All social insects live in elaborately organised societies. Their social structures enable them to continuously manage a large set of simultaneous tasks; from scouting and foraging to colony defence, nest building, thermoregulation, and brood care. To ensure colony survival and reproduction it is vital that the colony workforce is adequately allocated to these different tasks. Social insect colonies are able to perform such task allocation with an amazing degree of flexibility, continuously adjusting to changes in environmental conditions. The resulting division of labor (DOL) is a cornerstone of all social insect societies and commonly credited as a key factor for their enormous ecological success.
The vast majority of DOL modelling has either focussed on physiological factors or on individual-based behavioural mechanisms. Comparatively little attention has been given to how social interactions regulate task allocation. None of the existing frameworks provides a direct link to integrate environmental conditions as an integral part of the modelling process (beyond task-related stimulus levels). Entomologists are now investigating specifically these factors as the keys to a better and more comprehensive understanding of workforce allocation.
We propose a new mathematical modelling framework for task allocation in social insects that directly incorporates social interactions and environmental conditions as first class elements. We use evolutionary game theory to investigate how task preferences develop during the lifetime of a colony and how DOL emerges and morphs as a result. We model the task preferences of individuals as continuous strategy choices in a simple game, in which individuals choose how to divide their efforts between different tasks. Task execution results in rewards that may be shared between colony members or go directly to the individual. The amount of reward is modulated by the collective level of investment into the task as well as by environmental factors.
Based on this framework we show that ecological conditions are a crucial determinant for the emergence of different forms of specialisation. We also find strong interactions between the prevailing learning mechanisms and colony specialisation.
Contrary to intuition we find that strong specialisation does not always relate to improved colony efficiency. Particularly, social learning appears to lead to high colony performance only in a limited range of environment types and can drive a colony into “over-specialisation” in other conditions. This suggests that social learning should only have evolved in a limited range of environments and for certain tasks. Our theoretical results thus point towards promising new directions for empirical work that can bring us a step closer to understanding how social insects achieve their outstanding ecological success.