Against the Tide: A Fish Adapts Quickly to Lethal Levels of Pollution

volution is working hard to rescue some urban fish from a lethal, human-altered environment, according to a study led by the University of California, Davis, and published Dec. 30 in the journal Science.
While environmental change is outpacing the rate of evolution for many other species, Atlantic killifish living in four polluted East Coast estuaries turn out to be remarkably resilient. These fish have adapted to levels of highly toxic industrial pollutants that would normally kill them.
The killifish is up to 8,000 times more resistant to this level of pollution than other fish, the study found. While the fish is not commercially valuable, it is an important food for other species and an environmental indicator.

Genetic diversity speeds evolution
What makes Atlantic killifish so special? Extremely high levels of genetic variation, higher than any other vertebrate — humans included — measured so far. The more genetic diversity, the faster evolution can act. That’s one reason why insects and weeds can quickly adapt and evolve to resist pesticides, and why pathogens can evolve quickly to resist drugs created to destroy them.
Not all species are so lucky, however.
“Some people will see this as a positive and think, ‘Hey, species can evolve in response to what we’re doing to the environment!’” said lead author Andrew Whitehead, associate professor in the UC Davis Department of Environmental Toxicology. “Unfortunately, most species we care about preserving probably can’t adapt to these rapid changes because they don’t have the high levels of genetic variation that allow them to evolve quickly.”