Species survival and evolutionary stability in sustainable habitats - The concept of ecological stability

Whoever exists belongs to a species, which did not become extinct, has a (g eno-)type, which should be well adjusted, and lives in a habitat which has been sustainable for a long time. We do not only analyze interspecies compe tition and the conditions for species survival, but also intraspecies compe tition of (geno-)types as in evolutionary biology and game theory. Survival in inter and intraspecies competition together with sustainability define ecological stability, a concept which we illustrate by an example of solita ry and social grazers who compete for food supply and who are endangered by the same predators. Although our approach is inspired by empirical evidenc e, no systematic attempt is made to apply it to some specific ecology. JEL- classification: C70, C72.