CANADA: For the first time in more than a century, scientists have identified a new species of Galapagos tortoise; the grand giants of the Pacific archipelago that helped inspire Darwin’s theory of evolution.
The discovery, reported Wednesday in the journal PLOS One, adds pieces to the puzzle of the Galapagos tortoise, a celebrated and embattled symbol of the unusual islands.
The newly identified species lives on Santa Cruz, an island in the archipelago’s centre, but turns out to have less in common genetically with Santa Cruz’s main tortoise colony, and to be closer to a species of tortoise on other islands. While separate species are often considered incapable of breeding with each other, genetic evidence indicates that the two Santa Cruz species have mated, albeit not very often.
“Now the genetics has put some real evidence that says the simple explanations don’t hold, that some of the islands have tortoises that arrived at different times from different islands,” said Oliver Ryder, director of genetics at the San Diego Zoo’s Institute for Conservation Research, who was not involved in the new discovery. “The recognition of this separate evolutionary history I think will be very important.”
The new species lives in eastern Santa Cruz, in an arid, lava-laced lowland that has been called Cerro Fatal (Deadly Hill) ever since a park ranger had a bad fall on the harsh terrain, said Linda Cayot, science adviser for the Galapagos Conservancy and an author of the new study. There are about 250 Cerro Fatal tortoises, compared with about 2000 tortoises in a moister, more elevated south-western section of Santa Cruz, called La Reserva.
Cerro Fatal tortoises are smaller, with pointier plates on their shells, but these differences were merely considered variations on La Reserva tortoises, said Adalgisa Caccone, a senior research scientist at Yale and the study’s senior author.
