Effects of Gene-Environment Interactions on the Evolution of Social Behaviours

Inclusive fitness models in sociobiology emphasize the importance of relatedness, R, and synergy, S when exploring the evolution of social behaviours. Very few models explicitly consider ‘role’, or environmental stimuli, influencing the expression of behaviours, and none consider genetic-environment interactions where genotype predisposes individuals to certain roles. I propose a third key variable for inclusive fitness models, Q, which describes the overlooked potential bias in the genetic composition of individuals exposed to an environmental stimulus – here referred to as ‘role’. I describe a model built from Price’s formula which can be presented in a ‘Hamilton’s Rule’ format. I consider classic social behaviour models using this format, and find that the inclusion of gene-environment interactions dramatically changes the results. This, in conjunction with the increasing evidence supporting gene-environment interactions in eusocial caste determination, suggests that current inclusive fitness models may be missing key details about the evolution of social behaviours