Why is a “ring of life” more appropriate to describe the relationships between archaea, bacteria, and eukaryotes than a “tree of life?

 “Tree of life” is a traditional model that describes the origin of Eukaryotes and the relationships between organisms. According to this model, Eukaryotes and Archaea are sister lineages, both descended from bacterial ancestors.  

On the other side, “ring of life” is a modern model by which Eukaryotes arose from a fusion of the other two domains (Archea and Eubacteria) of life. Ancestors of Archea and Eubacteria fused their genomes to form the first Eukaryote-two different branches of the “tree of life” were fused to form the “ring of life”.