Organization within a social group: division of reproduction, labor, and space within the bumble bee colony, Bombus impatiens

Within-group conflict may influence the degree to which individuals within a group cooperate. For example, the most dominant individuals within a group often gain access to the best resources and may be less likely to perform risky tasks. We examine colonies of bumble bees, Bombus impatiens, and show that workers with the greatest reproductive potential do not behave selfishly by avoiding risky or more energy-expensive tasks. After the queen dies, workers with the greatest reproductive potential are more likely to incubate brood, whereas other workers are more likely to forage or become inactive. Furthermore, there is no evidence to suggest that workers with the greatest reproductive potential are found in the center of the nest, as is true in some other animal groups. However, after the queen dies, those workers tend to use smaller areas of the nest. We conclude that the maintenance of spatial organization among workers may be a mechanism that allows cooperation to persist at the colony level during a period of the highest within-group competition.