(Not Quite So) Lonesome George

I kind of doubt that Lonesome George, the giant Galápagos tortoise who geneticists believe is the last survivor of his species will view this as good news for his social life, but conservationists are ecstatic. No, they have not found another member of the species Geochelone abingdoni, but they've managed the next best thing, genetically speaking: discovering a tortoise that is the offspring of one parent from the Galápagos island of Isabela and one parent from the island of Pinta, which is where George hails from. That means the new tortoise, a male, has half his genes in common with Lonesome George.

George was found on Pinta, an isolated northern island of the Galápagos, in 1972 and taken to the Charles Darwin Research Station on the island of Santa Cruz. There, he lives with two female tortoises from a species found on Isabela, but for 35 years Lonesome George has shown approximately zero interest in "passing on his unique genes," as Michael Russello of the University of British Columbia put it. Even if he had taken a mate, the resulting offspring would have only half of his characteristic genes, the other half being those of the Isabela species.

Using newly-available genetic techniques, however, scientists led by a team at Yale University are announcing today that they have identified a better match, DNA-wise, should George ever get in the mood. As they describe the experiment in the journal Current Biology, the scientists analyzed DNA from George and from six museum specimens of Geochelone abingdoni and compared it to the DNA from all 11 existing species of Galápagos tortoises. In particular, they zeroed in on DNA of the Isabela species, called G. becki, of which there are some 2,000 individuals. (The scientists took DNA from 89.) They hit the genetic jackpot: one of the Isabela tortoises is a first-generation hybrid between a pure Isabela tortoise and a Pinta tortoise like George, sharing half his genes with Lonesome George.

The fact that the hybrid is a he sort of limits the possibilities for mating. But the scientists hope that among the unsampled 1,900-plus tortoises on Isabela they will discover another first-generation hybrid, but a female, or even a genetically pure Pinta like George. If so, then offspring of George and a hybrid would produce a 75-percent-pure Pinta, while offspring of George and a pure Pinta would of course produce another pure Pinta. As to whether Lonesome George finds it comforting to know that there are more of his kind of genes circulating among the tortoises of the Galápagos than scientists have suspected, he was unavailable for comment.