Cichlid fishes (Perciformes: Teleostei) found in the lakes
of Africa have served as model systems for the study of evolution. The
enormous number of species (1000 in Lake Malawi alone), the great
diversity of trophic adaptations and behaviors, and the extreme
rapidity of their divergence (<50,000 y for some faunas) single out
these organisms as examples of evolution in progress. Because these
fishes are confined to discrete lacustrine environments and their
origination is bounded by geological features, these groups provide
models with which to study evolution. We review theoretical studies and
empirical research on the cichlid faunas of Africa to provide a
synthetic overview of current knowledge of the evolutionary processes
at work in this group. This view provides the critical information
needed to formulate and test hypotheses that may permit discrimination
among the diverse theories and models that have been advanced to
explain the evolution of these fishes.