Social information-mediated population dynamics in non-grouping prey

Abstract

Inadvertent social information (ISI) use, i.e., the exploitation of social cues including the presence and behaviour of others, has been predicted to mediate population-level processes even in the absence of cohesive grouping. However, we know little about how such effects may arise when the prey population lacks social structure beyond the spatiotemporal autocorrelation originating from the random movement of individuals. In this study, we built an individual-based model where predator avoidance behaviour could spread among randomly moving prey through the network of nearby observers. We qualitatively assessed how ISI use may affect prey population size when cue detection was associated with different probabilities and fitness costs, and characterised the structural properties of the emerging detection networks that would provide pathways for information spread in prey. We found that ISI use was among the most influential model parameters affecting prey abundance and increased equilibrium population sizes in most examined scenarios. Moreover, it could substantially contribute to population survival under high predation pressure, but this effect strongly depended on the level of predator detection ability. When prey exploited social cues in the presence of high predation risk, the observed detection networks consisted of a large number of connected components with small sizes and small ego networks; this resulted in efficient information spread among connected individuals in the detection networks. Our study provides hypothetical mechanisms about how temporary local densities may allow information diffusion about predation threats among conspecifics and facilitate population stability and persistence in non-grouping animals. Significance statement The exploitation of inadvertently produced social cues may not only modify individual behaviour but also fundamentally influence population dynamics and species interactions. Using an individual-based model, we investigated how the detection and spread of adaptive antipredator behaviour may cascade to changes in the demographic performance of randomly moving (i.e., non-grouping) prey. We found that social information use contributed to population stability and persistence by reducing predation-related per capita mortality and raising equilibrium population sizes when predator detection ability reached a sufficient level. We also showed that temporary detection networks had structural properties that allowed efficient information spread among prey under high predation pressure. Our work represents a general modelling approach that could be adapted to specific predator-prey systems and scrutinise how temporary local densities allow dynamic information diffusion about predation threats and facilitate population stability in non-grouping animals.

Social Information Use in Herbivore Prey Can Influence the Success of Biological Control

“…Compared to GL prey, I found only small effects of ISI use on prey abundance in NG prey in some settings, most probably due to the implemented physiological constraints that led to low predator detection probabilities in individuals with low energy levels. Previous works proved that at least moderate detection probabilities are needed for NG prey to utilize social information in a predation avoidance context, while this condition is not crucial for GL prey (Tóth and Csöppü 2022;Tóth et al under review). When prey detection range exceeded that of the predators, prey abundance decreased in the presence of PE without a consumptive effect as well.…”

“…To track the emerging pattern of ISI use among prey (i.e., the diffusion of social information), temporary detection networks are constructed based on individuals' location and detection range. The rationale for the use and a detailed description of these networks can be found in Tóth et al (2020) and Tóth and Csöppü (2022). Briefly, the networks consist of nodes representing individuals and edges denote spatial proximity (i. e., being within each other's detection range).…”

“…Model parameters, state variables and their range for the global sensitivity analysis. The values for parameters E j,t , E max , and T were obtained from the original model of Gil et al (2017), P ISI had the same value as in Tóth and Csöppü (2022), parameters m and d prey had the same values as in Tóth et al (under review), whereas the values for parameters r social , r prey , and r P , were chosen arbitrarily (with the rule of r social < r prey ). The value of parameter P s reflects a conservative estimation of the hunting success of a generalist predator (for examples of higher success rates, see Beleznai et al 2015, Michálek et al 2017 pattern to that of the final prey number, except a much smaller influence of P s (Fig.…”

“…However, ISI use is also known to facilitate population abundance and stability under high predation pressure (e.g., Gil et al 2018) and thus may diminish the benefits of PEs if it results in a reduced feeding rate but at a larger equilibrium population size. Moreover, recent theoretical advancements suggest that temporary local densities in non-grouping organisms also allow information diffusion about predation threats among conspecifics that may facilitate population stability and persistence (Tóth et al 2020;Tóth 2021;Tóth and Csöppü 2022). Examples of ISI use in herbivore pests in foraging or predator avoidance contexts are currently lacking, however.…”