The Galapagos Islands are famous for exotic birds, tortoises, and iguanas, but recently the archipelago hadbecome overrun with more prosaic animals: rats and mouse. Rodents that went on old sail ships. Rodents that stowed away on modern cruises. Wherever they came from, rodents that feed the eggs and chicks and hatchlings of the animals that so dazzled Charles Darwin.
The same tale plays out on islands all over the world. So Island Conservation, a nonprofit that ridsislands ofinvasive species, has come up with a daring plan: genetically engineer the rodents so that they all turn into males, shrinking the population one lonely pest at a time.
This plan is far from going into effect, but it gets a serious airing in a report out today from the National Academy of Science, a prestigious group that often makes recommendations on controversial areas of research. The make-all-rodents-boys notion is one of 7 instance analyzes for the use of gene drives–engineered pieces of DNA that spread more quickly through a wild population than any normal gene would. You might say gene drives are a way to cheat evolution. Gene drives could also be dangerous and unpredictable; once a manmadeDNA sequence get into a wild population, its hard to get back out again. The National Academys report lays out the guiding principles of scientists to responsibly analyzed this method of genetically altering wild plants and animals.
Environmentalists have long decried genetically modified organisms, but will they espouse them for conservation?
Gene drives have gotten a lot of attention as a route to prevent mosquitoes from spreading illnes: Scientists have engineered mosquitoes with gene drives that kill the parasite behind malaria, and theyre working on gene drives that either eradicate the mosquitoes that spread dengue, chikungunya, and Zika or build them resistant to the viruses. The recent rise of Crispr gene-editing technology has induced it easier than ever for scientists to construct gene drives.
Butusing gene drives not to benefit humen but to restore natural habitats–like tropical islands beset with invasive rats–forces you to answer a very basic question: What is natural? What does it mean to technologist animals to restore nature? Environmentalists have long decried genetically modified organisms, but will they espouse them for conservation?
A New Natural
Kent Redford, former director of the Wildlife Conservation Society Institute, has questioned the working definition of natural, and in 2013 he wrote about the absence of dialogue between synthetic biologists and conservationists. The reaction among conservationists he says, was a range of rage and disgust to enthusiasm and excitement. Since then Redford, along with Ryan Phelan, executive director of Revive and Restore–an organization that promotes synthetic biology for the genetic rescue of imperiled and extinct species–have held sessions to get the two groups talking about specific problems, like invasive rodents on islands.
No matter how you feel about genetic modification, the current approach to killing island invasives might build you understand the exuberance for gene drives. It is not pretty. Recently, on the British island of South Georgia, pilots spread 200 tons of bait one helicopter loading at a time, blanketing the island in a rat poison called brodifacoum. Brodifacoum keepsblood from clotting, so the rodents succumb of internal bleeding–as canbirds and other mammals at high enough doses. But gene drives? We could do it in the most humane route possible by having them just turn to an all-male population and live out their natural lives, says Heath Packard, communications director for Island Conservation.
Islands are also well suited for gene drive answers because the ocean is a natural barrier against their spread. And invasive rodents are a critical problem: As Darwin discovered, islands are hotbeds of biodiversity, and 40 percentage of the critically endangered species in the world live on islands. Plus rats and mouse are an easy genetic target because scientists have long tinkered with their genetics in the lab. The downside, of course, are unintended repercussions. Ecology is complicated, and nobody has put a gene out in the wild before.
Island Conservations scientists were investigating gene drives as a possible game-changing eradication technology even before Crispr became hot. Their research partners at Texas A& M University and North Carolina State University are studying a naturally-occurring gene drive in mouse that doesnt even require Crispr technology. Island Conservation has also partnered with the US Department of Agriculture and Australias national Commonwealth Scientific and Industrial Research Organisation so when the time comes, it getsregulatory acceptance for field tests in the future. Thats all years away, says Packard, though the group is now planning to fundraise for the gene drive research.
The National Academy report considers other preservation scenarios for gene drives: killing off mosquitoes that spread avian malaria in Hawaii and controlling invasive knapweeds in US woods. But reading research reports, you get a sense that the scientists realize “they il be” out of their depth. Questions about how to define nature and how to understand the value attributed to nature create a number of difficult philosophical and social problems, says research reports. They are left here as open questions, and are part of a growing and heated debate among environmentalists about the values that underpin environmentalism. Consider this: Gene drives is a possibility unnatural, but how natural isdropping tons of rat poison out of the sky?
In any case, if scientists can construct such a gene drive, if conservationists can get permission to release mouse carrying them, and if everything runs as planned, then islands like theGalapagos stand to benefit. Ahuge rat poisoning campaign from 2007 to 2014 rid the Galapagos of most of its pests, but with so much barge traffic there, rodents couldmake their route to the islands again. Where Darwin first induced comments and observations that led him to understand the laws of evolution, scientists could usethe technology that will try to defraud the game.