The importance of resolving biogeographic patterns of microbial microdiversity

For centuries, ecologists have used biogeographic patterns to test the processes governing the assembly and maintenance of plant and animal communities. Similarly, evolutionary biologists have used historical biogeography (e.g. phylogeography) to understand the importance of geological events as barriers to dispersal that shape species distributions. As the field of microbial biogeography initially developed, the utilisation of highly conserved marker genes, such as the 16S ribosomal RNA gene, stimulated investigations into the biogeographic patterns of the microbial community as a whole. Here, we propose that we should now consider the biogeographic patterns of microdiversity, the fine-scale genetic diversity observed within a traditional ribosomal-based operational taxonomic unit.