Nature：有关地球上生命的“二类别”观点受到支持

自从被称为“古生菌”的一组微生物在1977年被发现以来，研究人员普遍假设地球上所有生命都可以被归入三个类别：细菌和古生菌（二者都没有细胞核，但彼此之间又显然不同）以及真核生物，后者有核细胞。

但在含有以前被认为是真核生物特有的基因的环境古生菌世系的发现刺激下，对认为生命由两个类别组成的模型的支持越来越多。按照这种模型，真核生物是在古生菌类别内演化形成的。

在这篇Review文章中，Martin Embley及同事得出结论认为，现在，有关古生菌多样性的不断增多的知识，再加上在重建长期被割裂的系统发展史方面所取得的进步，倾向于支持“二类别”观点。

原文出处：

Tom A. Williams，Peter G. Foster，Cymon J. Cox& T. Martin Embley.An archaeal origin of eukaryotes supports only two primary domains of life.Nature 504, 231–236 (12 December 2013) doi:10.1038/nature12779.

The discovery of the Archaea and the proposal of the three-domains ‘universal’ tree， based on ribosomal RNA and core genes mainly involved in protein translation， catalysed new ideas for cellular evolution and eukaryotic origins. However， accumulating evidence suggests that the three-domains tree may be incorrect： evolutionary trees made using newer methods place eukaryotic core genes within the Archaea， supporting hypotheses in which an archaeon participated in eukaryotic origins by founding the host lineage for the mitochondrial endosymbiont. These results provide support for only two primary domains of life—Archaea and Bacteria—because eukaryotes arose through partnership between them.