Does the DNA barcoding gap exist? – a case study in blue butterflies (Lepidoptera: Lycaenidae)

Abstract

Background: DNA barcoding, i.e. the use of a 648 bp section of the mitochondrial gene cytochrome c oxidase I, has recently been promoted as useful for the rapid identification and discovery of species. Its success is dependent either on the strength of the claim that interspecific variation exceeds intraspecific variation by one order of magnitude, thus establishing a "barcoding gap", or on the reciprocal monophyly of species.

DNA barcoding of 18 species of Bovidae

“…However, some researchers, particularly taxonomists, are suspicious of DNA barcoding [14], especially with regard to the application of a universal distance criterion for species recognition [15]. In addition, critics have argued that a test for the precision of DNA barcoding should include a large proportion of closely related taxa [14,16,17].…”

“…In addition, critics have argued that a test for the precision of DNA barcoding should include a large proportion of closely related taxa [14,16,17].…”

Introgression as a likely cause of mtDNA paraphyly in two allopatric skippers (Lepidoptera: Hesperiidae)

“…On the basis of this criterion, our mtDNA sequence data support accepted species delimitations for E. propertius, E. horatius and their congeners with an average interspecific divergence in nucleotide sequences of B4 to 10%. It has been demonstrated for some butterflies (for example, Lycaenidae) that there is an upper bound of intraspecific divergence in mtDNA of 3.2% for at least 95% of studies species, but there is no lower limit (Wiemers and Fiedler, 2007). This suggests that closely related species can have very similar mtDNA.…”

“…Recent studies estimate the proportion of non-monophyletic mtDNA in animal species at over 20% (Funk and Omland, 2003;Wiemers and Fiedler, 2007). This number may be an overestimate because some cases of apparent paraphyly result from poor taxonomy that has failed to reveal differentiation (Hebert et al, 2004;Borisenko et al, 2008).…”

“…Although the application of organelle DNA in the above-mentioned fields is widely accepted, discrepancies between phylogenies inferred from mtDNA and nuclear markers or morphological traits have repeatedly raised questions concerning the credibility of mtDNA for systematics and phylogeography (Shaw, 2002;Babik et al, 2005;Chan and Levin, 2005;Rubinoff and Holland, 2005;Wiemers and Fiedler, 2007). Owing to the lack of recombination (but see Slate and Phua, 2003;Rokas et al, 2003), mtDNA genes are inherited as a single linkage group, but the mitochondrial genome does not necessarily reflect the entirety of a species' evolution or population history (Ballard and Whitlock, 2004).…”