Fluctuating Population Size and Genetic Drift
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Revision as of 23:11, 19 September 2018 by Floyd (talk | contribs) (Created page with "In general the variance from a binomial process is <math>\sigma^2 = n p (1-p)</math>, where ''n'' is the number of trials and ''p'' is the probability of one of the two outcom...")
In general the variance from a binomial process is [math]\sigma^2 = n p (1-p)[/math], where n is the number of trials and p is the probability of one of the two outcomes.
The variance for the sampling of two alleles each generation is [math]2N p (1-p)[/math], where N is the diploid population size and p is the allele frequency.
We like to work with allele frequencies rather than allele counts in a population. The variation is scaled by 2N so the underlying standard deviation is a fraction between zero and one.
[math]\frac{\sigma}{2N} = \frac{\sqrt{2N p (1-p)}}{2N}[/math]
[math]\sigma^2 = \left(\frac{\sqrt{2N p (1-p)}}{2N}\right)^2 = \frac{2N p (1-p)}{4N^2} = \frac{p (1-p)}{2N}[/math]
to be continued ...
