Due to its enormous biodiversity, the cichlid fishes have been established as a prime model system for the study of evolution. While substantial knowledge has accumulated regarding ecology, mophology: bhayio and phylogeny, the question about the molecular basis leading to the diversity of this group remains unanswered. The evolutionary success of the cichlids has been attributed to the particular anatomy of their pharyngeal jaws and to the distinct coloration of cichlids. However, little is known about the development or evolutionary mechanisms underlying coloration in cichlids, even though colour-genes are potential speciation-genes. In this research project, we propose to design a cDNA-microarray to analyse the expression of genes involved in colour determination in cichlids. In order to isolate candidate genes we will apply two complementary approaches, the isolation of colour-genes known from zebrafish through RACE and the identification of differentially expressed genes between skin tissue of different cichlid colour morphs via SSH. The combination of RACE, SSH and the cDNA-chip technology will provide us with the first insights into the development and evolutionary mechanisms underlying coloration in cichlids, it might identify new genes involved in coloration, and it might indicate the role of alternative splicing in colour determination. This straight-forward approach will thus elucidate the role of possible speciation-genes in cichlid evolution. pWith the clarification of the phylogeny of the East African cichlids, alternative models of speciation and new insights into population dynamics, we have established teh framework to address questions about the molecular basis of the evolutionary success of cichlids. This new aspect in cichlid evolution requires the application of new methodologies.