2/18/11
Talk about a quick learner: in just 50 years, a fish has evolved a resistance to toxic chemicals polluting its Hudson River home, a new study finds.
Between 1947 and 1976, roughly 1.3 million pounds of polychlorinated biphenyls, or PCBs, were dumped in the Hudson by two General Electric facilities. The Atlantic tomcod, a small bottom-feeding fish, quickly accumulated high levels of the toxic compounds, which caused lethal heart defects in juveniles of the species.
Then, natural selection took over. In a matter of decades, a rare genetic mutation that allowed a small number of tomcod to tolerate PCB contamination spread through the broader population, allowing the species to thrive, scientists concluded after a four-year study.
“We think of evolution as something that happens over thousands of generations,” Isaac Wirgin, a population geneticist at New York University and the study’s lead author, said in a statement. “But here it happened remarkably quickly.”
Documented instances of rapid evolution in response to environmental contamination are quite rare, Dr. Wiggin said.
The tomcod had long been known for its remarkable tolerance to PCB pollution, but the biological mechanism responsible for its survival was unclear until now. Researchers found that a mutation to just one gene effectively blunted the chemical’s toxic effects, and that fish with the mutation survived and reproduced while those without it died off.
The study appears in the journal Science this week.
