Ten years from now, you are sitting in a sunny garden when all of a sudden a butterflyor is it a moth?of the most brilliant blue flies past, landing on a nearby flower. I wonder what sort of insect that is? you muse. What do you do? Consult your handy field guide to insects? No needif University of Guelph biologist Paul Hebert’s vision comes to fruition, you could simply pull out your pocket DNA barcoding device, insert a sample from the butterfly (no killing involved), and produce a DNA sequencelike a barcodeidentifying the species.
For now, DNA barcoding takes place in a lab in Guelph. The Canadian Centre for DNA Barcoding, which Hebert directs, is associated with the Consortium for the Barcode of Life, an international organization based in Washington, D.C. There are several barcoding campaigns on the go: All Leps is focusing on collecting data for 25 000 lepidoptera species; the goal of FISH-BOL is to barcode all species of fish; Canadian Fauna is assembling barcodes for the plant life in Canada; and the All-Birds Barcoding Initiative expects to have barcodes for all 10 000 bird species within the next five years.
Animals don’t actually come with barcodes, but with something close: a standard region of mitochondrial DNA, encoding cytochrome c oxidase 1 (CO1). Cytochrome c 1 is found in almost all species of plants, animals, and unicellular organisms, and its gene sequence can be used to identify species with a success rate of 96.4 percent. A sequence of about 650 base pairs from this segment of DNA will be 99.75 percent identical within members of the same species, whereas a match of 97.5 percent or less indicates that the samples are from different species.
Hebert’s technique will help taxonomists in the ongoing struggle to identify all species on Earth. Until now, using the far slower traditional method of identification, taxonomists have at best identified about 13 percent of all species of life. With a community of scientists working together to collect specimens for the barcode database, and the potential involvement ofwellanyone with a DNA sequencing handset, he hopes to have the entire planet classified within 20 years.
So, what’s the big dealwhy should we care?
The accurate identification of endangered or dangerous species would aid in their protectionand ours. Water sources could be analyzed in terms of the life they contain as well as their mineral and chemical content. Not only that, but new disease outbreaks would be far easier to manage if we could already identify the agents responsible (remember SARS and the avian flu?).
Of course, not everyone likes the idea of life on Earth being summed up in a Wal-Mart-like inventory, and many are worried that the hype surrounding DNA barcoding is going to take funding away from other methods of taxonomy. For that 37.6 percent of species that can’t be identified with a barcode, however, we still need traditional taxonomists. Let us think of barcoding as a way to speed things up and open new fields to taxonomic study: for example, what used to be considered one species of butterfly was revealed by barcoding as being, in fact, at least ten distinct species. There is still plenty of room for further investigation.
And I, for one, would really enjoy having my very own hand-held DNA sequencer…
Further Reading:Canadian Centre for DNA Barcoding www.dnabarcoding.ca
Barcode of Life Data Systems (BOLD) www.barcodinglife.org
Consortium for the Barcode of Life www.barcoding.si.edu
Taxonomy isn’t Black and White http://www.the-scientist.com/article/display/22424/
Canadian Geographic, March/April 2007: “Life Lines: The Race to Barcode all Species.”
