Antiherbivory defense mechanisms along an environmental gradient in restinga

ABSTRACT

Plant-herbivore interactions have directed the evolution of defense mechanisms in plants, which can vary intraspecifically according to environmental quality. This study evaluated variation in the production of antiherbivory defenses in plant species distributed along an environmental gradient of restinga. The study was performed in Parque Estadual Acaraí, state of Santa Catarina, Brazil. Three species of four plant formations with different abiotic conditions were selected for study. Specific leaf area; water, nitrogen and carbon content; and presence of phenols, tannins, lignin and alkaloids, were evaluated in leaves of ten plants per species per plant formation. The results indicated that Symphyopappus casarettoi possesses Low Nutritional Quality Syndrome, characterized by low specific leaf area, presence of secondary metabolites and low nitrogen content. Dodonaea viscosa and Varronia curassavica possess Nutrition and Defense Syndrome, characterized by a balance between nutritional quality (high nitrogen content and lower C:N ratio) and protection (greater thickness of leaves and higher density of trichomes). The results did not confirm the Resource Availability Hypothesis. The absence of a pattern in antiherbivory response due to the environmental gradient may indicate that the investment in defense by plants is not unidirectional and that certain morpho-anatomical attributes are typically related to conservation of resources.

Keywords
coastal plain; herbivore-plant interaction; histochemistry; Parque Estadual Acaraí; physical defense; secondary metabolites