Range dynamics of Palaearctic steppe species under glacial cycles: the phylogeography of Proterebia afra (Lepidoptera: Nymphalidae: Satyrinae)

Abstract

Despite high representation of steppe elements in Northern Palaearctic temperate biota, the Pleistocene history of such species is still insufficiently understood. The steppe specialist butterfly Proterebia afra (Lepidoptera: Nymphalidae: Satyrinae) inhabits both the continental Palaearctic steppe biome and southern mountain steppes; it occurs as a relic on the Balkan Peninsula. Based on mitochondrial (cytochrome c oxidase subunit I), nuclear (arginine kinase) and genome-wide (amplified fragment length polymorphism) molecular markers and species distribution modelling (MaxEnt), we analysed its historical biogeography. In the assumed ancestral range (northern Iran and southern Caucasus), the populations form distinct units, which probably differentiated during downhill–uphill shifts during the Pleistocene glacial cycles. Populations north and east of the Caucasus Mountains form a single lineage, separated from the southern populations for the entire Plio-Pleistocene. According to species distribution modelling, this lineage retained a contiguous distribution during glacial maxima, documenting that this steppe species inhabited vast areas during glacial times. The Balkan populations are distinct, revealing in situ survival within glacial cycles, but were repeatedly connected to the rest of the range in the past. The connection between the south-eastern Balkans and the Black Sea surroundings could had been lost in relatively recent times, owing to human-induced changes in land use.