One-Locus Selection - Simulation
Adjust the initial allelic frequencies (p,q) and relative fitness (w) to the right:
For best results, begin by setting the fitness values to 1.0, and initial allelic frequencies to 0.5. Then, decrease one or more of the fitness values by a small amount.
Selection against the A allele occurs when wAA<wAa and/or wAA<waa. The strength of this selection is a function of the differences among the three fitness values. Selection of this type (directional) generally leads to fixation of one of the two alleles.
Selection against the a allele occurs when waa<wAa and/or waa<wAA.
Heterozygote advantage occurs when wAA<wAa>waa. In this case both alleles are preserved in the population. Note that allelic frequencies do not change when wAA=waa.
Heterozygotes can also be selected against, when wAA>wAa<waa. Note that allelic frequencies do not change when wAA=waa.
The population represented to the right possesses 5000 randomly breeding individuals. This large size is chosen to minimize the effects of drift so that the effect of selection would be clear. The background mortality rate for this simulation is 0.1. In other words, 10% of the individuals will die each generation in addition to the mortality induced through the fitness values chosen.