Can animals use iridescent colors to communicate?

A new paper from the University of Melbourne reveals how animals use beautiful but unreliable iridescent colors as communication signals. Special adaptations allow animals to control the appearance of these changing colors so that they can convey reliable information. The new work now published in Trends in ecology and evolution brings together studies from across the animal kingdom to find out how animals control the appearance of iridescent colors in nature.

“Iridescence is difficult to study because the hue you see depends on the viewer’s position and the direction of the light,” said senior author, Dr Amanda Franklin of the School of BioSciences. “This means that iridescent colors are constantly changing, so it’s hard to see how they can convey reliable information. Rule number one for communication is that information must be reliable – it’s the same for both animals and humans!”

But paradoxically, iridescent colors, such as dazzling butterfly wings or dramatic peacock feathers, are prevalent in the natural world.

Co-author and Ph.D. student Leslie Ng explains, “By studying how animals detect and process iridescence, we can get a better idea of ​​when iridescence is actually a useful communication signal. Reliable iridescent signals are usually provided. with behavioral or physical adaptations that help animals control the visual effect. For example, male Anna’s hummingbirds precisely control their courtship flights so that their iridescent throats appear a constant bright pink color to alert females “.

Dr. Franklin said organisms can do beautiful things with light. “Through evolution, they have adapted microstructures to produce specific effects. Some use microstructures to control the precise angle at which the hue of iridescent colors appears to change. In this way, they control the information that communicates with the color.”

Ms Ng said that many studies suggest that iridescent colors are important for courtship or camouflage, but they rarely consider how these flashy cues are actually seen by animals. “Because of this, we know very little about how iridescence is processed in the animal’s brain.”

The detection of iridescent signals also depends on the way in which organisms visualize the color spots and on the physical location of both the beacon and the viewer. For example, an iridescent color can be processed differently if it blinks quickly or if the colors are fast moving.

Lead author Professor Devi Stuart-Fox said the insights shed new light on the colorful world of animal communication and highlight the challenges of carefully studying how iridescent colors work in nature.

“Nature provides a test bed for the detection and processing of dynamic and colorful signals,” he said. “Understanding how animals reliably use and produce these shift signals can aid in the development of bio-inspired iridescent materials designed for human observers.”