Figure P20.3

Figure P20.3. (A) Male mating success, 1 + x, increases with antler size x. (B) Contours of male survival, 1 – x + (2/3) x y, plotted against male quality y and antler size x. Contours are at intervals of 0.05, and run from 1 at the left down to 0 at bottom right. Antler size and male quality are measured on an arbitrary scale.