Biological identifications through DNA barcodes

Although much biological research depends upon species diagnoses, taxonomic expertise is collapsing.We are convinced that the sole prospect for a sustainable identification capability lies in the construction of systems that employ DNA sequences as taxon 'barcodes'.We establish that the mitochondrial gene cytochrome c oxidase I (COI) can serve as the core of a global bioidentification system for animals.First, we demonstrate that COI profiles, derived from the low-density sampling of higher taxonomic categories, ordinarily assign newly analysed taxa to the appropriate phylum or order.Second, we demonstrate that species-level assignments can be obtained by creating comprehensive COI profiles.A model COI profile, based upon the analysis of a single individual from each of 200 closely allied species of lepidopterans, was 100% successful in correctly identifying subsequent specimens.When fully developed, a COI identification system will provide a reliable, cost-effective and accessible solution to the current problem of species identification.Its assembly will also generate important new insights into the diversification of life and the rules of molecular evolution.