Nozaki Hisayoshi, Misumi Osami, Kuroiwa Tsuneyoshi
Department of Biological Sciences, Graduate School of Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Mol Phylogenet Evol. 2003 Oct;29(1):58-66. doi: 10.1016/s1055-7903(03)00089-7.
Since the phylogenetic relationships of the green plants (green algae and land plants) have been extensively studied using 18S ribosomal RNA sequences, change in the arrangement of basal bodies in flagellate cells is considered to be one of the major evolutionary events in the green plants. However, the phylogenetic relationships between biflagellate and quadriflagellate species within the Volvocales remain uncertain. This study examined the phylogeny of three genera of quadriflagellate Volvocales (Carteria, Pseudocarteria, and Hafniomonas) using concatenated sequences from three chloroplast genes. Using these multigene sequences, all three quadriflagellate genera were basal to other members (biflagellates) of the CW (clockwise) group (the Volvocales and their relatives, the Chlorophyceae) and formed three robust clades. Since the flagellar apparatuses of these three quadriflagellate lineages are diverse, including counter clockwise (CCW) and CW orientation of the basal bodies, the CW orientation of the basal bodies might have evolved from the CCW orientation in the ancestral quadriflagellate volvocalean algae, giving rise to the biflagellates, major members of the CW group.
由于利用18S核糖体RNA序列对绿色植物（绿藻和陆地植物）的系统发育关系进行了广泛研究，鞭毛细胞中基体排列的变化被认为是绿色植物主要的进化事件之一。然而，团藻目内双鞭毛物种和四鞭毛物种之间的系统发育关系仍不确定。本研究使用来自三个叶绿体基因的串联序列，对四鞭毛团藻目的三个属（卡特藻属、假卡特藻属和哈夫尼藻属）的系统发育进行了研究。利用这些多基因序列，所有这三个四鞭毛属都位于顺时针（CW）组（团藻目及其近缘类群绿藻纲）其他成员（双鞭毛藻）的基部，并形成了三个稳健的分支。由于这三个四鞭毛谱系的鞭毛器多种多样，包括基体的逆时针（CCW）和CW方向，基体的CW方向可能是从祖先四鞭毛团藻目藻类的CCW方向进化而来的，从而产生了双鞭毛藻，即CW组的主要成员。
