An introduction to the biogeography of aquatic microbes

Abstract

Aquatic microbes, like all organisms, have biogeographies, but this subject has attracted relatively little attention. In this review, recent results exploiting techniques of molecular biology are summarized to place in perspective the studies of this Theme Section. The studies considered concern large-scale patterns of spatial distribution among heterotrophic planktonic prokaryotic and eukaryotic microbes. For freshwater bacterioplankton communities, reported patterns are inconsistent. Taxonomic richness may increase with system size, and composition may be related among neighboring bodies of water. However, inconsistencies in patterns may be due to differences in the temporal and spatial scales considered. Among planktonic marine prokaryotes, biogeographic patterns are known only in terms of high level groups, e.g. Archea are perhaps dominant in deep oceanic waters. However, studies of large-scale patterns have just begun and they suggest that some ribotypes or species may be restricted to certain oceanic areas. Eukaryotic microbes appear to characterised by high capacities for both dispersal and gene flow. Recent studies appear to conclude that we can form morphological, genetic and physiological groupings but their inter-relationships are obscure at this point in time.KEY WORDS: Bacteria · Protists · Latitudinal diversity gradient · Island biogeography · BiodiversityResale or republication not permitted without written consent of the publisher

The power of species sorting: Local factors drive bacterial community composition over a wide range of spatial scales

“…This sampling design ensured that very similar lakes were selected in the different regions, although this strategy worked better for BNL and DK than for SP (24). Even though this sampling design made our study ideally suited to detect a signature of biogeography (22), no strong effect of geographic distance was detected. Although there are some recent reports demonstrating that dispersal limitation may occur at large spatial scales for some microbial organisms (12), the environments involved were extreme and isolated, and may thus perhaps not be representative of typical and common surface water categories (rivers and rivulets, ditches, ponds, and lakes).…”

“…Our results further agree with Horner-Devine et al (2), who found that the taxa-area relationship for bacteria in salt marsh sediments was driven primarily by environmental heterogeneity, which increased with increased area considered, rather than by geographic distance itself. Dolan (22) suggested that a signature of biogeography would more likely emerge in studies that focus on similar habitats across space. A key feature of our study is that similar lake types were selected across all spatial scales.…”

Analysis of bacterial core communities in the central Baltic by comparative RNA–DNA-based fingerprinting provides links to structure–function relationships

“…The current discussion about the community structure of marine bacterioplankton is focusing on two key questions: (i) Is there a biogeography of bacterioplankton communities across marine ecosystems (Dolan, 2005;Pommier et al, 2007) and (ii) What are the environmental factors regulating the community structure of bacterioplankton (Galand et al, 2010). On top of these questions remain the detailed understanding of the overall community structure of bacterioplankton, that is, what are abundant and rare species (phylotypes) and how do they influence the overall biogeochemical functioning of this community (Pedró s-Alió , 2006).…”

A biophysical perspective on dispersal and the geography of evolution in marine and terrestrial systems

“…However, there is also abundant cellular material in the atmosphere, including pollen, spores, bacteria, algae (including marine plankton), fungi and viruses ranging in size from tens of nanometres to millimetres (Jaenicke 2005; see also Wilkinson 2001 figure 3), a variety of aerial and marine microbes should have similar dispersal abilities, realized dispersal distances and gene flow and geographical ranges (figures 5 and 6). Evidence on dispersal and biogeographic patterns in aerial and marine microbes is somewhat sparse, due in part to limited geographical sampling of typically widely distributed taxa and the varied import given to DNA analyses versus phenotypes in inferences of species entities (Dolan 2005;Fenchel 2005;Mitchell & Meisterfeld 2005;Esteban et al 2007). The initial picture is that marine bacterioplankton are very widely dispersed but not ubiquitous.…”