Differences in prey personality mediate trophic cascades

Abstract

Functional trait approaches in ecology chiefly assume the mean trait value of a population adequately predicts the outcome of species interactions. Yet this assumption ignores substantial trait variation among individuals within a population, which can have a profound effect on community structure and function. We explored individual trait variation through the lens of animal personality to test whether among‐individual variation in prey behavior mediates trophic interactions. We quantified the structure of personalities within a population of generalist grasshoppers and examined, through a number of field and laboratory‐based experiments, how personality types could impact tri‐trophic interactions in a food chain. Unlike other studies of this nature, we used spatial habitat domains to evaluate how personality types mechanistically map to behaviors relevant in predator–prey dynamics and found shy and bold individuals differed in both their habitat use and foraging strategy under predation risk by a sit‐and‐wait spider predator. In the field‐based mesocosm portion of our study, we found experimental populations of personality types differed in their trophic impact, demonstrating that prey personality can mediate trophic cascades. We found no differences in respiration rates or body size between personality types used in the mesocosm experiment, indicating relative differences in trophic impact were not due to variation in prey physiology but rather variation in behavioral strategies. Our work demonstrates how embracing the complexity of individual trait variation can offer mechanistically richer understanding of the processes underlying trophic interactions.

Predator Group Composition Indirectly Influences Food Web Dynamics through Predator Growth Rates

“…Indeed, prey behavior can also contribute to the strength of trophic cascades and consequent effects on ecosystem functioning, and not all prey species, or individuals within the same species, may respond to predation threat in the same way (Sommer and Schmitz 2020). Additionally, prey species perceive risk also by direct encounters with predators, and these were effectively constrained within the quadrats in our experiment.…”

“…Such stable behavioral differences among individuals of a predator population can have knock-on effects on lower trophic levels if predator behavior alters the direct consumption of intermediate prey (Schmitz et al 1997;Trussell et al 2006) or prey behavior in response to predation risk (i.e. trait-mediated effects: Bolker et al 2003;Werner and Peacor 2003;Sommer and Schmitz 2020). For example, the behavior of an individual predator has been shown to predict the behavior of the prey that predator consumes (McGhee et al 2013;Toscano and Griffen 2014).…”

Prey metabolic responses to predators depend on predator hunting mode and prey antipredator defenses

“…where live mass (g) of each individual was measured immediately following respiration measurements and μl CO 2 was adjusted based on the volume of the respirometer, barometric pressure and temperature (Hawlena and Schmitz 2010a, Rosenblatt et al 2016, Sommer and Schmitz 2020). We then corrected mass‐specific respiration rates by subtracting blank runs corresponding to each day of measurement.…”

Revisiting two dogmas of conservation science

“…Emerging animal personality studies can also be considered. Defined as behavioral tendencies that consistently differ from other individuals of the same species (Wolf & Weissing, 2012), personalities can be important in species persistence, ecosystem function, and conservation practice (Collins et al., 2022; Nilsson et al., 2014; Sommer & Schmitz, 2020). For example, in wildlife introductions and reintroductions, personality traits can help individuals and species establish successfully (Sih et al., 2004).…”