Origin of steppe flora and fauna in inner-Alpine dry valleys

Large portions of the Earth’s surface are covered by steppes. Highly insular steppe areas are situated in interior parts of large mountain chains such as the European Alps. The steppes of the inner-Alpine valleys and the Eurasian steppes have many animal and plant species in common. Most of these are distributed continuously from Central Asia to Eastern Europe, but are restricted to the most continental areas in Western and Central Europe. This implies that the present disjoint patches of steppe vegetation did not develop independently, but rather were interconnected in former times. Migration patterns on a regional scale, such as within the Alps, are much less evident. It is not clear, if the steppe biota in the inner-Alpine dry valleys are true relicts, restricted to areas with unfavourable conditions by the postglacial reforestation, or if dispersal among the dry valleys played a major role as well.

There is rich knowledge about the past range dynamics of many alpine and subnival plants and animals. This is in stark contrast to the virtual absence of information on the immigration history of steppe elements in the Alps. We will explore the origin and diversification of the Alpine steppe flora and fauna by testing explicit hypotheses. In doing so, we will apply brand-new approaches taking advantage of next-generation sequencing (i.e., Restriction site associated DNA sequencing) to a representative array of characteristic taxa (four species of vascular plants, one grasshopper, one ant and one spider) sampled throughout most of their distribution ranges. Data will be evaluated using traditional and new, highly sophisticated approaches such as Approximate Bayesian Computation and interpreted in the light of palaeovegetational evidence.

The following topics will be tackled in this project: (1) Did the steppe biota colonise each Alpine dry valley independently or is there evidence for genetic exchange among the insular steppe habitats of different valleys? (2) What are the biogeographic connections of steppe biota from the Alpine dry valleys with other areas of steppe vegetation in Eurasia? (3) Are phylogeographic patterns seen in steppe plants and animals congruent, implying range shifts of entire communities or rather idiosyncratic suggesting individualistic responses to climatic oscillations? (4) Our phylogeographic approach will unravel intraspecific patterns of spatial differentiation and temporal diversification across steppe plant and animal lineages. These will then not only be compared to each other, but also to independent data sources. Changes of distribution ranges of our study taxa through time will be hindcasted using environmental niche modelling. Finally, we aim to synthesize our results gained from the molecular investigations with palaeoecological evidence to provide a complete picture of the history of the steppe vegetation in and around the Alps during the Pleistocene and the Holocene.