In a diverse group of fish called the stickleback, nature took advantage of the same genetic trick time and again to allow freshwater species to shed their burdensome body armor and transform into a lighter, spryer fish. This is among the first times scientists have shown that the same genetic change is responsible for an evolutionary adaptation in disparate populations.
"Almost every time the stickleback evolves in fresh water it loses the armor," said David Kingsley, PhD, professor of developmental biology and lead author of the study. "Although the trait evolved many times all over the world, nature uses the same gene each time."
Sticklebacks evolved from a relatively uniform marine population into today's broad spectrum of shapes and sizes when the last Ice Age ended roughly 10,000 years ago. Because ocean fish quickly evolved into such distinct populations when they colonized new freshwater lakes and streams, they are an ideal model for understanding how animals adapt to their unique environments.
The recent work carries a few surprises. Kingsley said that the gene in question, called Eda, is an old friend to laboratory researchers who have found that mutations in the same gene in mice cause altered hair patterns. However, in mice similar alterations can also be created by defects in any one of three different genes. "Based on the mouse work you'd predict we would find mutations in any of the three genes in sticklebacks," said Kingsley, who is also a Howard Hughes Medical Institute investigator. "That's not what we see."
Instead, the gro
Contact: Amy Adams
Stanford University Medical Center