Researchers believe they have discovered a new species of giant tortoise in the Galapagos Islands, which is news they'd be happier about if it didn't also mean that another species has apparently gone extinct. Scientists who analyzed genetic material from museum samples discovered that samples brought back from San Cristobal Island by an expedition in 1906 are from a different species than the giant tortoises found on the island today, Gizmodo reports. In a study published in the journal Heredity, researchers say the thousands of tortoises that inhabit the island's lowlands are genetically distinct from Chelonoidis chathamensis, the tortoises once found in the island's highlands.
Researchers now believe C. chathamensis, also known as the San Cristobal giant tortoise or the Chatham Island giant tortoise, went extinct some time in the middle of the 20th century. "The team of investigators is recovering more DNA from the species thought to be extinct to clarify the state of the tortoises and determine how these two species (the living and the extinct) relate," Galapagos National Park said in a statement, per Reuters. "For them, the name Chelonoidis chathamensis should be assigned to the disappeared species and the living taxon should receive a new name."
The 1906 expedition didn't visit the island's lowlands, which are now home to around 8,000 giant tortoises, up from as few as 500 in the 1970s. Those tortoises should now be considered "a genetically distinctive and undescribed group of organisms" that is "new to science," the team said. The researchers, who found that the highland tortoises were more closely related to other giant tortoises in the archipelago than to the lowland tortoises, believe high sea levels once cut the island in half, causing the two species to evolve separately, though there was also a long period of coexistence. (Lonesome George, the last giant tortoise of his kind, died in 2012.)
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