Infodoc : Sciences, Techniques et Culture

We develop a theory of competition based on two mechanisms that we call the cost of rarity (Mechanism R) and the cost of commonness (Mechanism C). These reduce the rate of population increase only at high densities (asexual organisms) or both at high and low densities (sexual species). The theory predicts that, in certain circumstances, the number of coexisting species in any assemblage will be finite and that these species will differ in their utilization of resources (and in associated morphological traits) more than expected by chance. Specifically, it predicts such nonrandom assortment in assemblages of three or more (i.e. multispecies) sexual species, especially in those communities where a few species are numerically dominant, but not in two-species associations and not in asexu[...]

We develop a theory of competition based on two mechanisms that we call the cost of rarity (Mechanism R) and the cost of commonness (Mechanism C). These reduce the rate of population increase only at high densities (asexual organisms) or both at high and low densities (sexual species). The theory predicts that, in certain circumstances, the number of coexisting species in any assemblage will be finite and that these species will differ in their utilization of resources (and in associated morphological traits) more than expected by chance. Specifically, it predicts such nonrandom assortment in assemblages of three or more (i.e. multispecies) sexual species, especially in those communities where a few species are numerically dominant, but not in two-species associations and not in asexual forms. Unlike other theories, however, ours does not predict any specific value of morphological ratio or limiting similarity.