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Tetrapod phylogeny as inferred from 18S and 28S ribosomal-RNA sequence comparisons

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Title: Tetrapod phylogeny as inferred from 18S and 28S ribosomal-RNA sequence comparisons
Author(s): Moberg, Kirk David
Doctoral Committee Chair(s): Daniel, William L.
Department / Program: Biology
Discipline: Biology
Degree Granting Institution: University of Illinois at Urbana-Champaign
Degree: Ph.D.
Genre: Dissertation
Subject(s): Biology, General Biology, Molecular Biology, Zoology
Abstract: The superclass Tetrapoda consists of several well defined monophyletic taxa: Anura, Urodela, Gymnophiona, Testudinata, Squamata, Rhychocephalia, Crocodilia, Aves and Mammalia. The relationships among these groups, however, is controversial. Neither paleontological evidence nor morphological, physiological, biochemical or available macromolecular sequence data from living forms has provided a definitive solution.A new data base consisting of 18S and 28S ribosomal RNA sequences was generated. Ribosomal RNA was extracted from liver and mature ova of select tetrapods and directly sequenced using the enzyme reverse transcriptase and deoxy and dideoxynucleotides. Approximately 95% of the 18S and 20% of the 28S were sequenced form twenty tetrapods. In addition, nearly all of the 18S molecule was sequenced from the coelecanth (Latimeria chalumnae). Sequences were aligned and variable sites identified. Four methods of phylogenetic tree construction were employed consisting of (1) least squares distance matrix, (2) maximum parsimony, (3) maximum likelihood and (4) evolutionary parsimony. The effects of character weighting, inclusion or exclusion of taxa, and outgroup choice were also investigated.Analysis of both the 18S and 28S ribosomal RNA sequences were consistent with the monophyly of the Lissamphibia, Anura, Urodela, Amniota, Squamata, Aves and Mammalia. The relationships between these groups including the Testudinata, Gymnophiona and Crocodilia, however, were not resolved. Character weighting, choice of taxa to be included and outgroup choice were shown to affect the tree topology. In addition, separate analyses of the 18S and 28S molecules yielded different tree topologies.
Issue Date: 1989
Type: Text
Language: English
URI: http://hdl.handle.net/2142/20202
Rights Information: Copyright 1989 Moberg, Kirk David
Date Available in IDEALS: 2011-05-07
Identifier in Online Catalog: AAI8924900
OCLC Identifier: (UMI)AAI8924900
 

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