Preliminary results on climate change evidence from coprolites of Myotragus balearicus Bate 1909 (Artiodactyla, Caprinae)

Plants may vary their stomata density as a function of environmental factors, such as [CO2], drought and temperature. Under the present atmospheric conditions, it is expected that leaves have different stomata density than they had hundreds or thousands of years ago, due to the rise of CO2 in the atmosphere. Microhistological analyses of coprolites of the extinct Myotragus balearicus from Cova Estreta (Pollença, Mallorca), with a radiocarbon age of 4950 ± 38 BP (3775-3640 2σ cal BC; Wk-33010), have shown a diet including an important amount of Buxus balearica epidermal fragments. Three of these coprolites were used to estimate the stomata density on Buxus balearica epidermal fragments from this period. Additionally, three samples of the endangered Buxus balearica, the sole species of Buxus currently present on Mallorca, were collected in three different localities and leaves were examined under microscopy to determine the stomata density. A significant difference between epidermal fragments from coprolites and epidermal fragments of living plants (c² = 34.46, P<0.0001, L-R c² test), with a density average of 27.21 and 19.05 stomata/mm2 res pectively, has been recorded. The current lower density of stomata could be a plant response to climatic change in the Mediterranean islands.