Correction to: Nature https://doi.org/10.1038/s41586-020-1936-2Published online 22 January 2020

In this Article, owing to errors during the production process, the black line in Fig. 3c was incorrectly labelled ‘Δcas1’ instead of ‘Δcas7’, and the y-axis label in Fig. 4b was incorrectly shown as ‘DMS3 fraction’ instead of ‘Relative fitness of DMS3’. These errors have been corrected online.