Evolutionary divergence and biogeography of sympatric niche-differentiated bacterial populations

Using multiple lines of evidence from denaturing gradient gel electrophoresis, environmental sequences and TaqMan quantitative PCR assays targeting a functional gene for sulfate respiration (dsr)affiliated with the geochemically important genus Desulfobulbus, we revealed strongly restricted distributions of specific genotypes and opulations correlated with sampling position along an estuarine gradient free of dispersal barriers. Evidence of evolutionary divergence of populations was provided by three complementary analyses. First, analysis of molecular variance rejected the null hypothesis that genetic diversity within each sampling site was not significantly different than that of all sites pooled together (P<0.0001). Second, UniFrac and Parsimony tests showed phylogenetic clustering of sampling sites was highly significant (P