Czech Republic butterfly barcoding: The distribution of butterfly genetic lineages in Europe is not random and it depends on species traits

DNA Barcoding, sequencing of a short standardised gene fragment, originally aimed for a simple tool for species identification. An important step towards this goal was building well-curated databases covering as many species and samples as possible, such as the BOLD database (Barcoding of Life Data System). The DNA barcode widely used in insects (mitochondrial gene for cytochrome c oxidase), proved effective also for biogeographic studies.

European butterflies are one of the best DNA-barcoded groups of organisms. The sampling is strongest for the Mediterranean region, where there is the highest species and intraspecific diversity, and the number of database sequences declines in the north-eastern direction. However, especially Central Europe represents an important suture zone of lineages which either differentiated in Southern Europe and expanded postglacially or thrived during the cold and dry glacial periods.

We sequenced DNA barcodes of the entire Czech butterfly fauna (140 species, 959 sequences) and used BOLD sequences from other countries to visualise the species' biogeographic patterns across Europe (Fig. 1). We categorised the distribution patterns of lineages inhabiting the Czech Republic and used multivariate statistics to interpret these categories by the butterflies' habitats, life history traits and threat levels (Fig. 2).

We found out that Czech steppe butterflies had lineages related to Southern, Eastern, or temperate parts of Europe. Such species tend to have specialist traits (herbs as host plants, small wings, low number of generations, and short flight periods). Such pattern can be attributed to the Quaternary history of Central Europe and the geography of the Czech Republic. Lowland corridors for steppe species are situated in Pannonia, in the southeast of the territory. On the other hand, the mountains alongside the western border block these lineages in the west. In many species, the Czech Republic was inhabited by temperate lineages, distributed alongside a temperature belt. These continental species might have expanded westwards during the arid glacials, establishing stable widespread populations. The species with specialists traits are also the most threatened, because they could not survive in simplified landscapes without habitat patches within reach.

On the other hand, generalists and woodland species had Western, mixed or low diversity lineages in Czechia. Their larvae often develop on trees, the adults are large with long flight periods and higher number of generations. Woodlands reestablished across Europe in the Holocene. Hence, in woodland species, a low population structure is expected. Generalists, which are good dispersers, likely diversified in different refugia when they were climatically restricted, and then they colonized vast areas and their lineages mingled. Good dispersers could more easily cross mountains and reach our territory also from the west.

DNA barcoding in under-sampled areas, even if not particularly biodiversity-rich, still represents a powerful tool for discovering the driving forces of biogeography on large scales, such as the links between phylogeography and species-specific traits. Czech butterfly barcoding library is an important contribution to the world-wide barcoding efforts.

Sucháčková Bartoňová A., Škopek P., Konvička M., Beneš J., Spitzer L., Sbaraglia C., Vrabec V., Papp Marešová J., Konvičková H., Faltýnek Fric Z. (2024) Czech Republic butterfly barcoding reveals that distribution of genetic lineages depends on species traits. Journal of Biogeography Early View: DOI: 10.1111/jbi.14848

Fig. 1. Examples of butterfly species displaying different mitochondrial genetic patterns inhabiting the territory of the Czech Republic. BAPS1-5 refer to clusters of related individuals within the species, termed here as lineages. Examining the map, based on the presence of lineage(s) in the Czech Republic, we assigned each of the 140 species into one or two of nine categories.  CC BY 4.0 (figure in the original version). https://creativecommons.org/licenses/by/4.0/

Fig. 2. Relationship between genetic patterns of Czech butterflies and individual species traits, interpreted by (a) habitats, (b) life history traits, (c) Red List categories (threat status) of individual species (Canonical correspondence analyses). CC BY 4.0 (figure modified from the original version). https://creativecommons.org/licenses/by/4.0/