Weak Predation and Competition Dynamics
in a Food Webchain Model
We model the food chain between a single prey, two
competing predators, and one top-predator that is at the top of the food
chain. The food chain is carefully
constructed out of the standard Rosenzweig-MacArthur model for a tritrophic
food chain. Alternatively, one could
consider our full system a construction from a prey-2 predator food web.
The
actions and behaviors of the system depend heavily on different initial
parameters of the system, parameters which model the behaviors and attributes
of the various species. We distinguish
mathematically a weak predator from a stronger predator, because the weak
predator produces a certain qualitative behavior in the system, which is
totally different from the behavior a strong predator produces. Additionally, we can define a dominant and
non-dominant predator.
We
scale the system conveniently, and using singular orbit / singular perturbation
analysis, we are able to prove the existence of certain orbits for the limiting
condition (and slightly perturbed condition) of the full system. We demonstrate that the Competition
Exclusion Principle holds for the food web, but not for the full system, as
well as analyzing other facts about the food chain and food web.
Finally, for the more perturbed full system,
we show some chaotic orbits and chaotic structures possible. We do not analyze all the behaviors of the
full system, as it would be a massive undertaking. However, we take a sub case of the food chain called the “slow
flow case”, and analyze the various possible behaviors that can occur when a
predator is added to the food chain.
Even from the simple case in the food chain, where there are no complex
structures present, the generalized food chain provides chaos and many complex
orbits.