Color signals have exploded in the last 100 million years

Nov. 8 () –

In the last 100 million years there has been a spectacular explosion of warning and sexual signals in the form of color among animals.

Researchers at the University of Arizona analyzed the evolutionary timeline of color vision in animals and the different functions of “bright colors” in animals and plants. Bold colors include colors such as red, yellow, orange, blue and violet, that stand out from most backgrounds.

Colors are widely used in communication within and between animal species. For example, peacocks proudly display their vibrant tails, adorned with iridescent eyespots, to attract peahens for courtship. This is a classic example of sexual selection through color signaling. The striking colors are also exhibited by toxic animal species, including many venomous snakes and the brightly colored poison dart frogs of Central and South America, as a warning to possible predators.

The new study, which is published in the journal Biological Reviews, focuses on two different types of color signals that animals use: warning signals and sexual signals. It also analyzes the color signals that plants use for flowers and fruits.

In plants, striking colors have two main functions: in fruits, to disperse seeds; in the flowers, distribute the pollen.

“We wanted to know when bright coloration evolved and what the purpose of that coloration was. That’s largely why we did this study,” he said. in a statement Zachary Emberts, co-author of the study and associate professor of integrative biology at Oklahoma State University. Emberts was a postdoctoral researcher at the University of Arizona when the study was conducted.

Color vision in animals evolved about 500 million years agowhile colorful fruits appeared about 350 million years ago and colorful flowers about 200 million years ago.

Lead author John J. Weins, a professor of evolutionary ecology, said warning color signals arose before sexual color signals, about 150 million years ago. Sexual color signals emerged about 100 million years ago.

“In the last 100 million years there has been a spectacular explosion of warning and sexual signs in color form“Wiens stated.

This occurs even though color vision evolved about 400 million years earlier. The exact reason for the explosion is unknown, but the research team identified three key groups that likely drove the warning signs explosion: ray-finned fish in marine environments and birds and lizards on land.

Wiens stated that color warning signals are much more widespread among animals than sexual signals, which are limited to arthropods and vertebrates.

“The warning signs are at least five times more widespread. That’s the general pattern”said Wiens.

Colored warning signs may be so widespread because the colorful animal does not need to have color vision to warn other animals of danger. In fact, species with warning signs in the form of color do not even need well-developed eyes.

But when it comes to sexual signals in the form of color, males and females need to have advanced vision to send signals to each other using color cues. For this reason, sexual signals are manifested only in two groups of animals that have eyes: vertebrates, which include fish, amphibians, mammals, birds and reptiles, and arthropods, such as insects and spiders.

“In the future, it would be even more interesting to study what drives animals’ ability to see specific colors like red or blue,” Emberts said.