Explosive speciation in cichlid fishes of the African Great Lakes: a dynamic model of adaptive radiation

In the African cichlid species Becks several corresponding ecotypes and species communities have evolved independently in each of the lakes. These flocks can be viewed as reiterations of a process, induced by the same type of external event (the formation of a lake) and seeded by the same group of organisms, equipped with the same innovative potential. The East African lakes differ in their ages, so that different stages of adaptive radiation of a single group of fishes can be studied simultaneously. This review combines findings on various African cichlid species flocks and derives a generalized model of cichlid adaptive radiation. The model constitutes four stages, defined by the most influential habitat characteristics and interactions among members of the species community at each phase. It is an attempt to provide an explicit hypothesis for a dynamic evolutionary process, as a basis to future studies. (C) 1998 The Fisheries Society of the British Isles.