Effects of Warming on Intraguild Predator Communities with Ontogenetic Diet Shifts

Abstract

Species interactions mediate how warming affects community composition via individual growth and population size structure. While predictions on how warming affects composition of size-or stagestructured communities have so far focused on linear (food chain) communities, mixed competitionpredation interactions, such as intraguild predation are common. Intraguild predation often results from changes in diet over ontogeny ('ontogenetic diet-shifts') and strongly affects community composition and dynamics. Here we study how warming affects a community of intraguild predators with ontogenetic dietshifts, consumers and shared prey by analyzing a stage-structured bioenergetics multispecies model with temperature-and body size-dependent individual-level rates. We find that warming can strengthen competition and decrease predation, leading to a loss of a cultivation mechanism (the feedback between predation on, and competition with, consumers exerted by predators), and ultimately predator collapse. Furthermore, we show that the effect of warming on community composition depends on the extent of the ontogenetic diet-shift and that warming can cause a sequence of community reconfigurations in species with partial diet-shifts. Our findings contrast previous predictions concerning individual growth of predators and the mechanisms behind predator loss in warmer environments, and highlight how feedbacks between temperature and intraspecific size-structure are important for understanding such effects on community composition.

Exploring temporal patterns in fish feeding ecology: Are ontogenetic dietary shifts stable over time?

“…Thus, species-specific readjustments in trophic ontogeny linked to new environmental conditions driven by the current climate warming (Smalås 2021) can be essential for understanding the coexistence of intraguild communities in a changing environment. This view supports recent theoretical considerations underlining the importance of intraguild predators with partial, rather than complete, ontogenetic dietary shifts as a key for understanding community reconfigurations and consumer coexistence for predictions about how warming may affect species composition and interactions (Thunell et al 2021).…”

“…Brown trout is considered a superior competitor compared to Arctic charr (Hesthagen et al 1997;Prati et al 2021), and the presence of profitable small fish prey (three-spine stickleback) and mixed competitor-prey interactions among the fish species in the study system are likely to support early piscivory in brown trout populations (Sánchez-Hernández et al 2017). Although it is reasonable to posit that the resulting ecosystem stability of the studied system (Takvatn lake) will provide resilience to future multiple stressors like climate warming (favouring brown trout over Arctic charr in northern systems) or other anthropogenic impacts (e.g., overfishing, species introductions or pollution), these may in future have destabilising effects due to, e.g., loss of ontogenetic diversity within the populations (Rudolf and Eveland 2021) and increases in competition strength (Thunell et al 2021), which eventually would lead to unpredictable ecosystem consequences.…”

Fish life histories in a warming climate: a mechanistic basis of change and a community context

“…by intense harvesting of predators or as shown in Paper IV, via warming effects on competition and predation, this has "depensatory" (i.e. negative effects) on the population growth rate Gårdmark et al 2015;Thunell et al 2021). Consequently, this causes alternative stable states in community composition, i.e.…”

Temperature‐Dependence Assumptions Drive Projected Responses of Diverse Size‐Based Food Webs to Warming

“…Further, the effects of temperature may also depend on body mass, which means that animals of different weight might have different scaling of intake or metabolic rates (Killen et al, 2010;Lindmark, Ohlberger, & Gårdmark, 2022;Ohlberger et al, 2012). An important consequence is that different life stages may respond differently to warming, which may alter population regulation, stage structure, and species interactions, given that predation in aquatic systems is strongly size-structured (Lindmark et al, 2018(Lindmark et al, , 2019Thunell et al, 2021). Controlled simulation experiments that systematically test how different individual-level temperature hypotheses propagate through species and food webs have until now only been done in single models (Lindmark, Audzijonyte, et al, 2022;Lindmark et al, 2019;Reum et al, 2020), and we do not know how conclusions from these cases can be generalized across other food web models.…”

“…While originally developed to describe temperature effects on chemical reaction rates, the Arrhenius equation is now often applied to many physiological and ecological rates over biologically plausible temperature ranges (Brown et al., 2004; Kooijman, 2000). For example, in physiologically structured food web models, temperature‐dependencies have been applied to rates controlling body growth and mortality (Blanchard et al., 2012; Lindmark et al., 2019; Maury, Shin, et al., 2007; Thunell et al., 2021; Zhang et al., 2017). However, biological rates do not all scale with temperature in the same manner.…”