Nucleotide sequence of the 18S ribosomal ribonucleic acid gene from two teleosts and two sharks and their molecular phylogeny.
The 18S rRNA sequence was determined for two teleostean fish species, Fundulus heteroclitus and Sebastolobus altivelis, and two sharks, Squalus acanthias and Echinorhinus cookei. To study the molecular phylogeny of these taxa, the sequences were compared with 18S rRNA sequences of the Coelacanth Latimeria chalumnae, the frog Xenopus laevis, and humans. Maximum parsimony analysis of the sequences resulted in a single most parsimonious tree that is in agreement with the expected phylogeny. The correct phylogenetic tree was also found when using S. altivelis alone as the teleost representative. In contrast, the most parsimonious tree found by using F. heteroclitus as the teleost representative presented anomalous groupings (the teleost branch being grouped with humans), matching results previously obtained. However, a bootstrap analysis showed that some branches containing anomalous relationships were not significantly supported. An explanation for this peculiarity, the differences between our tree and previously identified ones, and their phylogenetic implications are discussed.
Bernardi
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Stanford University, Department of Biological Sciences, Pacific Grove, CA 93950.
Sordino
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Powers
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D000818:Animals; D001482:Base Composition; D001483:Base Sequence; D004275:DNA, Ribosomal / Q000737:chemistry; D005399:Fishes / Q000145:classification / Q000235:genetics*; D007695:Killifishes / Q000145:classification / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012337:RNA, Ribosomal, 18S / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D012754:Sharks / Q000145:classification / Q000235:genetics*
D004275:DNA, Ribosomal; D012337:RNA, Ribosomal, 18S