DNA barcoding Central Asian butterflies: increasing geographical dimension does not significantly reduce the success of species identification

Abstract

DNA barcoding employs short, standardized gene regions (5' segment of mitochondrial cytochrome oxidase subunit I for animals) as an internal tag to enable species identification. Prior studies have indicated that it performs this task well, because interspecific variation at cytochrome oxidase subunit I is typically much greater than intraspecific variation. However, most previous studies have focused on local faunas only, and critics have suggested two reasons why barcoding should be less effective in species identification when the geographical coverage is expanded. They suggested that many recently diverged taxa will be excluded from local analyses because they are allopatric. Second, intraspecific variation may be seriously underestimated by local studies, because geographical variation in the barcode region is not considered. In this paper, we analyse how adding a geographical dimension affects barcode resolution, examining 353 butterfly species from Central Asia. Despite predictions, we found that geographically separated and recently diverged allopatric species did not show, on average, less sequence differentiation than recently diverged sympatric taxa. Although expanded geographical coverage did substantially increase intraspecific variation reducing the barcoding gap between species, this did not decrease species identification using neighbour-joining clustering. The inclusion of additional populations increased the number of paraphyletic entities, but did not impede species-level identification, because paraphyletic species were separated from their monophyletic relatives by substantial sequence divergence. Thus, this study demonstrates that DNA barcoding remains an effective identification tool even when taxa are sampled from a large geographical area.

Diversity, specificity and speciation in larval Diplostomidae (Platyhelminthes: Digenea) in the eyes of freshwater fish, as revealed by DNA barcodes

“…4), and the scale at which diplostomid species are sampled is not a significant predictor of CO1 NN ratios, once sampling effort is taken into account. Overall, the data provide additional evidence that the effect of spatial scale on species delineation and specimen identification using CO1 is small in many (Hebert et al, 2004;Lukhtanov et al, 2009;Mutanen et al, 2012;Huemer et al, 2014;Locke et al, 2015) if not all cases (Meyer and Paulay, 2005;Bergsten et al, 2012).…”

Unexpected layers of cryptic diversity in wood white Leptidea butterflies

“…Thirteen GenBank COI sequences of L. sinapis from Spain 30 , France 31 , Slovenia 32 , Greece 21 and Kazakhstan 33 , seven sequences of L. juvernica stat. nov. from Slovenia 32 , three sequences of L. amurensis 33 from Russia and two sequences of L. morsei 33 from Kazakhstan were also added to the dataset.…”

“…nov. from Slovenia 32 , three sequences of L. amurensis 33 from Russia and two sequences of L. morsei 33 from Kazakhstan were also added to the dataset. Additionally, one sequence of L. sinapis from Austria and three sequences of L. juvernica stat.…”

Geographical distribution of the cryptic species Agrodiaetus alcestis alcestis, A. alcestis karacetinae and A. demavendi (Lepidoptera: Lycaenidae) revealed by cytogenetic analysis

“…Since A. dantchenkoi and A. karacetinae are parapatric in distribution (Lukhtanov et al, 2003), we can not exclude that the similarity between these taxa in COI barcodes is a consequence of mitochondrial introgression between them and does not refl ect their close relatedness. The possibility of interspecifi c mitochondrial introgression was recently demonstrated in Lepidoptera Lukhtanov et al, 2009). Therefore, the conclusion about not-sister relationship between A. karacetinae and A. alcestis sensu stricto should be checked in the future studies by analyzing not only mitochondrial, but also nuclear molecular markers.…”

“…dolus clade. This fragment was selected as it was available from Genbank for almost all taxa of the "brown" complex, and its effectiveness for solving species-level taxonomical problems in butterfl ies was previously demonstrated (Wiemers, 2003;Hebert et al, 2004;Lukhtanov et al, 2009).…”