Literaturdatenbank
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Selman, W., & Hagen, C. (2012). Turtles in dixie: Map turtles and sawbacks. TSA Magazine, 2012, 21–23.
Added by: Admin (06 Jan 2014 18:25:21 UTC) |
| Resource type: Journal Article BibTeX citation key: Selman2012b View all bibliographic details  |
Categories: General Keywords: Emydidae, Graptemys caglei, Graptemys ernsti, Graptemys flavimaculata, Graptemys geographica, Graptemys gibbonsi, Graptemys nigrinoda, Graptemys oculifera, Graptemys ouachitensis, Graptemys pulchra, Habitat - habitat, Nordamerika - North America, Schildkröten - turtles + tortoises, Systematik - taxonomy Creators: Hagen, Selman Collection: TSA Magazine |
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The genus Graptemys, commonly referred to as map or sawback turtles, contains the most turtle species of any North American turtle genus. With such an incredible taxonomic diversity, as well as their intricate patterns, shapes, and colors, map turtles as a group have been a favorite of hobbyists for a very long time. Of the 14 species, eight are endemic to single river drainages of the southeastern United States, with two endemic species occurring together in three of the Gulf of Mexico river systems: the Mobile River system (G. pulchra, Alabama Map Turtle; G. nigrinoda, Black-knobbed Sawback), the Pascagoula River system (G. gibbonsi, Pascagoula Map Turtle; G. flavimaculata, Yellow-blotched Sawback), and the Pearl River system (G. pearlensis, Pearl River Map Turtle; G. oculifera, Ringed Sawback; Buhlmann et al. 2008). Three species of Graptemys occur within the Cahaba River system of Alabama (Alabama Map Turtle, Black-knobbed Sawback, and the Common Map Turtle, G. geographica), but researchers have only found localities where two of the three species occur. The epicenter for Graptemys diversity is in the state of Mississippi, which boasts nine species, while Alabama and Louisiana host six and five species, respectively. Most map and sawback turtle species are primarily found in rivers, streams, bayous, or oxbow lakes that drain into the Gulf of Mexico (Ernst and Lovich, 2009). Even though the genus Graptemys has a large number of species, researchers still know little about their basic life history and ecology. Their taxonomy has been equally challenging, with six Graptemys species described between 1950 and 2000 (G. ouachitensis, Ouachita Map Turtle 1953; G. flavimaculata 1954; G. nigrinoda 1954; G. caglei, Cagle’s Map Turtle 1974; G. ernsti, Escambia Map Turtle 1992; G. gibbonsi 1992). The last species to be formally described was the Pearl River Map Turtle, G. pearlensis (Ennen et al. 2010), further underscoring the relative little we know about the genus. It is possible that additional “cryptic species” may occur and may be described in the future. Unfortunately, many of these attractive turtle species are considered species of concern or are considered state threatened/endangered. Population declines in the 1980’s and 1990’s of the Ringed Sawback and Yellow-blotched Sawback led to these species being listed as federally threatened under the Endangered Species Act (USFWS 1986, 1991). There are many threats to the genus and most are associated with loss of riverine habitat and habitat alteration, which includes the desnagging of river systems (removal of fallen trees which provide basking and prey species habitats), construction of reservoirs, river channelization, excessive water withdrawal, and water quality degradation. Additional threats include shooting of turtles as target practice, collisions with boats, collection for the pet trade, fisherman by-catch, and the destruction of nests on sandbars by recreational ATV riding (Buhlmann et al., 2008; Lindeman, in press). All 16 currently recognized species and subspecies of map turtles are being maintained and bred in captivity. Several species of narrow-headed map turtles are reproducing regularly in many captive collections and large scale turtle farms in the Southeastern United States have been massproducing a few species, including the Mississippi Map Turtle and Ouachita Map turtle for decades. As a result, these two species have been commonplace in pet stores and reptile trade shows across the U.S. for a many years, as well as available in international pet markets. In addition to private keepers, public institutions such as the Tennessee Aquarium continue to safeguard species like the federally threatened Yellow-blotched Map Turtle through successful captive breeding programs.
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