Ribosomal DNA phylogeny of the Bangiophycidae (Rhodophyta) and the origin of secondary plastids

Abstract

We sequenced the nuclear small subunit ribosomal DNA coding region from 20 members of the Bangiophycidae and from two members of the Florideophycidae to gain insights into red algal evolution. A combined alignment of nuclear and plastid small subunit rDNA and a data set of Rubisco protein sequences were also studied to complement the understanding of bangiophyte phylogeny and to address red algal secondary symbiosis. Our results are consistent with a monophyletic origin of the Florideophycidae, which form a sister-group to the Bangiales. Bangiales monophyly is strongly supported, although Porphyra is polyphyletic within Bangia. Bangiophycidae orders such as the Porphyridiales are distributed over three independent red algal lineages. The Compsopogonales sensu stricto, consisting of two freshwater families, Compsopogonaceae and Boldiaceae, forms a well-supported monophyletic grouping. The single taxon within the Rhodochaetales, Rhodochaete parvula, is positioned within a cluster containing members of the Erythropeltidales. Analyses of Rubisco sequences show that the plastids of the heterokonts are most closely related to members of the Cyanidiales and are not directly related to cryptophyte and haptophyte plastid genomes. Our results support the independent origins of these secondary algal plastids from different members of the Bangiophycidae.

Gene Replacement of Fructose-1,6-Bisphosphate Aldolase Supports the Hypothesis of a Single Photosynthetic Ancestor of Chromalveolates

“…Among those algae with red algal secondary plastids, there is a great diversity of both host and plastid characteristics, which originally led to the belief that these plastids arose through many independent endosymbioses. This conclusion was apparently supported by phylogenetic analyses of both plastid and host gene sequences, which consistently failed to unite these groups but provided no strong alternative (6,15,22,25). Based on the perceived complexity of plastid gain, it was nevertheless proposed that all these groups and their aplastidal relatives originated from a common ancestor and that their plastids are derived from a single, common endosymbiotic event involving a red alga (5).…”

A single origin of the peridinin- and fucoxanthin-containing plastids in dinoflagellates through tertiary endosymbiosis

“…Based on our results and the accepted secondary endosymbiotic origin of the haptophyte plastid (e.g., ref. 33), we postulate that the ancestral dinoflagellate acquired its plastid from a haptophyte through a tertiary plastid replacement. The SH test shows the haptophyte origin model to have significantly greater support than any of the alternative hypotheses (Fig.…”

Building trees of algae: some advances in phylogenetic and evolutionary analysis

“…in genome-scale studies), the interaction between saturation and systematic error becomes a major issue that has to be dealt with in detail (Philippe et al, 2005b;Rodrı´guez-Ezpeleta et al, 2007a). Because the algae consist of some ancient groups, extreme care should be taken to avoid phylogenetic biases (Mu¨ller et al, 2001;Rodrı´guez-Ezpeleta et al, 2007b). Systematic error has also been suggested to be at play at lower taxonomic levels in algae Verbruggen et al, 2007), so it is advisable to be alert to this problem in all phylogenetic endeavours.…”