A species of giant tortoise, previously thought to be extinct, may be still alive and hiding around Volcano Wolf on Isabela Island according to a report published in "Current Biology" by a group of researchers led by a team from Yale.
To be clear, they did not find any living specimens of the species Chelonoidis elephantopus, thought to be native only to the island of Floreana. The researchers did, however, find hybrid giant tortoises whose genetic make-up reveals that they are first generation descendents of pure-bred C. elephantopus parents. The individuals identified were as young as 15 years old, making it likely that the parents may still be alive on Isabela Island. The genetic analysis revealed that some of the hybrids had C. elephantopus mothers, while others had a father of the species.
The variations among animal species of the Galapagos Islands inspired Charles Darwin's pursuit of the theory of natural selection as a dominant force in evolution. He found that animals on the different islands had developed different characteristics from one another over time to the point of making them unique species. This was particularly evident in the shape of the carapace or shell of the various species of Galapagos giant tortoises.
Because giant tortoises were so slow moving, plentiful, and were able to survive in the hold of a ship for months without food, they were often used as a plentiful supply of meat for whaling ships stopping in the Galapagos Islands. The research team believes that it is quite likely that the ancestors of the surviving Floreana tortoises were moved between the islands by these ships.
Genetic material from Floreana tortoises was previously identified on Isabela Island by a Yale team in 2008, leading to the possibility that an extended breeding program might restore the species by breeding out the non-Floreana genes from hybrids. The new data, however, provides evidence that such a multi-generational effort may not be necessary to preserve the species if living specimens can be found around Volcano Wolf.
Another species of Galapagos tortoises, Geochalone abingdoni, represented by the lone surviving individual named Lonesome George, is thought to be the rarest species on Earth. Similarly, though, a hybrid of G. abindoni parentage was found on Isabela Island in 2007, again by Yale researchers, opening the possibility of finding more hybrids with which to breed the species back into existence.