Flatfish got weird fast due to evolutionary cascade – EurekAlert


IMAGE: Rice University bioscientist Kory Evans with a 3D printed skull of a jack, a close symmetrical relative of flatfish. Evans and colleagues found flatfish rapidly evolved their asymmetric shape thanks… view more 

Credit: Jeff Fitlow/Rice University

HOUSTON – (May 3, 2021) – Ever look at a flatfish like a flounder or sole, with two eyes on one side of its head, and think, “How did that happen?”

You’re in luck. Rice University biologist Kory Evans has the answer.

“Flatfishes are some of the weirdest vertebrates on the planet, and they got weird very, very fast by changing multiple traits at once over a short period of time,” said Evans, an assistant professor of biosciences at Rice who specializes in studying the evolution of fish over long time scales.

Of all mammals, reptiles, birds, amphibians and fish, flatfish are easily the most asymmetric. Evans, the corresponding author of a study on flatfish evolution in the Proceedings of the National Academy of Sciences, said it helps to keep that in perspective.

“Imagine any other animal,” he said. “Like, say you’re out walking and you see a squirrel, and one eye is here and the other is there,” he said, pointing to two places on the same side of his face. “That squirrel