Island Conservation brings CRISPR to its fight against invasive species
In 1994, two UC Santa Cruz professors, Dr. Bernie Tershey and Dr. Don Croll, founded Island Conservation, a global conservation NGO whose sole mission was to prevent extinctions by removing invasive species from islands. Over the past 25 years, the organization, headquartered on Santa Cruz’s Westside, has cleared 63 islands of invasive species, protecting 1,173 populations of threatened animals.
In advance of his appearance at SCW’s Get Bioscience event, we spoke with Island Conservation’s Heath Packard.
You are participating in next week’s Get Biotech event, which Santa Cruz Works is hosting. [Info at bottom.] Can you give us a little preview of what you will be talking about?
Okay—but first let me give you my elevator pitch. The reason we focus on islands is because they offer a very special and unique conservation opportunity. But also a conservation challenge.
Islands are the epicenter of the extinction crisis. Seventy-five percent of the world's known extinctions have happened on islands. And invasive species are implicated in most of those—non-native, introduced plants and animals that harm the local and native plants, animals and ecosystems. The really good news is that is that we can and have successfully eradicated invasive species from islands thousands of times.
What we're going to be talking about at Get Bio is our Genetic Biocontrol of Invasive Rodents program—that's GBIRd for short. (You can read about it at geneticbiocontrol.org.) We have developed a research program with seven partners from three countries—Australia, New Zealand, and the United States—research universities, NGOs and government agencies that are investigating the possibility of creating a self-limiting mouse.
We're looking at a mouse construct that would use a gene drive, which is a selfish gene that drives inheritance, that biases inheritance of a specific gene. Once we have the construct in place, we would use CRISPR/Cas9 as an editing tool. There's also a natural gene drive we're investigating within the mouse genome, and we're trying to hitch to it the male sex selection chromosome. So we could drop a box of the these mice onto an island, they would interbreed with the non-native population of invasive mice; it would drive maleness through multiple generations.
Ultimately after several generations you would get a population of mice that are only male. They would live out their merry days and die of natural attrition, and we would thereby affect an eradication through attrition.
To illustrate what it is that Island Conservation does, can you tell one recent story about one island?
I think one of the best stories we have is about Pinzon Island in the Galapagos. Many of the Galapagos Islands have their own unique species of giant tortoise. And these tortoises weigh thousands of pounds— they're too big to fit in the back of a pickup truck. The giant Pinzon tortoise was declared functionally extinct. What that means was that it can't reproduce in its natural habitat. And the reason for that was because the tortoise’s eggs and hatchlings were being eaten by rats.
So in 2012 we worked with Galapagos National Park and removed invasive rats. Fortunately, decades ago, the Park and others had the foresight of trying to protect this species with a captive breeding program where they would incubate the eggs in the safety of a laboratory, hatch the hatchlings, grow them to be big enough that they were rat-proof, paint numbers on their backs so that they could keep track of them and then put them back out in the wild.
These tortoises can live to be 110, 120, 130 years old. They're quite incredible individuals and they can go an awful long time without food and water too, which is quite interesting. But they had not been able to breed for a hundred years on their own island. And now today, because of the removal of rats and the restoration of the island, once again these cute little hatchlings are crawling out of these little dirt nests ,and they're able to do so without any direct predation.
Because it’s the focus of your work, let’s talk more about invasive species. What are the species, how did they get there, and how do you get rid of them?
The invasive species include plants and animals, but we focus primarily on invasive vertebrates because they have the greatest impact. So we're talking about mice, several species of rats, sometimes feral cats, oftentimes feral pigs, feral goats, donkeys, water buffalo, mules. Those are some of the leading examples.
Rats and mice have been brought to islands simply by virtue of human exploration and diaspora. They have stowed away on our ships for hundreds and hundreds of years, and jump ship when we've gotten to islands, sometimes through shipwrecks, but oftentimes through exploration. And they've overwhelmed those islands.
Goats have been intentionally introduced, and sometimes pigs as well, as a food source by early explorers, whalers, buccaneers on multi-year tours around the world's oceans. They'd drop a pair of breeding goats or a pair of breeding pigs on an island only to come back a year or two later to find all sorts of fresh meat that they can hunt and feed their crews. Quite a clever strategy for explorers, but it was at a time before we understood the implications for the native island species and the importance of the world's biodiversity.
And the last part of that question was how do you get rid of them?
Today we get rid of rodents, and this has been done more than 500 times, using a conservation bait that is laced with a rodenticide. And it's spread typically through aerial application by helicopters with a large bait bucket that's swung underneath it. We use GPS, GIS and track mapping to make sure that we get an appropriate amount of bait to every rat territory or every mouse territory to ensure appropriate dosage to remove those rodents.
Larger vertebrates are most often managed through a suite of project-specific methods that can include hunting, trapping, and toxicants.
In all of our endeavors, we go to extensive lengths to ensure the methods are applied in the most humane ways possible. In fact we’ve worked with animal welfare experts from academia and the SPCA to publish humane guidelines to govern the applications of these tools.
WRT rodenticides: Do you mitigate somehow, so if there are owls on the island, they don't all get killed off by eating poisoned rats?
Yes—we are conservationists, and first and foremost our job is to protect wildlife. We do not take pleasure in lethal control methods., and we are looking for alternatives. This is exactly one of the motivations behind GBIRd, because it would allow us to avoid using those toxicants.
We are also on record, both at the federal level and at the state level in California, supporting restrictions of these same toxicants for commercial sales and use, because there is a risk to native species here on the mainland when these are applied in haphazard ways by untrained consumers. We don't do an operation until we've studied the island, sometimes for many years, to minimize and mitigate the impacts.
When the risks can't be avoided, we've been known to collect native species including Galapagos hawks, native deer mice in the Channel Islands, and other species, and hold them in protective captivity to ensure that they don't get exposed to the toxicant.
How does the business end of your organization function? How are you funded, and what kind of dollars are we talking about?
We’re incorporated in California as a nonprofit conservation organization. All of our projects are funded by a mix of resources—some come from major philanthropic foundations; many come from major donors, high-net-worth individuals, family foundations. And we also get some government contracts and funding through developing nations and developed nations.
But all of our work, even in developed nations, needs to be subsidized ’cause there's never enough resources to go around for all the good work.
And we rely on a community like Santa Cruz to help provide friends, advocates, connections and of course supporters to help us get this work done. And our annual budget is hovers right around $6.5 million.
Get Biotech 2019, the Santa Cruz Works New Tech MeetUp, takes place Wednesday, Sept. 4 at the Dream Inn, with a meet-and-greet beginning at 6pm. Pioneering geneticists David Deamer and David Haussler will deliver keynotes at 7:10. For tickets, visit Get Biotech 2019.
To learn more about Island Conservation, or to donate, visit Island Conservation.
Don’t Miss the next Santa Cruz Works New Tech Meetup on Sept 4 - Get Biotech