Barcoding by using DNA (Herbert et al, 2003) is a method that exploits genetic markers in DNA of an organism to find out its belonging to an existing species or to categorize it as new one. Cytochrome c oxidase I (COX I) is a component of mitochondria in vertebrates and invertebrates that is used for DNA barcoding. The reason for using it is that the mutation rate in mitochondrial DNA is much faster and the variations created there in could be used for species categorization.
A very recent study in The Netherlands used a set of sympatric birds to test the DNA barcoding and its efficiency. A total of 147 bird species (387 individuals) were used for the study among which 134, i.e., 95% showed to have unique barcodes. About 83 species had more than two sequences for their representation. Among all the species included in the study, one showed high intra-specific distances (lineage divergence by 6%). This one namely Sylvia curruca actually has two sub-species namely S.c. curruca and S.c. blythi. The result of divergence on the mitochondrial gene tree may be due to mitochondrial introgression that happened anciently.
This study has once again proved the efficiency of DNA barcoding to be about 95% for avifauna and has made it believe that a universal gene like COX I can be used to handle a larger taxa with reliable effieciency.
This study was published in ZooKeys and is licensed under Creative Commons Attribution License
1.Mansour Aliabadian, Kevin Beentjes, Kees (C.S.) Roselaar, Hans van Brandwijk, Vincent Nijman, Ronald Vonk. DNA barcoding of Dutch birds. ZooKeys, 2013; 365: 25