Scientists from the University of California (UC), Berkeley have revamped the tree of life through the addition of more than 1,000 new species that have been discovered in recent years. The additions are mostly comprised of Archaea, a kingdom of single-celled microorganisms, revealing the abundance of life and biodiversity that remains unseen to the human eye.
"The tree of life is one of the most important organizing principles in biology," said Jill Banfield, a professor at UC Berkeley. "The new depiction will be of use not only to biologists who study microbial ecology, but also biochemists searching for novel genes and researchers studying evolution and earth history."
The newly added microbial diversity was unearthed due to the ability of scientists to now directly search for genomes in the environment as opposed to culturing them in a lab dish. Since many of these microbes cannot be cultured as they do not have the ability to live on their own, this genome revolution opens up an opportunity to reveal the numerous Archaea that would otherwise have never been discovered.
"Bacteria and Archaea from major lineages completely lacking isolated representatives comprise the majority of life's diversity," said Banfield. "This is the first three-domain genome-based tree to incorporate these uncultivable organisms, and it reveals the vast scope of as yet little-known lineages."
The newly reported organisms on the revised tree of life originate from a variety of environments including Yellowstone National Park, Chile's Atacama Desert and the inside of a dolphin's mouth. Each of the newly discovered organisms were revealed using just their genomes.
"What became really apparent on the tree is that so much of the diversity is coming from lineages for which we really only have genome sequences," said Laura Hug, first author of the study and a member of the biology faculty at the University of Waterloo. "We don't have laboratory access to them, we have only their blueprints and their metabolic potential from their genome sequences. This is telling, in terms of how we think about the diversity of life on Earth, and what we think we know about microbiology."
Although the tree of life has yet to solve the mystery of the relationship between Archaea and eukaryotes - any organism whose cells are contained in a nucleus - the new tree offers a new perspective on the history of known organisms.
"This incredible diversity means that there are a mind-boggling number of organisms that we are just beginning to explore the inner workings of that could change our understanding of biology," said Brett Baker, co-author of the study and a researcher from the University of Texas.
The findings were published in the April 11 issue of Nature Microbiology.
