Some controversial aspects of speciation of african cichlid fishes

" A clear distinction must be made between the intralacustrine speciation shown by some groups of African cichlid fishes and the simple specific proliferation shown by others. The former phenomenon is exhibited by several genera but hardly at all by the genus Tilapia.

Inshore dwelling habits and an algal diet have not had restrictive effects on speciation. In fact it is among inshore species that speciation has been most active.

While, partially by exploiting their small size, genera which have given rise to the endemic species flocks of the great lakes have become highly specialized for the exploitation of specific niches, the species of Tilapia have usually remained large and unspecialized and therefore capable of existing in a variety of environments.
Further consideration of the effects of predation supports the idea that it has accelerated rather than retarded the process of speciation.

If certain conditions are fulfilled, closely related species can co-exist throughout life in one habitat, eat the same kind of food and breed in close proximity to each other "