When I think of evolution, I think of small changes over millions of years, but not so for the hardy tomcods of the once heavily polluted Hudson river. Deadly PCBs (polychlorinated biphenyls) were discharged to the river by General Electric Co between 1947 and 1976. This naturally had a deadly impact on the inhabitants, with the tomcod being hit quite hard, as they are filter feeders (PCB contaminants settle on the bottom river bed ). Their life span was reduced from an average 7 years to 2 years and many suffered from tumours.
However, they are fighting back and have evolved to be resistant to the toxin (unlike their counterparts in other ecosystems). Studies continue into their mutated, toxin resistant genes. Refer to this LiveScience.com link for the related article
Go, Tomcod, go !!
🙂