Eco-evolutionary Dynamics of Above- and Belowground Herbivores and Invasive Plants

Abstract

Selection on plants imposed by herbivores can trigger adaptive evolution in growth, reproduction, and defense. Such evolutionary changes in plant traits in turn may affect herbivores and other organisms. These interdependent ecological processes and evolutionary changes have been demonstrated for plant–herbivore interactions aboveground. But, increasing evidence highlights the importance of belowground herbivores for plant performance and population dynamics and demonstrates complex interactions between above- and belowground herbivores. In this chapter, we explore eco-evolutionary dynamics of above- and belowground plant–herbivore interactions. We focus on invasive plants since many of them have novel herbivore assemblages in the introduced range, a setting in which plant traits may evolve and then exert new impacts on above- and belowground herbivores. The literature suggests that both above- and belowground herbivores drive changes in plant traits but that their effects are not simply additive since there is substantial variation in the effects of herbivores on plants. Furthermore, responses of herbivores to variation in plant traits cannot be predicted by feeding compartment, feeding mode, or diet breadth. Variation in plant traits is consistent with differences in herbivore loads, non-herbivore organisms, and abiotic stresses between native and introduced ranges. Therefore, without integration of herbivores in both above- and belowground compartments, it is hard to make accurate predictions of eco-evolutionary dynamics of plant–herbivore interactions.