# Will Fst (inbreeding coefficient) always be a value close or at 0 in asexual populations?

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.

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.
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.