Modeling the relations between species similarity and competitive exclusion in ecological communities
The competitive exclusion principle determines that when two species occupy the same niche at the same geographic territory, the species whose reproduction rate is higher will outcompete the other. However, the competitive exclusion principle mechanism fails to explain the observed coexistence of similar species in the same community in many types of ecosystems, such as in the paradox of the plankton.
This research proposes that similarity between species can be decomposed into two components that affect species coexistence: (1) Niche similarity- to what extent does the species consumes the same resources, and (2) Similarity of competitive ability – how similar are the abilities of the species to compete.
As niche overlap increases, the competition among the species become more severe (Fig 1.a.), while as the species competitive abilities become similar, the ability of one species to completely exclude the other species from the habitat decreases (Fig 1.b.). The mutual effect of species similarity on competitive exclusion rate might be a unimodal in which very different and very similar species coexist (Fig 1.c.).
The above hypothesis is examined using computer models that are developed and analyzed in R programing language.