Seychelles giant tortoises
|Seychelles giant tortoises|
Aldabra giant tortoise ( Aldabrachelys gigantea )
|Loveridge & Williams , 1957|
Seychelles giant tortoises ( Aldabrachelys , Syn . : Dipsochelys ) are a genus of tortoises in the tortoise family (Testudinidae). Recent studies assign the genus only a recent species that is native to islands in the Indian Ocean .
Giant tortoises inhabited many of the islands of the western Indian Ocean until the middle of the last century. In Madagascar they lived until about 1000. the year populations in the Comoros and Glorieuse are only fragmentary remains known about 1,100 to 125,000 years old. On the Mascarenes they (genus: Cylindraspis ) became extinct from around 1795. They survived to this day in the Aldabra archipelago, Farquhar and the Seychelles. One of the largest contiguous populations can be found on the Seychelles, namely the less than 1 km² island of Moyenne . There was evidence that there were large populations of giant tortoises on 20 islands off the East African coast until the 18th century .
There are two theories as to why there are giant tortoises on the remote and very remote island groups ( Aldabra Atoll , Farquhar Atoll , Seychelles and Galapagos ). According to one, smaller animals washed ashore with flotsam on the islands have developed into giant forms (Obst 1985). The second says that these giant forms on the isolated islands are the last survivors, possibly even miniatures of their species that were once spread around the world (Pritchard 1996, Caccone 1999).
In fact, genetic analyzes have shown that the closest relatives of the Aldabra turtle come from Madagascar and probably colonized the Seychelles and the Mascarene Islands (Mauritius, Réunion, Rodrigués) from there.
Only recent species:
- Aldabra giant tortoise ( Aldabrachelys gigantea )
- Aldabrachelys abrupta † (from Madagascar, extinct in the 10th century)
- Aldabrachelys grandidieri † (from Madagascar, extinct in the 10th century)
- JJ Austin, EN Arnold, R. Bour: Was there a second adaptive radiation of giant tortoises in the Indian Ocean? Using mitochondrial DNA to investigate speciation and biogeographie of Aldabrachelys (Reptilia, Testudinidae). In: Molecular Ecology. Vol. 12, No. 6, 2003, pp. 1415-1424. (Abstract)
- Justin Gerlach, KL Canning: Evolution and History of the Giant Tortoises of the Aldabra Island Group. ( Memento from January 31, 2013 in the web archive archive.today ) on: phelsumania.com , 2004.
- Justin Gerlach : Giant Tortoises of the Indian Ocean - The Genus Dipsochelys inhabiting the Seychelles Islands and the extinct giants of Madagascar and the Mascarenes. In: Frankfurt contributions to natural history. Volume 21, Edition Chimaira, Frankfurt am Main 2004.
- Gerlach Justin: Rescuing the critically endangered Seychelles giant tortoises. In: Testudo (SIGS). 14 (1), 2005, pp. 9-20.
- EP Palkovacs, J. Gerlach, A. Caccone: The Evolutionary Origin of Indian Ocean tortoises (Dipsochelys). In: Mol Phylogenet. Evol. 2002. (Abstract) ( Memento from January 27, 2013 in the web archive archive.today )
- Fritz Wüthrich: Seychelles Giant Tortoise Conservation Project: First successes in breeding. (PDF; 354 kB). In: Testudo (SIGS). 12 (1), 2003, pp. 19-22.
- Fritz Wüthrich: Seychelles Giant Tortoise Conservation Project: First reintroduction of Arnold's giant tortoise Dipsochelys arnoldi (BOUR 1982) on Silhouette, Seychelles. (PDF; 582 kB). In: TESTUDO (SIGS). 16 (1), 2007.