RoseTriComm · Evolution of Rose Gall Tritrophic Communities

Evolution of Rose Gall Tritrophic Communities

The overall objective of this project is to develop and apply an analytical approach that allows discrimination between competing hypotheses for observed patterns of interaction in tritrophic communities of plants, herbivores and parasitoid natural enemies. At one extreme, the Sequential Radiation Hypothesis (SRH) sees herbivore-parasitoid interactions as driven from the 'bottom-up', by plant-herbivore interactions. The SRH predicts that diversification of herbivores will track diversification of their food plants, and that related herbivores (and related parasitoids) will be found on related plants. In contrast, the Tritrophic Niche Concept (TNC) sees a major role for 'top-down' effects resulting from parasitoid-imposed selection on herbivore traits. If parasitoids drive the evolution of herbivore defences, then these, rather than patterns at lower trophic levels, could structure herbivore-parasitoid interactions. We develop a generalisable statistical approach for analysis of tritrophic interactions, and illustrate its use by application to an unparalleled dataset for replicate real-world communities of plants, gall wasp herbivores and parasitoid natural enemies. Our approach combines trophic interaction, herbivore trait and phylogenetic data for all three trophic levels to address four questions: 1. Do plant-herbivore interactions match the predictions of the Sequential Radiation Hypothesis? 2. Are herbivore-parasitoid interactions structured by herbivore host plant associations (SRH), herbivore defence traits (TNC), or both of these? 3. Have herbivore defence traits evolved convergently in replicate natural communities? If herbivore defences target fundamental aspects of parasitoid attack behaviour, then the TNC predicts that they should. 4. Can we use statistical models to accurately predict the parasitoid assemblages associated with unsampled herbivore hosts?

Data: CORDIS, © European Union