In the great debate of quantity versus quality, Paul Hebert insists on quantity — but refuses to sacrifice quality to get it. A member of the zoology department at Canada’s University of Guelph, Hebert is involved in massive-scale genomics research that he believes will lead to the definitive guide to speciation. As he puts it, “people are committed to every gene [in an organism]. We’re talking one gene in every organism.”
For as long as he can remember, Hebert has been dedicated to his pursuit of biological knowledge, particularly in taxonomy. With a doctorate in population genetics and a particular zeal for the moth and butterfly family, he has spent his career figuring out how to improve the current system for distinguishing one species from another. Today’s technique is what Hebert calls “creature gazing”: “You stare at them long and hard and [hope] you will be able to tell them apart.”
Despite his hunch that genomics would provide a better way to do this, Hebert was stymied in the beginning because the idea looked like a call for full-scale sequencing of every genome on the planet.
Struck by how everything around him seemed to come equipped with a UPC code, he began to wonder if something like barcoding could work for telling species apart as well. About three years ago he found what he was looking for: a short stretch of highly conserved but rapidly evolving DNA within the mitochondrial genome. What he discovered is present “in all aerobic life,” he says. That stretch is what Hebert considers the DNA barcode, and with the right primers, it can reveal definitively which species is which in all the organisms he’s examined so far.
Studying several thousand species from the lepidoptera family so far has shown that “just a single pair of primers” has led to clear differentiation, Hebert says. Same with the birds of North America, in which Hebert’s team has analyzed 200 of roughly 1,000 species. Along the way, he’s been revisiting the rules of taxonomy as they’ve been laid out so far: While he hasn’t found major mistakes, his bird studies discovered what appear to be three previously undistinguished species. And he expects to finally be able to understand species distinction in the viral and bacterial domains, where such boundaries have never been well defined, Hebert says.
Hebert, 56, is collaborating with several museums that send him “little bits of bodies” — a fast way to get DNA samples from as many as 1 million specimens stored in museum archives. With the necessary resources, Hebert envisions this leading to a system where people could use a handheld diagnostic device: “paper chips embedded with the right primers, dab the insect or the frog, and you’re golden,” he says. His team is developing a Web infrastructure right now, adding pictures and descriptions of organisms to their DNA information.
“We’re seeing that you could build a library of animal life with perhaps just 50 million reads,” Hebert says. “That’s a sort of enterprise that can be done with a single sequencing facility.”