Blackwell Publishing

Random events in population genetics - How do we calculate the march to homozygosity?


Predicting future generations

Now we can write the frequency of homozygotes in the next generation in terms of the frequency of homozygotes in the parental generation:

f' = 1/2N + 1-(1/2N)f

Since heterozygosity (H) = 1 - f , it can be shown to decrease at the following rate:

H' = 1 - (1/2N)H

This means that heterozygosity decreases at a rate of 1/(2N) per generation until it is zero. The population size, N , governs the influence of genetic drift: if N is small, the march to homozygosity is rapid, if it is infinitely large we have the Hardy-Weinberg equilibrium.

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