Figure 1. Phenotypic variation in Onthophagus nigriventris. A: Scaling relationship between body size (x-axis) and horn length (y-axis) of male (open circles) and female (solid circles) O. nigriventris. Body size was measured as pronotum width (see Moczek and Emlen 1999 for justification). Horn length was measured as pronotum length. B: Typical male and female phenotypes. Left: large, horned (major) male. Center: small, hornless (minor) male. Right: female.