The Pinta Island tortoise (Chelonoidis niger abingdonii), also known as the Pinta giant tortoise, Abingdon Island tortoise, or Abingdon Island giant tortoise, is a recently extinct subspecies of Galápagos tortoise that was native to Ecuador's Pinta Island. The subspecies was described by Albert Günther in 1877 after specimens arrived in London. By the end of the 19th century, most of the Pinta Island tortoises had been wiped out due to hunting. By the mid-20th century, the subspecies was assumed to be extinct until a single male was discovered on the island in 1971. Efforts were made to mate the male, named Lonesome George, with other subspecies, but no viable eggs resulted. Lonesome George died on 24 June 2012, and the subspecies was believed to have become extinct with his death. However, 17 first-generation hybrids were reported in 2012 from Wolf Volcano on Isabela Island during a trip by Yale University researchers. As these specimens were juveniles, their parents might still be alive. The subspecies is classified as extinct on the IUCN Red List.
Taxonomy Lonesome George, along with other of the tortoises on Pinta Island, belonged to a species of 15 subspecies. Giant tortoises were once found on all of the continents except Australia and Antarctica. The Galápagos tortoises remain the largest living tortoises.
The Pinta Island tortoise was originally described in 1877 by German-born British herpetologist Albert Günther, who named it Testudo abingdonii in his book The Gigantic Land-tortoises (Living and Extinct) in the Collection of the British Museum. The name abingdonii derives from Abingdon Island, now more commonly known as Pinta Island. The knowledge of its existence was derived from short statements of the voyages of Captain James Colnett in 1798 and Basil Hall in 1822. In 1876, Commander William Cookson brought three male specimens (along with other subspecies of Galápagos tortoise) to London aboard the Royal Navy ship HMS Peterel.
Synonyms of Chelonoidis abingdonii include Testudo abingdonii Günther, 1877; Testudo elephantopus abingdonii Mertens & Wermuth, 1955; Geochelone elephantopus abingdonii Pritchard, 1967; Geochelone nigra abingdonii Iverson, 1992; and Geochelone abingdonii Valverde, 2004.
Evolution The Galápagos tortoise is most closely related to the three living species of tortoise found on the South American mainland, which make up the genus Chelonoidis. Multiple phylogenetic studies support its closest living relative being the Chaco tortoise (C. chilensis), the southernmost distributed species of the genus. The ancestral population of C. niger was thought to have split into the 15 different subspecies approximately 1.27-1.79 million years ago (Mya). Phylogenetic analysis of mitchondrial genomes of the extant subspecies (as well as the now-extinct C. n. abingdonii and C. n. niger) supports the hypothesis that the species progressively diverged as it colonized the islands, with the most recent divergences occurring furthest from the mainland on Isabela Island. Curiously, repeated analyses suggest that the closest relative of the Pinta Island tortoise is the Española Island subspecies C. n. hoodensis, which is the most geographically distant population from Pinta Island. Despite the long journey of founder individuals, this colonization (approximately 0.25 Mya) was likely facilitated by northwest-traveling ocean currents.
Behaviour and ecology In the wild, Galápagos tortoises, including the Pinta Island subspecies, rested about 16 hours a day. Galápagos tortoises are herbivores, they fed primarily on greens, grasses, native fruit, and cactus pads. They drank large quantities of water, which they could store in their bodies for long periods of time for later use. They can reportedly survive up to six months without food or water. For breeding, the tortoises were most active during the hot season (January to May). During the cool season (June to November), female tortoises migrated to nesting zones to lay their eggs. Galápagos giant tortoises represent the top herbivores in the Galápagos, and as such they shape the entire island ecosystem. They provide critical ecosystem services by dispersing seeds and by acting as ecological engineers through herbivory and nutrient cycling. The extinction of the Pinta Island tortoise has diminished the functioning of the island ecosystem.
Relationship with humans
Threats and conservation Several of the surviving subspecies of Galápagos tortoises are endangered. The decline of the population began in the 17th century as a result of visits by buccaneers and whalers. They hunted tortoises as a source of fresh meat, taking about 200,000 tortoises altogether. In 1958, goats were brought to Pinta Island and began eating much of the vegetation, to the detriment of the natural habitat. A prolonged effort to exterminate the goats was begun. As the goat populations declined, the vegetation recovered. Small trees began regenerating from the stumps left by the goats. Highland shrub subspecies, forest tree seedlings, Opuntia cactus, and other endemic subspecies increased. In 2003, Pinta Island was declared goat-free. In addition to conservation efforts such as the elimination of goat populations in the Galápagos, there has been an effort to revive a number of subspecies of Galápagos tortoise through captive breeding. Future efforts may aim to recreate a population genetically similar to the original Pinta Island tortoise by breeding the first-generation hybrids discovered on Wolf Volcano.
Lonesome George
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