Frequency-Dependent Selection¶
Biological selection in which a type's relative fitness depends on how common it or other types are in the population.
Core Idea¶
Frequency-dependent selection occurs when a biological type's relative survival or reproductive success depends on its frequency or on the population's type composition. In a model, fitness is \(w_i(p)\) rather than one fixed value for type \(i\). Negative dependence can favor rare types; positive dependence can favor common ones, but neither sign alone dictates permanent coexistence or fixation.[^ref-ad92c51f5b64]
Scope of Application¶
The identity spans genotype and heritable-phenotype contexts with different channels. Hughes et al. report rare male guppy color patterns with greater reproductive fitness in studied populations. Chouteau and colleagues report fewer attacks on artificial butterfly models bearing locally common warning signals, with nonlinear saturation; protection of natural butterflies is an inference, not a directly measured survival outcome. These are bounded original-study instances, not universal statements about either species or all selection outcomes.[ref-a9b09fa2ec84][ref-9bbd06bcdfb9]
Clarity¶
Frequency dependence separates the type's properties from the advantage those properties have at a given prevalence. A change in the population composition can change the relative fitness ranking without changing type identities. It is not merely selection pressure changing for an external reason, and it is not synonymous with prey switching or a protected polymorphism.[ref-ad92c51f5b64][ref-9cb942c6d756-4][^ref-9cb942c6d756-5]
Manages Complexity¶
The same roles—types, current frequencies, relative fitness, interaction channel and differential continuation—compare a rare-male mating case with a common-warning-signal protection case. The sign is a useful summary, but a local fitness contrast cannot replace the additional evidence and model assumptions needed for a long-run equilibrium claim.[ref-a9b09fa2ec84][ref-9bbd06bcdfb9][^ref-ad92c51f5b64]
Abstract Reasoning¶
If fitness is \(w_i(p)\), then as type frequencies shift, selection can alter the pressure acting next. Rare advantage may oppose further growth of a type, and common advantage may reinforce it, yet global outcomes depend on invasion conditions, other fitness components and dynamics. Trotter and Spencer show that even positive frequency dependence need not be read as automatic monomorphism under every multiallelic model.[^ref-ad92c51f5b64]
Knowledge Transfer¶
The mathematical relation between frequency and relative fitness transfers from guppy reproductive success to butterfly warning-signal protection while their mechanisms differ. Live prime Selection is the proposed strict genus because both cases have a candidate population, pressure and unequal continuation.
[^ref-a9b09fa2ec84]: Kimberly A. Hughes et al., “Mating advantage for rare males in wild guppy populations”, Nature 503 (2013), 108–110; original abstract inspected 2026-10-01.
[^ref-9bbd06bcdfb9]: Mathieu Chouteau, Mónica Arias and Mathieu Joron, “Warning signals are under positive frequency-dependent selection in nature”, PNAS 113 (2016), 2164–2169; original full paper.
[^ref-ad92c51f5b64]: Meredith V. Trotter and Hamish G. Spencer, “Frequency-Dependent Selection and the Maintenance of Genetic Variation”, Genetics 176 (2007), 1729–1740; original full paper.
[^ref-9cb942c6d756]: Encyclopedia of Abstractions, live prime_abstractions/v2/selection.md, Core Idea/Signature, inspected 2026-10-01.
[^ref-9cb942c6d756-4]: Encyclopedia of Abstractions, live domain_specific_abstractions/v2/prey_switching.md, Core Idea, inspected 2026-10-01.
[^ref-9cb942c6d756-5]: Encyclopedia of Abstractions, live domain_specific_abstractions/v2/protected_polymorphism.md, Core Idea, inspected 2026-10-01.
Relationships to Other Abstractions¶
Current abstraction Frequency-Dependent Selection Domain-specific
Parents (1) — more general patterns this builds on
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Frequency-Dependent Selection is a kind of Selection Prime
A frequency-conditioned biological fitness difference is a special selection basis.
Hierarchy path (1) — routes to 1 parentless root
- Frequency-Dependent Selection → Selection
Neighborhood in Abstraction Space¶
Frequency-Dependent Selection sits in a sparse region of the domain-specific corpus (71st percentile for distinctiveness): few abstractions share its structure, so a faithful description tends to retrieve it precisely.
Family — Selection, Speciation & Experimental Evolution (22 abstractions)
Nearest neighbors
- Genetic Load — 0.88
- Fixation (population genetics) — 0.86
- Complete mixing — 0.85
- Wallace Effect — 0.83
- Differential Evolution — 0.82
Computed from structural-signature embeddings · 2026-10-08