Cichlid fish vision change helped species diverge

The researchers looked at two species, marked by their red or blue colors, found off five islands throughout the lake.

They determined through lab experiments that certain genetic mutations helped some fish adapt their vision at deeper levels to see the color red, and others in shallower water to recognize shades of blue.

That gave blue males a mating advantage in shallower water and red ones an edge in deeper parts of the lake because they were more attractive to female fish.

"In short, what you see determines what you get, and with whom you get it on," Mark Kirkpatrick of the University of Texas, Austin and Trevor Price of the University of Chicago, wrote in a Nature commentary.

(Reporting by Michael Kahn; editing by Tim Pearce)