In a recent article, published in the journal Nature Microbiology, a group of researchers from UC Berkeley, in collaboration with other universities and institutes, proposed a new version of the tree of life, which dramatically changes our view of the relationships between the species inhabiting planet Earth.
Many depictions of the tree of life tend to focus on the enormous and well known diversity of eukaryotes, a group of organisms composed of complex cells that includes all animals, plants and fungi.
This version of the tree of life, now published, uses metagenomics analysis of genomic data from many organisms little known before, together with published sequences of genomic data, to infer a significantly different version of the tree of life. This new view reveals the dominance of bacterial diversification. A full scale version of the proposed tree of life enables you to find our own ancestors, in the extreme bottom right of the figure, the Opisthokont group of organisms. The Opisthokonts include both the animal and fungus kingdoms, together with other eukaryotic microorganisms. Opisthokont flagelate cells, such as the sperm of most animals and the spores of the chytrid fungi, propel themselves using a single posterior flagellum, a feature that gives the group its name. At the level of resolution used in the study, humans and mushrooms are so close that they cannot be told apart.
This version of the tree of life maintains the three great trunks that Carl Woese and his colleagues published in the first “universal tree of life”, in the seventies.
Our own trunk, known as eukaryotes, includes animals, plants, fungi and protozoans. A second trunk included many familiar bacteria like Escherichia coli. The third trunk, the Archaea, includes little-known microbes that live in extreme places like hot springs and oxygen-free wetlands.
However, this more extensive and detailed analysis, based on extensive genomic data, provides a more global view of the evolutionary process that has shaped life on Earth for the last four billion years.
Images from the article in Nature Microbiology, by Hug et. al., and the work of Woese et al.