Galapagos tortoise species may not be extinct
A few survivors of a giant Galapagos tortoise species thought to have gone extinct in the 1840s may still exist on a volcanic island in the Pacific, genetic analysis reveals.
A giant Galapagos tortoise species thought to have gone extinct may still exist, genetic analysis reveals.
Researchers did DNA testing of 1,600 tortoises on Isabela Island in the Galapagos and found at least 84 animals who were the direct offspring of a different tortoise species from nearby Floreana Island long believed gone.
“This is some of the most exciting news that I’ve seen for the Galapagos in a long time,” says Linda Cayot, science adviser to the Galapagos Conservancy of Fairfax, Va. “To have a species that was thought to be extinct in the middle of the 1800s come back is amazing.”
Galapagos giant tortoises are famous as one of the species that helped Charles Darwin develop his theory of evolution. When he visited in 1835 Darwin discovered that many of the islands in the remote Pacific islands west of Ecuador were home to their own, distinct, tortoise species. Each differed slightly from those on nearby islands. His theory of evolution helped explain how each species had evolved to survive best in its home island.
One of the species he described was Chelonoidis elephantopus, which lived on Floreana Island. Within a decade after his expedition left, whalers had killed them all off for food.
Now researchers have found DNA evidence that purebred Floreana tortoises must be living on Isabela Island among a population of its native Chelonoidis becki species. The researchers think there could potentially be 38 or more of the Floreana among an estimated 8,000 or so Isabela tortoises. Their paper is in Monday’s edition of the journal Current Biology.
The discovery dates back to 1994 when the same researchers took 60 blood samples from tortoises living on the sides of rocky and forbidding Wolf volcano on Isabela. But what lay locked in the DNA of some of the samples was surprising.