Personality-based individual differences in foraging efficiencies and metabolic rates and their consequences for predator-prey interactions.

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The importance of intraspecific variation in species traits is currently intensively debated by population and community ecologists. In particular, there have been repeated calls to integrate animal behaviour with more traditional, population-oriented ecological research to provide an improved understanding of functional relationships between behavioural traits and foraging ecology. My proposed research project addresses the question how intraspecific variation in metabolism and feeding rates can be explained by individual differences in behavioural types (sometimes also denoted animal personalities). I propose to analyse prey-density dependent feeding rates of juvenile European perch (Perca fluviatilis) in laboratory experiments based on the functional response model framework. This provides the notable opportunity to link behavioural-mediated functional outcomes to population-level consequences via consumption rates of prey by predators. The objective of my research is to gather integrated knowledge on how the energetic demands of individuals (i.e., individual metabolism) constrain the basic mechanisms of capturing and handling prey and if this is mediated by the behavioural types. Hence, I will assess how the range of intraspecific variation in the critical functional response parameters capture rate and handling time is mechanistically linked to key personality traits (namely activity, agility and exploratory behaviour) and I will analyse how these personality traits affect the feeding rate on different prey types (i.e., benthic Asellus aquaticus versus pelagic Daphnia magna). The research project features a particularly innovative approach by combining observations with high speed cameras and in a 3D-environment with conventional model estimation procedures in functional response research. My main hypotheses are, (1), high-activity, high-agility, and more exploratory individuals have significantly higher metabolism and feeding rates than the population average and, (2), these high feeding rates are driven mainly by higher encounter rates of the more active types. (3) prey perception and detection will also be affected by behavioural types. This research project provides a critical step towards an urgently-needed evaluation of current standard procedures of inferring predator-prey interaction strengths from natural populations.Overall, the proposed research project will improve our current understanding of predator-prey interactions and, simultaneously, it will facilitate an integration of the intraspecific variation in prospective models of trophic interactions furthering our understanding of population ecology using perch as a model species. At the end of the proposal I am also outlining how I could later implement the findings from my research into such an advanced type of predator-prey population models together with my collaborators.