Molly Herring writes:

The natural world is awash with color, and many of these vibrant hues are meant to be seen. Apples blush red to coax animals to spread their seeds, lavender blooms are violet to lure in pollinating bees, and male peacocks trailed by flashy blue trains more successfully attract mates.

However, the world is colorful only for some of us. These vivid signals can be perceived by animals that can see in color; to organisms that have limited or no color vision, many of these bright colors don’t mean anything at all. This raises interesting evolutionary questions. Which came first: colorful signals or the color vision needed to see them? And when did these optical signals emerge and take off, painting the natural world in the kaleidoscopic spectrum we see today?

“Some birds are red, some snakes are red, and some plants have red fruits. In each of these cases, the red coloration serves as a signal,” said Zachary Emberts, an evolutionary biologist at Oklahoma State University. “This led us to wonder: What was the initial function of conspicuous coloration, like red, and color vision?”

Emberts and his former postdoctoral adviser John Wiens, an evolutionary ecologist at the University of Arizona, combed through research encompassing hundreds of millions of years of evolutionary history to offer a scientific answer to the chicken-and-egg question of color. The researchers used the fossil record and phylogenetic trees — timelines of species emergence that are based largely on modern traits — to infer when colorful signals may have first emerged in plants and animals. Then they tested their hypothesis that color vision and colorful signals evolved together. [Continue reading…]