Published online by Cambridge University Press: 14 July 2016
Recently, the properties of ESSs for random payoff matrices, and stable polymorphisms for random fitness matrices, have been investigated. These problems are very closely related, and some similarities and differences are examined here. In contrast to some earlier work, non-robustness of the conclusions, to changes in the distribution of the random matrices, are found in two areas: in the asymptotic number of polymorphisms (or ESSs) whose support is a given size, and in the location of a polymorphism (or ESS) whose size of support is 2 or 3, in a large matrix.