Keep relationships being modeled in mind. Efficiency of selection expressed as the number of generations necessary to effect a change in gene or genotype frequency. Plot of delta q across gene frequencies. Selection against recessives always proceeds very slowly, and any level of survival among recessive homozygotes will slow selection even more. Effect on natural selection is only near total elimination in geological time .
Rare traits tend to be lost through drift, but to reappear through recurring mutations.
Haldane first produced this model of selection in 1924. The model allows one to understand how rapidly selection can drive evolution. Thus, another perspective of gene changes we have modeled involves the rapidity of change in gene frequencies when q is relatively large. We will describe major aspects of changes in gene frequencies for each of these models. The formulas and models will not be considered here.