Long‐term continuity of steppe grasslands in eastern Central Europe: Evidence from species distribution patterns and chloroplast haplotypes

Abstract

Aim The steppe grasslands of eastern Central Europe are exceptionally species rich and valuable from a nature conservation point of view. However, their historical biogeography is still poorly understood. Here we use the regional diversity of habitat specialists and chloroplast DNA data to investigate potential long‐term refugia of steppe species in this region. Location Pannonian Basin and adjacent regions; SW Russia. Taxon Vascular plants. Methods After identifying habitat specialists of the three main steppe types (meadow steppes, grass steppes and rocky steppes), we compiled their regional presence–absence in grid cells of 75 km × 75 km. We analysed the dependency of habitat specialist diversity to climate, topographic heterogeneity and geographical distance to potential refugia. For genetic analysis, we sampled three or four habitat specialists of each steppe type and used cpDNA markers to investigate intraspecific diversity and geographical distribution of haplotypes. We also tested for correspondence between the number of habitat specialists and haplotype diversity. Results Climate and topography explained between 40% and 63% of the variance in habitat specialist diversity. Adding geographical distance to potential refugia increased the explained variance in the models for all steppe types. Chloroplast haplotypes featured a complex pattern across the study area. Several species showed a strong geographical differentiation, suggesting migration waves from multiple refugia with only limited subsequent genetic intermixture. Maximum haplotype diversity in a region showed a better correlation with the number of habitat specialists per steppe type than mean haplotype diversity. Main conclusions We can clearly reject the scenario of a late‐Holocene immigration of steppe species from areas outside the Pannonian Basin. Most species must have been present in the region since at least the early Holocene, highlighting the importance of the lower mountain ranges surrounding the Pannonian Basin as long‐term refugia for European steppe species. Dispersal limitation and resulting migration lags seem to have a strong influence on the distribution of steppe species in Central Europe.

Central European forest–steppe: An ecosystem shaped by climate, topography and disturbances

“…Divíšek et al, 2020; Jamrichová et al, 2017; Magyari et al, 2010; Willis & van Andel, 2004). The same questions are also addressed by phylogeographical analyses (Kajtoch et al, 2016; Kirschner et al, 2020; Willner et al, 2021). These studies support the hypothesis that forest–steppe mosaics have survived in several regions of Central Europe during periods of both arid and humid climatic conditions since the last ice age.…”

“…Conversely, the survival of steppe patches in the humid Mid‐Holocene (Feurdean et al, 2015; Pokorný et al, 2015) is probably also due to such rugged landscapes. In particular, steppe species might have survived this wet period in the lower mountain ranges around the Pannonian Basin (Willner et al, 2021). In some cases, human influence might have been of predominant importance (Novák et al, 2019).…”

Genotyping-by-sequencing reveals range expansion of Adonis vernalis (Ranunculaceae) from Southeastern Europe into the zonal Euro-Siberian steppe

“…This transition and the major glacial/interglacial cycles of the Middle and Late Pleistocene may have provided opportunities for population differentiation in the southern part of Europe, in the western and central Mediterranean on the one hand and in Southeastern Europe on the other hand. Particularly the Southern Carpathians and adjacent regions were recently characterized as having long-term continuity of other meadow steppe plants 33 .…”

Origin of the central European steppe flora: insights from palaeodistribution modelling and migration simulations

“…Recent genetic analyses (Kajtoch et al 2016, Kirschner et al 2020, Willner et al 2021) demonstrate that several steppe plant and animal species survived in situ in central Europe. The presence of distinct clusters of genetically similar individuals in parts of central Europe suggests an ancient (Pleistocene) origin of these populations.…”

“…The steppe grasslands of central Europe comprise several habitat types with different species compositions and environmental affinities (Wendelberger 1954, Willner et al 2017, 2021, Chytrý et al 2020). The coarsest classification includes three types: rocky steppe, grass steppe (slope steppe on moderately deep soils over rocky substrates and drier types of loess steppe) and meadow steppe (steppe meadows and mesic types of loess and chernozem steppes).…”