Fig. 7

Simulation results of non-informative versus informative environment. The evolution of the three components of protection—protection increase, protection decrease, and basal protection—differed between informative (Fig. 6a) and non-informative environments (Fig. 6b and c). 20 simulations with a population of 10’000 individuals each were run for 100’000 time steps in the two different types of environments. For each time step in the simulation cells survived and reproduced depending on the individual protection level and amount of produced protection. Left panels: The lower and upper boundary of each area corresponds to the minimal and maximal trait value of the 20 simulation runs at each simulation step. The line corresponds to the median trait value. The population means (reported below) were calculated by taking the mean of the 20 population mean trait values of the 10’000 individuals of a particular trait at the end (time point 100’000) of a single simulation. Right panels: For each trait the distribution of the trait values at the end of the simulation (time point 100’000) of all 20 × 10’000 individuals across all 20 simulations is displayed (see Additional file 4: Figure S8.1 for trait distributions of single simulation runs). a In an environment where warning and stress periods occurred at random, cells evolved a high basal protection (evolved trait was 0.97, standard error 0.004, left panel: dark blue evolutionary trajectory, right panel: trait values were distributed towards 1). Traits that controlled changes in protection did not evolve to any specific levels, but were random, indicating no selection (protection increase, green: 0.43, standard error 0.038 and protection decrease, light blue: 0.54, standard error 0.036). At the end of the evolutionary process, populations were dominated by types that maintained protection during all times, regardless of history or present environmental conditions (right panel of this figure and schematically represented in Fig. 5c, lower panel). b In an environment with correlated warning and stress events, cells evolved a high protection increase (green: 0.94, standard error 0.014) while keeping the basal protection at a low level (dark blue, 0.15, standard error 0.043). This corresponds to up-regulating protection when a warning or stress period was encountered. Protection was not actively down-regulated (light blue: 0.07, standard error 0.042), it gradually decreased at cell division when protection level was evenly distributed to the two cells emerging from division (schematically represented in Fig. 5c, upper panel)