A Fish Adapting Quickly to Lethal Levels of Pollution

Evolution is working hard to rescue some urban fish from a lethal, human-altered environment, according to a new study published Dec. 9 in the journal Science. Researchers from the University of California, Davis and the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science conducted the study.

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.

What makes Atlantic killifish so special is their 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. 

“The whole genome sequencing of the Atlantic killfish revealed innovative insights into how animals quickly evolve and may adapt to climate change because of its biology and ecology.  Two co-authors from UM Rosenstiel School, Douglas Crawford and Marjorie Oleksiak, initiated genomic research in the Atlantic killfish by isolating more than 69,000 genes sequences and discovered large genetic variation.  “Killfish have large populations that make natural selection more effective and live in a diversity of environments which enhances the genetic diversity,” said Douglas Crawford. “This genetic diversity is the basis for evolutionary adaptation that was revealed by taking the ambitious goal to sequencing the whole genome of 394 individuals.”  

“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 and lead author of the study. “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.”

Continue reading at the University of Miami.

photo: M. F. Oleksiak, UM Rosenstiel School of Marine and Atmospheric Science