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Giant tortoise, thought extinct, makes comeback
By Catholic Online (NEWS CONSORTIUM)
January 10th, 2012
Catholic Online (www.catholic.org)
January 10th, 2012
Catholic Online (www.catholic.org)
"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," Yale University researcher Ryan Garrick, said in
a statement. "These findings breathe new life into the conservation
prospects for members of this flagship group." A breed of tortoise long
thought extinct, is in fact fathering a mutant strain of tortoise off
the Galápagos Islands.
Researchers "found" the lost species by analyzing the genome of a closely related species, Chelonoidis becki, which lives on Isabella Island, which is the largest of the Galápagos Islands in the Pacific Ocean. The island lies about 200 miles from Floreana Island, where C. elephantopus was last spotted before vanishing, likely due to hunting by whalers, more than a century ago.
Two species of gigantic tortoise, both living in the Galápagos Islands, famously studied by Charles Darwin and proved to be influential in regards to his theories of evolution, have different shaped shells. The shells of C. elephantopus on Floreana Island were saddle-shaped while tortoises on other islands, including C. becki, had domed-shaped shells. These giant tortoises can weigh nearly 900 pounds and reach almost 6 feet in length.
The researchers noticed three years ago that some of the C. becki shells were more saddle shaped than domed shaped. These shells were found by hybrid offspring from matings between the two species. They took samples for genetic analyses from 1,669 of the large tortoises on the island.
Scientists found some snippets of the C. elephantopus genome in the population. Using a special computer model analyzed how recently these genes would have entered the population.
This offspring only could have happened when a living C. elephantopus mated with a C. becki. These findings were indirect proof that at that time living C. elephantopus existed.
Biologists found that 84 of the tortoises had genetic indicators that one of their parents was a C. elephantopus, 30 of which were less than 15 years of age. Given the 100-year lifespan of the tortoises the researchers say there is a good chance that their C. elephantopus parents are still alive.
Due to the genetic differences between the hybrid tortoises, the researchers estimate that at least 38 C. elephantopus left behind hybrid descendants on the Galápagos Islands, and many may still be alive.
If the researchers can find this hidden population, they could capture individuals to set up a breeding program to regenerate the species.
© 2012, Catholic Online. Distributed by NEWS CONSORTIUM.