The Stability/Diversity Controversy: A Test of Hypotheses

Abstract

This paper uses the hypothetico-deductive method (i.e., hypothesis testing) to ex- amine a venerable and still unresolved ecological issue: the relation between species diversity and community stability. Data from freshwater fish communities are used to test two related hypotheses. The data presented on fish species diversity from the four major lake basins of Africa support the hypothesis that stable environments have more species than relatively less stable ones. The data presented from a natural perturbation in Panama, the introduction of a predatory fish, refute the hypothesis that stable environments have greater resilience (i.e., faunal stability). In the latter test, predation by an introduced piscivore caused the local extermination of 13 of 17 native fish species in the environmentally stable lake system, but caused no local extermination in the adjacent and rela- tively less environmentally stable river system. The results provide empirical support for the hy- pothesis that stable environments, associated with a higher species diversity, will have lower (faunal) stability. It is suggested that system characteristics, such as physical heterogeneity or seasonality, may be more important in determining community species resilience than the number or species diversity of resident species.