Trophic cascade strength is influenced by size frequency distribution of primary consumers and size-selective predation: examined with mesocosms and modeling

Investigating the Dynamics of Elk Population Size and Body Mass in a Seasonal Environment Using a Mechanistic Integral Projection Model

“…Although environmentally-driven shifts in the body size distribution of elk in this study did not in themselves translate to changes at the population level, they are nonetheless likely to have important consequences for population dynamics when considered in the context of more complex community interactions. In multi-trophic systems, changes in body size distributions can influence both population dynamics and ecological structure by modifying the outcomes of inter-specific interactions (De Roos et al 2003;Griffiths et al 2018, Detmer andWahl 2019). For example, shifts in the body size distribution of one species can alter the balance of asymmetric competition between sympatric species competing for limited resources (De Roos et al 2003;Eccard and Ylönen 2003;Bassar et al 2017;Brose et al 2017).…”

“…For example, shifts in the body size distribution of one species can alter the balance of asymmetric competition between sympatric species competing for limited resources (De Roos et al 2003;Eccard and Ylönen 2003;Bassar et al 2017;Brose et al 2017). Similarly, selective predation can create asymmetries in mortality rates between small and large individuals, or individuals in poor or good condition, that can influence population dynamics or the strength of trophic cascades (Day et al 2002;Hülsmann et al 2011, Detmer andWahl 2019). The results of our seasonal simulations confirmed that milder winters enabled elk to be in better condition over winter (i.e.…”

“…Thus, environmentally driven changes to body size distributions can alter the strength of ecological interactions, potentially inducing/modifying feedback loops between population abundance, resource biomass and trait dynamics (Bolnick et al 2011;Hempson et al 2015;Griffiths et al 2018). In addition, environmentally driven shifts in body size can alter the balance of asymmetric interactions among individuals, which can have stabilizing or disruptive effects on population dynamics (Nelson et al 2019), weaken the strength of trophic cascades (Detmer and Wahl 2019), or lead to emergent phenomena, such as Allee effects, facilitation, or predator exclusion (De Roos et al 2003).…”

Predators drive community reorganization during experimental range shifts

“…all log ratios of chlorophyll‐ a in the presence and absence of fish are above zero). This result suggests that, in the absence of predation, community resilience through functional redundancy enhances the capacity of ecosystems to maintain structure and function in the face of a changing environment and shifting community members (Detmer & Wahl, 2019; McMeans et al., 2016). As lakes warm and new smaller species establish, these colonizers could recapitulate the role of lost species by feeding on similar phytoplankton, dampening changes to lake productivity, despite a change in species identity.…”