Here’s what you’ll learn when you read this story:

• Butterflies and moths are known to mimic one another in order to adopt warning colors that ward off predators.
• A new study investigates the genetic machinery behind these adaptations and finds that evolution has stuck to a similar “cheat sheet” for at least 120 million years.
• Understanding how these mechanisms work could help scientists better predict how certain species will adapt to a changing climate.

Despite the fact that evolution drives all life on Earth, there’s still a lot about it we don’t quite understand. While Charles Darwin laid out the foundation of how life differentiates through natural selection and random mutation, instances of convergent or parallel evolution challenge the idea that mutations are entirely random.

Now a new study published in the journal PLOS Biology examines this question further by investigating the genomes of species found in the order Lepidoptera, which includes butterflies and moths, two distinct types of insects that have undergone a good deal of parallel evolution. The wing patterns found on some of these insects advertise to predators that they’re toxic, and other toxic species of moths or butterflies have gradually evolved precisely the same wing patterns, a phenomenon known as Müllerian mimicry. Even more amazingly, butterflies that aren’t toxic at all seemingly take cues from their toxic compatriots by adopting their color strategy to avoid predation through a process known as Batesian mimicry.

Here’s an example: everyone knows the Monarch butterfly (Danaus plexippus)—it may be the first thing you picture in your mind just from hearing the word “butterfly”—but the Viceroy (Limenitis archippus) looks almost identical to the Monarch, except with a slightly smaller stature and a black line that runs across the veins of its hindwings. Once thought to be a Batesian mimic of the monarch, it was later discovered that Viceroys were also distasteful to predators, and are now firmly in the Müllerian mimic camp.

To better understand how moths and butterflies undergo changes to mimic one another, an international team of scientists looked at Lepidoptera species, some of which had evolutionarily diverged up to 120 million years ago. Despite these large evolutionary timescales, the team found that many butterflies and moths used the same genetic “cheat sheet” to evolve identical warning patterns. This could mean that adaptation to future stressors, including climate change, could be more predictable than previously believed.

“Investigating seven butterfly lineages and a day-flying moth, we show that evolution can be surprisingly predictable,” University of York’s Kanchon Dasmahapatra, a co-author of the study, said in a press statement, “and that butterflies and moths have been using the exact same genetic tricks repeatedly to achieve similar color patterns since the age of the dinosaurs.”

The researchers focused on Heliconius butterflies—a group known for its extensive use of both types of mimicry—as well as insects belonging to the group Ithomiini, one of the most well-studied groups of Lepidopterans. The study also included Chetone moths, a genus of tiger moth from neotropical regions known to mimic both toxic Ithomiini and Heliconius butterflies.

The researchers set out to discover which genes control these shared patterns across species, and found that to pull off this “genetic trick,” the genes themselves do not vary. Instead, there are regulatory “switches” in two genes—named ivory and optix—that produce the identical color patterns. Across different butterfly species, these genetic switchers acted similarly, but moths used an “inversion mechanism,” according to the authors, to essentially flip a chunk of DNA code so that it closely resembles a beneficial butterfly adaptation.

“Not only did we find an association between a gene and colour variation in various species, but we also showed that breaking that gene through genetic modification actually changes the butterfly’s color,” the University of Cambridge’s Eva van der Heijden, a co-author of the study, said in a press statement. “This confirms our association analysis identified the correct gene.”

Understanding these mechanisms can identify mutation hotspots that allow for rapid adaptation. And by bringing order to what was previously believed to be a random process, it could offer researchers new insights into how species could adapt to our changing climate.