The Tasmanian devil is famous for two things. One, it's ornery as all hell. And two, it's the unfortunate carrier of a nasty transmissible form of cancer---one that causes deadly facial tumors. Since the scourge first appeared in 1996, the critter's population has crashed by 80 percent.
But a funny thing has happened to the Tasmanian devil---it’s survived, contrary to models predicting its total extinction. And today scientists have announced the discovery of genes that could be protecting the creatures from oblivion. It seems that in just four to six generations, some Tasmanian devils have evolved resistance to the cancer, carrying specific genes that may be related to immune function. Selectively breed those lucky devils, and you may have a way to guarantee the species survives.
Increasingly, genetic techniques are giving conservationists new strategies to protect endangered species smarter and faster. Traditional selective breeding---sticking two devils together that carry the newly discovered resistance genes, for example---is one way. But modern methods like gene drives could, in the future, help species recover even faster.
An organism has a 50 percent chance of inheriting a given gene from each of its parents. But using the Crispr gene-editing technique, scientists can pass on a gene 100 percent of the time, guaranteeing those genes spread rapidly through a population. For instance, researchers have engineered mosquitoes so they only give birth to males. Theoretically, releasing the things could crash a wild population, keeping mosquito-borne diseases from infecting birds or other animals (including humans).
Or they could potentially use gene drives to protect threatened species directly. “There's been some very preliminary discussion of the possibility of altering black-footed ferrets to protect them from plague, or of similarly protecting bats soon to be threatened by white-nose fungus,” says MIT biologist Kevin Esvelt.
The problem is that engineered genes spread rapidly through populations. And you can't get rid of them once they've entered the gene pool. If you’re not careful, you can extinct the species you’re just trying to control. Traditional conservation---trapping or shooting invasive species, captive breeding, and the like---is already a highly calculated endeavor that increasingly relies on computer models to get right. Taking a gene drive developed in a lab and applying it in the real world could have unintended consequences.
Tack that uncertainty onto general fear about genetic modification and you can see why people would be slow to adopt gene drives for conservation. But while your average American may not give two hoots about the black-footed ferret, they sure do give a hoot about their own safety. “If there's a pressing human health concern or conservation concern for which no other options are available, we might be able to tolerate greater uncertainty in making that jump from the lab to field trials,” says biologist and social scientist Jennifer Kuzma of the North Carolina State University School of Public and International Affairs.
If conservationists do start engineering animals, they'll run into a bunch of non-scientific challenges, too. It isn’t yet clear what governing body will assume regulation of gene drives: At the moment, the FDA claims authority over genetically modified animals, considering them as animal drugs. “It is very likely that the FDA is going to claim regulatory authority over gene drive animals,” says ethicist Zahra Meghani of the University of Rhode Island. “But should it? That question is part of the larger question whether genetically engineered animals should even be classified as new animal drugs.”
The ethics here are tricky. The gene drive is potentially an immensely powerful tool for fixing humanity’s ecological blunders. So are conservationists bound to wield it? “That ethical duty is compounded if humans are responsible for a species becoming endangered or a species entering an ecosystem and harming species that are native to that environment,” says Meghani. On the other hand, if scientists don’t approach this technology cautiously, it could do more harm than good.
As for the Tasmanian devil, don’t hold out much hope for its salvation being the gene drive. “I certainly wouldn't support it, and I'm pretty sure the government wouldn't let anybody do it anyway,” says Andrew Storfer, an author of the study. “Maybe we'll be at the state in some number of years where that that becomes something people are doing to help protect endangered species.”
So the Tasmanian devil will have to wait this one out. But thanks to some lucky genetics, things seem to be looking up for the world's feistiest marsupial.
