A MULTI‐GENE MOLECULAR INVESTIGATION OF THE KELP (LAMINARIALES, PHAEOPHYCEAE) SUPPORTS SUBSTANTIAL TAXONOMIC RE‐ORGANIZATION¹

Abstract

Every year numerous ecological, biochemical, and physiological studies are performed using members of the order Laminariales. Despite the fact that kelp are some of the most intensely studied macroalgae in the world, there is significant debate over the classification within and among the three ''derived'' families, the Alariaceae, Laminariaceae, and Lessoniaceae (ALL). Molecular phylogenies published for the ALL families have generated hypotheses strongly at odds with the current morphological taxonomy; however, conflicting phylogenetic hypotheses and consistently low levels of support realized in all of these studies have resulted in conservative approaches to taxonomic revisions. In order to resolve relationships within this group we have sequenced over 6000 bp from regions in the nuclear, chloroplast, and mitochondrial genomes and included 42 taxa in Bayesian, neighbor-joining, and parsimony analyses. The result is the first comprehensive and well-supported molecular phylogeny for the ALL complex of the Laminariales. We maintain the three recognized families (Alariaceae, Laminariaceae, and Lessoniaceae), but with vastly different compositions, as well as propose the Costariaceae fam. nov. for Agarum, Costaria, Dictyoneurum, and Thalassiophyllum, the only genera in the Laminariales with flattened, occasionally terete, stipes and either a perforate or reticulate blade. In addition, our data strongly support a split of the genus Laminaria. We resurrect the genus Saccharina Stackhouse for the Laminaria clade that does not contain L. digitata (Hudson) J.V. Lamouroux, the type of the genus.

Conservation and polymorphism of mitochondrial intergenic sequences in brown algae (Phaeophyceae)

“…The few exceptions were generally concordant with the current phylogenies (Yoon et al, 2001;Lane et al, 2006). For example, two loci (rps14/atp8 and rpl31/rns) amplify in only one of the two Lessoniaceae species of the tested taxa, Ln and Mp, but both Yoon et al, (2001) and Lane et al, (2006) demonstrated that these are paraphyletic.…”

“…In the Phaeophyceae, the existing repertoire of mitochondrial markers has generally been limited to conserved coding regions used for higher-order phylogenetics (Ehara et al, 1999;Lane et al, 2006;Oudot-Le Secq et al, 2006), detection of interspecific hybridization (Coyer et al, 2002a,b) and, more recently, for phylogeographic studies (Muraoka & Saitoh, 2005;Uwai et al, 2006a). However, for lower-level taxonomic and population-level studies, presumably neutral, non-coding regions, such as introns or intergenic spacers are preferable, to avoid the confounding effects of selection, which are particularly problematic in phylogeographic studies where patterns of gene flow must be inferred from gene genealogies.…”

Complete mitogenome of Saccharina cultivation variety ‘Ailunwan’(Saccharina japonica × latissima)

“…Phylogenetic analyses showed that 'Ailunwan' firstly groups with Saccharina japonica. It indicated that 'Ailunwan' had a closer evolutionary relationship with Saccharina than Laminaria, supporting current taxonomic systems (Yoon et al 2001;Lane et al 2006). …”

Deep-water kelp refugia as potential hotspots of tropical marine diversity and productivity

“…Second, east-west differences in deep-water tropical kelp genera are conspicuous. The eastern tropical Pacific contains Eisenia only, one of the most derived genera in the kelp order Laminariales (21). The western tropical Pacific and Atlantic Oceans harbor three species of deep-water Laminaria, all of which have primitive traits for the Laminariales (16,17), suggesting an ancient origin (Ͼ30 Mya) (22) and relative permanence of deep-water kelp refugia.…”