Scitech | Scientists to bring back extinct tortoise

Turtles to shack up, and one day give birth to long extinct species

A giant turtle is going to be brought back from the dead. Scientists in the Galapagos have found a species from the island of Isabela that shares DNA with the extinct turtle, G. elephantopus. Dr. Gisella Caccone, a lead researcher on the project, says that planned breeding of Isabela turtles will allow the extinct turtles to make a comeback.

“By mating Isabela tortoises that are most genetically similar to G. elephantopus, selecting the offspring that are most similar, and mating those, through successive generations the species’ genetic makeup may be largely restored,” she said in an interview with The New York Times.

When Darwin went through the Galapagos Islands he was almost as interested in turtles as in finches, and wrote about them in his Origins of Species. Noting that each of the islands housed many distinct species of tortoise, Darwin speculated that all the tortoises originated from one mainland species, but later evolved characteristics advantageous to their own particular islands.

Darwin also noted that, thanks to the fashionability of turtle soup and oil lamps, the tortoises were being killed in great numbers by passing sailors. Ironically, while the turtle meat and oil industries are responsible for the extinction of four Galapagos tortoise species, it is also partly responsible for the G. elephantopus’s resurrection. Researchers suspect that a few G. elephantopi were picked up from their island Floreana, then dropped off on the island Isabela where hunting was less intense. The lucky turtles then passed on their genes by interbreeding with natives of the island.

The genes of the first Floreanian-Isabelan hybrids were split evenly between the two species. Through the next few generations, the Floreanian genes became more diluted. Thanks to the tortoises’ long lifespans, only a few generations have passed since the first tortoises mated with Isabelan natives, so the genes aren’t too diluted. Consequently, it should be easy for scientists to retrace the mating steps and recollect all the Floreanian genes in one turtle. By comparing modern-day turtles’ genetic codes to that of a museum specimen of G. elephantopus, scientists will know which turtles should be mated in order to retrieve the species’ genes.

Professor Ehab Abouheif, an Evolutionary Biologist in the Biology department at McGill, said that this approach could be applied to other species as well.

“The same approach can be potentially applied to other organisms if the museum specimens are well maintained and properly curated. By identifying extinct species and their close relatives, we can understand how particular species were lost and formed…and this is particulary important in designing future conservation strategies for endangered species,” he said.

However, Abouheif expressed concerns about museum curation today. “The problem is that the curation of museum specimens is no longer given the respect that it deserves and as a result important collections have suffered,” he said.

Although it will take only a few carefully-selected matings to resurrect G. elephantopus, none of us will see this resurrection in our lifetime. Due to the tortoises’ long life span, mating of even four generations will take more than a century. But when this is done, the G. elephantopus will be reintroduced to Floreana and crossed off the extinction list.


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