As they evolved over millions of years to be better suited for life underwater, mammals such as whales, dolphins, and manatees lost the genetic code for enzymes that protect their land-dwelling counterparts from certain harmful chemicals. As oceans become increasingly polluted by pesticides, this loss may come back to haunt them, a study published this week in Science says. Through DNA analysis, researchers found that nearly all marine mammals have nonfunctional copies of a gene called PON1, which encodes an enzyme called paraoxonase that can quickly break down chemicals found in a number of common fertilizers, The New York Times reports. The study raises concerns that the increased presence of pesticides in marine ecosystems may have disastrous consequences for a number of aquatic species.
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