Balancing Selection

Overdominance maintains polymorphism — sickle cell anemia, ABO blood groups, MHC diversity

Fitness Parameters

Equilibrium p*:
Final p:
Mean fitness:
Sickle cell example: AA=0.85 (malaria risk), Aa=1.0 (protected), aa=0.65 (sickle cell disease). Equilibrium is maintained in malaria regions.
Allele Frequency
Phase Portrait
Fitness Landscape