Enter the variance in the allele frequency among different subpopulations and the variance of the allelic state in the total population into the Calculator. The calculator will evaluate the Fixation Index.

## Fixation Index Formula

FI = S/T

Variables:

• FI is the Fixation Index ()
• S is the variance in the frequency of the allele among different subpopulations.
• T is the variance of the allelic state in the total population

To calculate Fixation Index, divide the variance in frequency of the allele among the subpopulations by the variance of the allelic state in the total population.

## How to Calculate Fixation Index?

The following steps outline how to calculate the Fixation Index.

• First, determine the variance in the frequency of the allele among different subpopulations.
• Next, determine the variance of the allelic state in the total population.
• Next, gather the formula from above = FI = S/T.
• Finally, calculate the Fixation Index.
• After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem :

Use the following variables as an example problem to test your knowledge.

variance in the frequency of the allele among different subpopulations = 0.34

variance of the allelic state in the total population = 0.89

## FAQ

What is the importance of calculating the Fixation Index in population genetics?
The Fixation Index (Fst) is crucial in population genetics as it quantifies the genetic differentiation among subpopulations. By measuring the variance in allele frequencies between populations, researchers can infer the level of genetic diversity and the degree of gene flow, which are essential for understanding evolutionary processes and conservation genetics.

How does gene flow affect the Fixation Index?
Gene flow, or the transfer of alleles between populations, tends to reduce the Fixation Index (Fst) because it increases genetic similarity between populations. High levels of gene flow indicate less genetic differentiation, thus lowering the Fst value, while restricted gene flow results in higher Fst values due to increased genetic variance among populations.

Can the Fixation Index be negative? What does it signify?
Theoretically, the Fixation Index (Fst) should range from 0 to 1, where 0 indicates no genetic differentiation and 1 indicates complete separation. However, negative Fst values can occur due to sampling errors or when the within-population genetic diversity is unexpectedly high. Negative values are generally considered to signify no significant genetic differentiation.

What role does the Fixation Index play in conservation biology?
In conservation biology, the Fixation Index (Fst) is used to assess the genetic diversity within and between populations of endangered species. Understanding genetic differentiation helps in identifying genetically distinct populations, which can be crucial for designing conservation strategies that aim to preserve genetic diversity and reduce the risk of inbreeding and genetic drift in small populations.