Appendix 1—figure 2. Effect of sharing two resources.

When two resources are shared to different degrees, specified by $({\beta }_1,{\beta }_2)$, specialization is sometimes favored under conditions of sublinear returns on investment ${\alpha }^{*}<1.0$. Interestingly, specialization is favored when one resource is shared liberally while the other resource is shared sparingly (though it is not necessary to have one resource remain totally unshared).