Literaturdatenbank
Literaturdatenbank |
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Le, M. D. (2006). Systematics, biogeography, and conservation status of the turtle family geoemydidae. Unpublished thesis PhD, Columbia University.
Added by: Admin (15 Mar 2009 13:31:36 UTC) |
| Resource type: Thesis/Dissertation BibTeX citation key: Le2006a View all bibliographic details  |
Categories: General Keywords: Morphologie = morphology, Schildkröten = turtles + tortoises, Systematik = taxonomy Creators: Le Publisher: Columbia University |
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| Abstract |
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The systematics of the most diverse turtle family Geoemydidae has been a matter of debate over the last 40 years. This study addresses the family phylogenetic relationships using virtually complete taxon sampling and three mitochondrial and three nuclear genes with a total of 4056 aligned characters and 161 morphological characters. The molecular results strongly support the monophyly of the family as well as the monophylies of the sister families Emydidae and Testudinidae. In addition, these results strongly support the subfamily status of the genus Rhinoclemmys and four other clades within the Geoemydidae, regardless of the methods being used. However, the morphological analysis shows that convergence is substantially high among the three families as the morphological results support only the monophyly of the Testudinidae while Geoemydidae and Emydidae are shown paraphyletic with each other and with Testudinidae. The results of the combined analysis of molecular and morphological data are similar to results of the molecular analysis alone with increased support level at the tips of the tree and decreased support at the base of the tree. The biogeographic analyses based on resulting phylogenies support the hypothesis that geoemydids dispersed to the Americas from Asia across the Bering Straits in the early Eocene. Similarly, they might have migrated to Europe in the roughly same period of time. Within Asia, the DIVA analysis shows that geoemydids dispersed in several directions from their ancestral area in Pakistan, Northern India, and Bangladesh. Parsimony optimization of ecological traits on the preferred tree indicates that the direction change from generalist to specialist is evident only in the diet reconstruction, and that geoemydids are probably conservative in their habitat preference. The mapping of the IUCN's conservation status of these species on the phylogeny reveals that Cuora and a clade of Callagur, Batagur , and the large species of Kachuga are the most endangered. Finally, the results of the surveys in two protected areas in southern Vietnam suggest that viable turtle populations might still exist there despite pressures from exploitation, and that protection of these populations in the protected areas is probably the most effective conservation measure.
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