Disruptive selection

Disruptive selection
Natural selection favours organism with two extreme forms of a characteristic
Balanced polymorphism: equilibrium of non-carriers and carriers of a characteristic caused by natural selection
Sickle-cell anaemia ...

disruptive selection A process of natural selection that favors individuals at both extremes of a phenotypic range. PICTURE
distal tubule The section of the renal tubule where tubular secretion occurs.

Disruptive Selection
In some circumstances, individuals at both extremes of a range of phenotypes are favored over those in the middle. This is called disruptive selection.
An example: ...

Disruptive Selection
Disruptive selection favors individuals at both extremes of variation: selection is against the middle of the curve. This causes a discontinuity of the variations, causing two or more morphs or distinct phenotypes.

Disruptive selection: Selection against the middle range of variation causing an increase in the frequency of a trait showing the extreme ranges of its variation. Disruptive selection might cause one species to evolve into two.

2 Disruptive Selection on Drosophila melanogaster
Thoday and Gibson (1962) established a population of Drosophila melanogaster from four gravid females.

disruptive selection Natural selection that occurs when individuals of the most common phenotypes are at a disadvantage; produces contrasting subpopulations.
dissociation The breaking up of a molecule into ions when placed in water or other solvents.

"Speciation via disruptive selection on habitat preference: experimental evidence". The American Naturalist 131: 911-917.
^ Dodd, D.M.B. (1989) "Reproductive isolation as a consequence of adaptive divergence in Drosophila pseudoobscura.

See also: Plant, Natural selection, Selection, Species, Evolution