Nature 550, 244–248 (2017); doi:https://doi.org/10.1038/nature24265

In this Letter, the Source Data associated with Fig. 2a and d were incorrect. This was due to an error during manuscript preparation, when transformed data instead of the raw values plotted in the figure were included in the Source Data file. The figure panels are correct and remain unchanged, and these errors do not affect the results or conclusions of the Letter. We apologize for any confusion this may have caused. The original incorrect Source Data for Fig. 2 are provided as Supplementary Information to this Corrigendum, for transparency. The original Letter has been corrected online.