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Phylogeny of the chlorophyta: inferences from 18S and 26S rDNA
Author(s) -
Buchheim M. A.,
Buchheim J. A.
Publication year - 2003
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.0022-3646.2003.03906001_15.x
Subject(s) - biology , ulvophyceae , chlorophyceae , monophyly , chlorophyta , clade , phylogenetics , evolutionary biology , botany , algae , genetics , gene
Recent studies of the Chlorophyceae using 18S and 26S rDNA data in meta‐analysis have demonstrated the power of combining these two sets of rDNA data. Furthermore, the 26S rDNA data complement the more conserved 18S gene for many chlorophycean lineages. Consequently, this data approach was pursued in an expanded taxon‐sampling scheme for the Chlorophyta, with special reference to the classes Chlorophyceae and Trebouxiophyceae. Results of these new phylogenetic analyses identify Microspora sp. (UTEX LB 472) and Radiofilum transversale (UTEX LB 1252) as sister taxa which, in turn, form a basal clade in the Cylindrocapsa alliance (Treubaria, Trochiscia, Elakatothrix). The relative position of the “Cylindrocapsa” clade within the Chlorophyceae remains uncertain. The enhanced taxon‐sampling has not resolved the relative positions of the Oedogoniales, Chaetophorales or Chaetopeltidales. Furthermore, the Sphaeropleaceae are supported as members of the Sphaeropleales in only some analyses, raising concerns about the status of the order. Although based on a limited set of taxa (currently <10), a combined data approach reveals support for a monophyletic Trebouxiophyceae that includes the distinctive organisms, Geminella and Eremosphaera. The goal of a well‐resolved phylogeny for the Chlorophyta remains just that, a goal. Achieving that goal obviously will require additional taxon sampling in the Prasinophyceae and Ulvophyceae, as well as, the Trebouxiophyceae. Moreover, it is clear that other genes (e.g., cp‐atpB, cp‐rbcL, cp‐16S, mt‐nad5) will be needed to help address problems of resolution based on the rDNA data alone. Supported by NSF DEB 9726588 and DEB 0129030.