Newspaper article The Christian Science Monitor

Newly Discovered Microbes Expand Tree of Life, Say Scientists

Newspaper article The Christian Science Monitor

Newly Discovered Microbes Expand Tree of Life, Say Scientists

Article excerpt

If you are alive on Earth, there's a good chance you're microscopic.

"From a diversity perspective, 95 percent" of life on this planet is smaller than the eye can see, Laura Hug, an environmental microbiologist at the University of Waterloo in Canada says. And that collection of microorganisms just got a lot more complex.

Dr. Hug and her colleagues have reported more than 1,000 previously undocumented microbes in a paper published Monday in the journal Nature Microbiology. These additions greatly expand the tree of life, a model used by biologists to describe the phylogenetic relationships between all known species, living and extinct.

"The tree itself is a depiction of the relationship of all of the organisms that are on the planet, all living things," Hug tells The Christian Science Monitor in an interview. "That includes humans and plants and the things we can see, and it also includes all of the microorganisms that are too small to see with the naked eye."

The new additions are largely bacteria and archaea, two microscopic ancient lineages of life that were once thought to be the same. Together, they make up the vast majority, 95 percent, of life forms on Earth.

"Keep in mind that they've had 2 billion years longer to develop and to diversify than the eukaryotes [beings, like animals, with more complex cellular structure]. The eukaryotes emerged later, so they're running on a disadvantage," Hug says.

This new study was made possible by a scientific breakthrough. Previously, scientists looking to identify new organisms by their genomes would isolate and cultivate the cells in a lab. But not all organisms can survive and grow in that environment. Many of these microorganisms depend on other organisms. But now, using genome- based approaches developed in the past two decades, scientists are able to dig into the DNA of microbes in their environment.

The organisms in this study were found in a wide range of places. Some were found in mundane places like sediments, while others were in extreme environments, like a hot spring in Yellowstone National Park, or salt flats in the Atacama Desert. …

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