Figure 3

Scaling of the number of OTUs with the number of reads in an experiment. The number of prokaryote OTUs as a function of the number of reads is plotted, in a log-log scale, every two days as the experiment runs for 20 days in different conditions (A) control (Mesocosm C1 and C2), (B) single dose nitrate phosphate addition (NP) (Mesocosm C3 and C4), and (C) single dose nitrate phosphate sulfate addition (NPS) (Mesocosm C5 and C6). For all the conditions, we plot two replicates. The number of OTUs, S, scales with the number of reads, N, as S ~ N^γ, with γ = 0.44, 0.40 (control), 0.38, 0.40 (NP), 0.48, 0.52 (NPS). The insets show the same data in linear scale (same ranges as main plots) where an apparent saturation asymptote is observed. (D) Abundance vs rank plot for one of the controls for successive days from bottom to top. The exponent of a power-law distribution fit, P(x) ~ x^−1−α, for the aggregated data after 20 days (black line) is α = 0.52.