Eurasian butterfly inhabited vast steppe areas during both glacial and interglacial times

Photo description: left panel – female of the Dalmatian ringlet (Proterebia afra); right panel – steppe-like habitats in Askion Mountains (Greece).

Steppe species are still insufficiently studied group in the Quaternary biogeographic research. As the temperate-adapted species are supposed to expand northwards from Mediterranean Peninsulas during warm interglacial periods, the cold-adapted fauna exhibits the opposite pattern, retreating to the North or to the mountains during interglacials. However, apart from this temperature-driven gradient, also humidity changes during ice ages, and some species had to adapt to increased aridity and hence continentality in glacials.

Researchers from the Institute of Entomology (A. Bartoňová, M. Konvička and Z. Faltýnek Fric) and their colleagues examined the phylogeographic pattern of a steppe butterfly Proterebia afra (Nymphalidae: Satyrinae), which occurs in the Middle Asian steppes and inhabits also two apparently relic areas in the Balkans – inland Dalmatia in Croatia, and Askion Mountains in north-western Greece, both isolated from the rest of its range. The study published in the Biological Journal of the Linnean Society combines genetic data and climatic modelling. According to the results, the species ancestral range is in northern Iran and southern Caucasus, where the lineages differentiated during downhill-uphill shifts during the ice ages. The species expanded to the Balkans and north- and eastwards of the Caucasus Mountains several glacial cycles ago, where it retained contiguous distribution during the entire cycles. The Balkan populations are distinct, but were also reconnected to the rest of the range in the past. The species could have been present at the European banks of the Black Sea, and the populations could have been lost relatively recently due to the conversion of rich steppe soils into arable land.

Apart from small mammals such as the European ground squirrel and large herbivores (e.g., horse, auroch), also invertebrates complemented the biota of the Palaearctic steppes – the most extensive biome on Earth during the entire Quaternary.

Bartoňová A., Konvička M., Korb S., Krampl K., Schmitt T., Faltýnek Fric Z. (2018) Range dynamics of Palaearctic steppe species under glacial cycles: the phylogeography of Proterebia afra (Lepidoptera: Nymphalidae: Satyrinae). Biological Journal of the Linnean Society. Published online: 09 October 2018. DOI: 10.1093/biolinnean/bly136