FST is the average inbreeding coefficient of a total population. The equation is:

$F_{ST} = \frac{Var(S)}{Var(T)} $

$Var(S)$ = variance in the frequency of the allele between different subpopulations, weighted by the sizes of subpopulations

$Var(T)$ = variance of the allelic state in the total population

If $F_{ST}$ equals 0 that means there is no population differentiation and there is no heterozygosity in the population. The ceiling for $F_{ST}$ is one so there is population differentiation and the population is all heterozygotes.

If the population is asexual, meaning they are parthenogenetic, would $F_{ST}$ be at or close to 0? Can this not be assumed?

In the context of this question I am considering the whole genome or just one allele.


It depends on whether mutation exists. Generally mutation is happening in biology, but in its absence, yes it will be at or near zero:

Note that in the absence of any mutation, $F_{ST}$ would be defined but equal to 0, as all the genetic variance is within individuals and none between individuals and subpopulations.

From that paper, see this figure:

Fst across different rates of clonality

So, basically, the exact level of $F_{ST}$ in such cases will be controlled by the mutation rate. That figure shows a value above zero at 100% clonal reproduction because it does have a nonzero mutation rate. There is also nonzero migration between populations, so that will have the effect of reducing $F_{ST}$ somewhat. So here the value is controlled by those 2 factors. Another thing worth noting is that, if there is no initial variation between populations before the split, that will tend to increase $F_{ST}$. So it does matter how much variation exists overall.


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