Researchers discover new giant tortoise species on the island of Santa Cruz in the Galápagos, after conducting genetic tests.
In Santa Cruz there are giant tortoises that live on the western and eastern side of the island, and the researchers have long thought that they belonged to the same species. Since the tortoises from the two populations looked quite different, the researchers decided to run genetic tests on one hundred of them.
The results of the study – published October 21 in the journal PLOS ONE – showed that the tortoise populations, which lived of opposite sides of the island about six miles (ten kilometres) apart, were in fact distant relatives.
Chelonoidis porter is the name of the giant tortoises living on the western side of Santa Cruz called La Reserva. The researchers have now named the giant tortoises – which live on the eastern side of Santa Cruz, in the Cerro Fatal area – Chelonoidis donfaustoi.
“We immediately found that [the eastern tortoises] were very distinct from the other ones. As distinct as species from different islands,” Adalgisa Caccone, a senior evolutionary biology and ecology research scientist at Yale University, said.
The giant tortoise species from La Reserva evolved about 1,74 million years ago, much earlier than the ones living in Cerro Fatal. The tortoises from the eastern parts of Santa Cruz evolved about half a million years ago.
With the help of the genetic tests, the researchers also found that the Chelonoidis donfaustoi (in the east) were more closely related to tortoises living on another island in the Galápagos, rather than those on Santa Cruz.
According to Caccone, the conservation on the Galápagos tortoise species will have to change, because the tortoise population in the west has over 2000 individuals, while the population is the east is quite scarce – only 25 members. The eastern species may need increased habitat protection, now that it is clear that they belong to a different tortoise species, Caccone said.
James Gibbs, a conservation biologist at the State University of New York (SUNY) College of Environmental Science and Forestry in Syracuse, stated that the newly identified species of tortoise will receive special attention to make sure that the population fully recovers.
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