Genetic turnovers and northern survival during the last glacial maximum in European brown bears

Abstract

The current phylogeographic pattern of European brown bears (Ursus arctos) has commonly been explained by postglacial recolonization out of geographically distinct refugia in southern Europe, a pattern well in accordance with the expansion/contraction model. Studies of ancient DNA from brown bear remains have questioned this pattern, but have failed to explain the glacial distribution of mitochondrial brown bear clades and their subsequent expansion across the European continent. We here present 136 new mitochondrial sequences generated from 346 remains from Europe, ranging in age between the Late Pleistocene and historical times. The genetic data show a high Late Pleistocene diversity across the continent and challenge the strict confinement of bears to traditional southern refugia during the last glacial maximum (LGM). The mitochondrial data further suggest a genetic turnover just before this time, as well as a steep demographic decline starting in the mid‐Holocene. Levels of stable nitrogen isotopes from the remains confirm a previously proposed shift toward increasing herbivory around the LGM in Europe. Overall, these results suggest that in addition to climate, anthropogenic impact and inter‐specific competition may have had more important effects on the brown bear's ecology, demography, and genetic structure than previously thought.

Looking for the earliest evidence of Ursus arctos LINNAEUS, 1758 in the Iberian Peninsula: the Middle Pleistocene site of Postes cave

“…This would be consistent with the decrease of the bear population in Europe starting in the Middle Holocene, due to the increase of human density and the parallel loss of suitable habitats and resources (Ersmark et al . 2019). Based on the study of the cranium, Marciszak et al .…”

“…2008, 2011), as well as the presence of a genetic turnover just before the Last Glacial Maximum (Ersmark et al . 2019). Finally, a palaeogenetic analysis has demonstrated a more complex evolutionary history of the brown bear, with the presence of nuclear admixture with cave bears, which are not associated with mitochondrial exchange (Barlow et al .…”

Integrating multi-taxon palaeogenomes and sedimentary ancient DNA to study past ecosystem dynamics

“…[ 94 ]). This shift entailed a steady decline and fragmentation of forested areas through land clearing as well as a profound alteration of aquatic ecosystems through irrigation and wetland draining [ 40 ], which likely had important effects on animal species [ 95 ], plant communities [ 94 ] and associated trophic networks.…”

Bones of Contention: Reflections on Osteoarchaeology and the Baltic Region

“…Encouraging examples of recent projects run with the participation of researchers of the Osteoarchaeological Research Laboratory involve the traditional osteological analysis of animal and human remains in combination with advanced laboratory methods including aDNA research (e.g. Ersmark et al, 2019;Fraser et al, 2017;Ollivier et al, 2018;Frantz et al, 2019;Landeschi et al, 2019;Price et al, 2019). Of these, the current project titled 'The Atlas of ancient human genomes in Sweden' stands out.…”