Stable isotopes of mammoths and mastodons have the potential to illuminate ecological changes in late Pleistocene landscapes and megafaunal populations as these species approached extinction. The ecological factors at play in this extinction remain unresolved, but isotopes of bone collagen (δ13C, δ15N) and tooth enamel (δ13C, δ18O, 87Sr/86Sr) from midwestern North America are leveraged to examine ecological and behavioral changes that occurred during the last interglacial-glacial cycle. Both species had significant C3 contributions to their diets and experienced increasing levels of niche overlap as they approached extinction. A subset of mastodons after the last glacial maximum exhibit low δ15N values that may represent expansion into a novel ecological niche, perhaps densely occupied by other herbivores. Stable isotopes from serial and microsampled enamel show increasing seasonality and decreasing temperatures as mammoths transitioned from Marine Isotope Stage (MIS) 5e to glacial conditions (MIS 4, MIS 3, MIS 2). Isotopic variability in enamel suggests mobility patterns and life histories have potentially large impacts on the interpretation of their stable isotope ecology. This study further refines the ecology of midwestern mammoths and mastodons demonstrating increasing seasonality and niche overlap as they responded to landscape changes in the final millennia before extinction.

中文翻译：

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北美中西部晚第四纪长鼻类动物的生活史和生态位动态

随着这些物种濒临灭绝，猛犸象和乳齿象的稳定同位素有可能揭示晚更新世景观和巨型动物种群的生态变化。在这次灭绝中起作用的生态因素仍未解决，但骨胶原的同位素（δ13C, δ15N）和牙釉质（δ13C, δ18哦，87锶/86来自北美中西部的 Sr) 被用来检查在最后一个间冰期-冰期周期中发生的生态和行为变化。这两个物种对它们的饮食都有显着的 C3 贡献，并且随着它们濒临灭绝，它们的生态位重叠水平越来越高。末次冰期最大值后的乳齿象子集表现出低 δ15N 值可能代表扩展到新的生态位，可能被其他食草动物密集占据。随着猛犸象从海洋同位素阶段 (MIS) 5e 过渡到冰川条件（MIS 4、MIS 3、MIS 2），来自串行和微量采样牙釉质的稳定同位素显示出季节性增加和温度降低。牙釉质的同位素变异性表明迁移模式和生活史对其稳定同位素生态学的解释具有潜在的巨大影响。这项研究进一步完善了中西部猛犸象和乳齿象的生态学，表明随着它们在灭绝前的最后几千年对景观变化做出反应，季节性和生态位重叠不断增加。