November 24, 2012 | 12
The sad death of conservation icon Lonesome George this past June in the Galápagos Islands marked the long-dreaded extinction of the Pinta Island tortoise (Chelonoidis nigra abingdoni). Or did it?
A team of researchers from Yale University now says the Pinta Island tortoise subspecies may actually still exist—not on Pinta Island but on nearby Isabella Island. The team collected and analyzed DNA from more than 1,600 giant tortoises on the northern tip of the island and found that 17 tortoises carried some of the same genes as the extinct Pinta Island subspecies.
Several giant tortoise subspecies live on Isabella Island. The region the Yale researchers worked in is home to the Volcán Wolf tortoise (C. n. becki), a subspecies named after a nearby volcano.
Some of the same Yale researchers contributed to a 2007 paper in Current Biology that first revealed that a single tortoise on Isabella Island contained mitochondrial DNA similar to those of the Pinta Island subspecies. Now, several years and many DNA tests later, more hybrids have been found. Even more importantly, five of the 17 hybrid tortoises were juveniles—less than 20 years old—which lead the researchers to suspect that at least one purebred PInta Island tortoise may be hiding somewhere on Isabella Island.
Isabella and Pinta islands are located about 60 kilometers apart, so the researchers don’t think that Pinta Island tortoises swam or floated to their new home. Instead, the animals were probably carried all or part of the way by the sailors that overran the Galápagos Islands in the nineteenth century, Fishermen and pirates frequently dined on giant tortoises and were the main cause for the decline of Lonesome George’s subspecies.
The Volcán Wolf region might hold even more genetic promise: A study published earlier this year in Current Biology revealed that 11 tortoises from the area carried the genes of yet another Galápagos tortoise species, C. elephantopus from Floreana Island, which was hunted into extinction in the 1850s.
The researchers and officials at Galápagos National Park say the hybrids could now be selectively bred to resurrect the Pinta Island subspecies—a process that could take 100 to 150 years.
Photo by A. Davey via Flickr. Used under Creative Commons license