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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Phylogenetic History, Morphological Parallelism, and Speciation in a Complex of Appalachian Salamanders (Genus: Desmognathus)

Jackson, Nathan D. 10 March 2005 (has links) (PDF)
Understanding the mechanisms that generate shared morphologies across closely related taxa is important when identifying distinct evolutionary lineages using morphological characters. Desmognathus salamanders are an ideal group for testing hypotheses concerning the correlation between morphological similarity and genetic exchange within and among nominal species due to a pattern of high discordance between the two. Phylogeographic hypotheses are tested for populations of the D. quadramaculatus species complex throughout southern Appalachia by combining phylogenetic and population genetic methods with geographical information. Phylogenetic and phylogeographic inferences are then assessed in conjunction with morphological characteristics that have traditionally diagnosed taxonomic entities to understand the genetic basis of shared morphology in this complex, and to assess species boundaries. A history of fragmentation followed by range expansion is suggested as a recurrent pattern that has shaped the current population structure within this complex. The current taxonomy is found to unite populations that share similar morphologies due to parallel evolution rather than ancestry. We suggest revisions in taxonomy that will better reflect the evolutionary history of these lineages. Appreciation of the hidden genetic variation and homoplasious morphological variation often present in and among salamander species can foster the implementation of more appropriate methods for detecting and recognizing the complex history of these organisms.

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