Butterflies are are able to mimic other neighbouring species to avoid being eaten by birds because of a "supergene" – a cluster of genes that controls their wing patterns, researchers have found.
In the Amazon, for example, harmless butterflies can take on the appearance of poisonous species, and even species that are harmful themselves sometimes evolve to resemble other noxious types, which makes things more confusing for potential predators.
For the first time, researchers led by the Muséum National d'Histoire Naturelle in Paris and the University of Exeter have shown how butterflies perform this amazing trick, known as "Müllerian mimicry".
"This phenomenon has puzzled scientists for centuries, including Darwin himself," said Professor Richard French-Constant, from the University of Exeter.
"Indeed, it was the original observations of mimicry that helped frame the concept of natural selection."