Genetic equilibrium
Encyclopedia
A genetic equilibrium is at hand for an allele
in a gene pool
when the frequency of that allele is not changing (i.e. when it is not evolving). For this to be the case, evolutionary forces acting upon the allele must be equal and opposite. The only basic requirement is that the population be large enough that the effects of genetic drift
are minimized. For more see heterozygote advantage
, fixation
, mutation-selection balance
, negative frequency-dependent selection. There may be inbreeding
as this reduces heterozygosity but does not cause evolution.
Allele
An allele is one of two or more forms of a gene or a genetic locus . "Allel" is an abbreviation of allelomorph. Sometimes, different alleles can result in different observable phenotypic traits, such as different pigmentation...
in a gene pool
Gene pool
In population genetics, a gene pool is the complete set of unique alleles in a species or population.- Description :A large gene pool indicates extensive genetic diversity, which is associated with robust populations that can survive bouts of intense selection...
when the frequency of that allele is not changing (i.e. when it is not evolving). For this to be the case, evolutionary forces acting upon the allele must be equal and opposite. The only basic requirement is that the population be large enough that the effects of genetic drift
Genetic drift
Genetic drift or allelic drift is the change in the frequency of a gene variant in a population due to random sampling.The alleles in the offspring are a sample of those in the parents, and chance has a role in determining whether a given individual survives and reproduces...
are minimized. For more see heterozygote advantage
Heterozygote advantage
A heterozygote advantage describes the case in which the heterozygote genotype has a higher relative fitness than either the homozygote dominant or homozygote recessive genotype. The specific case of heterozygote advantage is due to a single locus known as overdominance...
, fixation
Fixation
Fixation may refer to the following:In science:*Fixation , the state in which an individual becomes obsessed with an attachment to another human, an animal, or an inanimate object...
, mutation-selection balance
Mutation-selection balance
The mutation-selection balance is a classic result in population geneticsfirst derived in the 1920s by John Burdon Sanderson Haldane and R.A. Fisher.A genetic variant that is deleterious will not necessarily disappear immediately from apopulation...
, negative frequency-dependent selection. There may be inbreeding
Inbreeding
Inbreeding is the reproduction from the mating of two genetically related parents. Inbreeding results in increased homozygosity, which can increase the chances of offspring being affected by recessive or deleterious traits. This generally leads to a decreased fitness of a population, which is...
as this reduces heterozygosity but does not cause evolution.
- No gene mutations
- Large population size
- Limited-to-no immigration, emigration, or migration (genetic flow)
- Gene of interest has no effect on survival/reproduction, and there is no natural selection
- Mating is random (panmixis)