Models of symbiotic associations in food chains

In this study we investigate various ecosystems containing always a symbiotic pair. In the first model, the latter is subject to the action of a predator. In the second system, the mutualistic association at the trophic level is located above a common prey population. In the third model a three level food chain is investigated, with the symbiotic populations constituting the intermediate trophic level. These are situations that can well arise in nature. Finally, we make considerations on a symbiotic system in which a population X predates on another population Z; a third population Y lives in symbiosis with X; finally Z predates on Y Such an association is rather difficult to find in nature, but an interpretation of it could come from the world of finance, in which biological "populations" are substituted by corporations. At times they interact among each other in search for synergies, but at the same time it may occur that part of these associations compete with each other in other fields, giving rise to rather intricated situations as the one described above. © 2013 Nova Science Publishers, Inc. All rights reserved.