Four of the fifteen historic tortoise species disappeared from the islands. The Floreana species "was believed to have been exterminated within 15 years of Darwin's historic visit," the study said.
But the exploitation had a silver lining, said lead author Adalgisa Caccone of Yale University.
Whaling ships would often take on so many whales and other sea creatures—including tortoises—that they would have to offload some of their catch on or near the islands. In this way, many of the tortoises ended up as transplants on new islands, where they found familiar habitats.
The practice, Caccone said, "allowed by chance the survival of these genes that otherwise would have been lost forever."
Turtle Mother Lode?
in 1994 Caccone and her colleagues saw tortoises from an area called Volcano Wolf, on Isabela Island. The animals were primarily dome-shaped, with a few saddlebacked varieties in the mix.
The researchers began meticulously combing Volcano Wolf specimens' genes for identifiers unique to the extinct Floreana species.
They found that the population on Floreana was in an evolutionary class by itself.
They also found genes in a few of the Volcano Wolf animals that were closer to that singular Floreana saddlebacked line than to the rest of the turtles on Isabela Island.
"Surprisingly, we found that these 'non-native' tortoises from Isabela are of recent Floreana ancestry and closely match the genetic data provided by the museum specimens," the study authors wrote.
Michel Milinkovitch is a tortoise expert at the University of Geneva in Switzerland who was not involved with the new study. He called it a nice demonstration of the use of molecular markers to unravel historical information.
"Theoretically, it would be possible to regenerate a pure Floreana genome, but it would require many generations of controlled breeding and the use of many molecular markers to guide/assist this breeding," Milinkovitch wrote in an email.
"It would obviously be easier with mice than giant tortoises, unfortunately."
Caccone agrees that such a breeding program will be tough, but she says she's eager to try.
In December, she and other researchers will team up with Galápagos National Park rangers to canvass the Volcano Wolf population—thought to number between 1,000 and 8,000—for blood samples. They'll put unique transmitters on each individual, so they have a way to find and recapture the ones that reveal hidden Floreana genes.
Caccone said she's excited about the possibility of bringing back one of the world's missing animals.
"This is the first case in which we could bring back from extinction a species that is gone," she said.
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