Phylogenomics – Origin of Eukaryotes and TACK superphylum

Phylogenomics – Origin of Eukaryotes and TACK superphylum

All visible life that surrounds us (humans, animals, plants, fungi, etc) belong to one single Domain of Life, the Eukaryotes. Apart from Eukaryotes, a vast unseen world exists that comprises of microscopically small organisms: microbes. These microbes, also referred to as ‘prokaryotes’, consist of the other two Domains of Life, Bacteria and Archaea. They are relatively simple life forms, in contrast to the complex eukaryotic cells, which contain many intracellular structures (nucleus, mitochondria, chloroplasts, etc).

Although many theories have been advanced to explain the rise of the Eukaryotes, none has reached a broad consensus among scientists. One idea that has gathered an important weight in the past decade is that Eukaryotes result from the fusion of two types of microbial cells. The identity of these cells however, remains to be a mystery to date. We aim to trace the identity of these ‘microbial ancestors’ of complex life on our planet using novel, revolutionary technology, in order to gain substantial insights in how complex life originated.

Our research has led us to define a new superphylum in Archaea, the TACK superphylum, that comprises Thauma-, Aig-, Cren- and Korarchaeota. Using phylogenies based on different subsets of conserved proteins, we showed that Eukaryotes are probably a sister clade to the TACK superphylum, or included in it.