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Biology

It's All in the Genes
A DNA bar code can help scientists ID species

Imagine working as an agricultural inspector at an airport and finding an insect in a passenger's fruit basket: Is it a foreign species that could damage crops? Problem is, depending on the bug, there might be only a handful of experts who could ID it—and you might have to mail the specimen to one of them.

Evolutionary biologist Paul Hebert of Canada's University of Guelph has proposed a system for using DNA to identify animals. If his idea is put into use, anybody with relatively cheap and portable DNA analysis equipment could identify almost any animal. Eventually, a new species could first be known by a short section of its DNA—Hebert calls it a bar code. The Latin name could come later.

Hebert wants to develop an electronic catalog of bar codes for all animal species, each represented by a string of 645 A's, C's, G's, and T's—shorthand for the chemical subunits, or bases, that make up DNA. This string of DNA is found in a specific gene common to practically all animals, yet it varies from species to species.

In a recent blind test of the system, Hebert received legs from 200 moth species. By grinding up each leg to obtain a DNA sample and analyze its bar code, he and his colleagues were able to ID each species—something a moth specialist would be hard pressed to do even with the luxury of whole animals to examine. (Many insects are identified by dissecting their abdomens to examine their sex organs.)

Bar coding would help biologists with another challenge: identifying a species with a complex life cycle when there is only an egg or a larva to work with. Many invertebrates, which account for more than 95 percent of all animal species, are only identifiable in their adult forms. Bar coding solves that because DNA's pattern is constant from day one to death.

—Hillel J. Hoffmann

Web Links

DNA Bar Coding
www.barcodinglife.com
Find out more about Paul Hebert's rationale for DNA bar coding and background information on the single mitochondrial gene upon which his bar code system is based.

Taxonomy
anthro.palomar.edu/animal/default.htm
Come here to take Palomar College's tutorial, Classification of Living Things.


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Bibliography

Blaxter, Mark. "Counting angels with DNA," Nature (January 9, 2003), 122-24.

Dobson, Roger. "Animal 'bar codes' to take over from Latin names," Independent on Sunday, March 9, 2003.

Hebert, Paul D. N., and others. "Biological identifications through DNA barcodes," Proceedings of the Royal Society of London (2003).

Hecht, Jeff. "Every species has a 'barcode,' " New Scientist (March 22, 2003).

"What's in a name?" The Economist, January 4, 2003.




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