Briefly, we designed a multilevel model to study an obligate endosymbiosis between two simple entities (designated as hosts and symbionts). In principle, the hosts and symbionts can evolve to coordinate their cell-cycles indirectly through a coupling with the shared environment...

... However, the close association/integration of host and symbiont likely presents a problem. For instance, signaling molecules from the symbiont may end up in the host (e.g. due to symbiont death inside the host) and vice versa, disturbing their cell cycles...