Biosystematist's meeting, Tuesday, April 13 at San Jose State U.

Christopher Meyer (Florida Museum of Natural History, University of Florida) - "Does Barcoding Work? An Empirical Test."

ABSTRACT The recently proposed DNA-based system for species identification has attracted much controversy. Proponents of DNA barcoding envision that a short fragment of mtDNA can be used to diagnose taxa, increasing the speed, objectivity and efficiency for circumscribing species. Opponents argue against DNA barcoding mostly because of the typological nature of its implementation. How typical is the type? Sources of typological error have been grouped into four categories: intraspecific variation, introgression/hybridization, gene tree vs. species tree, and ancestral polymorphism; and error rates can be estimated for each. However, as yet, no comprehensive data sets with adequate intraspecific sampling are available to assess the performance of this DNA-based approach, and most criticism remains philosophical and not empirical. In this paper we use a comprehensive molecular dataset composed of over 1,900 COI mtDNA sequences across almost all evolutionary units (N=269) within cowries (Gastropoda: Cypraeidae), a diverse, popular and well-documented family of snails, to empirically test the barcoding approach. A standard, tree-based approach to taxon identification was >96% successful at correctly assigning randomly-selected sequences (N=1000) to their appropriate sister. Additionally, we find that DNA barcoding performs reasonably well with error rates less than 2% for each of the four recognized categories. However, based on a novel phylogenetic approach, we identify a fifth, significant source of error: the preponderance of false negatives. Approximately 20% of recently derived taxa will be artificially lumped if a 3% divergence rule is employed.