EVIDENCE OF NICHE CONSERVATISM OVER PLEISTOCENE GLACIAL-INTERGLACIAL CYCLES FOR ANCIENT MAMMALS DURING THE PLEISTOCENE OF EUROPE

Niche conservatism posits that species maintain their ecological characteristics over time, which has implications for ecosystem assembly, speciation and creation of biodiversity. In general, the concept of niche conservatism has been supported by data. But, rather than directly examining aspects of species’niches over time, many studies use proxy data to infer niche characteristics, such as a species’ geographic range. The aim for this study was to investigate the ecological effects of climate change related to glacial-interglacial cycles on Pleistocene mammals in Europe. The study focused on identifying diet and habitat use in large mammals, and specifically tested the hypothesis that species maintain their ecology and ecological relationships over spatial and temporal scales during the Pleistocene of Europe.

To determine mammal ecology, stable carbon and oxygen isotope values from the tooth enamel of large mammals were examined. The analysis of δ¹³C and δ¹⁸O values obtained from the teeth of fossil mammals has proven extremely useful for ascertaining mammal (paleo)ecology. Hundreds of isotope samples were obtained and compared to previously published data from sites in Central and Western Europe. Results show that C₃ plants dominated the Pleistocene landscape of Europe as they do today. Horses (Equus sp.), red deer (Cervus elaphus), and bovids (i.e., Bos primigenius and Bison sp.) commonly displayed the most positive δ¹³C values and maintained a regular ecological relationship when present together at a locality. Consistently, the most negative δ¹³C values were displayed by individuals in the cave bear lineage (i.e., Ursus spelaeus, Ursus deningeri), and suggest herbivory. For oxygen, canids (Canis sp.) generally displayed the most positive δ¹⁸O values, which may relate to obtaining water from a different source than the other analyzed taxa. Overall, the data show limited isotopic differences over time and between localities implying that species maintained their ecology. These data support the tested hypothesis as well as the concept of niche conservatism in Pleistocene European mammals.