Monday, October 26, 2015

A new giant tortoise: Chelonoidis donfaustoi

There are two populations of giant tortoises on the island of Santa Cruz in the center of the Galapagos Archipelago: a large population on the west side in an area known as the "Reserve" and another on the lower eastern slopes around a hill named "Cerro Fatal" Until recently, researchers believed that these populations belonged to the same species of tortoise. New genetic and morphological analyses have now clearly identified the two populations as separate species: the Western Santa Cruz Tortoise (Chelonoidis porteri) and the new Eastern Santa Cruz Tortoise (Chelonoidis donfaustoi).

The new species was named to honor Fausto Llerena S├ínchez, known to his friends and colleagues as Don Fausto. Don Fausto dedicated 43 years (1971-2014) to giant tortoise conservation as a park ranger for the Galapagos National Park Directorate. He was the primary caretaker at the Tortoise Breeding and Rearing Center on Santa Cruz, which now bears his name. The restoration of several tortoise populations is due in part to Don Fausto's dedication and efforts. He successfully bred tortoises in Galapagos while many of the best zoos around the world have failed in their efforts to do so

For the experts: The taxonomy of giant Galapagos tortoises (Chelonoidis spp.) is currently based primarily on morphological characters and island of origin. Over the last decade, compelling genetic evidence has accumulated for multiple independent evolutionary lineages, spurring the need for taxonomic revision. On the island of Santa Cruz there is currently a single named species, C. porteri. Recent genetic and morphological studies have shown that, within this taxon, there are two evolutionarily and spatially distinct lineages on the western and eastern sectors of the island, known as the Reserva and Cerro Fatal populations, respectively. Analyses of DNA from natural populations and museum specimens, including the type specimen for C. porteri, confirm the genetic distinctiveness of these two lineages and support elevation of the Cerro Fatal tortoises to the rank of species. In this paper, we identify DNA characters that define this new species, and infer evolutionary relationships relative to other species of Galapagos tortoises.

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