Plant Defenses as Complementary Resources: A Test with Squirrels

摘要: Generalist herbivores often grow better on mixed diets suggesting that resource types are complementary. We use a consumer-resource framework to develop criteria by which nutritional relationships among foods can be determined from forager's patch behavior. Two resources complementary when at least one yields diminishing returns or the interact beneficially with each other. These sufficient conditions may arise food contain different plant secondary compounds. tested for complementarity using fox squirrels (Sciurus niger) and gray (S. carolinensis) feeding sunflower seeds treated tannic oxalic acid. used giving-up densities these two in experimental patches assay deterrent effect of toxin, determine whether treat toxins as Squirrels had their highest oxalate-treated lowest water-treated (control) seeds. Augmenting resulted an increased density relative tannin-treated The data suggest 1) oxalates strongly deter tannins mildly squirrels, 2) containing complementary, 3) is due primarily oxalates. marginal toxicity increases dose. while tannin does not seem increase