Figure 1

Evolution of altruistic suicide in the absence of adaptive immunity. A, B, C: Average suicide propensity of a population after the evolutionary process as a function on the efficacy of innate immunity and the population mixing rate. The color code in A indicates the mean suicide propensity. B shows results for varying immune efficacy in a fully structured population (mixing rate equal to 0). C shows the effect of weakening the population structure at a fixed immune efficacy equal to 0.2. D: Snapshots of the evolutionary process for an immune efficacy of 0.2 and no mixing. Grey to red colors indicate the suicide propensity of a host (as in the color bar in A), white denotes empty sites and black infected hosts. In this setting, the decision to commit suicide occurs before immunity. Maximum suicide efficacy CD _max  = 1.