Fig. 1.

(A) Coevolved hosts (Coevo) showed extensive resistance to phage, whereas populations evolved in the absence of phages (Evo) were sensitive to all the phage populations and genotypes they were tested against. The host resistance score is the mean (±SEM) proportion of phage that hosts were resistant to. (B) Boxplots showing coevolved hosts had a significantly lower fitness in the absence of phages than evolved hosts. The fitness of the ancestor or WT is indicated with the dashed line (=1).