A high-resolution genetic map of European butterflies provides a unique resource for research and nature conservation

The European butterfly fauna is arguably the most intensively studied invertebrate group in the world and represents a key resource in providing models for research and nature conservation. Therefore, accurate knowledge of butterfly species composition and distribution, as well as their genetic features, has numerous theoretical and practical implications. Since time and material resources are limited, wide-scale surveys based on DNA barcodes are particularly useful because they highlight patterns of notable interest that can be later investigated in a more detailed manner. Previous research using DNA barcodes highlighted complex biogeographic patterns and unexpected levels of potential cryptic diversity for some European regions, but a comprehensive overview of the continent’s butterfly fauna at high spatial resolution is lacking. Results: Within the framework of the EUGENMAP project, we assembled a high-quality, continental scale DNA barcode library for European butterflies, which comprises 20 000 DNA sequences representative for 99% (460 species) of the continent’s butterfly fauna. Ongoing analyses of this reference library allows us to assess patterns of genetic diversity, which help explain the phylogeography of numerous species and prioritize conservation efforts. Furthermore, we detect a series of cases involving either deep intraspecific divergence or DNA barcode sharing with one or several species, thus highlighting potential gaps in knowledge and the need for further research. Using a series of selected examples, we show what insights into the evolutionary history of organisms can be obtained when DNA barcodes are combined with additional data. Significance: Europe is the first continent to benefit from a comprehensive DNA barcode library for its butterfly fauna. This library represents a valuable resource that will likely foster research in butterfly taxonomy, ecology, and evolution, as well as practical applications in specimen identification and conservation.