Answers to such questions allow scientists to trace genetic evolution and better understand how genes function. And as more and more species are identified and placed on the tree, these comparisons become more effective and efficient, Donoghue says.
To date, scientists have identified about 1.7 million species living on Earth and estimate that at least 10 million more species await discovery. Millions more species are thought to have gone extinct.
"In trying to figure out how species are related to one another, it immediately becomes clear this is a very large problem that doesn't have an end in sight any time very soon," Donoghue said.
"We're still discovering species, much less figuring out who is related to whom."
The magnitude of the task, Donoghue said, is "enormous."
To help accomplish the task, the National Science Foundation (NSF) established the Assembling the Tree of Life (AToL) project in 2002.
(This news story and the related Pulse of the Planet radio program are funded in part by the National Science Foundation.)
James Collins is NSF's assistant director for biological sciences. He oversees how AToL funding is awarded.
Collins says that fostering collaboration among individual scientists is key to the project's success.
"That's a significant departure from the norm," he said. But the task of assembling the [branches] in today's world requires a new approach to science, he says.
"As you get [the DNA of] more and more organisms sequenced and more and more information about the evolutionary history of particular groups of organisms, it's not a trivial matter to finally come up with the [branches] themselves," he said.
Collins hopes the AToL initiative will eventually establish the major branches on the Tree of Lifegiving scientists a clear picture of gene-level differences among mollusks and worms, invertebrates and vertebrates, plants and animals, and so on.
"We can develop a relatively good picture of what the trunk and branches look like before we haveto continue the analogyall of the leaves done on the tree," he said.
Using the Tree
With the trunk and branches firmly established, Collins says, scientists will be able to use the Tree of Life as a research tool and even to fill in missing leaves.
"Based on the knowledge of the organisms that we already have in place, we can make predictions about organisms we don't know a lot about," he said.
For example, Collins says, if scientists want to find an organism that has properties useful in the cleanup of oil spills, they would first turn to microbes that have known beneficial properties and then examine the microbes' nearest relatives for good matches.
To help engineer new crops, agricultural researchers might study genetic traits that make crops drought resistant.
Donoghue, the Yale biologist, says scientists can use the tree to understand where emerging infectious diseases originate and to search for organisms that have evolved resistance to the diseases in question. Such clues can lead to the development of new drugs, he says.
"Applications are everywhere," he said.
So too are discoveries, he adds. For example, Tree of Life researchers have learned that fungimushrooms and the likeare more closely related to animals than plants.
"This is not just dotting I's and crossing t's," Donoghue saidassembling the tree is more than simply organizing previously known information.
"There are some really exciting things being discovered."
Free Email News Updates
Best Online Newsletter, 2006 Codie Awards
Sign up for our Inside National Geographic newsletter. Every two weeks we'll send you our top stories and pictures (see sample).
SOURCES AND RELATED WEB SITES