PHYLOGENY OF THE CONJUGATING GREEN ALGAE BASED ON CHLOROPLAST AND MITOCHONDRIAL NUCLEOTIDE SEQUENCE DATA¹

Abstract

The conjugating green algae represent a lineage of charophyte green algae known for their structural diversity and unusual mode of sexual reproduction, conjugation. These algae are ubiquitous in freshwater environments, where they are often important primary producers, but few studies have investigated evolutionary relationships in a molecular systematic context. A 109-taxon data set consisting of three gene fragments (two from the chloroplast and one from the mitochondrial genome) was used to estimate the phylogeny of the genera of the conjugating green algae. Maximum likelihood (ML), maximum parsimony (MP), and Bayesian inference (BI) were used to estimate relationships from the 4,047 alignable nucleotides. This study confirmed the polyphyly of the Zygnemataceae and Mesotaeniaceae with respect to one another. The Peniaceae were determined to be paraphyletic, and two genera traditionally classified among the Zygnematales appear to belong to the lineage that gave rise to the Desmidiales. Six genera, Euastrum, Cosmarium, Cylindrocystis, Mesotaenium, Spondylosium, and Staurodesmus, were polyphyletic in this analysis. These findings have important implications for the evolution of structural characteristics in the group and will require some taxonomic changes. More work will be required to delineate lineages of Zygnematales in particular and to identify structural synapomorphies for some of the newly identified clades.

Diversity and morphological disparity of desmid assemblages in Central European peatlands

“…6). While we know that most of these genera are, in fact, polyphyletic or paraphyletic (Gontcharov, 2008;Hall et al 2008), the similarity of their disparity or complexity is not surprising, given the fact that they have been defined almost entirely on the basis of morphological data. Members of the genus Micrasterias generally had the highest partial morphological disparities (PD), indicating their large contribution to the total morphological disparity of the entire set ( Fig.…”

“…The Desmidiales were chosen as a species-rich monophyletic group of green algae (Gontcharov, 2008;Hall et al, 2008), typically inhabiting benthic freshwater environments (Coesel & Meesters, 2007). Natural assemblages of desmids are known to subtly reflect the environmental conditions of localities (e.g.…”

Molecular and morphological diversity of Zygnema and Zygnemopsis (Zygnematophyceae, Streptophyta) from Svalbard (High Arctic)

“…sequences (Pichrtová et al ., 2013, 2014 b ), other unique rbc L Zygnema and Zygnemopsis sequences available in the GenBank database and several closely related Zygnematophyceae sequences (based on BLAST searches and Hall et al . 2008). The alignment also included Arctic Zygnema strain CCAC 1384B (ASW 07067), which was isolated from Möllerhafen in 1992 and sequenced by Gontcharov et al .…”

Phylogeny and Molecular Evolution of the Green Algae

“…The latter order consists of unicells, filaments and colonies with conspicuously ornamented cell walls and cells constricted in two half cells (semicells). The diversity and phylogenetic relationships within the lineage have been studied with nuclear rDNA and chloroplast rbcL sequence data (Denboh et al, 2001;Drummond et al, 2005;Gontcharov & Melkonian, 2005;Kim et al, 2006;Gontcharov & Melkonian, 2008;Hall et al, 2008a;Hall et al, 2008b;Gontcharov & Melkonian, 2010;Gontcharov & Melkonian, 2011).…”