Long-Term Evolution of 5S Ribosomal DNA Seems to Be Driven by Birth-and-Death Processes and Selection in Ensis Razor Shells (Mollusca: Bivalvia)
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A study of nucleotide sequence variation of 5S ribosomal DNA from six Ensis species revealed that several 5S ribosomal DNA variants, based on differences in their nontranscribed spacers (NTS), occur in Ensis genomes. The 5S rRNA gene was not very polymorphic, compared with the NTS region. The phylogenetic analyses performed showed a between-species clustering of 5S ribosomal DNA variants. Sequence divergence levels between variants were very large, revealing a lack of sequence homogenization. These results strongly suggest that the long-term evolution of Ensis 5S ribosomal DNA is driven by birth-and-death processes and selection.
Keywords5S ribosomal DNA Birth-and-death evolution Ensis Mollusca Bivalvia
We thank K. Thomas Jensen, Anne S. Lousdal, Ana de la Torriente, Rudo von Cosel, Virginie Héros, and Barbara Buge for providing us with some of the specimens studied. We are in debt to Ángeles Cid for her invaluable help. The support of the Consellería de Educación e Ordenación Universitaria (Xunta de Galicia, Spain) is greatly appreciated.
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