Different phylogenetic trees describing the relationship between eukaryotes and archaea. A) Three Sisters Tree- the three domains of life are nearly equally related, with no special relationship between Eukarya and Archaea. Although a trivergence is not allowed in phylogeny, one is shown here since it would be unclear in this model which domain diverged from the others first. B) Crenote Tree- (aka Eocyte Tree) Eukarya and Crenarchaeota are sister groups. C) Euryote Tree- Eukarya and Euryarchaeota are sister groups. D) Synote Tree- Eukarya are derived from a fusion between Crenarchaeota and Euryarchaeota. For simplicity, the genetic contributions arising from the α-proteobacteria endosymbiont are not included in any of these trees.