Hope that helps?

Although we enforce the endosymbiosis, host and symbiont normally adapt in such a way that preserves their regulatory autonomy. Only when we include regulatory conflicts, do host and symbionts evolve to communicate and to establish control mechanisms between them.

Regulatory conflicts between host and symbionts (i.e. signaling molecules of host and symbiont interfering with each other) promote host--symbiont integration, providing a narrative for how a transition in individuality may take place in a tight endosymbiotic relationship.

... Surprisingly, these regulatory conflicts inspire evolution to come up with new solutions for host--symbiont cell-cycle coordination. Host and symbiont evolve communication and various control strategies, and in some cases even manage to synchronize their cell cycles.

... 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...

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...