title: Another origin of coloniality in volvocaleans: the phylogenetic position of Pyrobotrys arnoldi (Spondylomoraceae, Volvocales).
abstract: Colonial volvocaleans (Chlorophyceae) are used as a standard model of multicellular evolution. However, the phylogenetic position of the colonial volvocalean family Spondylomoraceae has yet to be resolved. To examine this, the molecular phylogenies of Pyrobotrys stellata and Pyrobotrys squarrosa were analyzed using combined 18S rRNA, RUBISCO large subunit, and P700 chl a-apoprotein A2 gene sequences. In the phylogenetic trees, Pyrobotrys belonged to the clade Caudivolvoxa and was not closely related to other colonial volvocalean flagellates. The results indicate that colony formation of Spondylomoraceae independently evolved from unicellular volvocaleans. The phylogenetic position of problematic "Pascherina tetras" SAG 159-1 was also analyzed.
authors.affiliation: Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, Japan. naktak@ttck.keio.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakada
authors.forename: Hisayoshi
authors.initials: H
authors.lastname: Nozaki
authors.forename: Masaru
authors.initials: M
authors.lastname: Tomita
mesh_terms: D000460:Chlorophyta / Q000145:classification* / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification; D048028:DNA, Algal / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D019143:Evolution, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny
chemical_list: D048028:DNA, Algal; D004275:DNA, Ribosomal