To be or not to be a hamlet pair in sympatry

Recent adaptive radiations, such as the fringillid finches on the Galapagos archipelago or the cichlid fishes in the East African Great Lakes, are invaluable model systems for evolutionary and ecological research. Puebla et al., in this issue of Molecular Ecology, have established a group of colourful coral reef fishes from the Caribbean sea for studying the early phases of species formation in a marine adaptive radiation. It appears that local evolutionary processes are important in this system, which might have even triggered in situ speciation.