Overcompensation for insect herbivory: a review and meta-analysis of the evidence.

Not all herbivory is detrimental to plants. In some cases, plants can compensate for herbivory, maintain growth and fitness following damage, or even overcompensate for herbivory and perform better than if left undamaged. Examples of overcompensation to vertebrate herbivory are well known, but here we review the literature for examples of reproductive overcompensation (i.e., increased production of traits associated with fitness) and increased vegetative growth (i.e., vegetative overcompensation) following insect herbivory. We used a meta-analysis to explore the effects of plant growth form, evolutionary history, herbivore feeding guild, and other plant and insect traits on the expression of reproductive and vegetative overcompensation by plants. Our literature search revealed 86 studies documenting examples of overcompensation for insect herbivory by 67 plant species representing 26 families. These plants included monocots and dicots, annuals and perennials, and woody and herbaceous plants. We also found that varied insect herbivores induce overcompensation, including 75 insect species in six orders representing 27 families and myriad feeding guilds. In our meta-analysis, we calculated 53 effect sizes from 21 publications documenting reproductive overcompensation and 89 effect sizes from 40 publications documenting vegetative overcompensation. Variation in reproductive overcompensation was seen among plant growth forms, functional groups, cultivation, herbivore feeding sites, and plant and herbivore families. Variation in vegetative overcompensation was seen among plant families, herbivore families, and latitudinal gradients. We suggest overcompensation for insect herbivory may be far more prevalent than previously thought. Additional research focusing on the mechanisms, patterns, and ecological and evolutionary consequences of overcompensation for insect herbivory is likely to provide exciting new insights into this poorly understood and largely overlooked outcome of plant-insect interactions.