Global patterns in the biogeography of bacterial taxa

Abstract

Summary Bacteria control major nutrient cycles and directly influence plant, animal, and human health. However, we know relatively little about the forces shaping their large-scale ecological ranges. Here, we reveal patterns in the distribution of individual bacterial taxa at multiple levels of phylogenetic resolution within and between Earth’s major habitat types. Our analyses suggest that while macro-scale habitats structure bacterial distribution to some degree, abundant bacteria (i.e., detectable using 16S rRNA gene sequencing methods) are confined to single assemblages. Additionally, we show that the most cosmopolitan taxa are also the most abundant in individual assemblages. These results add to the growing body of data that support that the diversity of the overall bacterial metagenome is tremendous. The mechanisms governing microbial distribution remain poorly understood, but our analyses provide a framework with which to test the importance of macro-ecological environmental gradients, relative abundance, neutral processes and the ecological strategies of individual taxa in structuring microbial communities.

Biogeography and ecology of the rare and abundant microbial lineages in deep-sea hydrothermal vents

“…The abundance of a given OTU is distributed across space, leaving 388 many sites without rare taxa, and many sites where abundant taxa are present. Global 389 studies of microbial biogeography have confirmed this trend (Nemergut et al 2011). On 390 the large scale, our results here confirm that abundant strains tend to be more widespread 391 in vent systems.…”

Improving soil bacterial taxa–area relationships assessment using DNA meta-barcoding

“…Bacteria account for a major part of this biodiversity, and it is now clear that such microorganisms have a key role in soil functioning processes (for example, control of nutrient cycles, and directly influence plant, animal or human health; Nemergut et al, 2011). However, many of the environmental factors regulating the diversity of below-ground bacteria, still need to be investigated, which limits our understanding of the distribution of such bacteria at various spatial scales (Hanson et al, 2012).…”

“…Until recently, most biogeographic studies have been devoted to plants and animals, providing insights into the ecological processes (dispersal, selection, ecological drift and speciation), which shape the community assembly and dynamics of macroorganisms (Nemergut et al, 2011(Nemergut et al, , 2013Hanson et al, 2012). For microorganisms, the first biogeographic hypothesis was developed by Baas Becking in 1934: 'Everything is everywhere, but, the environment selects', implying that microbes would be homogeneously distributed on a broad scale and among various environments.…”

Determining indicator taxa across spatial and seasonal gradients in the Columbia River coastal margin

“…We know from biogeographical studies that there are differences in the dominant microbial taxa across habitats and over seasons (Nemergut et al, 2011;Caporaso et al, 2012). In aquatic systems, microbial communities vary spatially with water mass characteristics including depth, salinity, temperature, pH, hydrological conditions, organic matter, phytoplankton interactions, and other biological and physical factors (Field et al, 1997;Crump et al, 2003;Kent et al, 2007;Lozupone and Knight, 2007;Fuhrman et al, 2008;Ghiglione et al, 2008;Lauber et al, 2009;Galand et al, 2010;Fortunato and Crump 2011).…”