Examples of Disruptive Selection

Peppered moths in industrial and rural areas

One of the popular examples of disruptive selection is ​London’s peppered moths. In industrial areas with pollution, darker-colored moths were more likely to survive predation because they blended in with the polluted surroundings. In rural areas, lighter-colored moths had a survival advantage. There were very few moths with medium color in both places. This led to a bimodal distribution in wing coloration, representing disruptive selection.

Darwin’s finches on the Galapagos Islands

Different species of finches have evolved with distinct beak shapes and sizes, adapted to different food sources. For example, ground finches have beaks suited for eating seeds, while tree finches have beaks adapted for feeding on fruits and arthropods.

Mexican spadefoot toad tadpoles

Tadpoles exhibit a resource polymorphism with two extreme phenotypes – omnivores and carnivores. Omnivorous individuals have round bodies, and the carnivorous tadpoles have narrow bodies. The intermediate ones are smaller than those at either extreme of body shape and eating habits. Intermediate phenotypes experience increased competition and reduced fitness, leading to disruptive selection.

Lazuli Buntings

In habitats with limited nesting sites, both the dullest and brightest yearling males have higher fitness, obtaining high-quality territories and attracting females. Yearling males with intermediate feathers face aggression from adults, resulting in disruptive selection.