Researchers at the Stanford School of Medicine and the Broad Institute have discovered the entire genome sequence of 21 threespine stickleback fish.

“To the uninitiated, the tiny threespine stickleback might look like nothing more than a scruffy anchovy with an attitude,” wrote Krista Conger Ph.D. ‘99 on Scope, a Stanford School of Medicine blog. “But this tough little fish, with its characteristic finny mohawk, is a darling of evolutionary biologists.”

The researchers, led by developmental biologist David Kingsley, noted that the stickleback demonstrates some of the most dramatic and adaptive changes of any animal.

“Many genes work in multiple places in the body,” Kingsley said. “If you change their protein product, you simultaneously disrupt everything that gene does. In contrast, if you alter the regulatory switches that control where and when a gene is expressed, it may become possible to confine a change to one part of the body, or one developmental stage, for example, and avoid possible lethal consequences.”

The team discovered that the fish adapts to different environments by changing the same regions of its genome.

In fact, they found 147 regions that varied in marine-freshwater evolution. Most of these 147 regions were small, with less than 5,000 base pairs of DNA, so the research team was able to closely pinpoint which regulatory regions were most affected.

“Some sections of chromosomes are chock full of differences that are contributing to evolution,” said Kingsley. “It is quite dramatic to look at the entire genome and see these powerful chunks being used over and over again.”

The researchers’ findings will appear in Nature on April 5.

-Billy Gallagher