The role of omnivores for food web rewiring under global change

• Applicant: Dr. Jörg Albrecht
• Subject Area: Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 513874538

Changes in the structure of food webs due to global change can affect food web stability and ecosystem functions. Many studies have investigated the mechanisms behind changes in the structure of food webs under global change. However, changes in food web structure due to altered foraging behavior of consumers have received little attention. This mechanism is likely to be widespread and should be first detectable in omnivores, because they have a wide trophic niche, exhibit a high behavioral flexibility, and often respond rapidly to environmental change. Due to their key role in food webs, changes in the foraging behavior of omnivores in response to global change may fundamentally reshape the structure of food webs and may have consequences for entire ecosystems. Among all global change drivers, climate change and land use are likely to have particularly strong effects on the foraging behavior and trophic interactions of omnivores by altering net primary productivity (NPP) at the base of food webs. In addition, climate change may affect the foraging behavior and trophic interactions of omnivores by altering metabolic demands. However, the trophic responses of omnivores to climate and NPP are poorly understood.The project aims to fill these gaps of knowledge with a macroecological approach that systematically investigates, at the intraspecific level, how seasonal and geographic variation in climate and NPP shape the trophic interactions of omnivores. The project will address the following three overarching questions: (i) How strongly do trophic interactions of omnivores vary seasonally within populations and geographically across populations of the same species? (ii) To what extent is the seasonal and geographic variation in trophic interactions related to climate and NPP? (iii) How are the species-specific trophic responses to environmental conditions modulated by species’ traits related to resource use?To answer these questions, the project aims at compiling a unique highly-resolved macroecological database that documents trophic interactions of a wide range of mammalian omnivore species in space and time. This database will be combined with data on environmental conditions and species traits. By studying the trophic responses of omnivores to climate and NPP, the project will provide key insights into how behavioral responses to environmental change affect the structure of food webs. Moreover, linking trophic responses to species traits will provide a trait-based understanding of food web rewiring under global change.

• DFG Programme: Research Grants