Abstract
Understanding community structure and species interactions therein are major challenges in ecology. Classically, ecological communities are considered to be most profoundly structured by trophic relationships. More recently, however, it has been argued that indirect species interactions, rather than direct trophic interactions, are likely to be more important in structuring communities. In plant-associated communities, many indirect species interactions are mediated through the plant. Plants respond to their attackers by mounting a set of defences that can be specific for the type of attacker. These phenotypic changes in the plant result in altered interactions of that plant with the entire insect community. Plants have also been found to be physiologically constrained in their response to sequential herbivory. Especially, herbivore species that differ in feeding style require different responses of the plant that may work antagonistically. Therefore, the plant response to one attacker may not result in the most appropriate physiological or ecological response with respect to future attack by other organisms, rendering important fitness consequences for plants. The main challenge of this project proposal is to study the physiological and ecological constraints for plants to respond to sequential herbivory and to assess plant fitness consequences of those constraints. I will study these constraints in the annual weed Brassica nigra by using a multidisciplinary approach combining quantification of transcript levels of defence-related genes, morphology and secondary chemistry in response to sequential herbivory with their feed back to ecological responses of the insect community. Through laboratory, greenhouse and field experiments I will evaluate whether responses to early-season herbivory have predictable plant fitness consequences by manipulating the order of herbivore attack and the composition of the insect community. Thereby, this work will profoundly deepen our knowledge on the driving forces behind the structure of food webs and our understanding of the molecular ecology of induced plant responses.
Netherlands