Nature 481, 357–359 (2012)

There was a scaling error in the light attenuation values of Fig. 1 and Supplementary Fig. 2.1 (about 210 should have been subtracted from each value). Also, the sentence “We perturbed the populations every 4–5 days by removing 10% of their biomass through dilution.” on page 357 should have read “We perturbed the populations every 4–5 days by flushing with medium (10% of the volume), which was equivalent to a reduction of the biomass by 3–5% owing to incomplete mixing.”. This sentence and Fig. 1 and Supplementary Fig. 2.1 have been replaced in the PDF and HTML versions online. These changes do not alter any of the conclusions of this Letter. We thank J. Huisman for drawing our attention to these issues.