Inbreeding coefficient and heterozygosity

Under the chosen reference, observed heterozygosity is 25% below expected: HO=(1−F)HE. This is a relative deviation, not the share of individuals known to result from mating between relatives. Population structure or assortative mating can also cause it. F is meaningful only when loci, sample and expectation model are described and HE is not zero. State reference model, loci, population and estimation method. Heterozygote deficiency alone identifies neither individual relatedness nor a unique cause. Deviations can have several biological and technical causes. Null alleles and genotyping quality deserve particular scrutiny.

Yes. If observed heterozygosity HO exceeds reference HE, then F=1−HO/HE is negative. This indicates heterozygote excess relative to the model, not an impossible biological state. Mating patterns, selection, mixture or sampling variation can explain it. Bounds and interpretation depend on whether proportions for one locus, averages across loci or a population-genetic F statistic are used. State reference model, loci, population and estimation method. Heterozygote deficiency alone identifies neither individual relatedness nor a unique cause. Deviations can have several biological and technical causes. Null alleles and genotyping quality deserve particular scrutiny.

A positive value first indicates heterozygote deficiency relative to the chosen expectation. Mating between relatives is one possible cause, but subdivided populations, assortative mating, null alleles, selection and genotyping errors can produce a similar pattern. Demonstrating individual relatedness requires pedigrees or genomic relatedness measures. Interpret the formula as a population-level statistic with an explicit reference. State reference model, loci, population and estimation method. Heterozygote deficiency alone identifies neither individual relatedness nor a unique cause. Deviations can have several biological and technical causes. Null alleles and genotyping quality deserve particular scrutiny.

Reproduce the example calculation: If HO=0.30 and HE=0.40, FIS=1−0.30/0.40=0.25. Inbreeding coefficient and heterozygosity uses FIS = 1 − HO/HE. In plain terms, fIS summarizes relative heterozygote deficiency within a defined subpopulation against its reference expectation. Unit check: FIS, HO and HE are dimensionless proportions; FIS may be negative depending on reference. Compare observed and expected heterozygosity for the same loci and population definition; undefined if HE=0. Values are comparable only when their definitions, denominators and periods match. Record these details next to the result so the reference group is clear. If the direction is implausible, check data preparation and the calculation basis before discussing biological causes.

A key limit of Inbreeding coefficient and heterozygosity is this: Compare observed and expected heterozygosity for the same loci and population definition; undefined if HE=0. Do not use the metric without its reference; it is useful for Comparing observed and expected heterozygosity in a defined population. FIS summarizes relative heterozygote deficiency within a defined subpopulation against its reference expectation. When comparing populations or experiments, check whether definitions, denominators and observation periods match. If the assumption is implausible, the result shows only what the simplified model calculates from its inputs; it is not a reliable estimate for the target population. State this limitation in the report, and do not infer a causal effect from the formula alone.