Biogeography of Pannonian steppe grasslands
Runtime: 2015 – 2018
Funding: Austrian Science Fund (FWF)
Summary
The aims of this project are (1) to achieve a consistent classification of the steppe grasslands in the whole Pannonian region using multivariate methods and a supra-national network of plot data, (2) to identify patterns of regional species diversity, genetic diversity and areas of endemism for the species pool of each main type of steppe grassland, (3) to evaluate the explanatory power of historical versus present-day environmental factors to explain these patterns, and (4) to validate different potential refuge areas based on population genetic analyses of several diagnostic plant species representing the main types of steppe grassland.
Description
The steppe grasslands of the Pannonian Basin are refuges for many rare species of plants and animals, and significantly contribute to the biodiversity of European landscapes. From a long-term perspective, steppe grasslands have been the dominant vegetation in large parts of Europe for most of the Quaternary. The degree of continuity in the floristic composition of these grasslands, however, remains unclear. It has been hypothesised that a considerable portion of thermophilous steppe species that occur in the Pannonian grasslands today, was restricted to refuge areas near the Black Sea coast during the Last Glacial Maximum and re-immigrated from these refugia into the central Pannonian region during the late glacial interstadials or the early Holocene. On the other hand, it has been hypothesised that the southern slopes of the hills surrounding the Hungarian Plain might have provided refuge areas for some thermophilous steppe species. There is also growing evidence that the distribution of many species is limited not only by environmental factors but also by species-specific seed dispersal and colonisation capacity. For several taxonomic and ecological groups, distance to potential glacial refuge areas has been shown to be a better predictor of regional species richness than the current environmental conditions. As the species occurring in different types of steppe grasslands have different environmental requirements, they might have been subjected to different processes of glacial survival and post-glacial migration. These differences can only be disentangled based on a consistent classification of grasslands types and species groups being at hand. Thus, the two complementary aims of the proposed research are (1) to achieve a consistent classification of the steppe grasslands in the whole Pannonian region using multivariate methods and a supra-national network of plot data; and (2) to identify patterns of regional species diversity, genetic diversity and areas of endemism for the species pool of each main type of steppe grassland, to evaluate the explanatory power of historical versus present-day environmental factors to explain these patterns, and to validate different potential refuge areas based on population genetic analyses of several diagnostic plant species representing the main types of steppe grassland. Beside evidence based on genetic diversity patterns, intraspecific genetic structuring will allow insights into routes of migration connecting present-day occurrences with likely refuge areas. The proposed study will be an important step towards the development of a consistent international typology of European grasslands. It will provide new insights into refuge areas and post-glacial re-colonisation processes of Pannonian steppe species and the role of limited migration abilities in steppe grasslands under a changing climate.
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