Making the competitive exclusion principle operational at the biogeographical scale using fuzzy logic

In biogeography the competitive exclusion principle (CEP) has been confirmed in some cases but not others. This fueled an unresolved debate between those advocating niche theory or neutral biodiversity and biogeography. We suggest that this situation mainly arises from use of crisp logic, where CEP is defined as either completely true false. propose application fuzzy concepts favorability (the degree to which environmental conditions are propitious for occurrence individual species) favorableness simultaneously favorable competing operationalize a version CEP. Favorability was obtained by performing species distribution models applying functions, while derived intersection species. Then we plotted values along gradient favorableness. Two potentially would coexist high-favorableness locations, demands both be well fulfilled. locations low favorableness, result autecological segregation, abiotic unfavorable at least one Competitive occur intermediate stretch gradient, good enough persistence each separately permanent coexistence. According theoretical framework, observed probability location belongs area given two co-occur should lower than expected according tested prediction on published data about pairs native introduced deer Great Britain, using Bayesian approach. thirds comparisons predictions were corroborated, suggests these specific geographical areas affected exclusion. important theoretically conservation planning.