page_title: DNA barcoding
section_title: Delimiting cryptic species
hierarchical_section_title: DNA barcoding / Applications / Delimiting cryptic species
caption_attribution_description: Ekstraksjon av arvestoff (DNA) fra julemat på molekylærlaboratoriet ved NTNU Vitenskapsmuseet. DNA extraction from traditional Norwegian Christmas food at the molecular systematic lab at NTNU University Museum. Foto: Åge Hojem, NTNU Vitenskapsmuseet. Photo: Åge Hojem, NTNU University Museum.
context_page_description: DNA barcoding is a method of species identification using a short section of DNA from a specific gene or genes. The premise of DNA barcoding is that, by comparison with a reference library of such DNA sections, an individual sequence can be used to uniquely identify an organism to species, in the same way that a supermarket scanner uses the familiar black stripes of the UPC barcode to identify an item in its stock against its reference database. These "barcodes" are sometimes used in an effort to identify unknown species, parts of an organism, or simply to catalog as many taxa as possible, or to compare with traditional taxonomy in an effort to determine species boundaries.
  Different gene regions are used to identify the different organismal groups using barcoding. The most commonly used barcode region for animals and some protists is a portion of the cytochrome c oxidase I gene, found in mitochondrial DNA. Other genes suitable for DNA barcoding are the internal transcribed spacer rRNA often used for fungi and RuBisCO used for plants. Microorganisms are detected using different gene regions.
context_section_description: DNA barcoding enables the identification and recognition of cryptic species. The results of DNA barcoding analyses depend however upon the choice of analytical methods, so the process of delimiting cryptic species using DNA barcodes can be as subjective as any other form of taxonomy. Hebert et al.(2004) concluded that the butterfly Astraptes fulgerator in north-western Costa Rica actually consists of 10 different species. These results, however, were subsequently challenged by Brower (2006), who pointed out numerous serious flaws in the analysis, and concluded that the original data could support no more than the possibility of three to seven cryptic taxa rather than ten cryptic species. Smith et al. (2007) used cytochrome c oxidase I DNA barcodes for species identification of the 20 morphospecies of Belvosia parasitoid flies (Diptera: Tachinidae) reared from caterpillars (Lepidoptera) in Area de Conservación Guanacaste (ACG), northwestern Costa Rica. These authors discovered that barcoding raises the species count to 32, by revealing that each of the three parasitoid species, previously considered as generalists, actually are arrays of highly host-specific cryptic species. For 15 morphospecies of polychaetes within the deep Antarctic benthos studied through DNA barcoding, cryptic diversity was found in 50% of the cases. Furthermore, 10 previously overlooked morphospecies were detected, increasing the total species richness in the sample by 233%.
caption: Barcoding is a tool to vouch for food quality. Here, DNA from traditional Norwegian Christmas food is extracted  at the molecular systematic lab at NTNU University Museum.
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