Molecular Evolution in the Laminariales: A Review

Abstract

Analyses of specific regions of kelp chloroplast DNA and nuclear ribosomal DNA offer unambiguous estimates of phylogenetic relationships at all levels of taxonomic organization. For example, sequence analysis of the highly conserved small-subunit ribosomal DNA revealed a close evolutionary relationship among the kelp Costaria costata, chrysophytes and oomycetes. At the other taxonomic extreme, analysis of restriction fragment length polymorphisms (RFLP) resulting from restriction enzyme digestion of the small-subunit rDNA and associated intergenic spacer have been used to define populations of C. costata and identify interspecific hybrids of Alaria. RFLP analysis of chloroplast DNA has suggested an inter-generic phylogeny for the Lessoniaceae which challenges the composition of this family. Sequence analysis of rDNA of selected Alariaceae and Lessoniaceae strengthens the cpDNA challenge to the phylogeny of the Lessoniaceae.