Little divergence in ribosomal DNA internal transcribed spacer ‐1 and ‐2 sequences among non‐digitate species of Laminaria (Phaeophyceae) from Hokkaido, Japan

Abstract

SUMMARY The nuclear ribosomal DNA internal transcribed spacer (ITS‐1 and ITS‐2) sequences were determined for 10 of 12 Japanese non‐digitate Laminaria species, Kjell‐maniella gyrata (Kjellman) Miyabe, Costaria costata (Turner) Saunders, Alaria praelonga Kjellman and Chorda filum (L.) Stackhouse collected at Hokkaido. Phyloge‐netic analyses (maximum parsimony and distance matrix) of these sequences, including published data for L. sac‐charina (L.) Lamouroux from Canada, showed strong nucleotide conservation among these species of Laminaria, but two phylogenetically distinct species groups were recognized. A L. japonica group encompassing L. yapon/ca Areschoug, L. religiosa Miyabe, L. ochotensis Miyabe, L. diabolica Miyabe, L. longipedalis Okamura, L. angustata Kjellman and L. longissima Miyabe; and a L. saccharina group including L. coriacea Miyabe, L. sac‐charina, L. cichorioides Miyabe and L. yendoana Miyabe. As to other laminarialean genera, Kjellmaniella gyrata was most closely related to the genus Laminaria, being related to the second Laminaria species group based on both parsimony and distant tree values.

Characterization and physical mapping of nuclear ribosomal RNA (rRNA) genes in the haploid gametophytes of Saccharina japonica (Phaeophyta)

“…1), and all the sequences of the 18S rDNA, ITS1, 5.8S, and 25S rDNA are highly conserved, whereas that of ITS2 varied. The ITS2 heterogeneity showed both inter-specific variations as suggested by Yotsukura et al (1999), as well as intra-specific (within S. japonica) variations. Our findings also support the results of Coleman (2003) that there are variations among different ITS2 repeats that exist in a single eukaryote genome.…”

“…In addition to the reported sequences of 18S rDNA (Bi et al 2009), ITS1 and ITS2 (Yotsukura et al 1999), and 5S rDNA (Yotsukura et al 2002), this study cloned the coding sequence of the 25S rDNA so as to complete the rDNA repeat unit in the haploid gametophytes of S. japonica. The 18S-5.8S-25S rRNA gene cluster is about 5400 bp long (Fig.…”

“…Due to their universal presence in eukaryotic genomes, the number, position, and structure of the 5S and 18S-5.8S-25S rDNA loci are considered important characteristics of a given species, genus, or group (Garcia et al 2012). As we know, the sequences of 18S rDNA (Bi et al 2009), internal transcribed spacer (ITS) 1 and ITS2 (Yotsukura et al 1999), and 5S rDNA (Yotsukura et al 2002) in S. japonica and other closely related species have been extensively characterized. However, the molecular organization of these two families of rDNAs, copy number, and physical mapping on chromosomes yet remain to be completed.…”

The biogeography of kelps (Laminariales, Phaeophyceae): a global analysis with new insights from recent advances in molecular phylogenetics

“…More generally, the genetic relatedness between taxa at the same level of the hierarchy is less in brown than in red algae, for example . This proposal for reduction in the number of kelp genera has thus far not been followed by later authors (notably including Druehl and Saunders themselves), although Cymathaere, Kjellmanniella and Hedophyllum are now considered species of Saccharina by Lane et al (2006) (see also Yotsukura et al 1999). There has, rather, been a slight increase in recognised genera, with Pseudolessonia (Cho et al 2006), Aureophycus (Kawai et al 2008) and even Druehlia (Lane et al 2007; reduced to synonomy with the earlier Eualaria, Wynne 2009) being recently described, as well as the re-recognition of Saccharina (Lane et al 2006).…”

“…To my knowledge, there has been no deWnitive molecular taxonomic study on the possible conspeciWcity of these two taxa, although Baartsch et al (2008) cite the published abstract of Cho et al (2006) and are of the opinion that "there is much evidence … that S. longicruris is conspeciWc with S. latissima. There needs to be a consensus on how to deal with "incipient speciation" within genera: that is the existence of morphological forms with relatively slight diVerences within species, which have diVerent ecologies, and can be separated molecularly (Yotsukura et al 1999;Miller et al 2000;Erting et al 2004;Roberson and Coyer 2004;Lane et al 2007;Uwai et al 2007). As Lindstrom (2001) states: "more work is required to understand vicariance in seaweeds, especially in deciphering when a speciation event has occurred".…”