Chelonoidis phantasticus, the sole known member of the enormous Galapagos tortoise species, was discovered 113 years apart. A lone male was discovered wandering about Fernandina Island in 1906, but that was the last scientists saw of the species until 2019 when researchers discovered a second lone ranger: a 50-year-old female dubbed Fernanda, who appeared to be queen of her own island.
The unexpected finding increases the number of known C. phantasticus individuals from one to two, but it also perplexes evolutionary scientists since, while their genomes proved to be extremely similar (the male currently sits at the California Academy of Science), they appear very different. Fernanda’s shell was smaller and smoother than the male’s, whose carapace protruded like that of a saddleback tortoise.
Fernanda’s discovery is described in a publication published in Communications Biology under the short title: The Galapagos giant tortoise Chelonoidis phantasticus is not extinct.
“The discovery of one living specimen provides optimism while simultaneously raising new concerns, since many mysteries remain,” said senior author Adalgisa Caccone, a senior research scientist and lecturer at Yale’s Department of Ecology & Evolutionary Biology, in a press release.
“Are there any more tortoises on Fernandina that can be returned to captivity to begin a breeding program?” How did tortoises get to Fernandina? And how do they differ from the other huge Galapagos tortoises in terms of evolution?”
C. phantasticus was supposed to have been extinct owing to volcanic activity on Fernandina Island, the most isolated of the Galapagos Islands. It was anticipated to be a dreadful home turf for a slow-moving species like C. phantasticus, having undergone roughly 25 volcanic explosions in the previous 200 years and with limited area for foraging or escape, yet Fernanda has been living it up on the island for half a century.
“The island is one of the youngest in the Galapagos archipelago, and because it’s young geologically, it’s still highly active in terms of volcanic eruptions,” Caccone told IFLScience.
“This has resulted in the creation of new lava fields that are extremely difficult to traverse. It’s tough for people to explore properly, but for tortoises, it’s created isolated areas of ideal habitat so they can’t go from one spot to another.”
Despite their comparable genomes, the researchers discovered a few changes in the mitochondrial DNA (aka, the genetic code for “the powerhouse of the cell”) passed down from mother to daughter. It’s possible that some of them characteristics are due to Fernanda being a hybrid of two Galapagos tortoise species, such as a C. phantasticus male and a C. nigra female.
The latter is now extinct and comes from a separate island, but it’s likely she spent enough time in Fernandina (thanks to humans who relocated the tortoises) to breed and leave mitochondrial DNA for future generations to enjoy. The authors are keen to determine who the actual C. phantasticus is and whether Fernanda is a hybrid, but this will take many tortoises.
Another reason for their disparities might be that living on Fernandina Island is difficult.
“She is petite. She is presently in good condition and alive and kicking, but she is a little adult, which is why she morphologically differs from the male specimen at the museum “Caccone explained. “It’s most likely due to slowed growth due to a lack of nourishment. This animal was presumably stunted by being isolated in an area of vegetation.”
Despite the difficult times at Fernandina, tortoise scats on the island indicate that there may be more Galapagos giants to be found here. As a result, the Galapagos National Park and Galapagos Conservancy are planning a (non-violent) giant tortoise search in the hopes of discovering some of Fernanda’s cousins and maybe saving the species.
Caccone, on the other hand, believes that locating breeding-age people is only half the job. “The conservation concern we have is that if we locate additional animals and begin a breeding program, what are we going to do with them?” she explained. “Their house is no longer fit.”
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