Using DNA bar codes for species identification and their application for bioassessment.

S.L. Ball and P.D.N. Hebert. Department of Zoology, University of Guelph, Guelph, Ontario, Canada, N1G 2W1

All biological research depends critically on our ability to identify species correctly. This is particularly important in bioassessment studies where correct species identification provides important information about impacts of environmental stressors. Although traditional morphological taxonomy has been successful in distinguishing species for many groups, this approach can be problematic due to genetic and phenotypic variation in characters used for identification. Furthermore, successful use of many morphologically based keys requires significant expertise and many keys are specific to certain genders or life stages. DNA bar codes (short DNA sequences) provide a solution to these limitations in species identification. We created DNA profiles of known species of ephemeroptera, plecoptera, and trichoptera to test whether additional specimens could be correctly identified based on their DNA sequences. Results showed that we were 100% successful in correctly identifying species. Furthermore, intraspecific sequence divergences were consistently lower (mean nucleotide divergence < 2%; range: 0 – 4%) than interspecific sequence divergences (> 16%; range = 8 – 26%), suggesting that sequence divergence can be used as a guideline for distinguishing species. We feel that DNA bar coding, when combined with traditional morphological taxonomy, can provide a reliable, efficient and cost-effective means of species identification for bioassessment.