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In evolutionary biology, disruptive selection, also called diversifying selection, describes changes in population genetics in which extreme values for a trait are favored over intermediate values. In this case, the variance of the trait increases and the population is divided into two distinct groups.
The first is directional selection, which is a shift in the average value of a trait over time—for example, organisms slowly getting taller. [80] Secondly, disruptive selection is selection for extreme trait values and often results in two different values becoming most common, with selection against the average value. This would be when ...
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. This genetic selection causes the allele frequency to shift toward the chosen extreme over time as allele ratios change from generation to generation.
disruptive selection. Also diversifying selection. A mode of natural selection in which the extreme values of a trait or phenotype within a breeding population are favored over intermediate values, causing allele frequencies to shift over time away from the intermediate. This causes the variance in the trait to increase and results in the ...
The uncommon disruptive selection also acts during transition periods when the current mode is sub-optimal, but alters the trait in more than one direction. In particular, if the trait is quantitative and univariate then both higher and lower trait levels are favoured. Disruptive selection can be a precursor to speciation. [57]
The first and most common function to estimate fitness of a trait is linear ω =α +βz, which represents directional selection. [1] [10] The slope of the linear regression line (β) is the selection gradient, ω is the fitness of a trait value z, and α is the y-intercept of the fitness function.
Microevolution is the change in allele frequencies that occurs over time within a population. [1] This change is due to four different processes: mutation, selection (natural and artificial), gene flow and genetic drift. This change happens over a relatively short (in evolutionary terms) amount of time compared to the changes termed macroevolution.
Frequency-dependent selection is an evolutionary process by which the fitness of a phenotype or genotype depends on the phenotype or genotype composition of a given population. In positive frequency-dependent selection, the fitness of a phenotype or genotype increases as it becomes more common.