Evolution of colour patterns in East African cichlid fish

African cichlid fishes have undergone: outbursts of explosive speciation in several lakes, accompanied by rapid radiations in coloration and ecology. Little is-known about the evolutionary forces that triggered these events b ut a hypothesis, published by Wallace Dominey in 1984, has figured prominen tly. It states that the: evolution of colour patterns is driven by sexual s election and that these colour patterns are important in interspecific mate choice, a combination which holds the potential for rapid speciation. Here we present phylogenetic analyses that describe major events in colour evol ution and test predictions yielded by Dominey's hypothesis. We assembled in formation on stripe patterns and the presence or absence of nuptial colorat ion from more than 700 cichlid species representing more than 90 taxa for w hich molecular phylogenetic hypotheses were available. We show that sexual selection is most likely the selection force that made male nuptial colorat ion arise and evolve quickly. In contrast, stripe patterns, though phylogen etically not conserved either, are constrained ecologically. The evolution of vertical bar patterns is associated with structurally complex habitats, such as rocky substrates:or vegetation. The evolution of a horizontal strip e is associated with a piscivorous feeding mode. Horizontal stripes are als o associated with shoaling behaviour. Strength of sexual selection, measure d in terms of the mating system (weak in monogamous, strong in promiscuous species), has no detectable effects on stripe pattern evolution. Ln promisc uous species the frequency of difference between sister species in nuptial hue is-higher than in pair bonding and harem forming species, but the frequ ency of difference in stripe pattern is lower. We argue that differences be tween the two components of coloration in their exposure to natural selecti on explain their very different evolutionary behaviour. Finally, we suggest that habitat-mediated selection upon chromo-motor flexibility, a special f orm of phenotypic plasticity found in the river-dwelling outgroups of the l ake-dwelling cichlids, explains the rapid and recurrent ecology-associated radiation of stripe patterns in lake environments, a new hypothesis that yi elds experimentally testable predictions.