Massive Scientific Effort Maps Evolutionary Relationships
When Jim Clark (right) was a boy, he hunted fossils with a friend in California’s Mojave Desert. The biologist still hunts fossils, but for the last two decades he has done it in more exotic places, like China, and his discoveries have contributed to one of the planet’s biggest collaborative science initiatives: The Tree of Life, a scientific effort to map the evolutionary relationships among all species on earth—all 1.7 million of them.
At Columbian College’s Department of Biological Sciences, most of the 20 faculty members are involved in research with implications for the global project. But there are three endowed professorships specifically linked to Tree of Life work: Clark, who studies dinosaurs; Guillermo Orti, who works with fish; and Gustavo Hormiga, who researches spiders. All three hold endowed professorships funded through the philanthropy of the late Robert L. Weintraub, PhD ’38—a GW faculty member and alumnus—whose foresight and generosity has significantly advanced the study of evolutionary biology.
It was Charles Darwin who used “tree of life” to describe how all living things, from microorganisms to large vertebrate, were genetically related through evolutionary processes. He envisioned the connections as a grand tree “with its ever-branching and beautiful ramifications.”
Biologists around the world are involved in Tree of Life research, which has applications in nearly every aspect of modern life. Evolutionary information has already helped scientists to track the development and spread of diseases, to restore ecosystems, to manage food supplies and to conserve endangered species.
The Tree of Life work is one of GW's signature research programs. The initiative has received support from University Administration, the National Science Foundation and the Smithsonian’s Museum of Natural History, among others.
Clark’s expertise lies with fossil archosaurs, especially dinosaurs and crocodilians. One small group among them are alvarezsaurs, which were classified as birds but—as the GW professor’s Tree of Life research confirmed—were actually dinosaurs. (An upcoming issue of Science magazine will feature an alvarezsaurs paper by Clark’s student Jonah Choiniere and Clark.) He has also gained attention for his research into three other dinosaurs: the oldest tyrannosaur, the strange toothless theropod that was caught in mud pits and the oldest horned dinosaur. His work in the fossil beds of the western Gobi Desert of China has been featured in an article and documentary by National Geographic.
“The Tree of Life is the big picture of what’s related to what,” Clark explained. “Our specific project looks very closely at what happened in the transition from dinosaurs to birds.”
Mapping Spiders and Fish
Hormiga’s work with spiders contrasts to dinosaur research in that a great deal is already known about spiders which, with their arachnid relatives, are one of the oldest groups of terrestrial animals. Spiders stand out because of their role as the dominant invertebrate predators within most ecosystems. There are more than 41,000 known living spider species, although there are estimates that research could eventually identify up to 170,000. 
Hormiga’s lab is busy collecting new spider data, which it combines with relevant existing information.
Orti (left), who is mapping fish on the Tree of Life, noted that the process of describing and classifying nature is old. But the methods for and precision with which those evolutionary classifications are made has been revolutionized by technology.
“It’s called phylogenetic systematics,” Orti said. “The conceptual tools to do this in a formal way were not available until the 1960s. Before then, there was no direct way to know which species were closer to whom. In the old days, his was based mostly on personal opinion or authority.”
In the 1990s, computers became a critical tool for analyzing genetic sequence data, providing empirical evidence and greatly adding to scientists’ work in the area. Orti uses genetic sequence—or molecular—data to reconstruct the genealogical relationships of fish.
“We had what we knew about the relationships of fish based on traditional studies,” said Orti. “We believed a particular fish fit into a particular family. But now we’re finding the classifications may be different. And some of those new relationships are more surprising than others.”
It was GW’s focus on systematics that drew Orti to the University, along with impressive close-at-hand resources, including the Smithsonian Institution.
“We got into systematics before most other universities,” explained Biological Sciences Chair Diana Lipscomb, who has been involved with systematics her whole career. Calling GW “ahead of the game,” she said it was in the 1990s that GW started to set itself apart for its pioneering work in the area. So notable was Lipscomb’s and the University’s position in the field that the professor was invited to join the NSF team administrating major funding of Tree of Life work. She took an 18-month leave of absence from GW to help with the undertaking.
In late 2002, when the NSF announced that funding to flesh out the Tree of Life, it described the project as an “ambitious, multidisciplinary” program that would run as long as 20 years. Research was to span a multitude of disciplines, including taxonomy, paleontology, phylogenetics, computer science, statistics, anthropology, ecology, physiology, and developmental and molecular biology. Some $12 million in funding was earmarked for NSF grants in the first year alone.
“The beauty of this discipline is that you can see how a particular organism relates to everything else that’s alive. That’s very powerful knowledge to have,” said Orti. “This research takes you into the past—you have to understand where you’re coming from—so you can understand the potential impacts of the present and the future.”
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