An article published in the journal “Nature Microbiology” describes a genetic research that offers a broader vision of the tree of life. A team of researchers of the University of California, Berkeley, led by Laura Hug, who now works at the biology faculty of the University of Waterloo, Ontario, Canada, built a new tree of life showing a diversity formed for two thirds by bacteria and archaea.
In the last twenty years or so, with the growing possibility of genetic analyzes, the research on the tree of life and the relations among the various organisms has made enormous progress. The discovery of organisms very different from the ones already known has vastly expanded the tree of life known only a few decades ago, making it much more complex. This new research suggests an even greater diversity than expected among microorganisms.
The researchers analyzed the DNA of more than 1,000 new microorganisms they discovered in the last 15 years and of other representatives of the various taxonomic genera for which complete genomes were available for a total of 3,083 organisms. They represent the three domains of life: eukaryotes, bacteria and archaea. Only in 1977 the biologists added the archaea domain when their instruments became sophisticated enough to allow them to realize that the those microorganisms’ characteristics were very different from those of bacteria.
This extension of the tree of life is due to the many microorganisms discovered by Berkeley researchers. They were found in a variety of different environments, from the hot springs of Yellowstone National Park, in the USA, to the Atacama Desert in Chile. A new species was been found in the mouth of a dolphin.
A large branch added to the tree of life, for now called just with the vague expression “candidate phyla radiation”, is made only by bacteria that live in symbiosis. From the genetic point of view, these bacteria seem to constitute about half of the evolutionary diversity of bacteria. Isolating organisms that live in symbiosis with other species to analyze their DNA was a complicated undertaking and for that reason more research is needed to verify that no genomes are actually the result of contamination.
The results of this research are of such magnitude that they can be a starting point for a new phase in genetic research. This new tree of life is still growing and it’s impossible to say how many studies can be carried out about the strange microorganisms uncovered and what consequences they can have on our biological knowledge.