Neutral Wright–Fisher drift model
The neutral diploid Wright–Fisher model samples 2N gene copies independently from the previous generation.
Key knowledge
The neutral diploid Wright–Fisher model samples 2N gene copies independently from the previous generation. Given allele frequency p, the next copy count is binomial with parameters 2N and p. Its expected frequency is unchanged, but sampling variance is p(1−p)/(2N), allowing stochastic loss or fixation.
Values and equations
X′|p ~ Binomial(2N,p); E[p′|p]=p; Var(p′|p)=p(1−p)/(2N)
- N
- idealized diploid population size 1
- X′
- next-generation allele-copy count 1
- p,p′
- current and next-generation frequencies 1
Conditions and scope
- Assume constant N, discrete nonoverlapping generations, random reproduction, and no selection, mutation or migration.
- N is an idealized breeding population parameter; empirical effective size need not equal census size.
Sources · 1
References
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Evidence and review
Read conditional binomial-sampling formula and neutral heterozygosity/drift description; variance follows the stated binomial law.
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Entry details
Permanent link to this entry ↗- Record identity
- uni-bio-wright-fisher
- Revision
- core.1
- Structured reference record
- University core expansion