By Ellen Walker Ternes

Illustrations by Brian G. Payne

“As buds give rise by growth to fresh buds, and these if vigorous, branch out and overtop on all sides many a feebler branch, so by generation I believe it has been with the great Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its ever branching and beautiful ramifi cations.”
—Charles Darwin, 1856

IT WAS A LUCKY STROKE FOR SCIENCE, says Maryland’s Thomas Holtz, that Charles Darwin was prone to seasickness.

Darwin was sailing as a scientist aboard the HMS Beagle in 1836 for a mapping expedition of South America, observing and accumulating specimens to help him explore how and why species change.

One of the places the Beagle went was the Galapagos Islands.

“Because he got seasick, Darwin took every opportunity to get off the ship,” says Holtz, director of the College Park Scholars Earth, Life and Time program, and leader of fi ve student study-abroad trips to Galapagos.

It was on his walks around the Galapagos Islands that Darwin gathered some of the most important evidence for his theories of evolution. Darwin published them 23 years later in On the Origin of Species by Means of Natural Selection, or The Preservation of Favoured Races in the Struggle for Life. Those theories have underpinned all major biological breakthroughs since, and they drive much of today’s biology research at the University of Maryland.

This year, the bicentennial of Darwin’s birth, the University of Maryland, along with scientists and universities the world over, is recognizing the signifi cance of Darwin’s work by celebrating “The Year of Evolution.”

“Evolutionary theory had a profound scientifi c and social impact. The two don’t always go hand in hand,” says Chuck Delwiche, an associate professor of cell biology and molecular genetics.

BIG BANG
While theories of evolution had been bubbling among scientists, and farmers had long observed that animals changed with generations, Darwin’s publication arrived with a bang.

“What excited scientists and upset society,” says Charles Mitter, professor and chair of the Department of Entomology, “is that Darwin said that all present-day species descended from a common ancestor.” It was a notion that, even today, some people have trouble reconciling with religious and cultural beliefs.

Steven Salzberg, director of the university’s Center for Bioinformatics and Computational Biology, works on gene sequencing of viruses and bacteria. “A major misconception is that Darwin’s theory explains how life came to be,” Salzberg says. “But it doesn’t. It explains how once life appeared, it separated into distinct forms that led to the wonderful diversity on our planet.”

GENES AND EVOLUTION
A 20th-century scientific breakthrough gave new proof of evolution in a way that Darwin couldn’t have imagined. In 1980, the first genes were sequenced, or mapped out. It meant scientists could compare the genetic makeup of species and see where even changes in just a few genes could alter a species.

Comparing genetic codes shows that even after a billion years, humans share many of the same genes with life forms as lowly as E. coli. New genetics discoveries led researchers like Delwiche and Mitter to create the Tree of Life, a National Science Foundation-funded project that’s mapping out how all organisms alive today are genetically connected.

With gene sequencing, Delwiche’s research team identified a group of algae that are the closest living relatives to the  rst land plants that emerged 470 million years ago, moving a step closer to understanding how land plants came to dominate the planet.

SURVIVAL OF THE FITTEST
Gene sequencing shows with stunning clarity that species do evolve to survive when the going gets tough. Perhaps the poster children for evolution are viruses and bacteria, which rapidly reinvent themselves to fend off threats like antibiotics and vaccines.

Salzberg was on a research team that completed the first sequencing of more than 200 species of the influenza A virus, which causes flu in humans. Scientists hope to use the results to help them prepare the right vaccine for each flu season.

Biology professor Thomas Kocher and assistant biology professor Karen Carleton use gene sequencing to study the forces of nature that have driven the cichlid fish to evolve into hundreds of different species within the confines of several lakes in Africa. Their research may help scientists predict how modern problems, such as pollution, could affect the fish’s future diversity.

These gene maps also have led scientists down some new evolutionary paths, says biology assistant professor Eric Haag, who studies microscopic worms for insights into how different species evolve, sometimes for no apparent reason. “While it would make sense that species change their DNA only to adapt to their surroundings, genome sequencing shows the opposite. It does it even when things don’t need to be fixed,” Haag says.

WHAT’S UP WITH TERMITES?
One mystery that baffled Darwin—in fact delayed publication of his theory by more than 20 years—is the case of the social insects: termites, bees, wasps and ants. The question continues to intrigue scientists today.

“Social insects were a showstopper for Darwin,” says entomology professor Barbara Thorne, who studies the evolutionary biology of termites.

“Where almost all other species survive because the adults reproduce and pass on their genes, most individuals in a social insect colony are sterile. Only the queen and king reproduce.”

And yet these colonial creatures are overwhelmingly successful survivors, Thorne says.

“If you could weigh the biomass of all the social insects, they would encompass  percent of all the insects of the world.”

“A major misconception is that Darwin’s theory explains how life came to be,” Salzberg says. “But it doesn’t. It explains how once life appeared, it separated into distinct forms that led to the wonderful diversity on our planet.”

Thorne’s discoveries about one of the oldest species of termites have proven what Darwin suspected— that these social insects evolve as a social unit that survives by protecting the few members who can reproduce.

EVOLUTIONARY RESILIENCE
Insects of all sorts may be one of the evolutionary superheroes that keep on keeping on, in spite of humans’ efforts to eradicate them. Take mosquitoes, says Mitter. “Our e orts to get rid of them have failed because of evolution. They have evolved to become resistant to insecticides,” a survival skill that has thwarted virtually every attempt to rid the world of malaria.

Mitter and his students study the evolutionary biology of plant-eating insects. Working with the Smithsonian’s Museum of Natural History, they recently helped create a new exhibit on butterflies, plants and evolution. “Maryland is doing research that will result in understanding the evolution of moths and butterflies, which include a major portion of the insects that eat agricultural plants,” says Mitter.

THE FUTURE OF EVOLUTION
Biology professor Gerald Wilkinson is a leading researcher of species evolution, but his latest research may be revolutionary evolutionary.

Wilkinson is collaborating with linguistics professor Juan Uriagereka and computer science professor Jim Reggia to uncover clues to how language may have evolved in humans. And they’re doing it in a computer.

“We’re simulating evolution,” says Wilkinson. “We’re coming up with ways to create little computer agents that are allowed to evolve and communicate.”

Computer evolution is a long way from Galapagos, but it may add yet another chapter to the explosion Charles Darwin set o more than 150 years ago. “The history of evolution is like a catalogue to the museum of life,” says Mitter. “If you want to understand why things are the way they are today, you have to know what the ancestors were.” TERP

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