AIMS:

Plants face abiotic stress and enemy pressure in their environment. Enemy pressure is higher when the plant grows in a phylogenetically closely related neighborhood because such a neighborhood may be a reservoir of co-evolutionary shared phytophagous species. These differences in enemy pressure could lead to different selection pressure. A plant has a limited quantity of energy, therefore a strong investment in defenses against enemies could be traded off against the ability to tolerate abiotic stress. We studied the effect of the phylogenetic neighborhood on the evolution of defenses against phytophagous insects as well as the tolerance to abiotic stress, using oaks (Quercus petraea) as a model system. For this purpose, we measured in a common garden, different traits related to phytophagy and abiotic tolerance in the individuals from different populations that had evolved in neighborhoods of contrasting phylogenetic distance. We found that genotypes from the populations that had evolved in phylogenetically close neighborhood have tougher leaves, they are better defended against leaf miners, but less defended against chewers, than genotypes that evolved in phylogenetically distant neighborhood. We found no trade-off between the defenses against phytophagous insects and tolerance to abiotic stress. Overall, a phylogenetically closely related neighborhood does not seem to select for higher defenses, but rather for defenses against particular types of enemies. The phylogenetic neighborhood does not appear to affect oaks´ tolerance to abiotic stress. Key words: phylogenetic neighborhood, defense, abiotic tolerance, phytophagy, sessile oak