Stickleback Genomes Reveal Path of Evolution : Nature News & Comment
Scientists have pinpointed mutations that may help a tiny armoured fish to evolve quickly between saltwater and freshwater forms.
Since the last ice age ended about 10,000 years ago, ocean-dwelling threespine sticklebacks have repeatedly colonized streams and lakes worldwide. In as few as ten generations — an evolutionary blink of an eye — marine sticklebacks can swap their armoured plates and defensive spines for a lighter, smoother freshwater form.
David Kingsley, an evolutionary biologist at Stanford University in California, and his colleagues have now identified the DNA differences that distinguish ocean and freshwater sticklebacks around the world. Even though the switch has occurred on multiple separate occasions, it seems to involve many of the same genetic changes each time.
To trace the key DNA differences, the researchers sequenced the entire genetic code of 21 sticklebacks from ocean and freshwater sources on three continents. The results are published in Nature today1.