Archaea and the prokaryote-to-eukaryote transition

Since the late 1970s, determining the phylogenetic relationships among the contemporary domains of life, the Archaea (archaebacteria), Bacteria (eubacteria), and Eucarya (eukaryotes), has been central to the study of early cellular evolution. The two salient issues surrounding the universal tree of life are whether all three domains are monophyletic (i.e., all equivalent in taxanomic rank) and where the root of the universal tree lies....