Structural and physiological adaptations conferring herbivory resistance in wild olive (Olea europaea L. subsp. cuspidata).

Herbivory represents an important ecological pressure influencing plant structure and function, yet the integration of morphological and physiological responses under natural browsing remains insufficiently understood. In Olea europaea L. subsp. cuspidata, a widely distributed wild olive species in Punjab, Pakistan, we compared morpho-anatomical, biochemical, and physiological traits between browsed and non-browsed populations across ecologically distinct regions. Browsed populations exhibited pronounced phenotypic variation, characterized by a shift toward a compact, shrubby architecture with reduced leaf size, increased branching, and higher squama density. Concurrent changes included reduced stomatal size and density, thinner cortical and vascular tissues, and lower photosynthetic pigment and ionic contents. In contrast, levels of phenolics, antioxidant enzymes, and osmoprotectants were generally elevated in browsed plants, suggesting a potential trade-off between growth-related traits and stress-associated responses. The combination of structural and biochemical traits observed in browsed individuals is consistent with plant responses commonly associated with herbivory and environmental stress. However, as herbivore pressure, feeding rates, and preference were not directly quantified, these trait shifts should be interpreted as correlates of browsing exposure rather than definitive evidence of herbivore deterrence or resistance mechanisms. Overall, this study provides an integrated assessment of trait variation associated with browsing in O. europaea subsp. cuspidata, while highlighting the need for direct herbivore interaction studies to clarify functional defense roles.