Variability in resource consumption rates and the coexistence of competing species

A model which incorporates random temporal variation in resource consumption rates is used to investigate the effects that such variation has on the coexistence of competitors. The analysis of the model and several extensions of it suggests that such variation in consumption rates will often allow two or more competitors to coexist while limited by the same resource. For variability to promote coexistence, it is necessary that the time scale of resource population dynamics be fast relative to the time scale of environmental change. Variability is especially likely to promote coexistence if there is a large variance in consumption rates, negative correlation between the consumption rates of different species, and a linear or concave relationship between resource consumption and per capita population growth. Many previous studies which have found coexistence of two or more species on one resource can be interpreted as examples of coexistence due to varying resource consumption rates.