# Frequent question: What is the probability that the allele eventually becomes fixed?

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## What is the exact probability that allele A will eventually go to fixation?

For example, if a population includes allele A with frequency equal to 20%, and allele a with frequency equal to 80%, there is an 80% chance that after an infinite number of generations a will be fixed at the locus (assuming genetic drift is the only operating evolutionary force).

## How do you find the probability of an allele being fixed?

The fixation probability of a single copy of an A allele in a population of census size N is obtained by setting P = 1/(2N) in Equation 2.

## What is fixation probability?

The fixation probability, the probability that the frequency of a particular allele in a population will ultimately reach unity, is one of the cornerstones of population genetics.

## What happens to the A allele when the A allele is fixed?

When the allelic frequency in a population reaches 1.0, the allele is the only one left in the population, and it becomes fixed for that allele. The other allele is permanently lost. In populations in which an allele has become either fixed or lost, the process of random genetic drift stops at that locus.

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## What does it mean when an allele reaches fixation?

A gene has achieved fixation when its frequency has reached 100% in the population. At that stage, all individuals are homozygous for that allele until a new mutation arises. A gene may be taken to fixation by selection or genetic drift. Populations often maintain polymorphism at a locus.

## What are fixed SNPs?

SNPs that are fixed in only one population sample but absent in others are considered ‘private SNPs’ [15]. Populations whose genetic makeup was shaped through thousands of generations in distinct, relatively fixed environments were suddenly exposed to an entirely new world and unfamiliar environment.

## What is the probability that a neutral mutation with an initial frequency of P will eventually become fixed in the population?

The probability that a neutral mutation will eventually be fixed is 1/(2N ).

## In which situation will the A1 allele reach fixation?

– *A1 reaches fixation most rapidly when it is codominant with A2. – When A1 is dominant, its initial increase in frequency is most rapid, but its pace slows once it is common in the population. Occurs when the costs and benefits associated with a phenotype (trait) depend on its frequency in the population.