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 (geno-)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 competition and the conditions for species survival, but also intraspecies competition of (geno-)types as in evolutionary biology and game theory. Survival in interand intraspecies competition together with sustainability define ecological stability, a concept which we illustrate by an example of solitary and social grazers who compete for food supply and who are endangered by the same predators. Although our approach is inspired by empirical evidence, no systematic attempt is made to apply it to some specific ecology.