Principal coordinates analysis of unweighted UniFrac distances between samples. (a) Costello et al.  samples. (b) M3, F4 time series samples. (c) M3, F4 time series, PC1 versus time (days). Panels (a,b) and (c) show two independent principal coordinates analyses. To compare the Costello et al. 454 data (a) with the time series Illumina data (b), these data were generated in a single principal coordinates analysis of UniFrac distances at 500 sequences per sample. Panel (c) does not contain the 454 data, so makes use of the increased sampling depth possible on Illumina (evenly sampled to 5,000 sequences per sample for UniFrac calculations).
Caporaso et al. Genome Biology 2011 12:R50 doi:10.1186/gb-2011-12-5-r50