Giant Galapagos tortoises may not be extinct
The Giant Galapagos tortoise Chelonoidis elephantopus that was believed to have been hunted to extinction 150 years ago may not be extinct after all, according to a team from Yale University.
An expedition found hybrid tortoises on the Isabela island that have C. Elephantopus in their ancestry, and genetic testing suggests that 84 of the tortoises the expedition tested had a pure-bred C. elephantopus as a parent. As some of these hybrids are only 15 years old and this species of tortoise can live for over a century, the Yale team hopes that their parents might still be alive and undetected somewhere in the heavily forested Volcano Wolf region.
"Around Volcano Wolf, it was a mystery - you could find domed shells, you could find saddlebacks, and anything in between," relates Dr Gisella Caccone, a senior scientist on the new study. "And basically by looking at the genetic fingerprint of the hybrids, if you do some calculations you realise that there have to be a few elephantopus around to father these animals.
"To justify the amount of genetic diversity in the hybrids, there should be something like 38."
Some of the hybrids were found to carry C. elephantopus mitochondrial DNA, which is passed on by the mother. This suggests the possibility that breeding females are or were recently still alive. Absent the possibility of locating a live specimen, it is hoped that a careful cross-breeding program using the hybrids could recreate the lineage over several generations.
The Yale team will be in communication with the Galapagos authorities to discuss whether to launch further expeditions to locate live specimens or to start a breeding program in captivity.
The Veterinary Medicines Directorate (VMD) is inviting applications from veterinary students to attend a one-week extramural studies (EMS) placement in July 2026.
