Mariscal Carlos, Doolittle W Ford
Departments of Philosophy, Dalhousie University, PO Box 15000, Halifax, Nova Scotia, Canada B3H 4R2 Biochemistry and Molecular Biology, Dalhousie University, PO Box 15000, Halifax, Nova Scotia, Canada B3H 4R2.
Biochemistry and Molecular Biology, Dalhousie University, PO Box 15000, Halifax, Nova Scotia, Canada B3H 4R2
Philos Trans R Soc Lond B Biol Sci. 2015 Sep 26;370(1678):20140322. doi: 10.1098/rstb.2014.0322.
In the half century since the formulation of the prokaryote : eukaryote dichotomy, many authors have proposed that the former evolved from something resembling the latter, in defiance of common (and possibly common sense) views. In such 'eukaryotes first' (EF) scenarios, the last universal common ancestor is imagined to have possessed significantly many of the complex characteristics of contemporary eukaryotes, as relics of an earlier 'progenotic' period or RNA world. Bacteria and Archaea thus must have lost these complex features secondarily, through 'streamlining'. If the canonical three-domain tree in which Archaea and Eukarya are sisters is accepted, EF entails that Bacteria and Archaea are convergently prokaryotic. We ask what this means and how it might be tested.
自提出原核生物与真核生物二分法以来的半个世纪里，许多作者不顾普遍（甚至可能是常识性）观点，提出前者是从类似后者的某种东西进化而来的。在这种“真核生物先出现”（EF）的设想中，最后的共同祖先被认为拥有当代真核生物的许多复杂特征，这些特征是早期“原生生物”时期或RNA世界的遗留物。因此，细菌和古菌必然是通过“简化”而次生地失去了这些复杂特征。如果接受古菌和真核生物是姐妹关系的标准三域树，那么EF意味着细菌和古菌是趋同的原核生物。我们探讨这意味着什么以及如何进行检验。
