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Published in final edited form as: Evolution. 2012 Apr 10;66(8):2498–2513. doi: 10.1111/j.1558-5646.2012.01629.x

A.) Independent Evolution: The intensity of local competition, a, over the course of independent evolution of each altruism type (from simulations generating dashed curves in Figure 4). Evolution of survival/fecundity altruism (black dashed line) causes local competition to increase; alternatively, evolution of resource-based altruism (gray dashed line) weakens local competition. In both cases, the trait alters local competition in a direction that weakens selection on the trait, eventually causing evolution of the trait to stall at its single-trait ESS. B) Coevolution: The intensity of local competition, a, over the course of coevolution of survival/fecundity and resource-based altruism (from same simulation generating solid lines in Figure 4). C) A Closer Look: Coevolution simulation with same conditions as Figure 4 (and 5B), but zoomed in and slowed down by introducing new mutations when previous mutant frequency equals 0.9999 (instead of 0.99). D) Trait values from corresponding to C. The black curve denotes the trait value for survival/fecundity helping (φ_f), and the gray curve resource-based helping (φ_S). Note that the oscillations in C) correspond with changes in trait values from D): Local competition increases as survival/fecundity altruism (black line in B)) increases, but decreases as resource-based altruism (gray line in B)) increases.

A.) Independent Evolution: The intensity of local competition, a, over the course of independent evolution of each altruism type (from simulations generating dashed curves in Figure 4). Evolution of survival/fecundity altruism (black dashed line) causes local competition to increase; alternatively, evolution of resource-based altruism (gray dashed line) weakens local competition. In both cases, the trait alters local competition in a direction that weakens selection on the trait, eventually causing evolution of the trait to stall at its single-trait ESS. B) Coevolution: The intensity of local competition, a, over the course of coevolution of survival/fecundity and resource-based altruism (from same simulation generating solid lines in Figure 4). C) A Closer Look: Coevolution simulation with same conditions as Figure 4 (and 5B), but zoomed in and slowed down by introducing new mutations when previous mutant frequency equals 0.9999 (instead of 0.99). D) Trait values from corresponding to C. The black curve denotes the trait value for survival/fecundity helping (φ_f), and the gray curve resource-based helping (φ_S). Note that the oscillations in C) correspond with changes in trait values from D): Local competition increases as survival/fecundity altruism (black line in B)) increases, but decreases as resource-based altruism (gray line in B)) increases.