The taxonomy of vertebrates is primarily based on morphological, mostly cranial and dental characters. Teeth, often the only fossil remains of extinct taxa, are usually considered to exhibit important traits allowing to infer phylogenetic relationships among groups of vertebrates (obvious exceptions being toothless vertebrates like birds and turtles). Dental features and other morphological characters related to feeding constitute one of the major interfaces between toothed vertebrates and their environment. By examining the variability in morphological features within and among vertebrate species, it has recently been discovered that the characters associated with feeding - almost paradoxically - can be evolutionarily very plastic. Indeed, an increasing number of molecular phylogenetic studies in vertebrates yields results that are in conflict with trees derived from morphological features related to feeding. Because dental features are potentially very susceptible to homoplasy (RÜBER et al. 1999, SANDERSON & HUFFORD 1996), they are increasingly considered to be unreliable for diagnosing supra-specific relationships. Surprisingly, very little is known concerning the developmental and genetic processes that determine how dental (or other morphological) features evolve in a group of closely related taxa (MCELROY & KORNFIELD 1993). Therefore, we propose to study the developmental and genetic basis for the evolution of an adaptive morphological trait, in particular tooth shape, in a group of closely related cichlid fishes of Lake Tanganyika. Knowledge of developmental and genetic processes relevant to tooth shape formation in cichlid fishes may help us to understand how adaptive morphological change - often suggested to be one of the major driving forces in cladogenetic events - has contributed to the origin of this extraordinary interesting species assemblage (FRYER & ILES 1972).