NUCLEOTIDE-SEQUENCES OF THE SMALL-SUBUNIT RIBOSOMAL-RNA GENES FROM SELECTED LAMINARIALES (PHAEOPHYTA) - IMPLICATIONS FOR KELP EVOLUTION

The entire small-subunit (SSU) ribosomal ribonucleic acid sequence was inferred for kelp representing seven genera: Alaria marginata Postels and Ruprecht (1824 bp), Egregia menziesii (Turner) Areschoug (1825 bp), Lessoniopsis littoralis (Tilden) Reinke (1825 bp), Macrocystis integrifolia Bory (1825 bp), Nereocystis leutkeana (Mertens) Postels and Ruprecht (1824 bp), Postelsia palmaeformis Ruprecht (1826 bp), and Pterygophora californica Ruprecht (1825 bp). We obtained a partial sequence for Eisenia arborea Areschoug (1669 bp) from a single clone of polymerase chain reaction-amplified product. The SSU sequence was too conserved among these morphologically distinct taxa to permit phylogenetic analysis. The divergence between the most distant taxa was only 0.66%. This value was used in a SSU molecular clock to suggest that the most distantly related kelp investigated in this study diverged between 16 and 30 (more probably 16 and 20) million years ago.