Dry grassland butterflies are threatened by habitat loss, not climatic oscillations
In a recent paper published in Insect Systematics and Diversity, we investigated three butterfly species of dry grasslands, all extremely declining throughout Central Europe, despite their large overall distribution ranges. We reviewed the recent history of their populations on Central European scale, compiled field observation data, notes from captive breeding and reintroduction or assisted colonization programmes, analysed genetic patterns and reconstructed their biogeographic history using species distribution modelling.
Fig.: A - Raná (České středohoří), biotop of C. briseis, and until recently, also P. damon. foto Pavel Skala, B - Turqouise Blue (Polyommatus dorylas), foto Oliver Böck, C - the Hermit (Chazara briseis), foto Pavel Skala.
Dry grasslands of Central Europe are the westernmost patches of the Eurasian steppe biome. They host a remarkable biodiversity. They were long believed to be semi-natural, created by human forest clearance, followed by grazing and related activities. Currently, it is increasingly accepted that even grasslands on more fertile surfaces may have been continuously present through several glacial cycles, representing remnants of arid glacial habitats, and endured even the pre-agricultural phases of the Holocene owing to wild herbivores grazing and factors such as fire. Thermophilic species, possible interglacial immigrants from Mediterranean grasslands, further increase the dry grassland diversity.
In a recent paper published in Insect Systematics and Diversity, we investigated three butterfly species of dry grasslands, all extremely declining throughout Central Europe, despite their large overall distribution ranges. We reviewed the recent history of their populations on Central European scale, compiled field observation data, notes from captive breeding and reintroduction or assisted colonization programmes, analysed genetic patterns and reconstructed their biogeographic history using species distribution modelling.
Chazara briseis survives in a handful of steppe localities in Austria, Czech Republic, Germany and Hungary and it is already extinct from Poland and Slovakia. The species was widely distributed both during glacials and interglacials. Polyommatus damon is still present in the Alps, but it severely declined in lowlands of Germany and Austria, got extinct from Poland, Slovakia, Romania and most probably recently also from the Czech Republic. It resembles a cold-adapted (mountain) species: it is adapted to a glacial climate, and its climatic niche is fragmented in interglacials. Polyommatus dorylas is still distributed in a few localities in Central Europe; it is almost extinct from the Czech Republic. It prefers oceanic climate and probably (re)colonized Europe in Holocene from the south.
In the past, all three species probably depended on open habitats created and maintained by large ungulates, as all of them need disturbed ground or patches with short grass. All these butterflies survived severe climatic changes of the Quaternary period, but they almost succumbed to recent human induced habitat alterations. Conservation actions, including proper habitat managements, captive breeding, reintroductions, assisted colonization, hopefully resulting in metapopulation restorations, are being taken in Central Europe.
Sucháčková Bartoňová A., Konvička M., Marešová J., Bláhová D., Číp D., Skala P., Andres M., Hula V., Dolek M., Geyer A., Böck O., Kadlec T., Faltýnek Fric Z. (2021) Extremely endangered butterflies of scattered Central European dry grasslands under current habitat alteration. Insect Systematics and Diversity 5: article number: 6. DOI: 10.1093/isd/ixab017
