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Molecular evolution and phylogenetic implications of internal transcribed spacer sequences of Ribosomal DNA in Winteraceae |
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| Authors: | Youngbae Suh Leonard B Thien Helena E Reeve Elizabeth A Zimmer |
| Institution: | 1. Laboratory of Molecular Systematics, National Museum of Natural History, Smithsonian Institution, Washington, DC, 20560
Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana, 70118;2. #2 rue de Provence, Valley de Colon, Noumea, New Caledonia Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana, 70118 |
| Abstract: | The internal transcribed spacers and the 5.8S coding region of nuclear ribosomal DNA were sequenced and analyzed to address questions of generic relationships in Winteraceae. The molecular data generated a single tree that is congruent with one based on morphological data. The sequences of ITS 1 in the family range from 235 to 252 bases in size and of ITS 2 from 213 to 226 bases. The size of the 5.8S coding region is 164 bases. The range of ITS 1 and ITS 2 sequence divergence between pairs of genera within Winteraceae is relatively low in comparison to other plant families. Two types of ITS 1 and ITS 2 sequences were observed in the same individual for some taxa. Sequence variations between the two arrays are 4.7%–6.3% for ITS 1 and 5.1%–7.0% for ITS 2. Both arrays of sequences, however, generate the same phylogenetic relationships. Rates of nucleotide substitutions for the internal transcribed spacers are 3.2–5.2 × 10-10 substitution per site per year estimated in ITS 1 and 3.6–5.7 × 10-10 in ITS 2. |
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