Coevolution with phages does not influence the evolution of bacterial mutation rates in soil.

Coevolution with phages drive the evolution of high bacterial mutation rates in vitro, but the relevance of this finding to natural populations is unclear. Here, we investigated how coevolution affects mutation rate evolution in soil, in the presence and absence of the rest of the natural microbial community. Although mutation rate on average increased threefold, neither coevolving phages nor the rest of natural community significantly affected mutation rates. Our results suggest that features of the soil over and above directly interacting organisms constrain the evolution of strong mutators, helping to explain their relatively low frequency compared with some laboratory and clinical settings.