Journal Article

Microbial biogeography: putting microorganisms on the map

Green, Jessica L., Horner-Devine, M. Claire, Colwell, Robert K., Krumins, Jennifer Adams, Brown, James H., Staley, James T., Martiny, Jennifer B. Hughes, Bohannan, Brendan J.M., Naeem, Shahid, Fuhrman, Jed A., Reysenbach, Anna-Louise, Kuske, Cheryl R., Smith, Val H., Øvreås, Lise, Morin, Peter J., Kane, Matthew

2006

Overview

In recent years, the question of whether microbial life exhibits biogeographical patterns has come under increased scrutiny. In this article, leading scientists in the field review the biogeography of microorganisms and provide a framework for assessing the impact of environmental and historical processes that contribute to microbial biodiversity. Key Points Since the eighteenth century, biologists have investigated plant and animal biogeography, but only recently have the distributions of microorganisms been examined. We consider microbial biogeography in light of habitats types (the contemporary environment) and provinces (legacies of historical events such as dispersal limitation). This framework is useful for addressing whether the distributions of microbial taxa, like those of macroorganisms, reflect the influences of both contemporary environmental conditions and past events. We review a growing body of literature that suggests that microbial assemblages are not only influenced by their current environment, but that some display a degree of provincialism — evidence that these microbial assemblages have diverged and are maintained by genetic isolation. We also find that the relative influence of historical versus environmental factors appears to be related to the scale of sampling. As a first hypothesis, we suggest that the same processes that influence macroorganism biogeography (colonization, diversification and extinction) also apply to microbial life, but that their rates scale with body size, or for single-celled organisms, cell size. Therefore, we use the idea of allometry as a structure for discussing the rates of biogeographic processes in microorganisms. We conclude that the rates of biogeographic processes probably vary more widely for microorganisms of a given size than for macroorganisms of a given size. To tackle the mechanisms generating microbial biogeographic patterns, we recommend that new microbial biogeography studies should systematically sample and record data from various distances, habitats and environmental conditions. We review the biogeography of microorganisms in light of the biogeography of macroorganisms. A large body of research supports the idea that free-living microbial taxa exhibit biogeographic patterns. Current evidence confirms that, as proposed by the Baas-Becking hypothesis, 'the environment selects' and is, in part, responsible for spatial variation in microbial diversity. However, recent studies also dispute the idea that 'everything is everywhere'. We also consider how the processes that generate and maintain biogeographic patterns in macroorganisms could operate in the microbial world.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: Biogeography / Biomedical and Life Sciences / Ecology / Environmental conditions / Habitats / Hypotheses / Infectious Diseases / Influence / Life Sciences / Medical Microbiology / Microbiology / Microorganisms / Parasitology / Provinces / review-article / Virology