Fauna and vegetation changes in the western Mediterranean regions during the Middle Pleistocene Revolution

The Mediterranean Basin is of outmost interest to test hypotheses about the transition/s that took place in Europe during the so-called “Mid-Pleistocene Revolution” (MPR: approximately from 1.2 to 0.6 Ma), because of its strategic position between Africa and continental Europe and its abundant fossil record. The actual role played by climatic changes in the evolution of plant and animal species and communities is a matter of a long-lasting discussion in the literature, particularly concerning the extinction, dispersal and differentiation of taxa. While the distribution of vegetation is generally considered closely related to climate conditions, climatic control on the evolution of mammals, which are believed to have less environmental sensitivity than other organisms, is actually a high complex phenomenon. It seems reasonable that both climate changes and intrinsic biotic controls would contribute to fauna evolution, though at different temporal scaling and geographical extent. A comparison of vegetation and faunal records through space (W-E transect in the Mediterraanean basin) and time (MPR) may help disentangle this question. The MPR is clearly observed in the vegetation record and is recognized as a slow and progressive change from forests dominated by Quercus, Liquidambar, Carya, Tsuga, and Picea to forests dominated by Quercus, Abies, Carpinus, and Fagus, and glacial periods characterized by considerable expansions of steppe and grasslands. The faunal record shows important renewals, associated to a decline of forest dwellers, the progressive disappearance of Villafranchian carnivores and an increase in the number of herbivore species. Discrete bioevents (dispersals of taxa, most of which persisted throughout the Middle Pleistocene, and turnover phases) led to a progressive reconstruction of mammalian faunal complexes that came to an end during the beginning of the Middle Pleistocene.