Second Chance for Lost Galapagos Tortoises? (Chelonoidis elephantopus from Floreana Island) - via Herp Digest

By Bob Grant, The Scientist, September 14, 2017

Giant tortoises that once inhabited the Galapagos Island of Floreana may get another chance at existence, thanks to the efforts of researchers working to recreate a close genetic facsimile of the species by breeding together related species that contain traces of the extinct reptiles’ DNA.

Scientists working in the far flung archipelago have corralled more than 30 tortoises with morphologies reminiscent of Floreana tortoises that have the highest amounts of Floreana tortoise DNA, each enclosure containing three females and two males, in the hopes that the animals will mate and produce offspring that approach the genetic profile of the long lost species.

Scientists declared the Floreana tortoises (Chelonoidis elephantopus) extinct in the 1800s, a result of sailors of the era capturing and eating the animals on long ocean journeys back to Europe. 

But in 2008, researchers studying tortoises on the island of Isabela discovered that some individuals in that population contained genetic traces of Floreana tortoises.

“This is a species that was considered extinct for 160 years,” Washington Tapia, one of the scientists who studied the tortoises, tells The Associated Press. “We didn’t imagine what we would find.”

This week (September 13), an international team of researchers that included Tapia provided an update in Scientific Reports that described the genetic makeup of tortoises they captured and relocated from a remote volcano on Isabela Island to a captive breeding facility on Santa Cruz Island. Of 150 Isabela tortoises, 64 had marks of C. elephantopusancestry, and 32 were placed in breeding corrals on Santa Cruz Island. The hope is that these tortoises—who are thought to contain traces of C. elephantopus DNA because sailors would sometimes offload animals they had collected on Floreana on Isabela to lighten their ships’ loads—can mate and produce offspring that have even more substantial chunks of the extinct species’s DNA.

“I can assure you that I helped to clean and prepare the corrals where they were housed and there is space, plenty of food and water,” Luciano Beheregaray, a coauthor and geneticist at Flinders University in Adelaide, Australia, tells Wired.

As the lumbering reptiles are typically slow to reproduce—individuals can take 25 years to reach sexual maturity–the results of the resurrection effort will take some time to emerge. But the researchers hope that tortoises containing larger traces of C. elephantopus DNA will one day repopulate Floreana, which will slowly drive evolution of the translocated population and the island’s landscape.

“I am intrigued with letting these imperfect tortoises go and letting evolutionary process refit them to the island,” James Gibbs, a coauthor and researcher at the State University of New York College of Environmental Science and Forestry in Syracuse, tells Wired.

Extinct species of Galapagos giant tortoise may be resurrected

1 June 2017

Room for more giants

By Sam Wong

Conservationists believe they can bring back a species of giant tortoise unique to Floreana Island in the Galapagos and considered extinct since the mid-19th century.

Galapagos giant tortoises are sometimes divided into 15 species, 11 of which survive today. The tortoise populations on all the islands were decimated after humans arrived in the archipelago and began loading them onto ships for their meat. They also brought animals such as rats, which can prey on young tortoises, and goats, which destroy their habitat.

Tortoises were eliminated from Floreana Island shortly after Charles Darwin’s visit in 1835. Another species, the Pinta Island tortoise, lost its last remaining member, named Lonesome George, in 2012.
 
But these species may not be gone forever. Both Floreana and Pinta tortoises have a saddle-shaped shell, allowing them to raise their necks to reach higher vegetation. In 2008, researchers discovered a few similar saddle-shelled tortoises living around Wolf volcano on Isabela Island, differing from the dome-shaped shell of most of the island’s tortoises. DNA collected from the saddle-shelled animals suggested they were descended from Floreana and Pinta Island tortoises.

It is thought that tortoises were moved between the islands on ships. Even though some mated with local tortoises and produced hybrids, the retention of a saddle shell by the tortoises around Wolf volcano raised the possibility of restoring the Floreana and Pinta species through captive breeding.

In 2015, scientists returned to Wolf volcano to look for more tortoises with Floreana and Pinta ancestry. They carried out blood tests on 144 individuals, then lifted 32 promising candidates onto a ship by helicopter and took them to a captive breeding centre on Santa Cruz Island.

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