Attracting bodyguards: testing macro-evolutionary trends of belowground plant indirect defenses and effects on plant fitness
| Responsable du projet | Sergio Rasmann |
| Collaborateur | NA NA |
| Résumé |
Plants and their herbivores constitute more than half of the
organisms on earth. Therefore a better understanding of the evolution of plant defenses against their herbivores is central for our understanding of biodiversity and species interaction, as well as better managing insect pests in agro-ecosystems. When under above- or belowground attack, plants resist herbivores by different means, including the attraction of predators or parasitoids of the herbivores near the site of damage by producing volatile organic compounds (VOCs). This phenomenon has been referred to as ‘indirect plant defense’. The term defense here implies a fitness benefit for the plant, and consequently, an adaptive value for volatile production. However, whether the production of herbivore-induced VOCs has evolved and being maintained as a defense over evolutionary times, and whether the attraction of carnivores benefits plant fitness has not yet been proven. I therefore here propose to 1) study the macro-evolution of VOCs production and the subsequent carnivore attraction using a phylogenetic comparative approach, 2) test the fitness benefits of VOCs production and nematode attraction at the genotypic (within species) level, and 3) test whether there is local adaptation in the tripartite interaction between plants, herbivores and predators along the ecological gradients. I will use 40 species of grasses and measure root volatile production and subsequent predatory nematode attraction using a custom-designed belowground olfactometer. I will then test different models of evolution to address macro-evolutionary patterns of trait evolution. Second, I will focus on one grass species that has a broad distribution in the Alps to measure selection for increased VOCs production and subsequent nematode attraction. Third, I will perform reciprocal transplant experiments to test for local adaptation of tritrophic interactions. Overall, the combined approach of behavioral assays, chemical analysis, phylogenetic modeling, and field experiments that span macro- and micro-evolutionary times will answer and greatly contribute the debate around the adaptive role of herbivore-induced volatile organic compounds as plant indirect defenses. |
| Mots-clés |
indirect defenses, volatile organic compounds, macorevolution |
| Type de projet | Recherche fondamentale |
| Domaine de recherche | ecology |
| Source de financement | FNS - Encouragement de projets (Div. I-III) |
| Etat | Terminé |
| Début de projet | 1-5-2015 |
| Fin du projet | 30-4-2018 |
| Budget alloué | 399'767.00 |
| Contact | Sergio Rasmann |