Evolution in Mendelian Populations
Introduced the island model of population structure
This foundational paper introduced the island model of population structure, establishing the mathematical framework for understanding gene flow. Wright demonstrated that when Nm ≈ 1 (one successful migrant per generation), gene flow is sufficient to counteract genetic drift in moderate-sized populations.
This threshold is remarkably low - 99% of reproduction can be local, but 1% migration overpowers drift. For organizations, this means even small amounts of talent migration or idea exchange can homogenize practices across an industry, preventing differentiation.
Key Findings from Wright (1931)
- Introduced the island model of population structure
- Established Nm ≈ 1 threshold: one migrant per generation prevents genetic divergence
- Migration homogenizes allele frequencies between connected populations
- Gene flow and drift reach equilibrium based on relative strengths
- Random sampling in finite populations causes allele frequency changes independent of selection
- Effective population size determines the strength of drift relative to selection
- Variance in allele frequency scales inversely with population size
Used in 2 chapters
See how this research informs the book's frameworks:
Foundational paper introducing island model establishing that Nm ≈ 1 (one migrant per generation) is sufficient to counteract drift.
See gene flow mathematics →Established mathematical theory of genetic drift and effective population size showing how random sampling causes allele frequency changes.
See drift theory foundations →