Ecological response of large herbivores to the late Quaternary climatic changes in northeast Iberian Peninsula refugium

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The Iberian Peninsula is one of the southern regions in Europe that saw the persistence of human and animal occupation over the climatic changes of the late Quaternary. In this project, we aim at investigating to which extant the different colder and warmer climatic episodes between ca. 40,000 and 10,000 years ago have impacted the ecology of the large herbivores, namely red deer (Cervus elaphus) and horse (Equus sp.) in this refuge area. We intend to use the amounts of stable isotopes in their bone collagen and tooth enamel to reconstruct their diet, habitat and some parameters of their environment. We consider three key periods in Europe, which are 1) around the Heinrich event 4 (ca. 40 kyr cal BP), 2) around the Last Glacial Maximum (27-23 kyr cal BP), and 3) after the Heinrich Event 1 (ca. 15.6 to 9.8 kyr cal BP). Each of these key time ranges corresponds to a major change in the climatic conditions that have triggered human and animal population turn over in Europe. The studied material consists of skeletal remains of red deer (67 bones and 40 teeth) and horse (53 bones and 30 teeth) coming from seven archaeological sites of mid-range altitudes (170 to 760 m asl). The stable isotopes (carbon-13 and nitrogen-15) of bone collagen from mature individuals deliver a long-term record of adult lifetime as a result of the constant bone remodelling. Carbon-13 informs on the forage preferences but also reflects conditions of humidity and closure of the habitat. Nitrogen-15 is an indicator of the diet (grazing versus browsing) and of the environment, such as the local temperature and conditions of humidity. The dietary and environmental influences can be disentangled by examining the intensity of the dental wear that depends mainly on the consumption of grasses versus leaves. Short time seasonal record of temperature and habitat can be obtained by the sequential analysis of oxygen-18 and carbon-13 over the tooth enamel, which does not remodel after the formation of the tooth. The isotopic sequence of the third molar should reflect the second winter of the life of the individual for the red deer, and one summer and one winter between the second and fourth year of the individual life of the horse. The results of this project will contribute to test two scenarios: 1) the adaptation of the herbivores to a changing environment through changes in habitat and diet thanks to their ecological flexibility or 2) the local buffering of the variation in climatic conditions allowing the species to persist without a significant change of their ecology. Ultimately, understanding how red deer and horse could cope with climatic changes (habitat, diet adaptation) in the past can help us to predict how tolerant will be these species to present-day and future environmental changes.