The post-optimal animal: A psychological model of individual variation in a population

Background/Question/Methods

Organisms behave through emotions, and their motivational state restricts attention to a few stimuli to which they react. We present a model for fish behavior with explicit representation of alternative emotions (fear and hunger). By incorporating several levels of mechanism, such as perception, neuronal responses, developmental modulation, motivational state, and attention, we create an architecture that sustains individual variation, with emergent phenotypic and genotypic variation within and between populations.

Results/Conclusions

This happens because a particular adaptation at one level can be achieved by different adaptations at a lower level. Thus, populations adapted to the same environment can differ substantially with respect to genetics and motivational state, but converge in emergent behavior and life-history traits. Our study provides a mechanistic underpinning for how biological variability is maintained and constrained by several structures and processes common in nature, including flexible organismal architecture, fluctuating environments, gene-environment interactions, historical contingencies, frequency-dependent games, and individual behavioral constraints.