School of Biology and Environmental Science, UCD Science Centre, Belfield, Dublin 4, Ireland.
Proc Biol Sci. 2011 Nov 22;278(1723):3321-8. doi: 10.1098/rspb.2011.1581. Epub 2011 Sep 14.
The question as to the origin and relationship between the three domains of life is lodged in a phylogenetic impasse. The dominant paradigm is to see the three domains as separated. However, the recently characterized bacterial species have suggested continuity between the three domains. Here, we review the evidence in support of this hypothesis and evaluate the implications for and against the models of the origin of the three domains of life. The existence of intermediate steps between the three domains discards the need for fusion to explain eukaryogenesis and suggests that the last universal common ancestor was complex. We propose a scenario in which the ancestor of the current bacterial Planctomycetes, Verrucomicrobiae and Chlamydiae superphylum was related to the last archaeal and eukaryotic common ancestor, thus providing a way out of the phylogenetic impasse.
生命的三个域的起源和关系问题陷入了系统发育的僵局。主导范式是将这三个域分开来看。然而，最近被描述的细菌物种表明这三个域之间存在连续性。在这里，我们回顾了支持这一假设的证据，并评估了对生命的三个域起源模型的支持和反对的意义。三个域之间存在中间步骤，这排除了融合来解释真核生物发生的必要性，并表明最后一个普遍共同祖先很复杂。我们提出了一种情景，即当前细菌的浮霉菌门、疣微菌门和衣原体超门的祖先与最后一个古菌和真核生物的共同祖先有关，从而为走出系统发育的僵局提供了一种方法。
