TABLE 4.

Numbers of OTUs and slopes of pairwise distance values obtained using short and long sequences at different taxonomic cutoffs for three different clone libraries^a

Environment	Regionb	No. of OTUs at indicated taxonomic cutoff (%)					Slopec
		3	6	8	10	15
Trembling aspen soil	V1+V2	702	616	568	527	436	1.23
	V3	516	374	292	235	144	0.87
	V4	516	364	295	241	146	0.97
	V5+V6	658	550	480	420	283	1.05
	V6	761	656	585	511	339	1.8
	V6+V7	690	575	501	429	274	1.07
	V7	406	255	183	143	73	0.68
	V7+V8	569	374	294	221	118	0.73
	NFL	682	561	490	418	280	NA
Zebrafish gut	V1+V2	78	49	41	36	30	1.27
	V3	46	37	34	31	21	0.72
	V4	57	47	42	38	30	0.94
	V5+V6	56	40	35	30	24	1.02
	V6	77	59	47	40	27	1.35
	V6+V7	55	46	39	35	30	0.96
	V7	37	26	20	18	9	0.56
	V7+V8	45	34	28	21	12	0.65
	NFL	63	45	40	37	28	NA
Basalt oceanic floor	V1+V2	450	389	355	326	259	1.24
	V3	414	313	247	208	126	0.86
	V4	443	337	287	240	140	0.96
	V5+V6	440	368	309	256	163	1.02
	V6	521	440	390	341	246	1.74
	V6+V7	445	365	318	251	159	0.94
	V7	316	189	152	112	54	0.56
	V7+V8	390	258	191	148	66	0.66
	NFL	486	378	325	264	155	NA

^aNumbers of OTUs and slopes obtained using the nearly full-length sequences and each of the eight studied short, pyrosequencing-simulating regions at five different taxonomic cutoffs for three different clone libraries derived from soil, zebrafish gut, and ocean floor.

^bNFL, nearly full-length sequences (8F-1492R).

^cSlopes of regression lines constructed between pairwise distances in the short, pyrosequencing-simulating regions versus the nearly full-length regions and forced through the origin. NA, not applicable.