How Butterfly Wings Got Their Color

Sep 27, 2017 By James H, Young Editor
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Have you marveled at a butterfly's wings, and how the brilliant colors and patterns shimmer in the sunlight?

Scientists have been captivated by them too. They believe butterflies evolved from a moth-like ancestor, but then, why is there a big difference (especially in color) between the wings of a moth and a butterfly? 

In a recent study, scientists have finally identified the two primary genes that play the biggest role in creating these winged works of art. 

Genes That Color

To learn more about genes, read our earlier article here. Basically, genes carry information that determine traits such as your hair and eye color, or how tall you are. Genes are made up of a chemical called DNA (DeoxyRibonucleic Acid) which is the building block of life. 

To identify the genes that color butterfly wings, scientists used a tool that enables them to alter the butterfly's genes. In fact, scientists developed the gene editing tool by observing how bacteria defend themselves against attacking viruses.The bacteria simply cut up the invading virus's DNA, using a kind of chemical scissors! Scientists called this mechanism CRISPR (short for “clustered regularly interspaced short palindromic repeats”). 

Scientists used CRISPR to cut out two genes -- Optix and WntA, in the DNA of several butterfly species. Turned out, the wings without these genes were not as colorful anymore! In some butterflies, the patterns were blurred out into one blob of color; for others, the bright colors completely changed into a dull black and white. Some mutant butterflies lost their eyespots, and others had their color spots moved to other places. 

Why Is This Important?

By identifying these "paintbrush" genes, scientists can develop a better understanding of how the butterfly's colors and patterns evolved. 

Many butterflies have evolved their wings to help them survive. Bright colors like the orange on a monarch butterfly serve as a warning sign to tell possible predators that they are bad-tasting or poisonous. Dark colors help butterflies absorb heat as they are cold-blooded animals. Butterflies also recognize other members of its kind through their colored patterns, both visible and ultraviolet.

Some butterflies use their colored wings to camouflage into backgrounds like a tree or a leaf. Other have big eye spots on their wings to intimidate their predators. And yet others have evolved their wing patterns to mimic other bad-tasting species in their neighborhoods, simply to stay safe from predators!