"Bottom-feeding fish in the Hudson River have developed a gene that renders them immune to the toxic effects of PCBs, researchers say.

A genetic variant allows the fish to live in waters notoriously polluted by the now-banned industrial chemicals, and distinguishes the fish—Atlantic tomcod (Microgadus tomcod)—as one of the world’s fastest evolving populations.

"This is very, very ra­­­­­­­­­­­­pid evolutionary change," said Isaac Wirgin, an environmental toxicologist at New York University’s School of Medicine, and the study's lead investigator. "Normally you think of evolution occurring in thousands to millions of years. You’re talking about all this occurring in 20 to 50 generations maybe.”

The study appears in the Feb. 18 online issue of Science."

Anne Minard reports for National Geographic News February 17, 2011. [2]