Another Origin of Coloniality in Volvocaleans: The Phylogenetic Position of Pyrobotrys Arnoldi (Spondylomoraceae,Volvocales) |
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| Authors: | TAKASHI NAKADA HISAYOSHI NOZAKI MASARU TOMITA |
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| Institution: | 1. Institute for Advanced Biosciences, Keio University, 246‐2 Mizukami, Kakuganji, Tsuruoka, Yamagata 997‐0052, Japan;2. Graduate School of Media and Governance, Keio University, Fujisawa 252‐8520, Japan;3. Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7‐3‐1, Hongo, Bunkyo‐ku, Tokyo 113‐0033, Japan |
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| Abstract: | 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. |
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| Keywords: | Chlorophyceae molecular phylogeny multicellularity |
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