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  2. Disruptive selection - Wikipedia

    en.wikipedia.org/wiki/Disruptive_selection

    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.

  3. Glossary of genetics and evolutionary biology - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_genetics_and...

    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 ...

  4. Selection gradient - Wikipedia

    en.wikipedia.org/wiki/Selection_gradient

    The second fitness function is nonlinear ω = α +βz +(γ/2)z 2, which represents stabilizing or disruptive selection. [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 ...

  5. Evolution - Wikipedia

    en.wikipedia.org/wiki/Evolution

    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 ...

  6. Fisher's fundamental theorem of natural selection - Wikipedia

    en.wikipedia.org/wiki/Fisher's_fundamental...

    Fisher's fundamental theorem of natural selection is an idea about genetic variance [1] [2] in population genetics developed by the statistician and evolutionary biologist Ronald Fisher. The proper way of applying the abstract mathematics of the theorem to actual biology has been a matter of some debate, however, it is a true theorem.

  7. Haldane's dilemma - Wikipedia

    en.wikipedia.org/wiki/Haldane's_dilemma

    The total cost of substitution of the gene is the sum of all values of over all generations of selection; that is, until fixation of the gene. Haldane states that he will show that D i {\displaystyle D_{i}} depends mainly on p 0 {\displaystyle p_{0}} , the small frequency of the gene in question, as selection begins – that is, at the time ...

  8. Balancing selection - Wikipedia

    en.wikipedia.org/wiki/Balancing_selection

    Balancing selection refers to a number of selective processes by which multiple alleles (different versions of a gene) are actively maintained in the gene pool of a population at frequencies larger than expected from genetic drift alone. Balancing selection is rare compared to purifying selection. [1]

  9. Genetic divergence - Wikipedia

    en.wikipedia.org/wiki/Genetic_divergence

    Genetic divergence will always accompany reproductive isolation, either due to novel adaptations via selection and/or due to genetic drift, and is the principal mechanism underlying speciation. On a molecular genetics level, genetic divergence is due to changes in a small number of genes in a species, resulting in speciation . [ 2 ]