Changing interactions in a changing climate: combining modelling and experimental methods to unfold the consequences of warming on intraguild predation in Odonata

• Applicants: Professor Dr. Boris Schröder-Esselbach; Professor Dr. Frank Suhling
• Subject Area: Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions ; Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 556214684

The research project aims to investigate effects of climate change on intraguild predation (IGP) in freshwater insects. Shifts in biotic interactions may significantly alter entire communities if interacting species and their ontogenetic stages respond differently to climate change. We aim to better understand how particularly warming may affect such interactions and what may be the consequences at the community level. Our model system is the biotic interaction of Odonata, in which size-dependent intraguild predation is relevant. The larger larvae prey on the smaller larvae and the greater the size differences between predator and prey, the more pronounced the IGP. Two mechanisms associated with warming may cause shifts in size-structures in a community: (1) Larval development and growth may be affected asymmetrically due to species-specific temperature reaction norms. (2) Shifts in phenology may alter the sequence in which species enter an ecosystem, e.g., by changing pattern of colonization (via oviposition) or changing egg development. The impact of warming on interactions therefore depends on the strength and symmetry of warming effects on different species. Relevant variables are effects of increasing water temperatures on development and phenology, but also effects of increased drought. After having developed a mechanistic modelling system for dragonfly life cycles in a previous project, we will apply an innovative approach to this topic by first performing numerical simulation experiments and afterwards evaluating them by laboratory experiments. Our project comprises three work packages (WP): WP 1: Numerical experiments to simulate IGP at different warming scenarios and different species combinations (2-species and 3-species interactions) using mechanistic models. This is possible since most model parameters are known from preliminary work. The model results serve to predict possible effects of interactions. WP 2: Laboratory experiments to investigate specific components of interactions. The design follows the results of step 1, which will define the selection of experimental designs. This procedure reduces the need to run fully factorial experimental designs, i.e., reduce the experimental effort. The experiments will also be used to evaluate the models. WP 3: Landscape level modelling, which aims in transferring the outcomes of steps 1 and 2 to the larger landscape level, i.e., permits predictions of changes at the landscape level.

• DFG Programme: Research Grants