The taxonomy and of silica-scaled chrysophytes (microalgae) was once based on cell shape alone. With the event of electron microscopy, the ultrastructure of the silica scales became the main basis for the taxonomy and for our understanding of phylogenetic relationships. Most recently, it has become possible to evaluate these taxonomic classifications using DNA sequence data. This history of taxonomic developements is thoroughly reviewed in this new article, ending with the results of a completely new phylogenetic reconstruction based on both nuclear (SSU rDNA) and chloroplast (rbcL) sequences. The two datasets are shown to be highly incongruent, with the nuclear phylogeny being in best agreement with existing micro-morphological data. It is suggested that the rbcL gene has experienced positive selection in contrasting environments explaining its apparent incongruence with other sets of data. As a result of the newly constructed molecular phylogeny, a number of taxonomic rearrangements are proposed at both the ordinal and the species level and the non-monophyly of the silica-scaled chrysophytes as a whole is clearly demonstrated. onlinelibrary.wiley/doi/10.1111/j.1756-1051.2013.00119.x/abstract
Posted on: Tue, 16 Jul 2013 07:21:54 +0000
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