However, communities are actually even more complicated than mixing species. Relationships in fact always are between individuals . This bi-directionality is easier to see with humans, since we realize that each of us in a relationship have a perspective. A perceives B in a certain way, and B perceives A in a different way. Our emotional response may be a denial of the miscommunication, and eventual disruption of the relationship.
Oversimplification can be disastrous in our management of critical situations.
We cannot create a single, static state. If X happens to compete with A for B in a predatory context, but will also be a predator of A, we have a very different community dynamic than the first equation. Or, if the behavior of X changes with the availability of B, and shifts to A entirely after B reaches a certain density or quantity in the community, we have A changing from a predator of B to entirely the prey of X after some phase of the dynamics has changed. These are possible results in the nature of the community of three species, C', D', and Y, that cannot be known by an infinite amount of study of the community of C and D, much less by a study of A and B and X in isolation. This is a simple example of a fundamental limitation of scientific studies in ecological dynamics.