The immigration history and extinction dynamics of the Scandinavian aurochs ( Bos primigenius )

The final disappearance of the aurochs ( Bos primigenius ) from Poland in the 17th century marked the culmination of a decline that had begun as early as the Atlantic period. Although human activities primarily drove its extinction, the reasons for its earlier disappearance in Scandinavia remain uncertain. This study investigates the immigration and extinction dynamics of the Scandinavian aurochs during the Holocene. Utilising phylogenetic and palaeogenetic data, we trace its postglacial colonisation from a Western European refugium, delimiting the period of connectivity with the main European population before the land bridge was severed by rising sea levels. Genetic analyses further point to inbreeding and genetic drift, exacerbated by population bottlenecks and geographical isolation, diminishing resilience over time. Population modelling indicates a classic boom-bust pattern correlated with intensified human settlement and hunting. Despite environmental conditions initially permitting persistence amidst increasing forest cover, subsequent habitat loss and human pressures accelerated demographic decline. Our integrated approach indicates that the extinction resulted from a synergistic effect of habitat fragmentation and degradation, genetic depletion, and prolonged anthropogenic pressures. These findings highlight the complex, multifactorial processes underlying species extinction and emphasise the importance of cross-disciplinary methods in palaeoecological research.