Retreat and extinction of the Late Pleistocene cave bear (Ursus spelaeus sensu lato).

Mateusz Baca,Mikołaj Urbanowski,Adam Nadachowski,Adrian Marciszak,Krzysztof Stefaniak,Danijela Popović,Paweł Mackiewicz

doi:10.1007/s00114-016-1414-8

Abstract

The cave bear (Ursus spelaeus sensu lato) is a typical representative of Pleistocene megafauna which became extinct at the end of the Last Glacial. Detailed knowledge of cave bear extinction could explain this spectacular ecological transformation. The paper provides a report on the youngest remains of the cave bear dated to 20,930 ± 140 14C years before present (BP). Ancient DNA analyses proved its affiliation to the Ursus ingressus haplotype. Using this record and 205 other dates, we determined, following eight approaches, the extinction time of this mammal at 26,100–24,300 cal. years BP. The time is only slightly earlier, i.e. 27,000–26,100 cal. years BP, when young dates without associated collagen data are excluded. The demise of cave bear falls within the coldest phase of the last glacial period, Greenland Stadial 3. This finding and the significant decrease in the cave bear records with cooling indicate that the drastic climatic changes were responsible for its extinction. Climate deterioration lowered vegetation productivity, on which the cave bear strongly depended as a strict herbivore. The distribution of the last cave bear records in Europe suggests that this animal was vanishing by fragmentation into subpopulations occupying small habitats. One of them was the Kraków-Częstochowa Upland in Poland, where we discovered the latest record of the cave bear and also two other, younger than 25,000 14C years BP. The relatively long survival of this bear in karst regions may result from suitable microclimate and continuous access to water provided by deep aquifers, indicating a refugial role of such regions in the Pleistocene for many species.

Highlights

The extinction of large-bodied mammals is one of the most characteristic and inherent features of the Late Pleistocene
The second date obtained for the JST4 sample is older (26,114 cal. years before present (BP)) than the first one (25,251 cal. years BP) and their 95 % probability intervals
The results indicate that the cave bear did not survive into the Last Glacial Maximum (LGM), if we assume a rigorous definition of its duration from 23,000 to 19,000 cal. years BP (Waelbroeck et al 2009)

Summary

Introduction

The extinction of large-bodied mammals (called megafauna) is one of the most characteristic and inherent features of the Late Pleistocene. The disappearance began 50,000 years ago and affected a substantial number of mammalian genera, e.g. 36 % of them in Eurasia, 72 % in North America and 83 % in South America (Barnosky et al 2004) Both the climate and environment changes, as well as human influence, are believed to be the main causes of this extinction (Barnosky et al 2004; Cooper et al 2015; Koch and Barnosky 2006; Lorenzen et al 2011; Stuart 2015). Two small cave bear forms that had preserved some primitive traits were distinguished as subspecies of U. spelaeus: U. spelaeus eremus and U. spelaeus ladinicus (Rabeder and Hofreiter 2004; Rabeder et al 2004a) Their distribution was confined to the high alpine caves in Austria and Italy. They were named Ursus deningeri kudarensis, but recent genetic studies suggest that they should be considered a third species, Ursus kudarensis (Stiller et al 2014)

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Conclusion