Meta-analysis of trade-offs among plant antiherbivore defenses: are plants jacks-of-all-trades, masters of all?

On the basis of physiological and ecological costs of defense allocation, most plant defense theories predict the occurrence of trade-offs between resource investment in different types of antiherbivore defenses. To test this prediction, we conducted a meta-analysis of 31 studies published in 19762002 that provided data on covariation of different defensive traits in plant genotypes. We found no overall negative association between different defensive traits in plants; instead, the relationship between defensive traits varied from positive to negative depending on the types of co-occurring defenses. Evidence of trade-off was found only between constitutive and induced defenses. Therefore, to a large extent, plants appear to be jacks-of-all-trades, masters of all and may successfully produce several types of defense without paying considerable trade-offs. Our survey thus provides little evidence that genetic trade-offs between defensive traits significantly constrain the evolution of multiple defenses in plants