“They (the fish) shed some of the heavy armor plates that protect against ocean predators but seem to hinder quick escapes in freshwater; they lost belly spines that proved a handicap with insects grabbing at the young fish from below. Sticklebacks that live on lake bottoms are almost always lighter in color than their marine counterparts, probably for camouflage.
Those patterns repeat around the world. Researchers say that means it’s not chance, but natural selection, behind the wheel.
“One of the beautiful things about the stickleback is that the process of colonizing new lakes and streams from the ocean has played out countless thousands of times,” said Stanford University developmental biologist David Kingsley, who has led much of the genetic work. “You’ve got all these natural experiments replicated over and over again.”
To replicate those experiments — but in a controlled way — Schluter built more than 30 ponds on the University of British Columbia’s Vancouver campus, each up to 75 feet square. He jokingly calls the complex his “evolution accelerator.””