Department of Geosciences, Biogeology, University of Tübingen, Hölderlinstraße 12, 72074, Tübingen, Germany.
Nagoya University Museum, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan.
Sci Rep. 2020 Apr 20;10(1):6612. doi: 10.1038/s41598-020-62990-0.
Heavy reliance on plants is rare in Carnivora and mostly limited to relatively small species in subtropical settings. The feeding behaviors of extinct cave bears living during Pleistocene cold periods at middle latitudes have been intensely studied using various approaches including isotopic analyses of fossil collagen. In contrast to cave bears from all other regions in Europe, some individuals from Romania show exceptionally high δN values that might be indicative of meat consumption. Herbivory on plants with high δN values cannot be ruled out based on this method, however. Here we apply an approach using the δN values of individual amino acids from collagen that offsets the baseline δN variation among environments. The analysis yielded strong signals of reliance on plants for Romanian cave bears based on the δN values of glutamate and phenylalanine. These results could suggest that the high variability in bulk collagen δN values observed among cave bears in Romania reflects niche partitioning but in a general trophic context of herbivory.
在食肉目动物中，对植物的严重依赖很少见，而且大多局限于亚热带地区的相对较小的物种。古熊在更新世寒冷时期生活在中纬度地区，人们使用各种方法对其进行了深入研究，包括对化石胶原的同位素分析。与来自欧洲其他所有地区的洞穴熊不同，罗马尼亚的一些个体显示出异常高的δN 值，这可能表明它们食用了肉类。然而，根据这种方法，不能排除对具有高δN 值的植物的食草行为。在这里，我们应用了一种从胶原中单个氨基酸的δN 值来抵消环境中基线 δN 值变化的方法。基于谷氨酸和苯丙氨酸的δN 值，分析结果强烈表明罗马尼亚洞穴熊对植物的依赖。这些结果可能表明，在罗马尼亚观察到的洞穴熊的总胶原 δN 值的高度变异性反映了生态位的分化，但在一般的食草营养背景下。
