a, A neighbor joining phylogenetic tree of the RDP sequences representing the 454 reads from six samples of throat, stomach, and feces, respectively, was constructed. Branches in the tree represented in throat, stomach, and feces are labeled with green, yellow, and red, respectively. b, Hierchical clustering of the 18 samples based on how their reads were distributed within the tree using the weighted UniFrac metric for pair wise comparisons of the samples. The lower three samples are H. pylori positive stomachs.