Fig. 4. The relationship between discontinuities, variability and stability. Body size distributions of animals are characterized by aggregations and discontinuities (upper graphic, circles representing species). Aggregations reflect domains of scale and discontinuities reflect scale breaks. Within domains of scale, resource variation is low (lower graphic, dotted line), and at scale breaks resource variation is high. Stability (solid line) is inversely related to variability and is high within scales and low at scale breaks.