A Tortoise May Be Bred Back Into Being ˆ Giant Tortoises of Galapagos

By Henry Fountain, 9/22/08, New York Times,

Efforts to restore populations of the giant tortoises of the Galápagos Islands have been among the world‚s most visible and successful conservation programs. But the work came too late for several of the 15 generally recognized Galápagos species.

Or did it? Extensive DNA research on museum specimens and existing tortoise populations suggests there is the potential to restore Geochelone elephantopus, which lived on the island of Floreana.Charles Darwin witnessed the capture of large numbers of these tortoises for their meat, shells and fat, and the species is considered to have become extinct in the mid-1800s.

Gisella Caccone, an evolutionary biologist at Yale, and colleagues analyzed mitochondrial DNA from 25 Floreana specimens from the American Museum of Natural Historyand the Museum of Comparative Zoology at Harvard. They compared the findings to DNA data on other species including G. becki, which is found in large numbers on the slopes of Volcan Wolf on the island of Isabela.

The comparison, described in The Proceedings of the National Academy of Sciences, showed that a handful of the Isabela tortoises were closely related to the Floreana species. „We realized those individuals carry genes of populations that are now extinct," Dr. Caccone said.

It may now be possible to develop a breeding program to re-establish G. elephantopus, the researchers said. By mating Isabela tortoises that are most genetically similar to G. elephantopus, selecting the offspring that are most similar and mating those, through successive generations the species‚ genetic makeup may be largely restored. „The beauty of the story is that Volcan Wolf has a huge population size," Dr. Caccone said. „So there is a good chance of finding a lot of individuals with interesting mixed genetic characteristics."

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