Ancient feeding ecology inferred from stable isotopic evidence from fossil horses in South America over the past 3 Ma
Ancient feeding ecology inferred from stable isotopic evidence from fossil horses in South America over the past 3 Ma
复制标题
根据过去 3 Ma 南美洲化石马的稳定同位素证据推断出古代进食生态学
作者：
J. Prado;B. Sánchez;M. Alberdi
背景稳定同位素比化石牙齿和骨骼中的13 C/12 C和18 O/16 O为了解南美洲上新世-更新世灭绝马的生态学提供了关键档案;然而，在马属动物的同域区，（Amerhippus）和Hippidion是不太了解。我们使用来自25个不同地区的7种马的67个牙齿和骨骼化石样本中保存的稳定碳和氧同位素来记录马和古代马的饮食变化的幅度。上新世-更新世植物群的变化。从南美洲两种马属的稳定同位素推断的饮食重建记录了古代生态系统中的饮食分离和环境变化，包括C3/C4过渡。稳定的同位素数据表明，在C4草消费，种间饮食分区和同位素生态位宽度的变化与latitudialgradient.ConclusionsThe数据的混合馈线Hippidion表明不同的偏好从C3植物混合C3-C4植物在他们的饮食。马属（Amerhippus）的动物具有三种不同的食物分配模式。来自布宜诺斯艾利斯省的neogeus表明在饮食中偏好C3植物。马属（A.）来自厄瓜多尔和马属的andium（A.）来自玻利维亚的insulatus喜食C3-C4混合植物，而Equus（A.）产自拉卡罗来纳（厄瓜多尔的海平面）和巴西的santaeelenae大多是C4饲养者。这些结果证实，古代的摄食生态不能总是推断牙齿形态。虽然马骨骼材料的碳同位素组成随着纬度的增加而降低，但我们发现在32° S附近存在混合C3/C4饮食信号和纯C4信号之间的边界，并且在35°S附近从混合饮食信号转变为纯C3信号。我们发现生活在高海拔和低至中纬度的马仍然在其饮食中含有C4成分，除了4000米的标本，它有一个纯C3饮食。更新世期间海拔植被梯度的变化是解释生活在高海拔地区的马的C4饮食成分的几种可能性之一。另一种解释暗示，马在低海拔地区部分进食。
BackgroundStable isotope ratios (13C/12C and 18O/16O) in fossil teeth and bone provide key archives for understanding the ecology of extinct horses during the Plio-Pleistocene in South America; however, what happened in areas of sympatry between Equus (Amerhippus) and Hippidion is less understood.ResultsHere, we use stable carbon and oxygen isotopes preserved in 67 fossil tooth and bone samples for seven species of horses from 25 different localities to document the magnitude of the dietary shifts of horses and ancient floral change during the Plio-Pleistocene. Dietary reconstructions inferred from stable isotopes of both genera of horses present in South America document dietary separation and environmental changes in ancient ecosystems, including C3/C4 transitions. Stable isotope data demonstrate changes in C4 grass consumption, inter-species dietary partitioning and variation in isotopic niche breadth of mixed feeders with latitudinal gradient.ConclusionsThe data for Hippidion indicate a preference varying from C3 plants to mixed C3-C4 plants in their diet. Equus (Amerhippus) shows three different patterns of dietary partitioning Equus (A.) neogeus from the province of Buenos Aires indicate a preference for C3 plants in the diet. Equus (A.) andium from Ecuador and Equus (A.) insulatus from Bolivia show a preference for to a diet of mixed C3-C4 plants, while Equus (A.) santaeelenae from La Carolina (sea level of Ecuador) and Brazil are mostly C4 feeders. These results confirm that ancient feeding ecology cannot always be inferred from dental morphology. While the carbon isotope composition of horses skeletal material decreased as latitude increased, we found evidence of boundary between a mixed C3/C4 diet signal and a pure C4 signal around 32° S and a change from a mixed diet signal to an exclusively C3 signal around 35°S.We found that the horses living at high altitudes and at low to middle latitude still have a C4 component in their diet, except the specimens from 4000 m, which have a pure C3 diet. The change in altitudinal vegetation gradients during the Pleistocene is one of several possibilities to explain the C4 dietary component in horses living at high altitudes. Other alternative explanations imply that the horses fed partially at lower altitudes.