Phylogenetic Relationships and Morphological Character Evolution of Photosynthetic Euglenids (Excavata) Inferred from Taxon-rich Analyses of Five Genes.
Photosynthetic euglenids acquired chloroplasts by secondary endosymbiosis, which resulted in changes to their mode of nutrition and affected the evolution of their morphological characters. Mapping morphological characters onto a reliable molecular tree could elucidate major trends of those changes. We analyzed nucleotide sequence data from regions of three nuclear-encoded genes (nSSU, nLSU, hsp90), one chloroplast-encoded gene (cpSSU) and one nuclear-encoded chloroplast gene (psbO) to estimate phylogenetic relationships among 59 photosynthetic euglenid species. Our results were consistent with previous works; most genera were monophyletic, except for the polyphyletic genus Euglena, and the paraphyletic genus Phacus. We also analyzed character evolution in photosynthetic euglenids using our phylogenetic tree and eight morphological traits commonly used for generic and species diagnoses, including: characters corresponding to well-defined clades, apomorphies like presence of lorica and mucilaginous stalks, and homoplastic characters like rigid cells and presence of large paramylon grains. This research indicated that pyrenoids were lost twice during the evolution of phototrophic euglenids, and that mucocysts, which only occur in the genus Euglena, evolved independently at least twice. In contrast, the evolution of cell shape and chloroplast morphology was difficult to elucidate, and could not be unambiguously reconstructed in our analyses.
Department of Plant Systematics and Geography, Faculty of Biology, University of Warsaw, Warsaw, Poland; Department of Parasitology, Faculty of Science, Charles University in Prague, Prague, Czech Republic.
Anna
A
Karnkowska
Matthew S
MS
Bennett
Donovan
D
Watza
Jong Im
JI
Kim
Bożena
B
Zakryś
Richard E
RE
Triemer
D019295:Computational Biology; D016822:Euglenida / Q000145:classification* / Q000166:cytology / Q000235:genetics*; D019143:Evolution, Molecular; D017125:Genes, Protozoan; D018841:HSP90 Heat-Shock Proteins / Q000235:genetics; D045332:Photosystem II Protein Complex / Q000235:genetics; D010802:Phylogeny; D012335:RNA, Ribosomal / Q000235:genetics; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D017422:Sequence Analysis, DNA
D018841:HSP90 Heat-Shock Proteins; D045332:Photosystem II Protein Complex; D012335:RNA, Ribosomal; D012337:RNA, Ribosomal, 18S; C065096:RNA, ribosomal, 26S
Algae; Euglenea; Euglenida; LSU rDNA; SSU rDNA; hsp90; molecular phylogeny; protists; psbO