Modular nest structure influences activity cycle synchronisation in ant colonies

Periodic oscillations are widespread in biological systems, from heartbeats to predator-prey cycles. However, although oscillatory systems often exhibit modular organisation, how cycles are generated and coordinated across modules remains unclear. Here, we tested how modular nest architecture affects short-term activity cycles in the acorn ant Leptothorax acervorum. Activity cycles were consistently initiated by spontaneous pacemakers in the inner parts of the nest and transmitted toward the outer regions by intermediate 'transfer' ants. Compared to single-chamber nests, modular (double-chamber) nests induced partial decoupling of activity between chambers, resulting in reduced colony-wide rhythmicity. However, increased movement speeds of transfer ants in double-chamber nests relative to single-chamber nests enhanced activity transmission, partly restoring coordination between chambers. As well as illustrating how modular structure shapes collective dynamics, our results shed light on how ant colonies solve a fundamental challenge facing many biological systems: maintaining coordination between physically-segregated units.