‘Extinct’ Tortoise Discovered Living 200 Miles From Home
Recent research conducted by Yale University has re-discovered a species of Galápagos tortoise, previously thought to be extinct for 150 years.
The study, published earlier this week in the journal Current Biology, uncovered direct descendants of at least 38 purebred individuals of Chelonoidis elephantopus living on the volcanic slopes of the northern shore of Isabela Island — 200 miles from their ancestral home of Floreana Island. The tortoises disappeared from the island over a century ago as a result of vigorous hunting by whalers and workers at a heating oil factory that had been established there.
“This is not just an academic exercise,”says Gisella Caccone, senior research scientist of ecology and evolutionary biology at Yale University and senior author of the paper. “If we can find these individuals, we can restore them to their island of origin. This is important as these animals are keystone species playing a crucial role in maintaining the ecological integrity of the island communities.”
The unique shell shapes of tortoises living in the Galápagos Islands were one of the factors that inspired Charles Darwin to form his theory of natural selection during a visit to the area in 1835.
To confirm that the dome-shelled tortoises were in fact the missing species from Floreana, a team of Yale researchers visiting Volcano Wolf on the northern tip of Isabela Island in 2008 took blood samples from more than 1600 tortoises and compared them to a genetic database of living and extinct tortoise species.
An analysis detected the genetic signatures of C. elephantopus in 84 Volcano Wolf tortoises, meaning one of their parents was a purebred member of the missing species. In 30 cases breeding had taken place within the last 15 years. Since the lifespan of tortoises can exceed 100 years, there is a high probability that many purebreds are still alive, note the researchers.
“To our knowledge, this is the first report of the rediscovery of a species by way of tracking the genetic footprints left in the genomes of its hybrid offspring,” said former Yale postdoctoral researcher Ryan Garrick, now assistant professor at the University of Mississipi and first author of the paper.
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Image Credit: Yale News