Result of running PCA and choosing to output a ScatterPlot and the Bin envs by:first letter option. Blue squares represent the estuary, green triangles represent the river, and red circles represent the ocean. All points on the left side of the x-axis represent particle-associated bacteria (estuary and river) or bacteria in unfiltered water (ocean). All points on the right side of the x axis are from free-living bacterial communities. The full environment name can be seen by by moving the pointer over the symbols. The axes are labeled with the percent of the variation explained by each principal component.
Lozupone et al. BMC Bioinformatics 2006 7:371 doi:10.1186/1471-2105-7-371