Types of Natural Selection - Disruptive Selection

A graph of disruptive selection
By Selection_Types_Chart.png: Azcolvin429 (Selection_Types_Chart.png) [ GFDL or CC BY-SA 3.0], via Wikimedia Commons

Disruptive selection is a type of natural selection that selects against the average individual in a population. The make up of this type of population would show phenotypes of both extremes but have very few individuals in the middle. Disruptive selection is the rarest of the three types of natural selection.

The normal bell curve is changed greatly in disruptive selection. In fact, it looks almost like two separate bell curves.

There are peaks at both extremes, and a very deep valley in the middle. Disruptive selection can lead to speciation, and form two or more different species in areas of drastic environmental changes.

Like directional selection, disruptive selection can be influenced by human interaction. Environmental pollution can drive disruptive selection to choose different colorings in animals for survival.


One of the most studied examples of disruptive selection is the case of ​London's peppered moths. In rural areas, the peppered moths were almost all a very light color. However, these same moths were very dark in color in industrial areas. Very few medium colored moths were seen in either location. It seems that the darker colored moths survived predators in the industrial areas by blending in with the polluted surroundings. The lighter moths were seen easily by predators in industrial areas and were eaten.

The opposite happened in the rural areas. The medium colored moths were easily seen in both locations and were therefore very few of them left after disruptive selection.​​