Social information use and the evolution of unresponsiveness in collective systems

Abstract

Animal groups in nature often display an enhanced collective informationprocessing capacity. It has been speculated that natural selection will tune this response to be optimal, ensuring that the group is reactive while also being robust to noise. Here, we show that this is unlikely to be the case. By using a simple model of decision-making in a dynamic environment, we find that when individuals behave rationally and are subject to selection based on their accuracy, optimality of collective decision-making is not attained. Instead, individuals overly rely on social information and evolve to be too readily influenced by their neighbours. This is due to a classic evolutionary conflict between individual and collective interest. The result is a sub-optimal system that is poised on the cusp of total unresponsiveness. Individuals in the evolved group exhibit delayed reactions to changes in the environment, before responding with rapid, socially reinforced transitions, reminiscent of familiar human and animal social systems (markets, stampedes, fashions, etc.). Our results demonstrate that behaviour of this type may not be pathological, but instead could represent an evolutionary attractor for such collective systems.

Social Information Links Individual Behavior to Population and Community Dynamics

“…Moreover, modeling selection on individual decision making in dynamic environments revealed that individuals that behave rationally based on all available information generally do not reach optimal decision-making. Instead, evolved individuals become overly reliant on social information, exhibiting delayed responses to environmental change, followed by rapid compensatory reactions that drive costly population volatility [81]. These dramatic reactions result from information cascades, in which individuals copy the behaviors of others that, themselves, are often simply copying the behaviors of others[ 2 9 7 _ T D $ D I F F ] , as opposed to making decisions based on direct interactions with their environment.…”

“…Computational models have shown that social information can improve the ability of groups of foragers to track resources that shift at small spatial scales and over relatively short, behavioral timescales [5,9,79] or between breeding seasons [32], but that large-scale or longterm environmental changes can eliminate these benefits or cause social information to become highly detrimental to populations [32,80,81]. For example, habitat fragmentation can reduce or cease migration in populations that rely on information from a small number of leaders, the leadership by which can fail to evolve in a fragmented landscape [ 2 9 6 _ T D $ D I F F ] [80].…”

The content and availability of information affects the evolution of social-information gathering strategies

“…Specifically, when the environmental cue is about predators, the strategy being used by the majority sets a social context that can prevent other strategies from invading. Conversely, Torney et al (2015) found that an individual using a high amount of social information can do well when that is the minority strategy. Frequency dependence seems to be a common property of systems in which animals use social information (Rieucau and Giraldeau 2011).…”

“…While there are many models of the evolution of social-information use, few, to our knowledge, compare information about different facets of the environment (in our case, predators and resources). Additionally, while some models of the evolution of social-information use consider the weight given to social information (as opposed to personal information) (e.g., Pais and Leonard 2014;Shaw and Couzin 2013;Torney et al 2015), none to our knowledge consider the evolution of the number of neighbors in a topological interaction network. Finally, our work considers two group-level properties that have not previously been studied together.…”

A simple game-theoretic model for upstream fish migration

“…The conventional research suggests that schooling has many aspects of benefits, such as improvements of navigational performance (Berdahl et al 2014;Torney et al 2015), hearing perception (Larsson 2009(Larsson , 2012, and foraging efficiency (Di-Poi et al 2014;Wang et al 2016). These benefits are modelled in a lumped manner as…”