The Evolution of the Atlantic Tomcod

No one ever said New York's Hudson River was clean. But instead of killing off the Atlantic tomcod that live in the river, the contaminants have forced the fish to evolve to adapt to their environment. A team of researchers recently published a study in Science that shows the Hudson River fish have a gene variant in AHR2, a six-base deletion that is absent in other tomcod populations. This suggests that AHR2 is the tomcod's "basis of resistance" to PCBs. Because only the Hudson River population has the deletion, the researchers suggest it was the contaminants in the river that forced this quick evolutionary change so the fish could protect themselves from their environment.