The effects on gene frequencies are deduced from them. Contribution of each genotype to next generation Proportion of each genotype after a selective event n given geno. 0.5 Models of Selection We will address four different possible cases of natural selection. Two of the cases will be addressed in detail. Selection against recessives always proceeds very slowly, and any level of survival among recessive homozygotes will slow selection even more.
Rare traits tend to be lost through drift, but to reappear through recurring mutations.
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. Even the most vigorous selection against recessives will eliminate them from the population with utmost slowness. When the recessive allele becomes rare, selection against them becomes very ineffective, making complete elimination of recessives very difficult. Recurrent mutation may reintroduce dominant allele into population.