Reconstruction of phylogenies: A success story
There are two basic kinds of free-living organisms:
prokaryotes, that do not have a cell nucleus, and
eukaryotes, which do. Prokaryotes fall into two major
groups: Eubacteria and Archaea. Phenotypically,
eubacteria and archaea are very similar to each other.
However, it has been demonstrated by using molecular
data that archaea are more closely related to eukaryotes
than to eubacteria, and thus it appears that the
evolutionary branching between archaea and eubacteria
occurred before the branching of archaea and eukaryotes.