Multiple independent losses of photosynthesis and differing evolutionary rates in the genus Cryptomonas (Cryptophyceae): combined phylogenetic analyses of DNA sequences of the nuclear and the nucleomorph ribosomal operons

In this study, evidence for at least three independent losses of photosynthesis in the freshwater cryptophyte genus Cryptomonas is presented. The phylogeny of the genus was inferred by molecular phylogenetic analyses of the nuclear internal transcribed spacer 2 (nuclear ITS2), partial nuclear large...

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Bibliographic Details
Published in:Journal of molecular evolution 2005-02, Vol.60 (2), p.183-195
Main Author: Hoef-Emden, Kerstin
Format: Article
Language:English
Subjects:
Base Composition
Base Sequence
Cryptomonas
Cryptophyceae
Cryptophyta - classification
Cryptophyta - genetics
Cryptophyta - metabolism
DNA, Algal - genetics
DNA, Ribosomal - genetics
Evolution, Molecular
Models, Biological
Molecular Sequence Data
Nucleic Acid Conformation
Operon
Photosynthesis - genetics
Phylogeny
Rhodophyta - genetics
Rhodophyta - metabolism
RNA, Algal - chemistry
RNA, Algal - genetics
RNA, Ribosomal - chemistry
RNA, Ribosomal - genetics
Symbiosis
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Summary:In this study, evidence for at least three independent losses of photosynthesis in the freshwater cryptophyte genus Cryptomonas is presented. The phylogeny of the genus was inferred by molecular phylogenetic analyses of the nuclear internal transcribed spacer 2 (nuclear ITS2), partial nuclear large subunit ribosomal DNA (LSU rDNA), and nucleomorph small subunit ribosomal DNA (SSU rDNA, NM). Both concatenated and single data sets were used. In all data sets, the colorless Cryptomonas strains formed three different lineages, always supported by high bootstrap values (maximum parsimony, neighbor joining and maximum likelihood) and posterior probabilities (Bayesian analyses). The three leukoplast-bearing lineages displayed differing degrees of accelerated evolutionary rates in nuclear and nucleomorph rDNA. Also an increase in A + T-content in highly variable regions of the nucleomorph SSU rDNA was observed in one of the leukoplast-bearing lineages.
ISSN:0022-2844
1432-1432
DOI:10.1007/s00239-004-0089-5