"Individual variation and plasticity in tactic use in a producer-scrounger game: a threshold trait model"Bharath, DhanyaSocial systems often exhibit frequency dependence, where the optimal phenotype for an individual to adopt depends on the phenotypes of other individuals in the population. While evolutionary game theory predicts population-level ESS equilibria of phenotypes in frequency-dependent games, it does not discuss individual-level optimal strategies: when populations will consist of ESS frequencies of non-plastic individuals always playing the same fixed tactic, or individuals using plastic strategies to choose the more beneficial tactic preferentially, are unanswered questions. Furthermore, the reaction norm framework to study phenotypic plasticity of individuals in a population has almost always assumed traits that are continuously distributed. Yet, many socially and ecologically important traits have markedly non-linear phenotypic reaction norms and exhibit discrete rather than continuous variation. Therefore, to predict individual behaviour in socially foraging producer-scrounger systems, we use a threshold trait model where the choice to produce or scrounge depends on whether a continuously distributed ‘liability’ to produce is above or below a threshold. We perform agent-based evolutionary simulations to understand emergent variation in individual tactic use and plasticity in the producer-scrounger game, under diverse regimes of spatiotemporal environmental variation. Resulting reaction norms and population compositions indicate selection for significant among- and/or within-individual variation in tactic use, depending on the timescale and speed of environmental fluctuation., This work highlights the importance of considering the mechanisms of tactic choice when predicting population responses to environmental variation. |
« back