Disruptive Selection | Definition & Examples

By | October 2, 2019

Disruptive Selection

Disruptive Selection Definition:

The disruptive selection definition is defined as an evolutionary force that drives a population apart. The disruptive selection causes the organisms with intermediate traits in order to reproduce less, and allow those organisms with extreme traits to produce more. This fact causes the alleles for the extreme traits to increase the frequency. A population can completely be divided with enough disruptive selections over time.

The disruptive selections are also known as Diversifying selection on the basis of the variance of a trait in a population. A gene that has only one allele would have no variance and the selection could not act on the difference in traits produced by the gene.

Disruptive selections are often seen in the high-density population. In these populations, the resources become scarcer and competition for resources increases. This intraspecific competition may cause differences between organisms to have a more profound effect on each organism’s survival.

Disruptive Selection:

Examples of Disruptive Selection:

Examples of disruptive selection are mention below:

  • Finches on Santa Cruz Island:

Darwin’s finches are a group of finches that inhabit the long chain of island, called Galapagos. The birds have studied and many evolution patterns have seen in different populations.

On Santa Cruz Island, the disruptive selections were caused by speciation in the population of finches that reside there. Because of these forces of disruptive selections, the intermediate sizes of beak have selected against the generations. The resulting population has no medium sizes of beak mostly. The size of the beak is important for more than gathering food and found the change in beak size of many finches.

  • Disruptive Selection in Plants:

In 1960, a famous biologist, John Maynard Smith represented it as a method for plant speciation. Many plant traits including the color of pea pods are controlled by individual genes. The most intermediate individuals are usually heterozygous individuals in the scenario where disruptive selection is affecting the plants population.

Over time, many organisms differ much as they become reproductively isolated. Usually, the intermediates served the function of transferring genes between two populations.