Extinct or just hiding out? A long-lost species of the gigantic, slow-moving Galapagos tortoise that inspired Charles Darwin's theory of natural selection may still exist, according to the Yale University scientists behind what's been nicknamed "The Lazarus Project."
In the January 10 issue of Current Biology, researchers report evidence that the DNA of Chelonoidis elephantopus, supposedly extinct for 150 years, lives on in a few hybrid descendants. Using DNA snippets as clues, scientists found reason to believe that members of the believed-to-be extinct tortoise species may still be roaming Isabela Island of the Galapagos archipelago.
"To our knowledge, this is the first report of the rediscovery of a species by way of tracking the genetic footprints left in the genomes of its offspring," study co-author Ryan Garrick said in a written statement.
Biologists analyzed the genes of nearly 2,000 living giant tortoises and compared them to the genes of museum specimens of C. elephantopus. Data revealed that 84 of the living tortoises' genomes can only be explained if one of their parents were a member of the supposedly extinct species. In 30 cases, breeding had taken place in the last 15 years, and with a lifespan of over 100 years, researchers believe it is likely that the parents of these hybrid offspring are still alive.
"The only way these hybrids could be produced is if we had some pure[bred] animals still alive on the island...because some of these animals are hybrids, which are first-generation crosses," Yale evolutionary biologist and senior author Adalgisa Caccone told USA Today.
Even if purebred C. elephantopus individuals are never found, researchers believe intensive targeted breeding of the hybrids over four generations (roughly 100 years) may allow resuscitation of the long-lost species, hence the project name, "Lazarus." Genetic information from the hybrids could play a vital role in the giant tortoise's conservation efforts.
"Theoretically, we can rescue a species that has gone extinct," said Caccone according to the Yale News. "We won't be around to see it, but it can be done."
The Galapagos giant tortoises are aptly named, with some adults weighing over 880 pounds and measuring six feet in length. When Charles Darwin sailed the HMS Beagle to the Galapagos Islands in 1835, he noticed that each of the various Pacific islands that make up the Galapagos were home to its own distinct tortoise species. His theory of natural selection helped him make sense of the subtle differences between species: each species had evolved to adapt to its specific environment.
Shortly after Darwin left the Galapagos, C. elephantopus was believed to be killed off by whalers who hunted the tortoises for food.