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The Phylogenetic Relationships of New Caledonian Diplodactylid Geckos with Special Emphasis on Rhacodactylus

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Description: The diplodactylids of New Caledonia are a diverse gekkotan clade whose relationships and distribution have long presented problems for taxonomists and biogeographers. The use of six independent loci has recovered a phylogeny that suggests that this clade underwent a burst of speciation very early in its history. This is confirmed by dating methods that suggest that the majority of generic diversification occurred during the Miocene. Contrary to traditional theories, this radiation seems to have colonized New Caledonia through overwater dispersal in the mid to late Cenozoic. The success of this clade appears to have been largely the result of ecological opportunities arising from habitat fragmentation, promoting rapid adaptation. The earliest splits seem to have resulted in morphological diversification while the subsequent habitat fragmentation catalyzed non-adaptive change, forming widespread cryptic species complexes and short-range, habitat specific endemics. The non-monophyly of the troublesome genera Bavayia and Rhacodactylus has been confirmed here. The addition of several thousand bp of molecular data has failed to present a fully resolved tree, as has the use of coalescent species tree methods. In addition, the New Caledonian radiation provides an example of the justified use of concatenation as opposed to gene tree approaches in order to provide sufficient support for short, but significant branches.
Language: English
Format: Degree Work