“The paper uses a very smart [way] to find a clear answer to a longstanding question, which is why certain groups of organisms are more successful at forming many species over a short period of time,” says Claudius Kratochwil, an evolutionary developmental biologist at the University of Helsinki who was not involved with the work. The findings suggest opportunity and versatility matter more than primacy, adds George Turner, an evolutionary biologist and cichlid fish expert at Bangor University who was also not involved.