Model of Disruptive Selection (aka Diversifying Selection)

The phenotypic distribution before selection is a relatively broad bell-curve. The Fitness Function is an inverted bell curve, so that the extreme phenotypes have greatest fitness. The result of selection is reduction of the middle of the distribution, so the trait variance is increased while the mean remains the same. Where the emphasis is on preservation of the tails of the distribution, this may also be called diversifying selection.