Fig. 1

Hypothesized range size of an organism as a function of A resource abundance and B resource stochasticity. We expect low values of \(\text {E}(R)\) and large values of \(\text {Var}(R)\) to result in a large range, since organisms are forced to explore large areas to collect the resources they require to survive, whether they be range-resident, nomadic, or migratory. As \(\text {E}(R)\) increases or \(\text {Var}(R)\) decreases, range size should decrease nonlinearly until it reaches the minimum amount of space required by the organism to survive. Note that the relationship between range size and both \(\text {E}(R)\) and \(\text {Var}(R)\) cannot be of the form \(H = \beta _0 + \beta _1 \text {E}(R) + \beta _2 \text {Var}(R)\) because it would require range size to be negative for high values of \(\text {E}(R)\) or low values of \(\text {Var}(R)\)