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In Context #14 (Fall, 2005, pp. 6-7); copyright 2005 by The Nature Institute

Commentary on DNA Barcoding in Bioscience

In the last issue of In Context we reported on a letter by Malte Ebach and Craig Holdrege that was published in Nature. It dealt with DNA barcoding - the effort to identify every organism through a piece of its DNA. The letter was published in April and elicited critical response letters from barcoding enthusiasts in following issues of the magazine. The letter also caught the eye of the editor of BioScience, the journal of the American Institute of Biological Sciences. Recognizing that it addressed important concerns about the direction of biological research, he requested a viewpoint article from Malte and Craig, which appeared in the October, 2005 issue of the journal. Here are a few excerpts from that article:

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Imagine, for the sake of argument, that barcoders were able to tag each known taxonomic species with a DNA barcode, and that they discovered new and unique sequences that might indicate a hitherto unknown species. Since barcoders maintain that there exist "DNA species" that are impossible to tell apart from known species except through sequence comparisons, many new species identified by barcoding would not be morphologically distinguishable. The resulting, much larger number of "species" would be a number that means very little. What that number might tell us about actually existing species would have to be intensively investigated, because barcodes cannot reveal the types of their corresponding real species, those species' relationships, or their behavior. In the end, we will be left with a very large and arbitrary number of supposed species. Since barcoding does not classify or create readily usable knowledge, it remains simply a technique, and should not be taken for more than that. What science really needs is more naturalists and taxonomists, not more barcoders.

The CBOL Web site [Consortium for the Barcode of Life] claims that DNA barcoding is a "new and exciting addition to the taxonomists' toolbox." The observation prompts a question: What is already in a "taxonomist's toolbox"? It contains physical tools - such as a checklist, microscope, net, and plant press - and also years of training and experience gained from studying the taxonomy of one or more groups. If barcoding could be viewed and managed as one subordinate physical instrument to be implemented in specific instances, it would be a useful addition. The question, in the present climate of high-tech hype, is whether researchers will realize that barcoding cannot replace any of the already existing tools, especially detailed knowledge of organisms. This is not a casual concern: wherever one looks in biology, molecular techniques are replacing the study of whole organisms and their relationships....

Yet, if DNA barcoding receives major funding as a high-output, "big science" program, and as a result is viewed (wrongly) as a modernized taxonomy, it will in fact begin supplanting taxonomic projects.. In a funding climate focused on promoting sexy new high-output "solutions" to global problems, a scientific field that progresses by investing much time, energy, and funding into training taxonomists, doing careful fieldwork, and carrying out detailed morphological studies may seem outmoded. According to this view, taxonomists are clearly soon to become fossils in the strata of scientific evolution themselves.. It is ironic that DNA barcoding is often portrayed as central to the effort to protect biodiversity. The implication seems to be that only enormous numbers of cataloged species, each with its own unique mitochondrial DNA sequence, will motivate human beings to gain, at last, respect for life. But this approach tells us next to nothing about the creatures we are supposed to care about. Would it not make much more sense to invest resources in getting to know better the whole organisms and their ecologies?

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