Fig. 5

Cooperators, conditional defectors, and defectors can dynamically coexist under the surveillance of social punishment mechanism. a Frequencies of conditional defector (hollow symbols) and defector (filled symbols) during in vitro evolution of the punishment deficient strain (ΔrhlI) with (triangular symbols) or without (square symbols) the supplementation of C4HSL (C4, 20 μM), and the parental WT PAO1 (round symbols) in M9-casein (0.5%) broth at the end of each cycle. The proportion of cooperator in each culture was not shown in the panel. b Frequencies of cooperator, conditional defector, and defector at defined sampling points during in vitro evolution. 100 μl of liquid fractions from the cycle 6 of Fig. 1c were inoculated into M9-casein (0.5%) broth for further repeated subculture at 24-h intervals. Composition of the three strategists in the population was detected at 8 h, 16 h, and 24 h time points after the medium was refreshed in each round. Data shown are the mean values ± SD of three independent experiments. C, cooperator; CD, conditional defector; D, defector