Resource Availability Affects Seasonal Trajectories of Population-Level Learning

Environmental effects on learning are well known, such as cognition that is mediated by nutritional consumption. Less known is how seasonally variable environments affect phenological trajectories of learning. Here, we test the hypothesis that nutritional availability affects seasonal trajectories of population-level learning in species with developmentally plastic cognition. We test this in bumble bees (Apidae: Bombus), a clade of eusocial insects that produce individuals at different time points across their reproductive season and exhibit organ developmental plasticity in response to nutritional consumption. To accomplish this, we develop a theoretical model that simulates learning development across a reproductive season for a colony parameterized with observed life history data. Our model finds two qualitative seasonal trajectories of learning: (1) an increase in learning across the season and (2) no change in learning across the season. We also find these two qualitative trajectories revealed by empirical learning data; the proportion of workers successfully completing a learning test increases across a season for two bumble bee species (Bombus auricomus, Bombus pensylvanicus) but does not change for another three (Bombus bimaculatus, Bombus griseocollis, Bombus impatiens). This study supports the novel consideration that resources affect seasonal trajectories of population-level learning in species with developmentally plastic cognition.