Gene Flow Migration Rate Calculator
Estimate effective number of migrants (Nm) between populations from FST. Wright's island model: Nm = (1-FST)/(4*FST). Quantify population connectivity from genetic data.
🧬 Population Genetics📐 Nm = (1 - FST) / (4 x FST)🧬 Biology
FST value
Please enter valid values.
Formula & Reference
| Variable | Symbol | Formula | Units |
|---|---|---|---|
| Gene Flow Migration Rate Calculator | — | Nm = (1 - FST) / (4 x FST) | migrants/generation |
Step-by-Step Examples
Example 1
Coastal Fish
FST=0.05.
- Nm=(0.95)/(0.20)=4.75
- Moderate gene flow
- Populations similar but distinguishable
✓ Nm=4.75 — moderate connectivity
Example 2
Island Species
FST=0.30.
- Nm=0.70/1.20=0.583
- <1 migrant per generation
- Strong isolation — separate management units
✓ Nm=0.58 — strongly isolated
Example 3
Continental Humans
FST=0.01.
- Nm=0.99/0.04=24.75
- Near-panmictic — ~25 migrants/gen
- Consistent with high historical migration
✓ Nm=25 — very high gene flow
Real-World Applications
Conservation Biology
Identify isolated populations needing corridors or translocation.
Landscape Genetics
Relate migration to geographical barriers.
Population Structure
Determine if populations should be managed separately.
Epidemiology
Pathogen migration rate determines outbreak spread patterns.
Common Mistakes to Avoid
⚠️
Island model assumption
Wright's formula assumes symmetric migration between equal populations. Real migration is directional and distance-dependent.
⚠️
Large CI on Nm
FST-based Nm has huge uncertainty — treat as order-of-magnitude estimate.
⚠️
Cannot determine direction
Use MIGRATE-N or BayesAss for directional gene flow estimates.
Frequently Asked Questions
What is gene flow? ▾
Movement of alleles between populations. Homogenizes frequencies; opposes drift and selection.
What does Nm > 1 mean? ▾
More than 1 migrant per generation prevents strong differentiation by drift (Wright's rule).
How is migration measured directly? ▾
Mark-recapture, telemetry, stable isotopes, assignment tests in population genetics software.
What is isolation by distance? ▾
Migration decreasing with distance creates FST ~ log(distance) pattern. Detected by Mantel test.
What is a wildlife corridor? ▾
Habitat connection increasing Nm between isolated patches. Reduces genetic drift and inbreeding.