Chlorophyta research projects
Phylogeny and diversity
of Chaetomorpha, Rhizoclonium and related genera (Cladophorophyceae,
Chlorophyta)
Christian Boedeker, Dr. W. Prud’homme van Reine, Dr. J. Zuccarello – NHN Leiden
| The genus Chaetomorpha
consists of unbranched, uniseriate filaments, while the genus
Rhizoclonium has thinner filaments that can produce short lateral
rhizoids under certain conditions. Both genera lack complex
morphological features and the traditional diagnostic characters are
filament diameter, the length/width ratio of the cells, as well as the
presence, size and structure of the basal cell. The present taxonomy is
very confused since species definitions overlap and the few morphometric
characters that exist might be variable or not reflect phylogentic
relationships. Many species have been described from different regions
of the world and it is not clear which ones are synonyms of other
species. In addition, recent molecular studies of the Cladophorophyceae
indicate that both Chaetomorpha and Rhizoclonium are not
monophyletic genera. This study will try to understand the grouping of
taxa within the Cladophoraceae and the evolutionary relationship to the
branched genus Cladophora; to investigate biogeographic patterns
and to possibly identify introduced species. World-wide taxon sampling
is important. A phylogeny based on 28S rDNA sequences will be developed,
traditional morphological characters will be mapped on phylogenetic
trees to test their diagnostic value and their variability will be
examined in culture studies. Species of Chaetomorpha along with Enteromorpha and Ulva form part of green tides in different areas of the world and can be serious pests. To assess the genetic diversity within these blooms, the variation within species/between populations will be assessed by using a variable genetic marker. It will be especially interesting to see if unattached forms are distinct, if blooms consist mainly of clones and if these blooms are possibly formed by introduced species. |
Rhizoclonium lateral branches |
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