Genetic diversity of Scytosiphon lomentaria (Scytosiphonaceae, Phaeophyceae) from the Pacific and Europe based on RuBisCO large subunit and spacer, and ITS nrDNA sequences

Abstract

G.Y. Cho, K. Kogame, H. Kawai and S.M. Boo 2007. Genetic diversity of Scytosiphon lomentaria (Scytosiphonaceae, Phaeophyceae) from the Pacific and Europe based on RuBisCO large subunit and spacer, and ITS nrDNA sequences. Phycologia 46: 657–665. DOI: 10.2216/06-70.1

Sequence variations of the internal transcribed spacers (ITS) 1 and 2 of the nrDNA and the partial RuBisCO large subunit gene-spacer-partial RuBisCO small subunit gene (rbcL-sp-S) region were investigated in samples of Scytosiphon lomentaria (Lyngbye) Link from 50 localities in the Pacific (Australia, Japan, Korea, New Zealand, Russia and United States) and the North Atlantic. ITS1 and ITS2 sequences were determined for 83 samples, the rbcL-sp-S region for 43 samples, and complete rbcL sequences for two European and three Japanese samples. Molecular phylogenetic analyses using rbcL sequences were performed including S. lomentaria and 15 other scytosiphonacean species. In the rbcL analyses the S. lomentaria samples made a clade consisting of a Pacific and a European subclade. These two subclades also were supported by the ITS and rbcL-sp-S analyses. The nucleotide differences in rbcL were 1.8–2.3% (27–33 bp/1,467 bp) between the two subclades. Such differences are so large that they are considered as indicating different, although cryptic, species. In the ITS analyses the Pacific clade was further divided into two well-supported subclades. In the Pacific clade sample localities were not geographically related to the molecular phylogeny: both subclades included samples from Korea, Japan, Oregon and New Zealand. Artificial translocations are suggested to have occurred because identical sequences were found from localities far from each other, for example, Korea and the United States, the United States and New Zealand. The two Pacific groups are possibly two distinct but cryptic species.

Key Words::

• Cryptic species
• Intraspecific genetic variation
• ITS
• Molecular phylogeny
• rbcL
• RuBisCO spacer
• Scytosiphon lomentaria

ACKNOWLEDGMENTS

We thank Drs Joanna M. Kain, John A. West, Nathalie Simon, Nina G. Klochkova, Giuseppe C. Zuccarello, Judy Broom, Tae Oh Cho, Han Gu Choi, Michio Masuda, Taizo Motomura, Norishige Yotsukura and Kazuro Shida (Shinta) for their help in collecting specimens. We also thank Dr E.C. Henry for his valuable comments in revising the manuscript. This work was supported by the Korean Science and Engineering Foundation (KOSEF) grant funded by the Korean Government (MOST; R01-2006-000-10207-0) to S.M. Boo and the scientific research grant provided by Japan Society for the Promotion of Science (17570069) to K. Kogame.