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The highly fatal hantavirus is carried by deer mice, and genetic analysis has shown that mice and hantaviruses have a long co-evolutionary history in the Americas, suggesting that most major mice lineages may carry an associated hantavirus.
Blossoming of a billion-year-old tree
University researchers are part of a massive effort to construct the evolutionary tree of life
By Deane Morrison
Published on September 20, 2005
If you have siblings, you know the warm feeling when somebody tells you you don't look a thing like your bratty younger brother or snotty older sister. All well and good, but when close relatives in the plant, animal, or microbial world don't resemble each other, it can make it hard to target pesticides appropriately, identify invasive species before they damage an ecosystem, or predict a likely source organism for a drug, among other difficulties. That's why the National Science Foundation (NSF) in 2002 launched its 15-year "Assembling the Tree of Life"(ATOL) project to construct a family tree for 1.7 million known species of plants, animals, and microbes. Among the awardees are several researchers with the University's Bell Museum of Natural History. "We have four active grants. That's as many as any other institution in the country," says Bell Museum Director Scott Lanyon. The other institutions with four ATOL grants are the American Museum of Natural History in New York and the University of California, Berkeley--good company, indeed. Why is it so important to know the close relatives of organisms most people have never heard of? Consider the drug taxol, used to fight breast and ovarian cancer. It was discovered in the bark of the Pacific yew, a tree too rare to supply enough of the drug, not to mention that stripping its bark would kill it. But scientists knew that the English yew was a close relative, and it was found that taxol could be fairly easily made from a substance in its needles, meaning it was a renewable source of the drug.
"We have four active grants. That's as many as any other institution in the country," says Bell Museum Director Scott Lanyon. The other institutions with four ATOL grants are the American Museum of Natural History in New York and the University of California, Berkeley--good company, indeed.Another case concerned a type of marine algae found at several spots along the California coast. DNA analysis identified the algae and showed that it was closely related to a highly invasive strain that had caused grave damage in the Mediterranean. This led to an immediate eradication plan to save California's coastal ecosystem. A third example is the recently discovered--and highly fatal--hantavirus in the American Southwest. The virus is carried by deer mice, and genetic analysis has shown that mice and hantaviruses have a long co-evolutionary history in the Americas, suggesting that most major mice lineages may carry an associated hantavirus. In fact, dozens of additional hantaviruses have been found in the New World alone, and many cause disease in humans. This work implies the existence of even more hantaviruses still undiscovered in rodents around the world. For the University's part, its ATOL grants to date total more than $2 million and involve collaborative work with researchers at other institutions. Projects cover a wide variety of organisms:
- Lanyon, an expert on blackbirds, is working with researchers elsewhere on a bird lineage that represents about nine percent of all living birds. Besides blackbirds, it includes tanagers, warblers and sparrows. "With this work, we should get a better handle on the spread of avian diseases," he says. Also, knowing which species of birds (or other organisms) have close relatives, and who those relatives are, can help in conservation efforts. "If a threatened species has a close relative that's not threatened, there's the question whether we should concentrate on [saving] species that have no close relatives. It will help in conservation triage," he explains.
- Susan Weller, a curator of insects at the Bell Museum, is constructing an evolutionary tree for all butterflies and moths (Lepidopterans). Currently, no one knows which moth species are butterflies' closest relatives, she says. An example of a practical application is the tobacco hornworm, which is used to study how nerves form, develop, and die. But can that information be applied to other species, including humans? Before carrying out expensive and time-consuming experiments with mammals, scientists should first study a Lepidopteran species not closely related to the hornworm, for which a knowledge of the hornworm's relationships with other Lepidopterans is essential. Also, when scientists are designing a treatment to kill a troublesome species like the gypsy moth, they want to know who its closest relatives are so they can target the treatment to spare the "friendly" relatives.
- Andrew Simons, curator of fishes, and colleagues are studying the largest group of freshwater fishes. It includes minnows, carp, suckers, and loaches--3,000 to 5,000 species in all. One goal: "We want to know the adaptations that helped them radiate (spread)," says Simons. They seem to spread rather well; several carp and minnow species are already wreaking ecological havoc in North America, including the silver carp, which may actually jump in a boat and injure its occupants.
- David McLaughlin, curator of fungi, specializes in the group that includes mushrooms and toadstools. On the list of gifts fungi have given humanity are such items as penicillin and many culinary delicacies, and more may be on the way. Suppose, for example, one mold or fungus produces a drug. Scientists may want to identify and examine its close relatives, some of which may be easier to cultivate, to see if any produce the same or related drugs. Also, says McLaughlin, "Some fungi cause medical, plant, and animal diseases, and it's important to learn which ones are closely related so we can choose the correct model organism to study the troublemakers."