Reviving a long-dead Galapagos tortoise will take Jurassic Park-esque tactics—but have humans already intervened too much?
Today’s Galapagos tortoises mostly feature dome-shaped shells, like the one shown here. But researchers have found some that have the saddleback-shaped shells and longer necks that once characterized extinct Floreana and Pinta tortoises. (Sunshine Pics / Alamy)
This real life sci-fi plot all began when Gisella Caccone, senior research scientist at Yale University, took her first exploratory trip to the Galapagos Islands over 20 years ago to gather tortoise blood samples for genetic analysis. On one island, her team noticed a group of tortoises with saddleback-shaped shells rather than the prevalent dome-shaped shells, a morphological distinction reminiscent of the extinct Floreana and Pinta tortoises.
When they looked at the genomes of the tortoises on Wolf Island, over 200 miles away from Floreana Island, they noticed genetic divergences that did not match any known tortoise species. “I called them aliens because I thought they were from Mars or something,” she laughs.
Intrigued, her team headed to the museums, where bone samples from the rich history of humans mingling with Galapagos tortoises yielded DNA samples—the team’s very own mosquitos in amber. Using bone samples of tortoises at different museums including the Smithsonian’s National Museum of Natural History, Caccone and her team built genetic profiles for several extinct species.
In comparing them to the “alien” animals, the scientists noticed components of new genome that were closely related to two extinct species: Floreana and Pinta.
In the film, Jurassic Park was built on an island because isolation is key to developing new species and keeping them distinct. Similarly, the Galapagos naturally lends itself to speciation (hence, Darwin’s famous finches). The islands’ closed ecosystems allow species that arrive on this volcanic archipelago some 800 miles away from mainland Ecuador to interbreed and adapt to the specific islands’ geography until they no longer resemble their mainland relatives—or even their neighboring relatives on other islands.
That all changed, however, when humans arrived.
Logbooks from some of the Galapagos’ earliest visitors, in the late 17th century, reveal that mariners brought tortoises onto their boats for food, but would drop them onto other islands if their cargo was full of whale meat or other economically viable resources. The haphazard movement of tortoises from island to island allowed the species to intermingle and create hybrid populations like the ones found of Wolf Island.
The human impact on the fragile, isolated Galapagos was profound. Besides killing and cooking critters, mariners and buccaneers also brought rats and other pests with them to the islands that decimated the local populations. The last pure Floreana tortoise died out some time not long after Darwin visited in 1835—leaving him just enough time to enjoy some delicious tortoise soup.
But the same human carelessness that destroyed the Floreana tortoise now gives modern scientists the opportunity to bring it back: The transfer of tortoises from island to island ensured that their genes were distributed enough for today’s scientists to find them.
After identifying the genes from the extinct tortoises in the Wolf Island population, Caccone and her team returned to gather more DNA samples. They focused on Banks Bay Harbor on Wolf Volcano, a perfect spot for mariners to drop off wayward tortoises. They gathered 1,600 blood samples from tortoises by flipping the giant reptiles, drawing blood from a vein in their leg, equipping them with a microchip for tracking and sending them on their merry way.
Though the tortoises strongly exhibited Floreana genes, it seemed Pinta genes had all but disappeared (at least, based on the specimens Caccone and her team collected when they returned in 2008). When the results were published in 2013, locals and tortoise-loving scientists alike couldn’t help but be a little disappointed; the last Pinta tortoise, the beloved Lonesome George, died in 2012.
But Caccone is optimistic. Her earlier studies show that the Pinta genes are out there—her team just has to focus their efforts.
The next step in reviving the Floreana tortoise is a simple captive breeding program, which is being run by the Galapagos Conservancy and the National Park. The scientists play matchmaker with male and female tortoises to bring the Floreana gene expression to the forefront. Though breeding programs have been successful in the past—15 Española tortoises once brought their species back from the brink of extinction—such selective breeding has not been done before with tortoises in the Galapagos.
The conservationists in the Galapagos have something that those in Jurassic Park did not: purpose, and one grander than human entertainment. The Floreana tortoise is crucial for helping to restore the island ecosystem, explains Linda Cayot, science advisor at the Galapagos Conservancy explains. Cayot calls them the island’s “ecological engineers”; as they amble around, they plow trails, graze and deposit plants in their path.
“Tortoises are the dominant herbivore in the Galapagos,” she says. “They are incredibly important to maintaining the island ecosystems.”
Floreana is one of the islands that the National Park hopes to restore to its natural diversity—or at least get close. In an ideal world, the tortoises would be bred in captivity until the Floreana genes were brought to prominence, but tortoises mature slowly and the habitat restoration cannot wait. “I will not be alive to see a ‘pure’ Floreana tortoise,” Caccone says. It’s likely that no one will.
The first generation of Floreana tortoises will be raised in captivity on Santa Cruz Island for five years (any less, and the tortoises are small enough to be easy snacks for other Galapagos species). Once they are released, evolution will run its course and some genetic combinations that are favored for Floreana will reign supreme. The Galapagos will once again have a tortoise species tailored to the Floreana environment.
“It’s hugely exciting to even come close to something that we thought was extinct for 150 years,” Cayot says.
But another human-caused island disaster stands in the way first: pests. Floreana Island is overrun by invasive cats and rats, which carry diseases and dine on hatchlings tortoises and eggs. They have already wreaked havoc on unique endemic species like the Floreana mockingbird, whose population has been reduced to the hundreds on fringe islets near the island they once called home.
“The majority of extinctions occur on islands with animals with invasive species,” explains Paula Castaño, a restoration specialist at Island Conservation, an organization that aims to eliminate invasive pests from the Galapagos. Island Conservation successfully removed rodents from Pinzón Island to save their endemic giant tortoise, but this the first time such would be done on an island with human inhabitants.
Though they only inhabit about 2 percent of the land on Floreana, the island’s 150 human residents have played an enormous role in helping rebuild the habitat to make it more suitable for the tortoise and other native species driven out by pests. It is in their best interest for the agriculture and ecotourism industries that serves as the economic lifeblood of the community.
“Our target is not just to provide healthy ecosystems for tortoises. We are looking to provide a balanced, healthy ecosystem for all the nature on Floreana and the community that is living there,” says Gloria Salvador, Island Conservation’s Floreana project facilitator. “People are living on Floreana, have been living there for many years and have a relationship with the environment.”
Which is good because, as Jurassic Park so neatly illustrated, in our world there must always be a balance between humans and nature. Humans never have total control; that’s the illusion.
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