How do you bring an extinct species back to life? Use DNA testing to reveal it hidden in plain sight.
During a 2002 expedition to Wolf Volcano on Isabela Island, scientists took note of the saddleback tortoises living side-by-side with tortoises with dome-shaped shells. The results of DNA testing inspired the researchers to return to the field in 2008. Analysis of the more than 1,600 blood samples taken proved two species existed – and further testing showed that DNA of 80 of the saddlebacks matched that of museum samples of the long-extinct Floreana tortoise (Chelonoidis elephantopus, formerly Chelonoidis nigra).
In 2015, scientists undertook another expedition to Wolf Volcano to continue testing the tortoises, and to capture 32 specimens (13 males and 19 females) with likely high Floreana (and possibly Pinta) genetic material.
Extinction of the Floreana Giant Tortoise
When Charles Darwin visited Floreana Island in the Galapagos in 1835, he wrote in his field notes that the giant tortoises on that island were scarce. By 1846, according to a report by naturalist Berthold Seeman, this species of tortoise was extinct.
The extinction of the Floreana giant tortoise, along with three other species, was driven by the overhunting of this reptile by whalers who were active in the archipelago during the first half of the 19th century. The tortoises, which could be kept alive in ship holds for long periods of time, provided necessary fresh meat for crews.
But how did giant tortoises from Floreana Island end up on Isabela, more than 175 kilometers (110 miles) away as the waved albatross flies?
Scientists speculate that whalers and other mariners had dropped off some 40 Floreana tortoises at Banks Bay (Bahía Bancos) on the far northwest corner of Isabela Island, at the foot of Wolf Volcano. This bay was the last opportunity for sailors to lighten their loads before heading westward across the wide Pacific Ocean. Over the following two centuries, these gentle giants formed a colony, interbreeding with the volcano’s native species.
The Start of a New Galapagos Tortoise Breeding Program
Of the 32 giant tortoises captured during the 2015 expedition, about half proved to have high levels of Floreana genetic material. Unfortunately, traces of Pinta giant tortoise (Chelonoidis abingdonii) DNA did not appear. It seems that the species to which Lonesome George belonged may, indeed, be extinct.
The new breeding program, the Giant Tortoise Restoration Initiative (GTRI), is being conducted by the Galapagos National Park in collaboration with the Galapagos Conservancy at the Fausto Llerena Breeding Center on Santa Cruz Island.
Nine males and 14 females Floreana hybrid tortoise have been chosen for this program. Four breeding groups – composed of three females and two males each – will begin their journey in repopulating their ancestors’ home island.
In five years, the first hatchlings will be released on Floreana, to begin the process of repopulating that island with its own species of giant tortoise. Of course, never will the tortoises there be 100 percent pure Chelonoidis elephantopus, a fact Linda Cayot of the Galapagos Conservancy recognizes. “But we will have a tortoise population with many of the same genes as the original,” she stated. After 25 years, these tortoises will be of breeding age.
In the meantime, a project is underway on Floreana to restore the island’s ecosystem. This includes eliminating invasive flora and fauna – especially rats – that would keep the reintroduced tortoises from reproducing and thriving.
Details of this new breeding program were published in the September 13, 2017 issue of Nature’s “Scientific Reports.”
Galapagos National Park, along with the Charles Darwin Research Center and other institutions, has had great success in bringing back species from the brink of extinction. With only 15 individuals, the Española species of giant tortoise was revived with about 2,000 hatchlings being born and repatriated to that island. Another success story is that of the Baltra land iguana, whose population had been relocated to North Seymour Island in the 1930s due to threats of extinction by introduced species.
Visiting the Galapagos Tortoise Breeding Program
You’ll be able to see the stars of the Floreana tortoise breeding program in one of the corrals on the newly renovated Ruta de la Tortuga or Tortoise Route at the Fausto Llerena Breeding Center outside Puerto Ayora on Santa Cruz Island. The bilingual displays examine evolution in the Galapagos Islands, Charles Darwin, breeding giant tortoises in captivity and the environmental importance of giant tortoises. The last stop of the route is the Symbol of Hope Salon featuring Lonesome George, the last known Pinta Island tortoise.
The Ruta de la Tortuga is open daily 8 a.m. to 6 p.m. It is included on the itinerary of many Galapagos cruises.
With the anticipated success of the Floreana giant tortoise breeding program, in the future you may see these gentle giants once again on that island.
Photo credit: Parque Nacional Galápagos