Negative selection (artificial selection)

In artificial selection, negative selectionis where negative, rather than positive, traits of a species are selected for evolutionary continuance. It is generally not desirable, but may be caused by man-made conditions such as bad management, such as when humans eat the best plants or animals they have, leading to worse and worse stock; it occurred frequently, for example, in primitive beekeeping. Another, more modern, example are regulations on fish and game, where fish below a certain size had to be released, and deer below a certain size could not be hunted, leading to undersized deer and fish populations. Some, such as proponents of Social Darwinism and  eugenics argue that medicine and other technological, societal, and cultural practices cause negative selection in humans, also known as dysgenics. According to them, man, as a species, manifests more and more negative traits as a result of this.

In the case of microbiology and molecular biology, negative selection is used to screen for microorganisms that fail to possess a certain phenotype. An example of this is through replica plating.

Selezione negativa (artificiale)