Interplay between habitat subdivision and minimum resource requirement in two-species competition

This paper explores the effects of increasing spatial subdivision of habitat on competition between two species. An increase in the degree of subdivision without any increase in the total amount of resources in the environment leads to smaller patch sizes, and thus, fewer individuals supported per patch. This fact suggests that when the degree of subdivision is high, the minimum resources that an individual must obtain before reproduction become important. Competition equations derived from first-principles that incorporate the minimum resource requirement are employed to investigate the effects of spatial subdivision and how these effects depend on the minimum requirements of the two species, type of resource competition such as scramble or contest, and spatial aggregation level of individuals. The results show that increased subdivision leads to changes in “effective fecundities” of the species, and consequently, affects their competitive superiority. Species coexistence is promoted at intermediate subdivision levels, especially if there is a trade-off between the minimum resource requirement and inherent fecundity. The range of subdivision in which coexistence occurs depends on the spatial aggregation of individuals and inequality in competitive ability between the species.