A HYDRAULIC CONDUCTIVITY MODEL POINTS TO POST-NEOGENE SURVIVAL OF THE MEDITERRANEAN OLIVE

Abstract

Research on the subfossil record and paleoecology of Olea europaea suggests a new interpretation of its history and ecology with reference to the Mediterranean climate since the Neogene. New results are based on the wood anatomy of ancient and extant Olea and a model estimating hydraulic conductance established for wild forms belonging to Olea europaea subsp. europaea. These suggest that during glacial periods wild olive populations survived in protected microenvironments, particularly riparian habitats. Thereafter, the postglacial expansion of olive associated with climatic warming took place from these refuge areas. This new evidence suggests that the continued existence of Olea in Mediterranean areas since the Neogene was made possible either by preferential survival of Olea lineages adaptable to the Holocene climate or from enhanced adaptation to extreme environmental variation, a trait possibly originating from Tertiary predecessors and maintained in postglacial olive populations.