Natural Selection of Plant Defense Against Herbivores in Native and Non-native Ranges

Natural enemy release is one main historical event that promotes the evolution of alien-colonizing plants in a new range. During this process, it is expected that selection on characters that mediated the interaction between plants and their herbivores in the native range will change the average trait values in the new range and other correlated responses of introduced populations where the herbivores are absent. However, few studies have measured natural selection on plant defense in invasive species in the introduced range despite this assumption. We present a summary of the evidence available about the changes in characters associated with resistance, including chemical and physical traits, and tolerance to damage, between plant populations in native and non-native ranges. We present the basic predictions of selection on defense and the measurement of selection in the few studies carried out so far. We stress on the study of evolutionary ecology of plant-herbivore interactions in new environments, by means of quantitative genetics and the analysis of natural selection.