How common are cryptic species - those overlooked because of their morphological similarity? Despite its wide-ranging implications for biology and conservation, the answer remains open to debate. Butterflies constitute the best-studied invertebrates, playing a similar role as birds do in providing models for vertebrate biology. An accurate assessment of cryptic diversity in this emblematic group requires meticulous case-by-case assessments, but a preview to highlight cases of particular interest will help to direct future studies.
Since 2006, a team of researchers has barcoded all the 228 known species of butterflies of the Iberian peninsula. The result is a report that compiles more than 3500 barcodes for all the species, which were compared to the barcodes of other European populations.
It is this comparison that suggests that up to 28% of the species could be totally new to science as they represent distinct genetic lineages. Many of these represent cryptic species which are morphologically very similar and therefore have been classified as one single species.
European butterflies also include numerous model taxa for biogeography, ecology and speciation and are intensively used as bioindicators and as flagship group for invertebrate conservation efforts. As a consequence, any change in their taxonomy and any improvement of our knowledge will have consequences for both research projects and conservation policies. As noted, superficial taxonomic decisions may jeopardize an intensively studied system such as European butterflies. Given the alarming rates of global biodiversity loss and the limited resources available, the exploration of biodiversity through large-scale molecular approaches such as DNA barcoding combined with automated methods of ESU [Evolutionary Significant Unit] delineation can provide valuable guidelines for future efforts.
The comparisons here focus on three more densely sampled regions in Europe but there are efforts underway to barcode butterflies and moths in other regions of the continent (e.g. Finland, France). If the numbers revealed by this study hold up for future comparisons Lepidopterists in Europe will have a lot to do right in front of their own doors.