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Development and evaluation of a DNA-barcoding approach for the rapid identification of nematodes

first_imgFree-living nematodes are abundant in allmarine habitats, are highly diverse, and can be useful formonitoring anthropogenic impacts on the environment. Despitesuch attributes, nematodes are effectively ignored bymany marine ecologists because of their time-consumingtaxonomy. Nematode diagnostics has traditionally relied ondetailed comparison of morphological characters which,given their abundance, is difficult and laborious, meaningthat the biodiversity of the group is typically underestimated.Molecular methods such as DNA-barcoding offerpotentially efficient alternative approaches to studying thebiodiversity of marine nematode communities, allowingthese organisms to be more effectively exploited in ecologicalsurveys and environmental assessments. In this study, anumber of nuclear and mitochondrial genomic regions wereevaluated as potential diagnostic loci for marine nematodespecies identification. Of these, the 18S ribosomal RNAgene amplified most reliably from a range of taxa, and wastherefore evaluated as a DNA barcode. In a comparison ofmolecular and morphological identifications, over 97% ofspecimens sequenced were correctly assigned on the basisof a short stretch of 18S rRNA sequence (approximately 345bp), making this a potentially useful marker for the rapidmolecular assignment of unknown nematode species, andevaluation of nematode species richness during ecologicalsurveys or environmental assessments. This study showedthat a single marker approach based on amplification andsequencing may prove invaluable in the rapid identificationof nematodes during ecological surveys and, indeed,last_img read more