The Fernandina Island giant tortoise has just been rediscovered - DALTONHURD

The Fernandina Island giant tortoise has just been rediscovered

It was believed to have been extinct for over 100 years. Well hidden on an island lost in the middle of the Galápagos, she had in fact quietly continued her existence. The Giant Fantastic Tortoise of Fernandina Island (Chelonoidis phantasticus) has finally been rediscovered by a team of scientists.

The story begins in 2019 when scientists spot a female turtle living on Fernandina Island. He gives her the nickname “Fernanda”. For Science and Futurebiologist Stephen Gaughran, from Princeton University, reflects on this moment that marked him: “When it was discovered it was incredibly exciting as no turtles had been seen on this island for over 100 years and we thought the species was extinct.”.

Surprised by this encounter, he quickly hypothesizes that Fernanda is most likely a fantastic giant tortoise, the species that was thought to be extinct. To confirm this, the researchers decided to analyze its genome and compare it to that of 13 other species of giant Galápagos tortoises. But also to that of the turtle found in 1906 on the same island. His colleagues, Evelyn Jensen of Newcastle University and Adalgisa Caccone of Yale University, decide to recover the old specimen from the museum’s collection of the California Academy of Sciences. “They realized that this would be a great comparison to show not only that Fernanda was distinct from tortoises from other Galápagos Islands, but that she was also genetically very similar to the only known tortoise from Fernandina Island..”

The results of their study confirm the initial hypothesis: “We saw, honestly to my surprise, that Fernanda was very similar to the turtle found on this island over 100 years ago and that these two individuals were very different from all the turtles on the other islands“, said the scientist. These results therefore imply the continued existence of a lineage long thought to be extinct, with a currently known population size of a single individual.

A long-standing mystery

Since 1906, some traces could however suggest that giant tortoises were still living on Fernandina. In 1964, 18 scats attributable to the species were reported on this island. A visual observation from an airplane was also carried out in the early 2000s. But the piece of land had remained largely unexplored: an active volcano releases vast lava fields, blocking access to the interior of the island. Until then, no scientific study had been able to confirm that the species still existed.

Now that they know that individuals remain, the study scientists wonder how many individuals the island can count. “It’s still a great mystery! Galápagos biologists and conservationists believe that other turtles may still exist on Fernandina Island, but possibly very few. There have been reports of other turtle tracks, such as tracks and droppings, but so far no others have been found.”

However, Fernanda should not a priori be the only turtle to be on the island. There are necessarily other individuals, without whom it could not have seen the light of day. Even if these individuals must subsist in limited numbers: “Fernandina Island features rugged terrain and little vegetation. This means that the island is unlikely to have had a very large population of turtles due to limited resources..” The proof of the existence of the fantastic giant tortoise, however, motivated researchers to plan other expeditions to explore more intensely this small piece of land in the Galapagos, in search of tortoises. “survivors”.

The team is also thinking about the origin of the presence of these turtles on this island. Not being able to swim, tortoises can on the other hand float and thus be transported during major storms for example. These phenomena could have led to their genetic distinction. “Evolution is a very slow process and it takes many thousands of years for species to become distinct in this way. We therefore believe that Fernanda’s ancestors and the 1906 museum specimen may have arrived on Fernandina Island thousands of years ago, possibly having floated there from another Galápagos island..”

“Revive this species of turtle”

Although they don’t know much about the history of the turtles on this island and the number of potential individuals, the researchers are optimistic about the survival of the species. “LDiscovering Fernanda gives me hope! It is only one individual but our colleagues from Galápagos hope to be able to find more turtles on the island. If they find more, they can create a breeding program to produce more individuals of Fernandina Island tortoises and hopefully revive this species.” enthuses Stephen Gaughran.

This discovery is important for conservation biology in general. It testifies to the fact that certain rare species can persist in isolated places for a long time. However, the biologist believes he was very lucky to find a living individual of a species we thought was extinct. “In the vast majority of other cases, a living individual will never be found once a species is deemed extinct. This means that we must make considerable efforts to protect endangered species before they are threatened with extinction..”

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