Shortly after Charles Darwin came to the Galapagos, humans brought a species of giant tortoise, unique to the Floreana Island, to extinction. Now, 170 years later, scientists believe they can bring the species back to life.
The Floreana tortoise is one of 15 known species of giant tortoises, four of which went extinct over the past several hundred years due to overhunting and human-introduced predators. The Pinta Island tortoise was the latest of these four species to vanish. It went extinct in 2012 when its last remaining member, Lonesome George, died.
Conservationists believe that hope is not lost, at least not for the Floreana tortoise. These tortoises, along with the Pinta Island tortoises, had saddle-shaped shells, which allowed them to raise their necks to reach higher vegetation. In 2008, researchers found a few of these distinct saddle-shelled tortoises living around a volcano on Isabel Island. The tortoises were probably brought there by early colonizers of the islands, who would eat the meat. Results from DNA testing suggested that some were the descendants of Floreana tortoises.
In 2015, the researchers returned in the hopes of finding more of these saddle-backed tortoises. On this trip, they found 32 tortoises with promising genetics and brought them to a breeding center in California. DNA testing further suggested that two of the tortoises appeared to be purebred Floreanas—although it is unclear if this means the species never actually went extinct, or if they just have more recent ancestry with a purebred.
“We have discovered a trove of extremely unusual tortoises that although extinct on their islands of Floreana and Pinta Island. . . actually still occur on this remote site,” said Dr. James Gibbs, a vertebrate conservationist at the State University of New York, who led the expedition.
In the latest installment of the effort to bring the Floreana tortoise back to existence, the researchers published new results in bioRxiv late last month announcing that they have begun a captive breeding program with 23 tortoises, with the hope of returning them to Floreana Island.
“Our discovery raises the possibility the extinct Floreana species could be revived,” explained Dr. Joshua Miller of Yale University in the paper, who led the latest research.
“In this case, tortoises with Floreana ancestry are living ‘genomic archives’ that retain the evolutionary legacy of the extinct species, removing the need for the cloning methods that have been proposed to bring back extinct species.”
The group is hopeful that the breeding program will generate thousands of offspring over the next few decades.
If they are successful, that will be good news not just for the tortoises, but for the islands as well, which have seen an overall decline of 90 percent in the tortoise population.
Said Miller: “When repatriated to Floreana Island, these tortoises can once again play their critical role as ecosystem engineers.”