Literaturdatenbank
Literaturdatenbank |
|
 |
|
Rhodin, A. G. J., & van Dijk, P. P. , Setting the stage for understanding globalization of the asian turtle trade: Global, asian, and american turtle diversity, richness, endemism, and iucn red list threat level. Unpublished paper presented at USFWS Workshop on Conservation and Trade Management of Freshwater and Terrestrial Turtles in the United States.
Added by: Sarina Wunderlich (06 Jul 2014 16:17:16 UTC) |
| Resource type: Conference Paper BibTeX citation key: Rhodin2010a View all bibliographic details  |
Categories: General Keywords: Habitat - habitat, Nordamerika - North America, Schildkröten - turtles + tortoises, Südostasien - South East Asia, Testudinidae, Testudo graeca, Testudo hermanni, Testudo marginata Creators: van Dijk, Rhodin Collection: USFWS Workshop on Conservation and Trade Management of Freshwater and Terrestrial Turtles in the United States |
Views: 8/619
Views index: 17% Popularity index: 4.25% |
| Abstract |
|
The diversity of turtles and tortoises in the world that have existed in modern times, and currently generally recognized as distinct, consists of 334 species, of which 58 are polytypic, with 127 additional recognized subspecies, or 461 total taxa of modern turtles and tortoises. Of these, 9 species and 1 subspecies, or 10 taxa, have become extinct since 1500 AD, leaving 325 species, 126 additional subspecies, and 451 extant turtle taxa. Turtle species richness is highest in Southeast Asia, the northern Indian subcontinent, and the southeastern USA, with the latter representing a major Turtle Priority Area not included in current global conservation strategies such as biodiversity hotspots or wilderness areas. Turtle richness as based on number of taxa (species plus subspecies) per nation is highest in the world in the USA with 89 taxa, with Mexico, Australia, Brazil, Indonesia, and India rounding out the top 6 turtle richness nations. The states of Alabama, Florida, Georgia, Louisiana, Mississippi, and Texas, if counted as individual nations, would all warrant ranks near the 5th spot on the global list, reflecting the remarkable diversity and richness of turtles in the southeastern USA. In terms of endemic species and subspecies, the USA ranks number 1 globally for actual number of endemics (60 taxa), and number 2 behind Australia for percentage of endemics (67%). As of the 2010 IUCN Red List, of 207 turtle species officially listed, 129 (62%) are assessed as globally threatened (Critically Endangered, Endangered, or Vulnerable), with 70 (34%) endangered (Critically Endangered or Endangered). Based on a slightly different taxonomy assessed by the Turtle Taxonomy Working Group of the IUCN Tortoise and Freshwater Turtle Specialist Group, 134 species (40% of all 334 turtle species) are considered threatened, with another 10 provisionally assessed as threatened, yielding 43% of all turtles threatened. Turtles are among the most threatened of any major group of vertebrate species, nearly as high as primates (48%), and more than amphibians (30%), mammals (21%), or birds (13%). Based on additional draft Red List assessments and including Extinct in the Wild and Extinct species, 49% of all modern turtles are either extinct or threatened with extinction. Of the 129 species of turtles listed as threatened on the IUCN Red List, 88 (68%) are at least partially threatened by exploitation and trade. There are 64 species of threatened tortoises and freshwater turtles from Asia (50% of all threatened species), of which 55 (90%) are at least partially threatened by exploitation and trade. There are 14 species of threatened tortoises and freshwater turtles from the USA (11% of all threatened species), of which 7 (50%) are at least partially threatened by exploitation and trade. Total threat levels for turtle taxa per nation are the highest in China, with the Asian nations of Vietnam, Indonesia, Myanmar, Thailand, India, and Malaysia included in the global top 10, with the USA ranking number 10, though with a low average threat level per taxon. Threat levels for tortoises and freshwater turtles in the USA were reasonably low when last evaluated for the IUCN Red List in 1996, with only 14 threatened tortoise and freshwater turtle species, of which none were assessed as Critically Endangered, 4 Endangered, and 10 Vulnerable. Provisional draft Red List assessments of 51 American tortoise and freshwater turtle species evaluated by the IUCN Tortoise and Freshwater Turtle Specialist Group in 2010 now result in a higher number of threatened species, partially due to more detailed knowledge of the taxonomy, status, and population trends of these species, but also because of increased exploitation in recent years. As currently provisionally drafted, the USA has 19 threatened species of tortoises and freshwater turtles, of which 3 qualify as Critically Endangered, 9 Endangered, and 7 Vulnerable, and of which 11 (58%) are at least partially threatened by exploitation and trade. Three species are provisionally assessed as Critically Endangered: Glyptemys muhlenbergii (previously Endangered), Sternotherus depressus (previously Vulnerable), and Graptemys gibbonsi (previously Near Threatened). Nine species are provisionally assessed as Endangered: Clemmys guttata, Emydoidea blandingii, Glyptemys insculpta, Graptemys caglei, Graptemys flavimaculata, Graptemys pearlensis, Pseudemys alabamensis, Gopherus agassizii, and Gopherus polyphemus. Seven species are provisionally assessed as Vulnerable: Macrochelys temminckii, Actinemys marmorata, Graptemys barbouri, Graptemys oculifera, Malaclemys terrapin, Terrapene carolina, and Trachemys gaigeae. Seven species are provisionally assessed as Near Threatened: Graptemys ernsti, Graptemys pulchra, Pseudemys gorzugi, Pseudemys rubriventris, Terrapene ornata, Trachemys stejnegeri, and Gopherus berlandieri. Five species are proposed to have moved from non-threatened to threatened status: Emydoidea blandingii, Malaclemys terrapin, Terrapene carolina, Graptemys barbouri, and Graptemys gibbonsi, with one newly described species, Graptemys pearlensis, also assessed as threatened. One species (Kinosternon sonoriense) has moved from threatened to non-threatened status, based on improved knowledge of its distribution. Of the 28 species of American tortoises and freshwater turtles included on the 1996 Red List and now re-assessed in 2010, 13 (46%) are now considered more threatened, 10 (36%) show no change in status, and 5 (18%) are now considered less threatened. Of the 19 species classified as Least Concern in 1996, 18 remain at that status and only one (Graptemys pulchra) has moved to Near Threatened. Though deteriorating somewhat since 1996, the proposed IUCN Red List status of American turtles remains on average at much lower threat levels than for Asian species. However, as levels of exploitation and trade have increased steeply in several states in recent years—thereby increasingly affecting survival status and causing some of these states to regulate or curtail commercial take of turtles—it would possibly require broader enactment of proactive conservation measures to stabilize or reduce these national threat levels.
Added by: Sarina Wunderlich |