Animals Evolved Color Vision before Bright Colors Emerged

Animals Evolved Color Vision Before Bright Colors Appeared

Who Sarah Novak

The bold colors of red, orange, yellow, blue and purple help plants and animals communicate with their species and others in their quest for survival. Bright orange dart frogs warn predators of their toxicity. Different birds use the iridescence of their plumage to attract mates. The rainbow colored flowers attract birds and bees to disperse the pollen and seeds.

The coloration of living things has evolved slowly: colorful fruit-like seeds dotted the gentle landscape about 300 million years ago, vibrant flowering plants appeared 100 million years later, and animals—namely cockroaches and butterflies—began to have bolder pigmentation 70 million years later. . But now, in a surprising twist, new research shows that animals’ ability to perceive many colors came long before they saw the colors themselves.

last exam in the year Biological Reviews he found that color vision It was formed 500 million years ago against a stark background of muted shades of browns and grays and other colors. And it wasn’t until about 400 million years later that bright colors became widespread in vertebrates and arthropods (a group of invertebrates with an exoskeleton, such as insects and spiders). “There was this long lag between the color explosion and the origins of color vision,” he says John J. Wiensco-author of the study and professor of ecology and evolutionary biology at the University of Arizona.

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Researchers previously identified the origins of various colorations using a diagram called a phylogenetic tree, which maps the genetic relationships between organisms. This, along with fossils containing preserved pigments, allowed evolutionary biologists to trace bright colors back to the earliest types of organisms that carried the trait. Wiens and his co-author Zachary Emberts, an integrative biologist at Oklahoma State University, took this work a step further by analyzing genes that code for protein receptors in animals’ visual systems to determine when a species can perceive color. Analyzing the timeline of color vision and prominent coloration, the study showed that hundreds of millions of years passed between the development of the former and the latter.

An evolutionary trait almost always happens for a reason; This raises the question of why animals would acquire the ability to see distinctions in vivid color long before they need it. According to the new study, color vision played an important role in early species’ ability to see whether a plant had vibrant green or dead brown leaves, or to spot a predator from behind. Color vision was also particularly important underwater, where vertebrate species first evolved to distinguish the hues produced when light filtered through liquid. “In the marine environment, there’s a lot of movement where light moves, so color vision would be especially helpful for underwater navigation,” says Wiens.

The scope of the research is impressive, but it doesn’t tell the whole story of color vision, he says Innes C. CuthillProfessor of Behavioral Ecology at the University of Bristol, England, who was not involved in the research but provided comments on the manuscript. This research focused on trichromatic color vision—the type of visual color perception that humans have; it did not see ultraviolet (UV) vision, which most insects have. Bees, for example, use UV light to distinguish between different flowers. “The colors we see are not what most animals care about,” says Cuthill.

Wiens admits that many aspects of color vision are still a mystery. “There’s a really long fuse before this burst of color happens,” he says, “and we don’t really know why.”