Fig. 2.

Examples of the predictions of the Collective Investment game (and specific application to the D. discoideum system). Predictions are plotted as a function of a focal player’s relatedness to the group (i.e., a strain’s frequency in the group). For A–C the optimal investment (${\mathrm{\Theta }}_{\text{G}}$) was fixed at 0.3 and the strength of selection (Γ) was varied, while for D–F the strength of selection was fixed at 2 and the optimum was varied. (A and D) Predicted Investment $\left(I_{i|p_i}\right)$ in the public good (stalk investment) as a function of relatedness (frequency). (B and E) Predicted relative payoff (fitness) (${\rho }_i$) as a function of relatedness (frequency). (C and F) Predicted collective investment $\left(I_G\right)$ for a pair of players as a function of the relatedness (frequency) of the focal player to the group (see SI Appendix, Fig. S1 for illustrations across other parameter values).