Tracing back to the beginning of life on Earth more than 3.5 billion years ago, scientists have created the first "tree of life" for the roughly 2.3 million named species of animals, plants, fungi and microbes.
Tens of thousands of smaller trees have been built over the years for select branches of the tree of life--some containing upwards of 100,000 species--but this is the first time those results have been combined into a single tree that encompasses all of life, the study said.
A collaborative effort among 11 institutions, the tree depicts the relationships among living things as they diverged from one another over time.
Understanding how the millions of species on Earth are related to one another helps scientists discover new drugs, increase crop and livestock yields, and trace the origins and spread of infectious diseases such as human immunodeficiency virus (HIV), Ebola and influenza.
"This is the first real attempt to connect the dots and put it all together," said principal investigator Karen Cranston from Duke University in Durham, US.
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"Think of it as Version 1.0," Cranston noted.
Rather than build the tree of life from scratch, the researchers pieced it together by compiling thousands of smaller chunks that had already been published online and merging them into a gigantic "supertree" that encompasses all named species.
"Many participants on the project contributed hundreds of hours tracking down and cleaning up thousands of trees from the literature, then selecting 484 of them that were used to generate the draft tree of life," study first author Cody Hinchliff from University of Idaho in the US.
Combining the 484 trees was a painstaking process that took three years to complete, Stephen Smith, assistant professor at University of Michigan in the US, pointed out.
The end result is a digital resource that is available free online for anyone to use or edit, much like a "Wikipedia" for evolutionary trees.
The findings were published on Friday in the online edition of the journal Proceedings of the National Academy of Sciences (PNAS).
