Butterflies and Moths Reused Same Two Genes for 120 Million Years, Study Finds

Same Genetic Recipe, 120 Million Years Apart

Distantly related butterflies and moths have independently evolved strikingly similar warning colour patterns by reusing the very same pair of genes across 120 million years of evolution, according to a study published in PLOS Biology. The findings challenge the long-held idea that evolution is largely a game of chance, suggesting instead that nature often follows surprisingly constrained pathways.

The Research

An international team led by the University of York and the Wellcome Sanger Institute examined several butterfly and moth species from the South American rainforest that display nearly identical wing patterns. These bold colours act as warning signals to predators, advertising the insects' toxicity - a phenomenon known as mimicry. Despite being separated by enormous evolutionary distances, all seven butterfly lineages and one day-flying moth species in the study relied on the same two genes, ivory and optix, to produce their warning colours.

Switches, Not the Genes Themselves

Crucially, the genetic changes that drove these convergent patterns did not occur within the genes themselves. Instead, they appeared in regulatory "switches" - non-coding regions of DNA that control when and how the genes are turned on or off. In one striking case, a moth species used a DNA inversion mechanism, where a large section of DNA is flipped backwards, almost identical to a trick used by a distantly related butterfly.

Confirming the Link

Dr Eva van der Heijden, co-first author at the Wellcome Sanger Institute and the University of Cambridge, said the team went beyond association studies. By using genetic modification to break the gene, they were able to change a butterfly's colouration from orange and black to yellow, confirming the gene's direct role. Gene expression during the chrysalis stage reliably predicted the adult's final wing pattern.

A More Predictable Evolution

Professor Kanchon Dasmahapatra of the University of York said butterflies and moths have been using the exact same genetic tricks since the age of the dinosaurs. Professor Joana Meier of the Wellcome Sanger Institute added that these warning colours appear particularly easy to evolve thanks to a highly conserved genetic basis stretching back 120 million years. The researchers believe the findings could help scientists predict how species might adapt to environmental shifts or climate change, since nature seems to follow certain constrained pathways rather than proceeding purely by chance.