Trait-mediated effects of ants on arthropods: From individuals to communities

• Applicant: Dr. Laia Mestre
• Subject Area: Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
• Term: from 2016 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 314743975

Trait-mediated effects (TME) are predator-induced changes in prey phenotype that minimize predation risk. While the impact of TME on predator-prey interactions can be stronger than predation, our understanding of their role in structuring communities is still limited. This is due to a striking lack of TME research on intraguild interactions and in terrestrial systems, an overriding focus on isolated species pairs rather on multi-species interactions, and a general disregard for the involved chemical mechanisms. The aim of the project is to close three important gaps in this fundamental area of ecological research.In the first objective, we will perform behavioural trials with ant cues to document the occurrence of ant TME across a wide range of spider species in order to identify species with strong antipredator behavior and to test the influence of spider foraging mode on TME strength. The second objective focuses on the chemical mechanisms of TME: different ant chemical cues have contrasting decay rates, more volatile pheromones signaling currently active foraging areas and non-volatile hydrocarbons indicating ant home range We will extract different ant cues and do behavioural trials with spiders to identify their role in TME magnitude. In the third objective, we will use the strongest TME-inducing ant cue to examine the context-dependence of TME and their indirect effects on the food web. We will experimentally evaluate how ant TME are influenced by food availability to spiders and their previous experience of predation risk, and how this interplay leads to cascading consequences for the lower trophic levels of the arthropod food web. The proposal takes an integrative approach that joins the concepts of behavioural, chemical and community ecology and addresses neglected topics that are crucial to a mechanistic understanding of TME in species interactions.

• DFG Programme: Research Grants