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Butterflies Can Evolve New Colors Amazingly Fast

Butterflies can evolve new colors rapidly and simply by tweaking the structures of their wings, a new study says. 

A team of researchers who bred a species of brown African butterfly in the lab were shocked to discover that the offspring could turn purple in just six generations, or about a year. (See: “Pictures: Butterfly Wing Colors Imaged in 3-D.”)

A photo of a butterfly Bicyclus anynana.
The butterfly Bicyclus anynana before it was bred to turn purple. Photograph courtesy of Antónia Monteiro.

Scientists have long known that butterflies are sensitive to changes in their environment and can evolve new colors if it suits them. But until now, no one knew how the fragile insects were able to pull this off.

Such a speedy evolution is “amazing,” said study co-author Hui Cao, a physicist at Yale University. “Within one year they look purple—I could not believe it, to be honest.”

True Colors

In the laboratory, the team bred the butterfly Bicyclus anynana,  which lives for about two months. They used microscopes to determine which individual butterflies’ wings best reflected light of the wavelength that produces purple. (See: National Geographic’s gallery of purple colors in nature.)

Then they mated these butterflies several times, mimicking evolution. Eventually, the butterflies that emerged had wings that appeared purple, according to the study, published August 4 in the Proceedings of the National Academy of Sciences.

When the scientists examined these purple wings under the microscope, they discovered that each scale had evolved to have the specific thickness that allowed it to reflect violet light. In other words, the wing scales had become perfect for reflecting purple. (Watch video: “Growing Up Butterfly.”)

A photo of a comparison of wings of a butterfly
After six generations of breeding, B. anynana developed scales in its wings that reflected purple (right to left). Photograph courtesy of Antónia Monteiro

The team then compared Banynana and two distantly related species of butterfly in the same genus that had naturally evolved to be purple. They discovered that the same mechanism they’d observed in the lab had been at work in nature: All three species had wing scales of the same thickness.

A Butterfly of a Different Color

There are only two ways an animal can change its color: by altering its pigment, which requires the body to do some heavy lifting, or by tweaking the structure of its wings or other body parts that reflect light, Cao noted. (See: “Glowing Butterflies Outshine LEDs.”)

By changing their wings, butterflies had chosen the easier route. “That’s why they can evolve much faster and easier to really adapt to environmental change,” Cao said.

Scientists not involved with the study noted that the research advances science by showing both the speed and function of color evolution in butterflies.

“This paper nicely shows that underlying structural colors can evolve faster than pigment,” said Mark Scriber, professor emeritus in entomology at Michigan State University in East Lansing. “How quickly the response is to selection [for purple] was probably the most amazing thing.”

Butterfly expert Andrei Sourakov added by email, “This study contributes significantly to our understanding of an important trait frequently found in butterflies—iridescent coloration.”

Sourakov, of the Florida Museum of Natural History, suspects that many butterflies have evolved ways to change colors fast but using different mechanisms: “Nature has a way of achieving similar goals in multiple ways.”

For instance, common buckeye butterflies, which are usually almost entirely brown in Florida, are bred for the size of their iridescent blue patch, and can turn from brown to blue in six years, he noted.

Why So Colorful?

The reason butterflies sport colorful wings likely has to do with communicating with other butterflies or avoiding predators.

Scriber said that, among other things, specific colors may help male and female butterflies identify each other in an environment full of other insects.

Cao noted that brown butterflies often live in dense forests, where they blend into the surroundings, and purple butterflies live in the open, where their dazzling flashes may confuse predators. (Related: “People Can Hallucinate Color at Will.”)

Learning “how the butterfly tunes their optical properties gives us inspiration to mimic them,” she added.

For instance, she said, such research may help engineers build electronic devices, such as e-readers, that can switch colors quickly and efficiently.

Follow Christine Dell’Amore on Twitter and Google+.

Comments

  1. Evelyn vidos
    earth
    August 17, 8:01 am

    I loved this article on these delicate creatures of beauty.

  2. Tom Sweetnam
    Colorado remote
    August 6, 9:07 pm

    Interesting article that won’t get any argument from me. It seems that every spring and summer we get dozens of new moths here in Southern Colorado, yet I’m sure most are simply mutations of the same insects I’ve seen in years past. Like many people, I used to have an aversion for moths, but for the past few years now, I’ve started paying attention to them. They really are beautiful little creatures. Time to drag my macro camera gear out of the closet and start making a record of all this.

  3. Kaoru Kojima
    August 6, 7:32 pm

    According to the article, I think butterflies have acquired some ability to adapt to their environments.
    They are more likely to see a variety of insects including predators or counterparts while flying.
    As the result, the more frequently they see other insects, the more adaptability to survive they have got.

  4. Ashley Corona
    Los Angeles, CA
    August 6, 2:13 pm

    I love the white butterflies. They’re really beautiful.

  5. LOLA CORTÉS
    cartago, valle colombia.
    August 6, 11:00 am

    es preciosa, me gustan siempre sus publicaciones y como hago para enviar mis fotos, pues tengo algunas que tal vez les agraden.

  6. Mojtaba Najafi
    August 6, 12:09 am

    Amazing!

  7. Krishna Bhargava A
    Bangalore
    August 5, 12:39 am

    Butterflies are sensitive to colors, for example they like shades of blue and pink, and they may not like shades of grey or black. Fortunately this color difference is not present in humans, we are equal oriented with respect to the color spectrum. This color identification is one of the most prominent factors we must observe in butterflies.