New perspectives on the consumptive and non-consumptive effects of predators

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Owing to recent advances in ecological theory, lab and field studies, and technological/analytical tools, we are now at the cusp of major breakthroughs in predator-prey ecology. We are poised to explain the complex determinants of predation rate and how these are driven by factors like predator foraging behaviour and predator-predator interactions, as well as address the role of non-consumptive predator effects (i.e., perceived predation risk, PPR) on prey physiology, behaviour, and population dynamics. During this grant cycle my team will combine observational studies, field and lab experiments, and modelling exercises, to comprehensively address major knowledge gaps and establish a new basis for understanding predator-prey interactions. We will use satellite-based telemetry and accelerometry in Canada lynx, coyotes, and their primary prey (snowshoe hare) to test: 1) Whether predation rates are subject to ratio dependence and how this differs across predator and prey species; 2) If predator movements conform to prevailing foraging theory and how this varies with cyclic fluctuation in hare abundance; 3) If prey switching by predators corresponds to active choice vs. passive response to a change in prey species ratio; and 4) Physio-behavioural responses of hares to experimental and natural changes in predation risk. Maternal effects of increased PPR on juvenile hares will be monitored through a hare population low to determine whether adults and/or new recruits contribute to population recovery. These research efforts will be bolstered by experiments using a model predator-prey system (i.e., dragonfly larvae-tadpole), where we will manipulate predator-prey interactions and address longstanding questions related to consumptive effects of predators that have high tractability in this system. Importantly, the dragonfly-tadpole system also will serve to assess whether PPR responses, which are so prevalent in lab studies using this system, are replicable in the field. A second predator-prey model system (protist-alga), will address the longstanding enigma of whether non-consumptive effects of predators alone can affect predator-prey population dynamics. These investigations will inform the development and parameterization of a population model of the consumptive and non-consumptive effects of predators in this system, which will be extended to a related model of the effects of predation (and PPR) on the snowshoe hare population cycle. Collectively, these efforts will merge theory and data to explain fundamental mechanisms governing predator-prey interactions that to date have gone unresolved. This will set the stage for major breakthroughs in our understanding of predation as a dominant force in ecosystems. This work also will train HQP in robust scientific investigation and the application of novel approaches to address previously intractable ecological questions.