After Sewage Spill Cleanup, Fish in Lake Washington Evolving in Reverse

While locals were dealing with the fallout from a sewage spill in Lake Washington in the 1960s, the little threespine stickleback fish was evolving. It seems that the cloudy murkiness from the sewage allowed the fish to move beyond its need for armor that protected it from hungry trout. Unfortunately, now that the lake has been cleaned up, the fish has been slowly devolving back to its former state.

From Seattle PI:

By dusting off samples of the fish dating to the 1950s, researchers at the Fred Hutchinson Cancer Research Center and University of Washington on Thursday documented the stickleback’s “reverse evolution” triggered by the cleanup.

“This idea of reverse evolution has only been documented in a few cases in the wild,” said Katie Peichel, an author of the paper in Current Biology and scientist in the Hutch’s Division of Human Biology.

Sticklebacks originally were found in marine waters where they grew bony armor and prickly spines to ward off predators. As they migrated into freshwater and over many years, the widespread fish lost much of its skeletal shields, or plating.

That’s how they looked in Lake Washington — at least until recently.

Scientists have documented the change and done genetic studies on the fish, confirming that the armor transformation was due to genetic changes and not an influx of plated fish from the Puget Sound. It’s a stunning example of how fast some species are able to evolve, but scientists note that we shouldn’t expect such a thing from all species as the world struggles to adjust to global warming:

Take the case of polar bears, which this week were added to the Endangered Species list. The population of bears is too small, habitat needs are too specific, reproduction is too slow, genetic variability is too limited and the melting of the polar sea ice too fast for them to adjust, scientists said.

“Whether or not (polar bears) can find some different way of utilizing the environment and adapting to the changes seems improbable,” Reznick said.

“Polar bears are doomed,” he said. “Sticklebacks may not be.”

Link + Photo Credit [Seattle PI]

Related Posts:

Pavlov’s Fish: Researchers Train Fish to Swim Into Nets For Harvest
Creationist Science Tours: Helping Build Tomorrow’s Crack Ass Backwards Fundamentalist Christians
Officials in California Filling Pools with Mosquito Fish
Old Subway Cars Now Luxury Condos for Fish
Watch Al Gore’s Awesomely Updated Slideshow from TED: The Urgency of Manbearpig