Extremely Endangered Butterflies of Scattered Central European Dry Grasslands Under Current Habitat Alteration

Abstract

Central European dry grasslands represent extrazonal patches of the Eurasian steppe biome. They suffer from severe habitat alterations due to land-use changes, abandonment, or inappropriate management. The butterflies Chazara briseis (Linnaeus, 1764) (Lepidoptera: Nymphalidae), Polyommatus damon (Denis & Schiffermüller, 1775) (Lepidoptera: Lycaenidae), and Polyommatus dorylas (Denis & Schiffermüller, 1775) (Lepidoptera: Lycaenidae), specialized inhabitants of these steppe patches, are all swiftly disappearing from Central Europe. We reviewed data on the recent history of their population retractions in the region, including conservation efforts. Using samples from their whole distribution ranges, we sequenced and analyzed COI and wingless genes and together with Species Distribution Modelling reconstructed their biogeographic histories. Populations of C. briseis expanded over the Eurasian steppe biome, where large ungulates maintained extensive grasslands with short open sward. Polyommatus damon became widespread in the steppes during glacial times, and retracted during interglacials, resembling cold-adapted species. It is limited by too dry weather, and it requires disturbed grassland followed by temporal abandonment. Its present genetic structure was induced by the major Pleistocene Mountain glaciations. Polyommatus dorylas prefers an oceanic climate and populated Central Europe from the Balkans during the Holocene. The species depends on disturbed ground. Currently, all three species inhabit only a few remnant sites in Central Europe, and their populations have been further declining in recent years. Targeted conservation actions, including habitat management at remaining sites, ex situ breeding, and (re)introductions, are being taken in Austria, the Czech Republic, and Germany.