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Bocherens H.,University of Tubingen | Stiller M.,Research Group Molecular Ecology | Stiller M.,Pennsylvania State University | Hobson K.A.,Environment Canada | And 6 more authors.
Quaternary International | Year: 2011

In the Austrian caves of Gamssulzen and Ramesch, two genetically distinct cave bears, Ursus ingressus and Ursus spelaeus eremus, apparently lived side by side for 15,000 years, together with brown bears Ursus arctos. The possible ecological partitioning of these three types of bears was investigated using multi-isotopic tracking of organic (δ13Ccoll, δ15Ncoll) and inorganic (δ13Ccarb, δ18Ocarb, δ18OPO4) fractions of bone. The cave bears from Ramesch, Ursus spelaeus eremus, were ecologically distinct from the cave bears from Gamssulzen, Ursus ingressus, both being ecologically distinct from brown bears from Ramesch, Ursus arctos. Both cave bear types were purely herbivorous but likely consumed different plant types and/or plants from different habitats, while brown bears included some animal proteins in their diet. Bone apatite δ18O values strongly suggest that both types of cave bears used isotopically distinct water sources, indicating that they may not have occupied the same landscape, either separated in space or in time due to climatic shifts. Therefore, the influence of environmental conditions strongly constrained the genetic structure of these bears. © 2010 Elsevier Ltd and INQUA.

Munzel S.C.,University of Tubingen | Stiller M.,Research Group Molecular Ecology | Stiller M.,Pennsylvania State University | Hofreiter M.,Research Group Molecular Ecology | And 4 more authors.
Quaternary International | Year: 2011

Palaeogenetic investigations in three geographically close caves (Hohle Fels, Geißenklösterle, and Sirgenstein) in the Ach Valley near Blaubeuren (Swabian Jura) document the sudden replacement of Ursus spelaeus by Ursus ingressus around 28,000 14C BP. New radiocarbon dates suggest an earlier immigration of Ursus ingressus and at least a partial coexistence with Ursus spelaeus some 4500 years before the ultimate replacement. These two genetic types of cave bears used the same caves for hibernation and had the same herbivorous diet, as shown by the stable isotope results. In contrast, sympatric brown bears (Ursus arctos) exhibited a clearly different ecology, as shown by the carnivorous pattern of their isotopic signatures, and probably did not use the caves as dens before the Last Glacial Maximum (LGM).Once established, the younger cave bear (Ursus ingressus) remained the only cave bear for only another circa 2000 years after the last appearance of the classical cave bear (Ursus spelaeus) in the Ach Valley and elsewhere. The final appearance of cave bear (sensu lato) is now dated to 25,560 ± 130 BP, disproving a refuge area of this species in the Swabian Jura. After the extinction of cave bears (sensu lato), brown bears took over their cave dens and their nutritional niche as they shift to a diet dominated by plant food. © 2011 Elsevier Ltd and INQUA.

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