Producing and scrounging can have stabilizing effects at multiple levels of organization

Abstract

This study shows, for the first time, that the evolution of a simple behavior, scrounging, at the individual level can have effects on populations, food chains, and community structure. In particular, the addition of scrounging in consumer populations can allow multiple consumers to coexist while exploiting a single prey. Also, scrounging in the top predator of a tritrophic food chain can stabilize interactions between the top predator, its prey, and its prey's prey. This occurs because the payoffs to scrounging for food in a population are negative frequency dependent, allowing scroungers to invade a population and to coexist with producers at a frequency which is density‐dependent. The presence of scroungers, who do not search for resources but simply use those found by others (producers) reduces the total amount of resource acquired by the group. As scrounging increases with group size, this leads to less resource acquired per individual as the group grows. Ultimately, this limits the size of the group, its impact on its prey, and its ability to outcompete other species. These effects can promote stability and thus increase species diversity. I will further suggest that prey may alter their spatial distribution such that scrounging will be profitable among their predators thus reducing predation rate on the prey.

Social predation by a nudibranch mollusc

“…The choice of tactics is influenced by an individual's early life experience (Katsnelson et al, 2008), perceived predation risk (Barta et al, 2004), hunger (Lendvai et al, 2004), and the availability and quality of food sources (Kurvers et al, 2012). Modeling studies support the idea that social predation can be maintained in populations where individuals may inhabit temporary roles such as scrounging or producing where individuals either use the strategy of joining groups feeding at specific food sources or locate their own sources, respectively (Vickery, 2020).…”

“…A down side is that groups can make it easier for predators to spot and capture individuals and this is a reason many hunters specifically target colonial prey (Balaban-Feld et al, 2019;Sutton et al, 2015). Some individuals may inhabit temporary roles such as scrounging or producing where individuals either use the strategy of joining groups feeding at specific food sources or locate their own sources, respectively (Vickery, 2020). The choice of tactics is influenced by an individual's early life experience (Katsnelson et al, 2008), perceived predation risk (Barta et al, 2004), hunger (Lendvai et al, 2004), and the availability and quality of food sources (Kurvers et al, 2012).…”