Phylogeny of the Centrohelida Inferred from SSU rRNA, Tubulins, and Actin Genes |
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Authors: | Miako Sakaguchi Takeshi Nakayama Tetsuo Hashimoto Isao Inouye |
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Institution: | (1) Institute of Biological Sciences, University of Tsukuba, Tsukuba 305-8572, Japan |
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Abstract: | Amoeboid protists are major targets of recent molecular phylogeny in connection with reconstruction of global phylogeny of
eukaryotes as well as the search for the root of eukaryotes. The Centrohelida are one of the major groups of Heliozoa, classified
in the Actinopodida, whose evolutionary position is not well understood. To clarify the relationships between the Centrohelida
and other eukaryotes, we sequenced SSU rRNA, α-tubulin, and β-tubulin genes from a centroheliozoan protist, Raphidiophrys contractilis. The SSU rRNA phylogeny showed that the Centrohelida are not closely related to other heliozoan groups, Actinophryida, Desmothoracida,
or Taxopodida. Maximum likelihood analyses of the combined phylogeny using a concatenate model for an α- + β-tubulin + actin
data set, and a separate model for SSU rRNA, α- and β-tubulin, and actin gene data sets revealed the best tree, in which the
Centrohelida have a closer relationship to Rhodophyta than to other major eukaryotic groups. However, both weighted Shimodaira–Hasegawa
and approximately unbiased tests for the concatenate protein phylogeny did not reject alternative trees in which Centrohelida
were constrained to be sisters to the Amoebozoa. Moreover, alternative trees in which Centrohelida were placed at the node
branching before and after Amoebozoa or Viridiplantae were not rejected by the WSH tests. These results narrowed the possibilities
for the position of Centrohelida to a sister to the Rhodophyta, to the Amoebozoa, or to an independent branch between the
branchings of Amoebozoa and Rhodophyta (or possibly Plantae) at the basal position within the bikonts clade in the eukaryotic
tree.
Reviewing Editor: Dr. Martin Kreitman] |
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Keywords: | Heliozoa Centrohelida Tubulin Maximum likelihood Concatenate phylogeny Protists |
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