Saldarriaga J F, Taylor F J, Keeling P J, Cavalier-Smith T
Department of Botany, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, V6T 1Z4, Canada.
J Mol Evol. 2001 Sep;53(3):204-13. doi: 10.1007/s002390010210.
Dinoflagellates are a trophically diverse group of protists with photosynthetic and non-photosynthetic members that appears to incorporate and lose endosymbionts relatively easily. To trace the gain and loss of plastids in dinoflagellates, we have sequenced the nuclear small subunit rRNA gene of 28 photosynthetic and four non-photosynthetic species, and produced phylogenetic trees with a total of 81 dinoflagellate sequences. Patterns of plastid gain, loss, and replacement were plotted onto this phylogeny. With the exception of the apparently early-diverging Syndiniales and Noctilucales, all non-photosynthetic dinoflagellates are very likely to have had photosynthetic ancestors with peridinin-containing plastids. The same is true for all dinoflagellates with plastids other than the peridinin-containing plastid: their ancestors have replaced one type of plastid for another, in some cases most likely through a non-photosynthetic intermediate. Eight independent instances of plastid loss and three of replacement can be inferred from existing data, but as more non-photosynthetic lineages are characterized these numbers will surely grow.
甲藻是一类营养方式多样的原生生物，包括光合和非光合成员，它们似乎相对容易地摄取和丢失内共生体。为了追踪甲藻中质体的获得与丢失情况，我们对28种光合甲藻和4种非光合甲藻的核小亚基rRNA基因进行了测序，并利用总共81个甲藻序列构建了系统发育树。质体的获得、丢失和替换模式被绘制到这个系统发育树上。除了明显早期分化的聚缩虫目和夜光虫目外，所有非光合甲藻很可能都有含叶绿素a的光合祖先。对于所有具有除含叶绿素a质体之外其他质体的甲藻来说也是如此：它们的祖先将一种质体替换为另一种质体，在某些情况下很可能是通过一个非光合中间体实现的。从现有数据可以推断出8个质体丢失的独立实例和3个质体替换的实例，但随着更多非光合谱系被鉴定，这些数字肯定会增加。
