Figure 1.

Theoretical constraint space describing the functional relationship between the average body mass of individuals of a species and the extent of its geographical distribution. (a) The original constraint space proposed by Brown & Maurer [20]. (b) The modified constraint space proposed in this study. The red dotted line indicates the modal body size. Solid boundaries to the constraint space indicate absolute constraints; yellow dotted boundaries indicate probabilistic constraints. Positive and negative symbols indicate the direction of the relationship within the constraint space.