found this in an article in the Baltimore Sun...

http://www.sunspot.net/news/health/bal-te....ealth-headlines

Uncovering hidden species
DNA: Since the 18th century, taxonomists have identified plants and animals by comparing their anatomy. Now, genetic sequencing is revealing what scientists have missed.
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By Michael Stroh
Sun Staff
Originally published May 26, 2003

WASHINGTON - In an office filled with books, specimen boxes and the aroma of mothballs, John M. Burns hunches over a well-worn microscope and focuses on the reproductive organ of a skipper butterfly.

To the naked eye, it is a speck of coffee dust. Under the microscope, it looks like a whiskered jawbone. "Much more complicated than what you or I have," the 70-year-old scientist muses.

For most of his long career as a taxonomist - a scientist who catalogs and names living things - Burns has identified butterflies this way, by painstaking observation of their genitalia.

But one day last fall, Burns opened a mysterious shipment of skippers from Costa Rica. The butterflies were labeled as members of the same species, had identical genitalia and looked alike. But in the wild, the insects were behaving oddly.

To solve the mystery, Burns turned to a new investigative tool based on DNA - one of the most significant and controversial influences on taxonomy since the field was established more than 250 years ago.

Paul D. N. Hebert, an evolutionary biologist at the University of Guelph, was working on a technique to speed up identification of species with an idea borrowed from the supermarket checkout line: bar codes. Like the Universal Product Code on a can of soup, DNA sequences within a species are unique and can be assigned to particular creatures, Hebert says.

It's a proposal that could have a profound impact on the world's dwindling fraternity of taxonomists. For centuries, their discipline was one of biology's highest callings, but today it's a backwater, ignored by students and patrons of science in favor of genetics and other cutting-edge careers.

As a result, taxonomists have a lot of catching up to do. Only 10 percent of the estimated 15 million organisms that inhabit the planet have been caught and cataloged. Many wind up pinned or pickled in the dusty drawers of museums, unnamed and largely unexamined.

"Taxonomy is not a subject most people lay up at night thinking about," Hebert says. "There's also probably no discipline that has been so little impacted by technology."

Since Swedish scientist Carolus Linnaeus devised the modern classification system in the 18th century, scientists working with tweezers, microscopes and camel hair brushes have relied on observation of anatomy to determine who is related to whom.

But DNA analysis is redrawing many of those family trees. It has shown that the papaya and the cabbage are unlikely cousins, and that biologists somehow missed a whole species of African elephant, the largest land mammal on Earth.

In provocative study published last week, a DNA comparison of humans and chimpanzees is prompting some scientists to argue that chimps be allowed into the world's most exclusive taxonomic club: the genus Homo, currently reserved only for humans.

For Burns, the DNA journey began in the fall when a package arrived at the Smithsonian's Museum of Natural History, where the biologist examines butterflies in a fifth-floor office with a stunning view of the Capitol.

Shelves full of books and wooden boxes full of desiccated subjects decorate the room. Near Burns' desk is a cabinet with 5,469 pinkie-sized vials. Each contains the genitals of a single butterfly and bears an I.D. code - an "X" followed by a number. The "X" is Burns' joke, borrowed from the film industry's rating system to reflect the nature of the contents.

Extracting a butterfly's sex organ can take as long as a day and requires a delicate touch. "It can get tedious," he says.

In September, Burns opened a wooden box containing specimens of Astraptes fulgerator, better known as the two-barred flasher. They came from longtime collaborator Dan Janzen, a biologist at the University of Pennsylvania who has spent more than two decades collecting skippers in the rainforests of Costa Rica.

Burns and Janzen had noticed something unusual about the butterflies. Whereas most caterpillars feasted on a small collection of closely related plants, these flashers were gluttons, eating a wide and seemingly random variety of plants.

"It's like this puzzle in front of your face," says Janzen.

Could they be looking at different species? It hardly seemed possible. First identified in 1775, the flasher's banded wings and iridescent blue necklace make it one of the most recognizable in the region.

"This butterfly is to Central America what the monarch is to the U.S.," Janzen says.

When Burns inspected the genitalia of his specimens, they seemed to match. But their undersides showed subtle color variations. To confirm his suspicions, Burns turned to DNA and Paul Hebert.

Hebert had tried out his bar-coding technique on the genetic codes of more than 2,000 animal species and found they could tell all but a few apart. The system, he says, could allow taxonomists to catch up on their enormous backlog and ferret out misfit or overlooked animals and plants. It would also make it easier to classify creatures such as bacteria and viruses that don't have obvious anatomical differences.

To find out whether a lookalike butterfly species had been masquerading unnoticed for more than two centuries as Astraptes fulgerator, Burns and his staff plucked the legs off 50 flashers and shipped them to Hebert's lab.

After extracting the DNA and analyzing it, Hebert found at least 10 genetically distinct species in the batch - a big league discovery in the world of lepidopterology. Burns says the next step is to figure out which are the imposters and then describe their anatomy and name them.

"The DNA stuff is going to play an even more important role than it has in the past," says Kevin de Queiroz, a reptile biologist and associate curator of the National Museum of Natural History. "We don't have enough taxonomists."

But the use of DNA may have one unexpected downside, as Burns now knows - it can make more work for overwhelmed taxonomists, not less. "The question is: How common are cases like this?" says Burns. "There's still a hell of a lot of work to do."


Copyright © 2003, The Baltimore Sun