Back in April, I wrote in National Geographic about the provocative idea of bringing extinct species back to life. In the five months that have passed since then, I haven’t spotted any mammoths or saber-tooth lions drifting through my front yard. If “de-extinction” ever does become real, it won’t for quite a while.
What I have seen over the past five months is a new conversation. Part of the conversation has revolved around the specifics of de-extinction. Some people are open to the possibilities of rebuilding genomes and embryos of vanished species. Some people find it a flashy distraction from the real work of fighting the current wave of extinctions.
But the conversation is bigger than mammoths and saber-tooth lions. It makes us think about how much we could–or should–manipulate DNA of wild animals and plants. This question applies not just to extinct species that are gone, but to endangered species that are rolling down the road towards extinction. And with estimates that at least 15 to 40% of species will be effectively extinct by 2050, that road is wide indeed. Is it okay to use genetic engineering to save some of them?
In Nature today, a group of conservation biologists take this conversation much further. They report on a meeting they had this spring in New Mexico to discuss how the changing climate will push some species towards extinction and what can be done about it.
For a few years now, some conservation biologists have argued that we should move species to places where they’re more likely to survive. If Florida is too hot in 50 years for a tree to survive, move the tree to Virginia.
But what if we were to move genes instead? That’s the question that the scientists at the New Mexico meeting considered.
Their conversation was based on the fact that animals and plants have evolved genes that adapt them to their environments. As trees move into drought-stricken plains, natural selection may favor genes that help them conserve their water. When pathogens emerge, natural selection may favor genes that make hosts resistant. If Florida is going to become more like, say, Brazil, then maybe genes from Brazil will help species survive in Florida. (As for what genes we might give the species in Brazil…well, that’s hard to say.)
Farmers and livestock breeders have harnessed genetic variation for centuries. They’ve crossed different breeds to create a combination of traits they desire. Conservationists have sometimes used hybridization as well, to nurture endangered species.
In Florida, for example, the dwindling panther population became inbred, and they had less success producing cubs. Conservationists trucked in eight panthers from a related subspecies in Texas. It’s been a dozen years since this cross-breeding took place, and their genetic pool now has more variation.
Hybridization can be very effective, but it’s also slow and inefficient. It jumbles together lots of DNA in lots of different ways; breeders then pick out the crosses that seem to perform best. In recent decades, genetic engineering has made it possible to move individual genes from one subspecies to another, or even one species to another. It might be possible to move genes into wild species to help them thrive. The scientists from the New Mexico meeting point to gene variants in rainbow trout, discovered earlier this year, that help the fish survive in warm water. Those variant could be inserted into other trout that are going to be threatened by rising river temperatures.
The scientists call wildlife genetic engineering “facilitated adaptation.” While they’re ready to give it a name, they don’t want to launch into it without a lot of consideration, however. They want to make sure facilitated adaptation doesn’t cause harm to species that are already on the brink of extinction. Genes often carry out more than one function, and so even if an imported gene has one beneficial effect, it might have others that are dangerous.
The scientists also worry that facilitated adaptation might sap the energy for fighting the causes of today’s extinction crisis. If scientists tell us we can just engineer penguins to live in warm temperatures, then who needs to do anything about climate change?
Even if we stopped warming the planet tomorrow, though, endangered species would still face other threats, some of which genetic engineering might help. We humans move pathogens around the planet, bringing new diseases to new places. A fungus from Europe has killed millions of bats in the United States and show no sign of slowing down. If scientists can determine why bats in Europe don’t die of the fungus, they might be able to insert their gene variant into American bats and make them resistant.
And if this seems like wishful thinking, consider the case of the American chestnut. As I wrote on the Loom, another fungus has nearly annihilated the tree. Fungus-fighting genes from other plants are now bringing it back.
I’ll be very curious to see how this new stage of the conversation plays out in weeks to come. (Feel free to leave your thoughts on the comments below.) But I also hope it doesn’t veer over ideological guard rails.
Opponents may argue that the very act of moving genes from one organism to another is a violation of nature’s diversity. But this is a romantic, pre-genomic view of life. Genes have flowed from species to species for billions of years.
Some supporters of genetic engineering may consider this an easy fix for our extinction crisis. But for many species, genetic engineering won’t help, I expect. You can’t tweak an elephant’s gene to make it bullet-proof. And even for those species that could be helped, scientists know precious little about the genes that could help them. Scientists have started to gather together what little they know about life’s genetic diversity, but they have only started. And unfortunately, for a lot of species, they’re running out of time.