Strange organism has unique roots in the tree of life [View all]

[n2doc]

By Jennifer Welsh

updated 4/29/2012 8:03:01 PM ET

Talk about extended family: A single-celled organism in Norway has been called "mankind's furthest relative." It is so far removed from the organisms we know that researchers claim it belongs to a new base group, called a kingdom, on the tree of life.

"We have found an unknown branch of the tree of life that lives in this lake. It is unique! So far we know of no other group of organisms that descend from closer to the roots of the tree of life than this species," study researcher Kamran Shalchian-Tabrizi, of the University of Oslo, in Norway, said in a statement.

The organism, a type of protozoan, was found by researchers in a lake near Oslo. Protozoans have been known to science since 1865, but because they are difficult to culture in the lab, researchers haven't been able to get a grip on their genetic makeup. They were placed in the protist kingdom on the tree of life mostly based on observations of their size and shape.

In this study, published March 21 in the journal Molecular Biology Evolution, the researchers were able to grow enough of the protozoans, called Collodictyon, in the lab to analyze its genome. They found it doesn't genetically fit into any of the previously discovered kingdoms of life. It's an organism with membrane-bound internal structures, called a eukaryote, but genetically it isn't an animal, plant, fungi, algae or protist (the five main groups of eukaryotes).

"The microorganism is among the oldest currently living eukaryote organism we know of. It evolved around one billion years ago, plus or minus a few hundred million years. It gives us a better understanding of what early life on Earth looked like," Shalchian-Tabrizi said.

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