General selection model
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The General Selection Model (GSM) is a model of population genetics that describes how a population's genotype will change when acted upon by natural selection.
[edit] Equation
The General Selection Model is encapsulated by the equation:
![\Delta q=\frac{pq \big[q(W_2-W_1) + p(W_1 - W_0)\big ]}{\overline{W}}](../../../math/6/7/5/6753bf1ce1f1379b6da4e6d46348b1c5.png)
- where:
-
- p is the frequency of the dominant gene
- q is the frequency of the recessive gene
- Δq is the rate of evolutionary change of the frequency of the recessive gene
- W0,W1,W2 are the relative fitnesses of homozygous dominant, heterozygous, and homozygous recessive genotypes respectively.
is the mean population relative fitness.
In words:
The product of the relative frequencies, pq , is a measure of the genetic variance. The quantity pq is maximized when there is an equal frequency of each gene, when p = q. In the GSM, the rate of change ΔQ is proportional to the genetic variation.
The mean population fitness is a measure of the overall fitness of the population. In the GSM, the rate of change ΔQ is inversely proportional to the mean fitness -- i.e. when the population is maximally fit, no further change can occur.
The remainder of the equation, ![\big[q(W_2-W_1) + p(W_1 - W_0)\big ]](../../../math/2/5/a/25a35c3f330bd7a23f5cfad411eb170e.png)
, refers to the mean effect of an allele substitution. In essence, this term quantifies what effect genetic changes will have on fitness.
