The idea is that a short stretch of genetic code from a reference gene is sufficiently characteristic of one species to distinguish it from every other species, and that comparisons of sequence variations in that gene can also reveal evolutionary relationships among species. Hebert and colleagues tested the effectiveness of their genetic barcode in an extensive study of North American birds by comparing the 'species' identified from the barcode against those already established by taxonomic methods. They found that all 260 bird species had unique genetic barcodes. In the 130 species represented by two or more individuals, gene sequences were either identical or closest to other sequences within that species. The authors report that the genetic barcodes therefore "separate individuals into the categories that taxonomists call species."
As their technology matures, it could radically advance biologists' attempts to achieve the long-standing goal of cataloging life on earth, but the approach is very controversial, with critics questioning both the method and its applications. As Craig Moritz and Carla Cicero from the University of California, Berkeley, also point out in the correspondence section of this issue, the Hebert et al. study is "not yet a definitive test of the utili
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Contact: Paul Ocampo
pocampo@plos.org
415-624-1224
Public Library of Science
27-Sep-2004