Researchers say their creation reveals a process called hybrid speciation, in which the genes of two existing species combine to produce a third.

The study suggests hybridization may be more important to the evolution of new animals than had previously been thought.

Hybrids such as the mule, a cross between a donkey and a horse, are sterile. But the team says the butterfly hybrid brought together a combination of genes that allowed it to breed and there be considered a new species.