PHYLOGENY OF THE EUGLENOPHYTES INFERRED FROM SSU AND LSU rDNA

Abstract

Zimmermann, S. & Triemer, R. E.Department of Life Sciences, Rutgers University, Piscataway, NJ 08854 USAThe phylogeny of the Euglenophytes has previously been examined using the SSU rDNA. Results from these analyses indicated that the phototrophic genera are not monophyletic. To test this hypothesis, a second gene was sequenced, the LSU rDNA. The taxa used in this study were selected from clades represented in the SSU analyses so that comparisons could be made between gene phylogenies and a combined dataset could be created. Conserved areas of the aligned sequences for both the LSU and SSU were used to generate parsimony, maximum likelihood, and distance trees. Topology of the SSU and LSU trees was similar. The SSU and LSU data consistently generated the same four highly supported terminal clades and varied only in the placement of Euglena stellata and Euglena viridis. The internal nodes of the SSU trees were weakly supported, whereas the LSU provided higher support for these nodes. A combined LSU and SSU dataset was then created. Analysis of the combined dataset yielded trees with identical topologies to those found in the individual datasets and demonstrated strong support for the four terminal clades. These results show that phylogeny of the Euglenophytes as inferred previously from SSU data is confirmed by the LSU data and that the LSU rDNA gene may be useful in elucidating relationships among the major clades.