δ13C and δ15N herbivores variability in a longitudinal transect of southern Patagonia during the Holocene

TESSONE, AUGUSTO

Conferencia; 11th International Conference on the Applications of Stable Isotope Techniques to Ecological Studies; 2018

Climate-environmental variables influence the natural distribution of carbon and nitrogen stable isotopes. Continental Patagonia presents ecological diversity, conditioned in large part by variations in precipitation, which have a strong downward gradient in the west-east direction. Thus, this study aims to evaluate δ13C and δ15N variability in herbivores of Southern Patagonia during the Holocene from a transect of ca. 400 km between 47º and 49º south latitude, spanning from the Andes mountain to the Atlantic coast. We analyzed δ13C and δ15N of bone collagen from 103 specimens from the archaeological record. The transect is segmented in three areas. The Western section corresponds to the forest and the forest-steppe ecotone, with specimens of huemul (Hippocamelus bisulcus) and guanaco (Lama guanicoe). The second, Central area reflects samples from the steppe and, finally, the third, a coastal terrestrial ecosystem bordering the Argentine sea. Guanacos were sampled from the latter two areas. The guanacos from the coastal area had values (N = 8) of δ13C -19.5 ? ± 0.3 ? and δ15N 8.6 ? ± 1 ?. The guanacos from the central area had a mean (N = 57) of δ13C -19.3 ? ± 0.8 ? and δ15N 6.3 ? ± 1.2 ?. In the Western area guanacos showed values (N=18) of δ13C -20.0 ? ± 0.9 ? and δ15N 2.7 ? ± 2.1 ?, while the huemul (N=20) of -20.9 ? ± 0.7 ? and 1.3 ? ± 1 ? respectively. In this way, an increase in herbivore δ15N values can be seen from the Andes mountains to the Atlantic coast. It is proposed that these variations respond to climatic environmental variables that affect the natural distribution of stable isotopes. In conclusion, these δ15N values allow herbivores from the three areas to be differentiated and represents an opportunity to discuss aspects of diet and/or mobility, for either hunter-gatherers or faunal species.