Abstract

African cichlid fishes are a textbook model of evolution in motion but the molecular genetic bases and mechanisms involved in their rapid speciation largely remain elusive. Emerging experimental evidence now suggests that African cichlids have undergone rapid speciation due to a combination of their molecular genetic potential and the influences of the environment on this potential. The genetic potential of the cichlids lies mainly in the ecomorphological plasticity of their feeding apparatus and their strong sexual selection. Putative genes that underlie the phenotypic variations in African cichlids are beginning to be unravelled but their coverage in the literature remains modest and scattered. This review forms one of the first comprehensive attempts to consolidate emerging data that explain various genes and mechanisms underlying explosive speciation in this family of fishes. The review analyzes the modes of African cichlid speciation, radiation-in-stages model, molecular genetic bases of plastic pharyngeal jaws and teeth and signature genes for sexual selection premised mainly on nuptial colour patterns, egg dummies and maternal mouth brooding, opsins and the sensory drive hypothesis. Explaining sexual selection mechanisms based on colour patterns and sensitivity to light is crucial to understanding African cichlid species biodiversity and conservation in polluted lakes.

Key words: African cichlids, rapid speciation, sexual selection, genes.