EVOLUTION OF COLONY CHARACTERISTICS IN SOCIAL INSECTS .2. NUMBER OF REPRODUCTIVE INDIVIDUALS

The inclusive-fitness models and single-locus gene frequency models suggest different thresholds for the cost allowing worker reproduction to evolve. The advantage of the inclusive-fitness approach is that it allows combining the invasion and loss of worker reproduction in the same model. According to the results derived here through this model, both polyandry and polygyny can restrict the conditions for the evolution of worker reproduction. There is a conflict between queens and workers concerning both worker reproduction and sex allocation. If a colony becomes either polygynous or polyandrous, the queens and workers can have similar interests concerning reproduction, and the colony could act in harmony to increase the inclusive fitnesses. This requires that the workers can recognize the genetic heterogeneity within the colony and adjust their own behavior optimally. If the workers can so behave, polyandry could colony and adjust their own behavior optimally. If the workers can so behave, polyandry could evolve as the queens' way of reducing the queen-worker conflict and manipulating the workers.