Short-term activity cycles in ants: age-related changes in tempo and colony synchrony

Summary This paper examines the characteristics of the spontaneous acivity levels of individual worker ants of Leptothorax allardycei and explores the influence of spontaneous worker activity on colony activity patterns. While there are substantial differences among workers in the characteristics of their spontaneous activity, all of the variation occurs within the colony. There are virtually no differences in the levels of spontaneous activity between colonies. Variation among workers is due to age; workers decline exponentially in their probability of becoming active, p_a,at a rate of -0.02 per day. I built computer models under four different sets of assumptions about the spontaneous activity patterns of workers, and performed simulations to test the ability of colonies of simulated workers to synchronize their movement activity. The most realistic results are obtained with models in which workers already have an underlying propensity to oscillate and which interact with one another to produce Type 1 phase resetting. The simulations generate predictions concerning the ability of colonies to synchronize, the most significant of which is that the average age of workers in a colony is very important in determining the extent of colony synchrony, while the distribution of ages is not.