Three aspects of evolutionary stability. All panels show configurations of the adaptive landscape (fitness, G, plotted against the strategy of the focal individual, v, for some population value of the strategy, u, shown as the red dot on a given landscape). On each landscape, the population's strategy yields a fitness of G = 0, indicating that the population is at its equilibrium population size, x*. Panels (a–c) all show a case where a strategy is an ESS and a peak of the adaptive landscape. In (a), the ESS is both convergent stable and NIS; in (b) it is convergent stable but not NIS; and in (c), the ESS is not convergent stable or NIS. Panel (d) shows a strategy that has evolved to a minimum of the adaptive landscape that is convergent stable and NIS.