A DNA barcode library for European butterflies
Understanding the patterns of global biodiversity is central for addressing major scientific issues, such as the factors influencing rates of speciation. The EU-funded EUGENMAP project exploited the power of DNA barcoding to deliver a synoptic overview of biodiversity patterns. DNA barcoding is a powerful taxonomic method that relies on short genetic markers called barcodes, to classify species. EUGENMAP utilised butterflies as a model system as they are the most intensively studied invertebrate group in the world. To assemble a comprehensive DNA barcode reference library for the European butterflies, researchers investigated cases of potential cryptic species as well as cases of oversplitting, where species incorrectly split into two or more. To examine the impact of the Quaternary ice ages on the diversification dynamics of butterflies in Europe, North America, and Australia, scientists used DNA barcode libraries of the North American and Australian butterfly faunas and performed comparative analysis. The generated European barcode library covered nearly 97 % of the European species with over 18 000 DNA barcodes. Nearly 30 % of the species analysed contained evolutionary units and some species displayed deep intraspecific splits, indicating the presence of cryptic species. These species were further investigated using nuclear markers, chromosome number as well as morphometric and chemical analyses. Overall, these methods alongside next generation sequencing led to the documentation of new species in the European butterfly fauna. Furthermore, the DNA barcode library provided a high-resolution map of mitochondrial DNA diversity for European butterflies with numerous potential applications. In conclusion, the EUGENMAP project provided important information on the factors influencing the levels of geographic differentiation in a single species. Importantly, the employed method of DNA barcoding represents a major advance in the global study of biodiversity and could serve as a model for implementation on other taxonomic groups.
Keywords
DNA barcode, butterflies, speciation, biodiversity, cryptic species, EUGENMAP
