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|Title:||Molecular evolution of the cytochrome b gene among percid fishes|
|Doctoral Committee Chair(s):||Page, Lawrence M.|
|Department / Program:||Biology|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||To better understand the evolution of the cytochrome b gene and its implications for evolutionary relationships among percid fishes, the entire cytochrome b gene (1,140 base pairs) was amplified via PCR using the tRNA flanking primers and sequenced. Twenty-two species were examined, including 20 species of Percidae (representing all percid genera except Percarina and Romanichthys), one species of Centrarchidae (Micropterus salmoides), and one species of Moronidae (Morone mississippiensis); the latter two species were used as outgroups for phylogenetic analyses.
Uncorrected sequence divergence among the fishes examined ranged from 7.8% to 26.5% and indicated that percids were more closely related to centrarchids than to moronids. Two unique codons were observed. One was the TGC termination codon at the 3$\sp\prime$ end of the gene of all species examined. The other was an AGA codon in the 311th amino acid residue of Percina maculata and Micropterus salmoides suggesting that AGA does not function as a step codon in teleosts as it does in other vertebrates.
Phylogenetic analyses using maximum parsimony, maximum-likelihood, and the neighbor-joining method, suggested that the family Percidae and the tribe Etheostomatini are monophyletic, that Ammocrypta and Crystallaria should be recognized as genera, and that the genus Etheostoma may be paraphyletic.
Multiple substitutions at the same nucleotide positions, which are thought to have caused incongruent results among tree-building methods, accounted for nearly 30% of the total nucleotide differences. Estimated divergence times among the major lineages of fishes examined suggested that percid fishes may have diverged from their ancestral form between the end of the Cretaceous and the beginning of the Eocene. Within Etheostomatini, darter genera may have diverged from one another during a relatively short period of time about 35 million years ago.
|Rights Information:||Copyright 1994 Song, Choon-Bok|
|Date Available in IDEALS:||2011-05-07|
|Identifier in Online Catalog:||AAI9416438|