In humans, the composition of microbial communities differs among body sites and between habitats within a single site. Patterns of variation in the distribution of organisms across time and space are referred to as "biogeography." The human oral cavity is a critical observatory for exploring microbial biogeography because it is spatially structured, easily accessible, and its microbiota has been linked to the promotion of both health and disease. The biogeographic features of microbial communities residing in spatially distinct, but ecologically similar, environments on the human body, including the subgingival crevice, have not yet been adequately explored. The purpose of this paper is twofold. First, we seek to provide the dental community with a primer on biogeographic theory, highlighting its relevance to the study of the human oral cavity. We summarize what is known about the biogeographic variation of dental caries and periodontitis and postulate that disease occurrence reflects spatial patterning in the composition and structure of oral microbial communities. Second, we present a number of methods that investigators can use to test specific hypotheses using biogeographic theory. To anchor our discussion, we apply each method to a case study and examine the spatial variation of the human subgingival microbiota in 2 individuals. Our case study suggests that the composition of subgingival communities may conform to an anterior-to-posterior gradient within the oral cavity. The gradient appears to be structured by both deterministic and nondeterministic processes, although additional work is needed to confirm these findings. A better understanding of biogeographic patterns and processes will lead to improved efficacy of dental interventions targeting the oral microbiota.
Keywords: biogeography; oral microbiome; oral microbiota; spatial pattern; subgingival; supragingival.
© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Conflict of interest statement
Conflicts of interest
The authors declare no conflicts of interest.
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- 5T32GM007276/NIH Cellular and Molecular Biology Training Grant
- Chan Zuckerberg Biohub Microbiome Initiative
- R01 DE023113/DE/NIDCR NIH HHS/United States
- T32 GM007276/GM/NIGMS NIH HHS/United States
- T32 AI007328/AI/NIAID NIH HHS/United States
- R01DE023113/NH/NIH HHS/United States
- Thomas C. and Joan M. Merigan Endowment at Stanford University
- 5T32AI007328/NIH Molecular Basis of Host Parasite Interactions Training Grant
- R01 DE013541/DE/NIDCR NIH HHS/United States
- Stanford Graduate Fellowship through the Office of the Provost for Graduate Education