A novel route to cyclic dominance in voluntary social dilemmas

Abstract

<jats:p>Cooperation is the backbone of modern human societies, making it a priority to understand how successful cooperation-sustaining mechanisms operate. Cyclic dominance, a non-transitive set-up comprising at least three strategies wherein the first strategy overrules the second, which overrules the third, which, in turn, overrules the first strategy, is known to maintain biodiversity, drive competition between bacterial strains, and preserve cooperation in social dilemmas. Here, we present a novel route to cyclic dominance in voluntary social dilemmas by adding to the traditional mix of cooperators, defectors and loners, a fourth player type, risk-averse hedgers, who enact tit-for-tat upon paying a hedging cost to avoid being exploited. When this cost is sufficiently small, cooperators, defectors and hedgers enter a loop of cyclic dominance that preserves cooperation even under the most adverse conditions. By contrast, when the hedging cost is large, hedgers disappear, consequently reverting to the traditional interplay of cooperators, defectors, and loners. In the interim region of hedging costs, complex evolutionary dynamics ensues, prompting transitions between states with two, three or four competing strategies. Our results thus reveal that voluntary participation is but one pathway to sustained cooperation via cyclic dominance.</jats:p>

Exit rights open complex pathways to cooperation

“…Parallels between our exiters and well-known loners, which rose to prominence as a mechanism behind cyclic dominance [3,42,43], undoubtedly invite comparisons between the two. Loners are similar to exiters in that they opt out of the game to avoid getting exploited by defectors; in doing so, loners differ from exiters in that they generate a small-butpositive pay-off for the co-player in the game, regardless of whether this co-player is a cooperator, defector, or another loner.…”

“…In our case, cooperators dominate exiters, who dominate defectors, who dominate cooperators. Cyclic dominance has proven influential in ecological [40] and evolutionary game-theoretic [41] contexts, especially in voluntary dilemmas and extensions thereof [3,42,43].…”

Strategy dependent learning activity in cyclic dominant systems

“…In the simplest and highly simplified case a species A dominates species B, but he latter outperforms species C. More interestingly, species C invades species A, which establishes a fine balance among all participants. This relation is in the heart of the celebrated rock-scissors-paper (RSP ) game, which was identified in many biological and social systems, ranging from interaction between bacterias [9, 10, 11], plants [12], animals [13,14,15], and even humans [16,17,18,20,21,19].…”

Effect of mobility in the rock-paper-scissor dynamics with high mortality

“…It has already been studied (both theoretically and experimentally) that parameters such as system size, mobility, interaction region, protection spillover, risk-averse hedgers affect the stability and evolution of the system in a significant manner [4,8,[24][25][26][27][28]. In particular, demographic fluctuation breaks the coexistence leading to the extinction of certain species [29][30][31][32].…”