Molecular phylogenetics and evolution of subgenus Notropis /
Mitochondrial protein-coding DNA sequences from 16 species considered to be members of subgenus Notropis and several outgroup taxa were analyzed phylogenetically. Complete cytochrome b sequences (1140 bp) and a DNA fragment comprised of the complete ND4L gene and part of the adjacent ND4 gene (916...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2000.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=727726121&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Mitochondrial protein-coding DNA sequences from 16 species considered to be members of subgenus Notropis and several outgroup taxa were analyzed phylogenetically. Complete cytochrome b sequences (1140 bp) and a DNA fragment comprised of the complete ND4L gene and part of the adjacent ND4 gene (916 bp) were analyzed separately and in combination. Separate analyses of cytochrome b and the ND4-ND4L fragment were sensitive to outgroup taxa. However, estimation of an ingroup topology, using combined sequences, was not sensitive to outgroup taxa. Effects of outgroup taxa on estimation of an ingroup topology appeared to be related to both random errors associated with finite sample size and systematic errors associated with substitutional rate heterogeneity among outgroup taxa. Analysis of combined mitochondrial DNA sequences strongly supported (i) removal of N. candidus and N. shumardi from subgenus Notropis, and (ii) monophyly of the 14 remaining species. Relationships among the remaining 14 species were incongruent with hypotheses of relationships derived from morphology. Phylogenetic relationships derived from combined sequences suggested that morphological characters associated with olfaction, food capture, and food processing capabilities were independently derived among members of subgenus Notropis. Implications of the inferred phylogeny for historical biogeography and speciation in subgenus Notropis also are discussed. Partial sequences (873 bp) of the cytochrome oxidase I (COI) gene were analyzed along with cytochrome b and the ND4-ND4L fragment in order to investigate rates and patterns of nucleotide substitution. Analyses of these sequences suggested the occurrence of significant strand bias in the rate of C[] T transition. Results were consistent with increased sensitivity of mitochondrial H-strand DNA to hydrolytic deamination of cytosine. However, comparisons among genes indicated that this bias was homogeneous across the three sets of sequences. |
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| Item Description: | Vita. "Major Subject: Genetics". |
| Physical Description: | x, 144 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 121-138). |