But the biggest existential threat to the pupfish comes from its own DNA. Once upon a time, pupfish lived in a sprawling lake. Around 20,000 years ago, water levels dropped, the landscape turned to desert, and the pupfish ended up in disconnected ponds. Today, nine different species are scattered across the Southwest, and half of them are endangered. Devils Hole is the worst case; as of September 2012, there were 75 fish left. Thousands of years of adaptation have left the Devils Hole pupfish able to live only in one very particular environment: It needs 90-degree water, low oxygen, and a shallow submerged ledge on which to spawn. It’s hard enough being endangered; being endangered and picky is a deadly combination.
Endangered, picky, and unlucky? Even worse. Beginning in the 1970s, government scientists built three pools to contain backup populations of Devils Hole pupfish as a final hedge against extinction. At two of these refuges, pumps, valves, and other mechanical bits malfunctioned repeatedly, killing most of the fish. In one case, lightning struck a transformer. But at the third site, called Point of Rocks, something more interesting happened. Somehow a few pupfish of a different species managed to infiltrate the refuge and—to put it politely—their DNA quickly spread through the population. After about half a decade, every fish in the pool was descended from the invaders, who gave their offspring telltale genes and an extra set of fins. Wildlife officials moved all the hybrids to a hatchery, where, unlike captive Devils Hole pupfish, they couldn’t stop making babies. “There were floor-to-ceiling tanks of these hybrid fish,” says Andy Martin, an evolutionary biologist at the University of Colorado at Boulder who led the research into the hybrids’ DNA. “This was a population that had been sputtering away, and now it was going like mad.”
To Martin, the fact that an influx of new genes caused a population explosion suggested what was wrong: “genetic load,” a glut of defective DNA that accumulates in a small population. On the upside, that diagnosis suggests a cure—a way to save the species. Martin has a plan to bring the fish back from the brink. But to the kind of people who have battled extinctions in the past, his solution is heresy.
For half a century, conservationists have seen themselves as preservationists: Protect species X as it exists in place Y at time Z. Of course, nature has no such compunctions. Evolution is change. So the way to save the Devils Hole pupfish, Martin says, is to introduce genes from its cousin, the Ash Meadows Amargosa pupfish—C. nevadensis, the same little Casanova from the refuge—which is native to a spring just a few miles away. Martin wants to take one or two and drop them in with their endangered relatives. That simple act would have profound implications. It would protect the Devils Hole pupfish by rewriting its genome.
Whether or not you care about pupfish, this plan represents a major philosophical change in how we think about our relationship with nature—because it doesn’t end with the pupfish. It ends with us becoming architects, engineers, and contractors for entire ecosystems. The old approach involved fencing off swaths of wilderness and stepping aside. In the new order, we’d be the stewards not just of land or wildlife but of individual chromosomes. So far, in the world of Devils Hole pupfish conservation, Martin has run into a wall of no. But around the world, in other places where other species are in trouble, the answer, increasingly, is yes.
by Hillary Rosner, Wired | Read more:
Photo: Jesse Chehak
