Four species of giant tortoise have gone extinct over the past few hundred years due to overhunting. However, one of these species might have a second chance thanks to some lost tortoises discovered on a remote volcano.
A team of conservationists led by Yale University has gathered more evidence and made a fresh pledge to resurrect the Floreana tortoise (Chelonoidis elephantopus), a saddle-shelled beast from Floreana Island in the Galápagos. Charles Darwin documented this species during his famous trips to the Galápagos in the 19th century but they were deemed extinct within just 15 years of his visit.
The new study, which is available on the biology preprint server BioRxiv, is the latest installment in a long line of previous work, has found 114 tortoises that share the saddleback morphology of the Floreana tortoise. They carried out blood tests on some of the tortoises to discover that 35 individuals had a mitochondrial DNA haplotype that belongs to the Floreana species.
DNA evidence also identified two tortoises that appeared to be purebred Floreanas. That might just mean they have had a more recent ancestry with a purebred than the others but it potentially suggests the species never actually went extinct.
The researchers flew 23 of these individuals to a breeding center via helicopter to join 44 other tortoises from the 2015 expedition. If their breeding program succeeds, the hope is to return them back to Floreana Island.
“Our discovery raises the possibility that the extinct Floreana species could be revived. In this case, tortoises with Floreana ancestry are living ‘genomic archives’ that retain the evolutionary legacy of the extinct species, removing the need for the cloning methods that have been proposed to bring back extinct species,” the authors write.
“The Floreana tortoise breeding program is anticipated to generate thousands of offspring over the next few decades. When repatriated to Floreana Island, these tortoises can once again play their critical role as ecosystem engineers.”
The story of how these similar tortoises became castaways on this faraway island is a fascinating one. These individuals are thought to be descendants of tortoises moved around by early colonizers of the islands who acquired a taste for tortoise meat. These sailors darted between the islands, taking live tortoises for food as they went. Somehow during this haphazard back-and-forth between the islands, some of the Floreana tortoises were probably left stranded away from their native island.
Since this era around 300 years ago, all giant tortoise populations have declined by over 90 percent due to overhunting and being outcompeted by invasive species introduced by humans. This new discovery brings fresh hope to the ongoing research into how these beloved creatures might someday not be totally screwed.
[H/T: New Scientist]
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