Phylogenetic Relationships of the "Green Algae" and "Bryophytes"

Abstract

Considerable progress has been made recently, based on classical morphological characters and newly described ultrastructural features, in understanding the phylogenetic relationships of the tracheophytes to the green algae and bryophytes. Recent technological advances in molecular biology, particularly the advent of the polymerase chain reaction (PCR), have allowed nucleotide sequence data relevant to such large-scale phylogenetic questions to accumulate, especially ribosomal RNA gene sequences (both the large and small subunits) from the nucleus and the chloroplast. We present synthetic cladistic analyses of the green plants that combine and compare available morphological and molecular data sets. Although the resulting phylogenies are poorly resolved in some areas at present, certain conclusions are supported: (1) The green plants are composed of two major monophyletic groups, one containing the "charophyte green algae and the land plants (i.e., "bryophytes" plus tracheophytes), the other containing the bulk of the classically delimited "green algae" (chlorophytes, pleurastrophytes, and ulvophytes). ( 2) The land plants are a well-supported monophyletic group, but neither the specific outgroup for the land plants nor the precise relationships among basa lineages of land plants are clear. In many analyses (including the combined molecular and morphological analysis) the three major lineages (i.e., liverworts, hornworts, and mosses) appear to be paraphyletic with respect to the tracheophytes, with an indication that the mosses alone may be the sister group of the tracheophytes; however, in other analyses the "bryophytes" are supported as a monophyletic group. (3) The ulvophytes, chlorophytes, and pleurastrophytes are each supported as monophyletic (with the exception of a few taxa that may be misplaced m the current classification), with the topology: [ulvophytes [chlorophytes + pleurastrophytes]]. Combined analyses o! molecular and morphological data offer the greatest potential for resolving these relationships.

Monophyly of Genera and Species of Characeae based on rbcL Sequences, with Special Reference to Australian and European Lychnothamnus barbatus (Characeae: Charophyceae)

“…New rbcL sequences for 18 species in five genera of Characeae are provided. Outgroup taxa were chosen from other charophycean green algae and land plants, which are well supported as members of the same clade containing the Characeae (Graham et al 1991;Mishler et al 1994;McCourt 1995).…”

Phylogeny and Molecular Evolution of the Green Algae

“…Analyses of DNA sequence data took a start in the mid 1980's with the first phylogenies of green plants inferred from 5.8S nrDNA sequences (Hori et al, 1985;Hori & Osawa, 1987), soon followed by 18S and 28S nrDNA sequence analyses (Gunderson et al, 1987;Perasso et al, 1989;Buchheim et al, 1990;Zechman et al, 1990;Chapman et al, 1991;Mishler et al, 1992;Chapman et al, 1998). Ribosomal sequences were chosen at the time because enough RNA could be obtained for direct sequencing and (later) because regions of the gene were conserved enough to make universal primers.…”

Hormonal regulation in green plant lineage families

“…This lineage is believed to be monophyletic in origin (Graham, 1996). The phylogenetic relationships of different lineages of land plants -the embryophytes represented by green algae, bryophytes, pteridophytes and seed plants have been reviewed extensively (Karol et al, 2001;Kendric and Crane, 1997;Mishler et al, 1994;Renzaglia et al, 2000). Here, only the salient features of the most widely accepted viewpoint will be discussed.…”