Comparative analysis

The Dodo is dead. The passenger pigeon has passed on. But Lonesome George, the iconic Galapagos tortoise whose death marked the end of his species, is in post-mortem luck. A scientific expedition has discovered some of his close blood relations alive and well. With careful breeding, biologists now hope to revive George's species. Originally there were at least eight species of Galapagos tortoise, scientists now believe. At least three species are now extinct, including tortoises on Pinta Island. The last one, George, was discovered wandering alone in 1972 and taken into loving custody. His death, in 2012 at more than 100 years old, was a powerful reminder of the havoc unleashed by humans on delicate ecosystems worldwide over the last two centuries. But, now the story of extinct Galapagos tortoise has taken a hopeful twist. More than a century ago, it turns out, sailors dumped saddlebacked tortoises they did not need into Banks Bay, near Wolf Volcano on Isabela Island. Luckily, tortoises can extend their necks above water and float on their backs. Many of them made it to shore, lumbered across the lava fields and interbred with Isabela's native domed tortoises. In 2008, scientists tagged and collected blood samples from more than 1,600 tortoises living on the flanks of the volcano. Back in the laboratory, there was a genetic eureka: Eighty-nine of the animals were part Floreana - whose full genetic Profile DNA had been obtained from museum samples. Some had genes indicating their parents were living purebred Floreana tortoises, hinting that the species may not be extinct. Seventeen tortoises were shown to have high levels of Pinta DNA. Tortoises can live for more than 150 years, so some of them may well be George's immediate next of kin. Last month, scientists went back to find them. Their plan was to capture and separate tortoises with high levels of Pinta and Floreana DNA, and then breed animals that are genetically closest to the original species. In a few generations, it should be possible to obtain tortoises with 95 percent of their "lost" ancestral genes, the scientists said.