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Stabilizing selection is the most common form of nonlinear selection (non-directional) in humans. [13] There are few examples of genes with direct evidence of stabilizing selection in humans. However, most quantitative traits (height, birthweight, schizophrenia) are thought to be under stabilizing selection, due to their polygenicity and the ...
Selection has different effects on traits. Stabilizing selection acts to hold a trait at a stable optimum, and in the simplest case all deviations from this optimum are selectively disadvantageous. Directional selection favours extreme values of a trait.
[1] [5] The quadratic regression (γ) is the selection gradient, ω is the fitness of a trait value z, and α is the y-intercept of the fitness function. Here, individuals with intermediate trait values may have the highest fitness (stabilizing selection) or those with extreme trait values may have the highest fitness (disruptive selection).
This was translated by Theodosius Dobzhansky and appeared in English as Factors of Evolution: The Theory of Stabilizing Selection in 1949. [4] On 23 August 1948 he became victim of order 1208, one of a series signed by Minister of Higher Education in the USSR, Sergei Kaftanov , which led to the mass dismissals of many university professors ...
Graph 2 depicts stabilizing selection, where the intermediate phenotype is favored over the extreme traits. Graph 3 shows disruptive selection, in which the extreme phenotypes are favored over the intermediate. In evolutionary biology, disruptive selection, also called diversifying selection, describes changes in population genetics in which ...
In particular, stabilizing selection, mechanical, and physical constraints might lead through time to developmental integration and canalisation. However, without any clear idea of any of these mechanisms, deducing them from mere patterns of stasis as deduced from phylogenetic patterns or the fossil record remains problematic. [ 3 ]
Middle (Graph 2) represents stabilizing selection with the moderate trait favored. Bottom (Graph 3) represents disruptive selection with both extremes being favored. In population genetics , directional selection is a type of natural selection in which one extreme phenotype is favored over both the other extreme and moderate phenotypes.
Many traits in humans and other species are highly polygenic, i.e., affected by standing genetic variation at hundreds or thousands of loci. Under normal conditions, the genetic variation underlying such traits is governed by stabilizing selection, in which natural selection acts to hold the population close to an optimal phenotype.