[The following is an exact transcript of this podcast.]

They say that beauty is in the eye of the beholder. It turns out that maybe speciation is, too. Because a study in the October 2nd issue of Nature suggests that how fishes see one another can drive the formation of new species.

Scientists in the U.S. and Switzerland were studying the cichlids that live in African lakes. These fishes have evolved into a stunning variety of species—more than 500 of which live in Lake Victoria alone. The species differ in their behavior and coloration. For example, in some parts of the lake, blue-colored species tend to live in the shallows, and red ones near the bottom. That makes sense, because the deeper you go, the harder it is to see blue.

What the scientists found is that the blue fish that live in the shallow waters also tend to have visual pigments that are fine-tuned to see the color blue. And the red fish that live deeper can better see red. So, red females are more likely to mate with red males. And pretty soon you’ve got two species in which a female of one color won’t even look at a male of another color. Because she can’t see him. It’s probably little consolation when she says “It’s not you, it’s me.”

—Karen Hopkin 

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