Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

What do soap bubbles and butterflies have in common?

09.04.2020

Butterfly breeding gives insight into evolution of iridescence

Edith Smith bred a bluer and shinier Common Buckeye at her butterfly farm in Florida, but it took University of California, Berkeley, graduate student Rachel Thayer to explain the physical and genetic changes underlying the butterfly's newly acquired iridescence.


The butterflies that Edith Smith selectively bred are much bluer and more iridescent than the wild Common Buckeye, which is mostly brown (see below). The breeding, UC Berkeley researchers discovered, changed the structure of the wing scales to produce a blue rather than golden structural color. (Photo courtesy of Edith Smith)

In the process, Thayer discovered how relatively easy it is for butterflies to change their wing colors over just a few generations and found the first gene proven to influence the so-called "structural color" that underlies the iridescent purple, blue, green and golden hues of many butterflies.

Her findings are a starting point for new genetic approaches to investigate how butterflies produce intricate nanostructures with optical properties, which ultimately could help engineers develop new ways to produce photonic nanostructures for solar panels or iridescent colors for paints, clothing and cosmetics.

Structural color is different from pigment color, like that in your skin or on a canvas, which absorbs or reflects different colors of light. Instead, it comes from light's interaction with a solid material in the same way that a transparent bubble develops a colorful sheen. The light penetrates it and bounces back out, interfering with light reflected from the surface in a way that cancels out all but one color.

At the Shady Oak Butterfly Farm in Brooker, Florida, Smith's breeding experiments with the Common Buckeye (Junonia coenia) -- a mostly brown butterfly with showy, colorful spots, found throughout the United States and often raised by butterfly farmers for butterfly gardens or wedding ceremonies -- were ideal for Thayer's study of structural color.

"Edith noticed that sometimes these butterflies have just a few blue scales on the very front part of the forewing and started breeding the blue animals together," said Thayer, who is in UC Berkeley's Department of Integrative Biology. "So, effectively, she was doing an artificial selection experiment, guided by her own curiosity and intuition about what would be interesting."

In a paper appearing online today in the journal eLife, Thayer and Nipam Patel, a UC Berkeley professor of molecular and cell biology who is on leave as director of the Marine Biological Laboratory in Woods Hole, Massachusetts, describe the physical changes in wing scales associated with Smith's experiment on the Common Buckeye, and report one genetic regulator of blue iridescence.

"I especially loved the clear evolutionary context: being able to directly compare the 'before' and 'after' and piece together the whole story," Thayer said. "We know that blueness in J. coenia is a recent change, we know explicitly what the force of selection was, we know the time frame of the change. That doesn't happen every day for evolutionary biologists."

Structural color produces showy butterflies

According to Thayer, hundreds of butterflies have been studied because of the showy structural color in their wing scales. The showiest is the blue morpho, with 5-inch wings of iridescent blue edged with black. Her study, however, focused on a less showy genus, Junonia, and found that iridescent color is common throughout the 10 species, even the drab ones. One unremarkable light gray butterfly, the pansy J. atlites, proved under a microscope to have iridescent rainbow-colored scales whose colors blend together into gray when viewed with the naked eye.

One major lesson from the study, she said, is that "most butterfly patterns probably have a mix of pigment color and structural color, and which one has the strongest impact on wing color depends on how much pigment is there."

Thayer raised both the wild, brownish Common Buckeye and the cross-bred, bluer variety obtained from Smith. Using a state-of-the-art helium ion microscope, she imaged scales from the wings to see which scale structures are responsible for the color and to determine whether the color change was due to a change in structural color, or just a loss of brown pigment that allowed the blue color to stand out.

She found no difference in the amount of brown pigment on the scales, but a significant difference in the thickness of chitin, the strong polymer from which the scale is built and that also generates the structural color. In the wild buckeye, the thickness of the chitin layer was about 100 nanometers, yielding a golden hue that blended with the brown pigment. The bluer buckeye had chitin about 190 nanometers thick -- about the thickness of a soap bubble -- that produced a blue iridescence that outshined the brown pigment.

"They are actually creating the color the same way a soap bubble iridescence works; it's the same phenomenon physically," Thayer said.

She also found that, though the scales from the Junonia butterflies have an elaborate microscopic structure, structural color comes from the bottom, or base, of the scale.

"That is not intuitive, because the top part of the scale has all of these curves and grooves and details that really catch your eye, and the most famous structural colors are elaborate structures, often in the top part of the scale," she said. "But the simple, flat layer at the bottom of the scale controls structural coloration in each species we checked."

"The color comes down to a relatively simple change in the scale: the thickness of the lamina," said Patel. "We believe that this will be a genetically tractable system that can allow us to identify the genes and developmental mechanisms that can control structural coloration."

Thayer also investigated the scales of mutant buckeyes created by Cornell University researchers that lacked a key gene, called optix, that controls color. The micrograph images demonstrated that lack of the gene also increased the thickness of the thin film of chitin in the scales, creating a blue color. Optix is a regulatory gene that controls many other butterfly genes, which Thayer will be looking at next.

"One thing that I thought was cool about our findings was seeing that the same mechanism that has recurred over millions of years of butterfly evolution could be reproduced really rapidly in (Smith's) artificial section experiment," she said. "That says that color evolving by changes in lamina thickness is a repeatable, important phenomenon."

###

Frances Allen, a research scientist in UC Berkeley's Department of Materials Science and Engineering, is also a co-author of the paper. The work was supported by the National Science Foundation (DEB-1601815, DGE-1106400).

Media Contact

Robert L Sanders
rlsanders@berkeley.edu
510-915-3097

 @UCBerkeleyNews

http://www.berkeley.edu 

Robert L Sanders | EurekAlert!
Further information:
https://news.berkeley.edu/2020/04/08/what-do-soap-bubbles-and-butterflies-have-in-common/
http://dx.doi.org/10.7554/eLife.52187

Further reports about: brown pigment bubbles butterfly nanometers nanostructures

More articles from Life Sciences:

nachricht Organized chaos in the enzyme complex: surprising insights and new perspectives
06.07.2020 | Max-Planck-Institut für Entwicklungsbiologie

nachricht Gut bacteria improve type 2 diabetes risk prediction
06.07.2020 | Technische Universität München

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Electrons in the fast lane

Solar cells based on perovskite compounds could soon make electricity generation from sunlight even more efficient and cheaper. The laboratory efficiency of these perovskite solar cells already exceeds that of the well-known silicon solar cells. An international team led by Stefan Weber from the Max Planck Institute for Polymer Research (MPI-P) in Mainz has found microscopic structures in perovskite crystals that can guide the charge transport in the solar cell. Clever alignment of these "electron highways" could make perovskite solar cells even more powerful.

Solar cells convert sunlight into electricity. During this process, the electrons of the material inside the cell absorb the energy of the light....

Im Focus: The lightest electromagnetic shielding material in the world

Empa researchers have succeeded in applying aerogels to microelectronics: Aerogels based on cellulose nanofibers can effectively shield electromagnetic radiation over a wide frequency range – and they are unrivalled in terms of weight.

Electric motors and electronic devices generate electromagnetic fields that sometimes have to be shielded in order not to affect neighboring electronic...

Im Focus: Gentle wall contact – the right scenario for a fusion power plant

Quasi-continuous power exhaust developed as a wall-friendly method on ASDEX Upgrade

A promising operating mode for the plasma of a future power plant has been developed at the ASDEX Upgrade fusion device at Max Planck Institute for Plasma...

Im Focus: ILA Goes Digital – Automation & Production Technology for Adaptable Aircraft Production

Live event – July 1, 2020 - 11:00 to 11:45 (CET)
"Automation in Aerospace Industry @ Fraunhofer IFAM"

The Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM l Stade is presenting its forward-looking R&D portfolio for the first time at...

Im Focus: AI monitoring of laser welding processes - X-ray vision and eavesdropping ensure quality

With an X-ray experiment at the European Synchrotron ESRF in Grenoble (France), Empa researchers were able to demonstrate how well their real-time acoustic monitoring of laser weld seams works. With almost 90 percent reliability, they detected the formation of unwanted pores that impair the quality of weld seams. Thanks to a special evaluation method based on artificial intelligence (AI), the detection process is completed in just 70 milliseconds.

Laser welding is a process suitable for joining metals and thermoplastics. It has become particularly well established in highly automated production, for...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International conference QuApps shows status quo of quantum technology

02.07.2020 | Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

Aachen Machine Tool Colloquium AWK'21 will take place on June 10 and 11, 2021

07.04.2020 | Event News

 
Latest News

Coupled hair cells in the inner ear – „Together we are strong!“

06.07.2020 | Health and Medicine

Innovations for sustainability in a post-pandemic future

06.07.2020 | Social Sciences

Carbon-loving materials designed to reduce industrial emissions

06.07.2020 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>