plus signs and filled dots represent niche differences with respect to salinity and season, respectively. The dotted vertical line gives the maximum peak for season; the bold vertical line gives the maximum peak for salinity.
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Figure 7: Between-OTU niche difference as a function of between-OTU phylogenetic distance. The data points represent means of OTU niche differences within phylogenetic distance bins. Plus signs and filled dots represent niche differences with respect to salinity and season, respectively. The dotted vertical line gives the maximum peak for season; the bold vertical line gives the maximum peak for salinity.

Mentions: To determine whether closely related OTUs share ecological niches with respect to season and salinity (“phylogenetic signal”), an abundance-weighted niche value was defined for each OTU for salinity and season using the congruent dataset (see section “MATERIALS AND METHODS”). The niche value differences between pairs of OTUs were plotted against their phylogenetic distance. A steep positive relationship was observed between niche value difference and phylogenetic distance for both salinity and season at low phylogenetic distances (Figure 7). The slope of the curve declined for season around phylogenetic distance 0.1 while it declined later for salinity, around 0.2.


Phylogenetic Signals of Salinity and Season in Bacterial Community Composition Across the Salinity Gradient of the Baltic Sea
Between-OTU niche difference as a function of between-OTU phylogenetic distance. The data points represent means of OTU niche differences within phylogenetic distance bins. Plus signs and filled dots represent niche differences with respect to salinity and season, respectively. The dotted vertical line gives the maximum peak for season; the bold vertical line gives the maximum peak for salinity.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5121245&req=5

Figure 7: Between-OTU niche difference as a function of between-OTU phylogenetic distance. The data points represent means of OTU niche differences within phylogenetic distance bins. Plus signs and filled dots represent niche differences with respect to salinity and season, respectively. The dotted vertical line gives the maximum peak for season; the bold vertical line gives the maximum peak for salinity.
Mentions: To determine whether closely related OTUs share ecological niches with respect to season and salinity (“phylogenetic signal”), an abundance-weighted niche value was defined for each OTU for salinity and season using the congruent dataset (see section “MATERIALS AND METHODS”). The niche value differences between pairs of OTUs were plotted against their phylogenetic distance. A steep positive relationship was observed between niche value difference and phylogenetic distance for both salinity and season at low phylogenetic distances (Figure 7). The slope of the curve declined for season around phylogenetic distance 0.1 while it declined later for salinity, around 0.2.

View Article: PubMed Central - PubMed

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.

No MeSH data available.