TABLE 2.

Number of OTUs observed per library versus number predicted by the power law model

Microbial groupSoil typeNo. of sequences analyzedNo. of OTUs observedMean (SD) no. of OTUs predicteda
BacteriaDesert408350336 (17)
Prairie358333331 (18)
Rainforest363327322 (17)
ArchaeaDesert306189180 (13)
Prairie865353 (7)
Rainforest1358484 (9)
FungiDesert304207215 (14)
Prairie305235224 (15)
Rainforest310216211 (14)
VirusesDesert1,640NAbNA
Prairie1,928NANA
Rainforest1,009NANA
  • a The number of OTUs was predicted from a collection of 1,000 random samples (of size equal to the library) taken from a community representing the corresponding power law model (equation 1) of each population.

  • b NA, not applicable. For the viral metagenomic libraries, estimates of OTU numbers are obtained by modeling the contig spectra, and therefore we cannot independently compare observed and predicted OTU numbers.