Tradeoff between resistance and tolerance to herbivore damage in a morning glory

MANY plant characters, including toxic secondary compounds, trichomes, spines and tough, nutrient-poor leaves have evolved at least in part as defences against pathogens and herbivores, including phytophagous insects1–-6. Models of the evolution of resistance7 9 predict that allocation to defence is determined by a tradeoff between the benefits of resistance, such as reduction in herbivore damage, and costs of resistance, generally envisaged as reduction in fitness in an environment in which herbivores are absent9. However, despite attempts to determine the costs of resistance, there is little convincing evidence that they exist and constrain the evolution of defences10,11. Here we report the existence of such a cost in the tall morning glory, Ipomoea purpurea: genotypes that exhibit relatively high levels of resistance to insects that cause damage to apical meristems exhibit relatively low tolerence to this form of damage. We also show how this type of tradeoff constrains the evolution of resistance. © 1995, Nature Publishing Group. All Rights Reserved.

Duke Scholars

Author Mark D. Rausher Biology