Appraisal of the entire mitochondrial genome for DNA barcoding in birds

Abstract

DNA barcoding based on a standardized region of 648 base pairs of mitochondrial DNA<br />sequences from Cytochrome C Oxidase 1 (COX1) is proposed for animal species identification.<br />Recent studies suggested that DNA barcoding has been effective for identifying 94% of bird<br />species. The proposed threshold of 10 times the average intraspecific variation could be used for<br />the identification and delimitation of new species. As a different part of the mitochondrial DNA<br />evolves at various mutation rates, they show a variety of capabilities to distinguish taxa to<br />species level. In order to compare the efficiency of protein-coding genes (PCGs) in birds, the<br />complete genome of 310 birds, including 12 mitochondrial genes (except ND6) and barcoding<br />the region of COX1, were examined. We concentrated on the intra- and inter-specific variations<br />and the degree of mutational saturation as criteria for our evaluations. Some genes like ATP8,<br />ND2 and ND5 showed the greatest divergence in intra- and inter-specific variations. The<br />overlap between intra- and inter-specific variability for all genes is still troublesome. Our results<br />may have been influenced by the sample size because our data were not representative of all<br />bird species. More additional taxa may shed light more on DNA barcoding candidate genes.<br />