ABSTRACT In this paper, we analyze the isotopic niche and resource use of the guanaco (Lama guanicoe), pampas deer (Ozotoceros bezoarticus) and marsh deer (Blastocerus dichotomus) on the temperate plain of the northern Pampa region in the southeast of South America. The measured stable isotope compositions in bone tissue are δ13C, δ15N and δ18O. All the analyzed samples were recovered from different archaeological sites from the late Holocene. According to the results, the guanaco was strictly confined to the Pampa plain environment, developing a broad niche based on C3 plants and a variable contribution of C4 grasses within a grazing trend. The pampas deer preferentially used the Pampa plain, but also the prairies on the borders of the wetland, showing eurioic characteristics and a narrower niche based on C3 plants. In turn, the marsh deer was strictly confined to wetland environments, developing a C3 diet–base, within a narrow isotopic niche and stenoic characteristics. The three mammals showed a wide range of intraspecific variability, which was a key factor in their adaptability to spatial and temporal changes in the vegetation coverage. In fact, the temporal trends of their isotopic values were concurrent with the major climatic variations of the Holocene. Differences in the correlations between the values of both carbon sources in both deer species compared with the guanaco suggest a distinct chemical composition of their diet and/or differences in the allocation of nutrients. The isotopic values of nitrogen and spacing of the carbon sources in guanaco (pseudoruminant) and both deer species (ruminants) show no significant differences between them, thus establishing the values for local large herbivores. Significant correlations between δ13C and δ15N were found in the guanaco and marsh deer. The regional and extra–regional variability in the guanaco's δ13Ccollagen and δ15N probably reflect the clinal variations in the vegetation coverage and the amount of rainfall. The collagen isotope values in the guanaco throughout the entire Holocene show that the humid Pampa would have shifted between being a more recurrent mesic and temperate plain with minor phases of dry–mesic conditions like during the Little Ice Age, and a humid and warm one at the peaks of the Holocene Thermal Maximum and the Medieval Climatic Anomaly. The guanaco and the pampas deer adapted to all the climatic changes that happened on the humid Pampa until the biological invasions of large European mammals changed the herbivores’ guild composition of this vast plain, pushing them into peripheral habitats due to competition. The within–species variability in isotopic signals through time and space make it necessary to carry out adequate sampling before reconstructing the diets of local past populations.

中文翻译：

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潘帕斯草原的原驼 (Lama guanicoe)、潘帕斯鹿 (Ozotoceros bezoarticus) 和沼泽鹿 (Blastocerus dichotomus) 之间的资源利用模式和同位素生态位重叠。生态、古环境和考古意义

摘要 在本文中，我们分析了南美洲东南部潘帕地区北部温带平原的原驼（Lama guanicoe）、潘帕斯鹿（Ozotoceros bezoarticus）和沼泽鹿（Blastocerus dichotomus）的同位素生态位和资源利用。骨组织中测得的稳定同位素组成为 δ13C、δ15N 和 δ18O。所有分析的样品都是从全新世晚期的不同考古遗址中回收的。根据结果​​，原驼严格限制在潘帕平原环境中，在放牧趋势中发展出基于 C3 植物的广泛生态位和 C4 草的可变贡献。潘帕斯鹿优先利用潘帕平原，但也利用湿地边界的草原，表现出欧洲特征和基于C3植物的较窄生态位。反过来，沼泽鹿被严格限制在湿地环境中，在狭窄的同位素生态位和狭窄的特征内形成 C3 饮食基础。这三种哺乳动物表现出广泛的种内变异，这是它们适应植被覆盖时空变化的关键因素。事实上，它们同位素值的时间趋势与全新世的主要气候变化同时发生。与原驼鹿相比，两种鹿种的两种碳源值之间的相关性差异表明它们饮食的化学成分不同和/或营养分配的差异。原驼（假反刍动物）和两种鹿（反刍动物）的氮同位素值和碳源间距均无显着差异，从而确立了当地大型食草动物的价值。在原驼和沼泽鹿中发现了 δ13C 和 δ15N 之间的显着相关性。原蜥蜴的 δ13Ccollagen 和 δ15N 的区域和区域外变异可能反映了植被覆盖度和降雨量的临床变化。整个全新世原驼中的胶原同位素值表明，潮湿的潘帕草原会在更频繁的中温带平原与小冰河期等干燥中温带条件的次要阶段之间转变，而在全新世热最大值和中世纪气候异常的峰值。原驼和潘帕斯鹿适应了潮湿的潘帕斯草原上发生的所有气候变化，直到大型欧洲哺乳动物的生物入侵改变了这片广阔平原的食草动物行会组成，由于竞争将它们推向外围栖息地。同位素信号在时间和空间上的物种内变异性使得在重建当地过去种群的饮食之前进行足够的采样是必要的。