It is called Fernanda, in honor of Fernandina, the island on which it was discovered, and it is the first of its kind identified for more than a hundred years, a specimen of “fantastic giant tortoise”, of which until now only one other was known. specimen found in 1906.
Fernanda was discovered in 2019 but thanks to a genetic analysis, a team led by Stephen Gaughran, from Princeton University (United States) has confirmed that the species is not extinct, at least while Fernanda is still alive.
Details of the finding and confirmation of the species were published in the journal Communications Biology. By sequencing the genomes of Fernanda and the specimen found in 1906, the team showed that the two Fernandina tortoises belong to the same species (Chelonoidis phantasticus or “fantastic giant tortoise”) and are genetically different from the others.
“For many years it was thought that the original specimen collected in 1906 had been transplanted to the island, as it was the only one of its kind, but now it appears to be one of the few that were alive a century ago,” summarizes Peter Grant, expert on the Galapagos Islands and researcher at Princeton.
And it is that, when Fernanda was discovered, many ecologists doubted that it was a native C.phantasticus turtle, since the specimen lacks the striking broadening of the back of the male historical specimen.
Another element of doubt is that although turtles cannot swim from one island to another, they can float and be transported from one island to another in the Galapagos by hurricanes or major storms, and there are also records of sailors moving turtles between islands.
To determine which species Fernanda was, Gaughran sequenced her genome and compared it with that of the specimen collected in 1906 and with samples of the other 13 species of Galapagos tortoises: three individuals each of the 12 living species and one individual from the extinct C. abingdonii.
“We saw – to my honest surprise – that Fernanda was very similar to the one found on that island over 100 years ago, and both were very different from all the other tortoises on the other islands,” Gaughran said. The team believes that Fernanda is over 50 years old, but she is small, possibly because the sparse vegetation stunted her growth.
For Adalgisa Caccone, lead author of the study and a researcher at Yale University, the finding is encouraging but also raises new questions such as are there more tortoises on Fernandina with which to start a breeding program? How did the Fernandina tortoises colonize the Galapagos and what is their evolutionary relationship to the other giant tortoises?
Since 1906, little but convincing evidence has been found that giant tortoises could continue to live on Fernandina Island, an active volcano on the western tip of the Galapagos archipelago that is reputed to be the largest virgin island on Earth.
The origin of these tortoises in the Galapagos dates back to two or three million years ago, when a storm swept one or several giant specimens from the South American continent to the west and, since they do not swim, they reproduced with others on their own islands, which which led to rapid evolution, the same pattern followed by the Galápagos finches.
Today, there are fourteen different species of Galapagos giant tortoises, all descended from the same ancestor.
Turtle populations were decimated by European sailors who hunted them for food, after discovering that they could keep the turtles alive on their ships with minimal effort, as the reptiles could survive on little food or water.
Fernanda is now at the Galapagos National Park Tortoise Center, a rescue and breeding center, where experts are seeing what they can do to keep her species alive.
