Table 1. Summary statistics for the 100 sites randomly selected for each environment.

These statistics reflect the data used for taxonomic coarse-graining, as OTUs lacking taxonomic labels were excluded from taxonomic coarse-graining analyses.

Environment	Total # OTUs	Mean # OTUs	Mean # reads
Marine	9090	690.80	95,129.43
Marine sediment	16,110	1,393.67	40,440.38
Human gut	6175	599.09	32,894.50
Human oral	4716	537.45	44,271.22
Human skin	17,955	1293.45	36,344.13
Freshwater sediment	12,231	1080.95	18,979.56
Microbial mat	5087	200.24	8,659.36
Freshwater	12,052	822.37	33,646.53
Soil	20,298	1814.76	36,268.93