Diploid viability selection as a recurrence
In a random-mating diploid model, genotype frequencies are reweighted by relative survival and normalized by mean fitness.
Key knowledge
In a random-mating diploid model, genotype frequencies are reweighted by relative survival and normalized by mean fitness. The resulting allele frequency can differ from its pre-selection value. Selection is therefore a quantitative change in reproduction/survival-weighted representation, distinct from random sampling drift.
Values and equations
p′ = (p²wAA + pqwAa)/w̄; w̄ = p²wAA + 2pqwAa + q²waa; q = 1 − p
- p,p′
- A frequency before/after viability selection 1
- q
- a frequency before selection 1
- wAA,wAa,waa
- genotype relative viabilities 1
- w̄
- mean relative viability 1
Conditions and scope
- Assume Hardy–Weinberg genotype proportions before viability selection, fixed genotype fitnesses and no other frequency-changing force in this step.
- A genotype's relative fitness is context-dependent; dominance for fitness is not necessarily dominance for a visible trait.
- Relative viabilities are nonnegative and mean viability w̄ is strictly positive. If no genotype survives, a post-selection allele frequency is undefined.
The source contains a conflicting displayed fitness-inequality direction in an AA-selection example. That example is excluded, as the existing author evidence already states.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Read genotype-proportion/survivorship normalization model and derived the allele recurrence by allele counting; excluded the source's conflicting direction of a displayed fitness inequality.
Relative viabilities are nonnegative and mean viability w̄ is strictly positive. If no genotype survives, a post-selection allele frequency is undefined. Lecture 3, printed pp24–28: relative survivorship and normalization model. Fresh actual PDF text body inspected for survivorship/normalization; image-only displayed formulas were not successfully screenshot-verified. The recurrence and zero-denominator exclusion were independently checked by allele counting/normalization algebra.
2026-10-10 · Independent AI editorial review: All 115 actual compact claims, hypotheses, equation/variable/unit tables and 251 origin semantic links independently read. All exact author source-binding rows and disclosed extents assessed; targeted original bodies or specifically identified indexed primary passages rechecked below. All retained biology compact records read for combined breadth. Independent AI editorial content and practical common-core inventory review; no human specialist, degree/laboratory proficiency, whole-textbook certification or experimental replication. Receipt: biology-independent-content-inventory-review.1.
Entry details
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