Researchers then need to provide evidence that intraspecific genetic variation in fitness covaries with both damage and the plant traits in question. Other factors intrinsic to the plant defense system may be involved. In addition, these plants may invest more resources in leaves to foster that rapid growth. Ability of the plants to resist and tolerate damage as discussed above. Tolerance essentially provides an interactive template for the evolution of plant resistance, while resistance does the same for tolerance.
High tolerance reduces selective impact of resistance.
High resistance makes high tolerance useless. The cost of the defensive system is a major factor in determining the evolution of defense. Benefits of a defense have to exceed the costs over the long term. Allocation-based costs are the most commonly discussed. Ecological costs occur when defenses against one organism may involve increased losses to others or to changes in the impact of natural enemies upon the herbivore.