Wataru Toyokawa | bioRxiv Science

bioRxiv2016

Scrounging by foragers can resolve the paradox of enrichment

Theoretical models of predator-prey system predict that sufficient enrichment of prey can generate large amplitude limit cycles, paradoxically causing a high risk of extinction (the paradox of enrichment). While real ecological communities contain many gregarious species whose foraging behaviour should be influenced by socially transmitted information, few theoretical studies have examined the possibility that social foraging might be a resolution of the paradox. I considered a predator population in which individuals play the producer-scrounger foraging game both in a one-prey-one-predator system and a two-prey-one-predator system. I analysed the stability of a coexisting equilibrium point in the former one-prey system and that of non-equilibrium dynamics of the latter two-prey system. The result showed that social foraging can stabilise both systems and thereby resolves the paradox of enrichment when scrounging behaviour is prevalent in predators. This suggests a previously neglected mechanism underlying a powerful effect of group-living animals on sustainability of ecological communities.

Ecology↗

bioRxiv2016

Individual differences in learning behaviours in humans: Asocial exploration tendency does not predict reliance on social learning

A number of empirical studies have suggested that individual differences in asocial exploration tendencies in animals may be related to those in social information use. However, because the exploration tendency in most previous studies has been measured without considering the exploration-exploitation trade-off, it is yet hard to conclude that the animal asocial exploration-exploitation tendency may be tied to social information use. Here, we studied human learning behaviour in both asocial and social multi-armed bandit tasks. By fitting reinforcement learning models including asocial and/or social decision processes, we measured each individuals (1) asocial exploration tendency and (2) social information use. We found consistent individual differences in the exploration tendency in the asocial tasks. We also found substantive heterogeneity in the adopted learning strategies in the social task: One-third of participants were most likely to have used the copy-when-uncertain strategy, while the remaining two-thirds were most likely to have relied only on asocial learning. However, we found no significant individual association between the exploration frequency in the asocial task and the use of the social learning strategy in the social task. Our results suggest that the social learning strategies may be independent from the asocial search strategies in humans.

Animal Behavior and Cognition↗