Geographic Patterns in Soil Bacteria

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Tiedje, JamesABSTRACT #DEB0075564 Soil harbors a tremendous diversity of microbes, most undiscovered. A key component to understanding the extent and patterns of this biodiversity is whether or not there are geographically unique populations. Century old dogma states that free-living bacteria are globally dispersed since microbes can be transported by wind, birds and humans. We propose to reevaluate this principle since understanding whether geographic population patterns exist is important to a number of basic and applied issues ranging from understanding biological diversification, to ecological roles, to quarantine, to new strategies for pharmaceutical discovery. We propose to test the bacterial endemism hypothesis using our existing collection of an important soil bacterial group (fluorescent Pseudomonas). These isolates are from undisturbed soil taken from 200m transects, at five different sites in each of six different continental regions. We propose to evaluate the degree of endemicity using a suite of molecular methods that will provide a continuum of genetic resolution of the population. The hypothesis will be supported if genetic distance increases with geographic distance, and if the phylogenetic analysis of genes shows geographic clades.