PALYNOLOGICAL DATA IN SUPPORT OF THE SURVIVAL OF WALNUT (JUGLANS-REGIA L) IN THE WESTERN MEDITERRANEAN AREA DURING LAST GLACIAL TIMES

This paper is based upon palynological data from Carihuela Cave (Granada, southeastern Spain), that support the presence of walnut (Juglans regia L.) in the western Mediterranean during the early and middle last-glacial stage. Pollen records of Juglans L. are closely associated with Mediterranean evergreen assemblages. particularly Quercus L., Oleaceae and other thermophilous taxa. Palaeo-climatic reconstruction, supported by sedimentological and palaeontological information, points to a further relationship between Juglans appearances and climatic improvements. Growth in refuges close to the site is proposed, perhaps in intramontane river valleys of the Betic ranges. Finally, the possibility of early diversification in the western Mediterranean is evaluated taking into account both the classical viewpoint about its allegedly first arrival during Roman times. and other palynological data suggesting a native character for walnut within the area. Some problems are discussed concerning the poorly understood relationship between cultivated and wild relatives.