Quaternary evolution of the river Danube in the central Pannonian Basin and its possible role as an ecological barrier to the dispersal of ground squirrels

ABSTRACT

Large rivers can act as important ecological barriers for small mammals, but their exact role is debated. Here we examine the effect of the river Danube on populations of the European ground squirrel, an important representative of steppe communities, by studying the Quaternary history both of ground squirrels and of the Danube in the Pannonian Basin, in Hungary. The Danube experienced considerable channel changes during the Quaternary, with >100 km westward shift of its middle reach, interrupted by temporary eastward movements. Besides autogenic river processes, tectonically induced avulsions have played a role in re-routing channels. Three of the four Spermophilus species certainly extended their ranges on both sides of the Danube, referring to repeated river crossings during the Quaternary. Hydrological events, most importantly rapid river course changes (avulsions) but also meander cut-offs are viable mechanisms to enable ground squirrel populations to cross large rivers. On longer timescales, oscillating river course changes can maintain gene exchange across the river.

KEYWORDS:

• Barrier
• souslik
• dispersal
• avulsion
• tectonics
• palaeogeography

Acknowledgments

This work was supported by the geological research project of Paks II. Ltd., by the INQUA HABCOM 1606P project and by the National Research, Development and Innovation Office of Hungary (NKFIH-OTKA) under Grant number 83610. This paper is MTA-MTM-ELTE Paleo contribution No. 299. We are grateful to two anonymous reviewers for their constructive comments, which greatly improved the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Paks II. Ltd.; INQUA [HABCOM 1606P project]; National Research, Development and Innovation Office of Hungary [83610].