What are the consequences of herbivore attack for floral signals?
Plants grow in complex ecological networks, and show finely tuned adaptations to attact mutualists such as pollinators, and deter enemies such as herbivores. To do so, plants use volatile signals (BVOCs biogenic volatile organic compounds) that are emitted from vegetative (e.g. leaves) or flowers. Leaf volatiles are often thought to be involved in defense, whereas floral volatiles are traditionally interpreted as attractants for pollinators. However, recent studies have shown that floral scent may as well be involved in defending reproductive structures against antagonists. This can be achieved by emitting repellent compounds from flowers. The obvious need of plants to attract pollinators to flowers on the one hand, and to defend flowers on the other hand, puts them into a dilemma. Such signaling dilemma or trade-offs suggest optimal fitness outcomes may be a compromise between attraction (pollinators, parasitoids) and deterrence (herbivores); a key factor selecting for differential signaling may thus be the abundance and species identity of these interacting organisms in a given habitat. Signaling conflicts may also differ among pollination systems, e.g. when pollinators are also herbivores (moth pollination), attracting an herbivore is unavoidable for pollination. Under strong herbivore attack, however, plants may even switch pollination system by changing BVOC signaling to escape the herbivore pressure.
This project will focus on ecological and evolutionary aspects of flower signaling to pollinators and the impact of novel herbivores on this mutualism. Up till now, we know surprisingly little about how herbivore induced changes in floral volatiles (HICFV) and the resulting change in flower attractiveness to pollinators. This IP will investigate HICFV after attack of established and novel herbivores (both on shoots and roots) and its molecular basis and variability. Lastly, natural selection on HICFV will be studied in populations with and without invasive herbivores, to asses their impact on the evolution of this key plant signaling trait and model future evolutionary change.