Inzuchtgrades

Inzuchtgrad (English: coefficient of inbreeding) is a genetic measure that quantifies the probability that two alleles at a given locus in an individual are identical by descent from a common ancestor. It is used to describe the degree of relatedness produced by mating between relatives and is commonly denoted by F. Higher Inzuchtgrade indicate greater homozygosity and a greater chance that recessive alleles will be expressed.

Calculation of the Inzuchtgrad can be done from pedigrees using formulas derived by Sewall Wright, which account for the path(s) of descent from common ancestors. Modern approaches also estimate inbreeding from molecular data, such as runs of homozygosity (ROH) or genomic relationship matrices, providing direct measures that do not rely on complete pedigrees.

The concept is important in animal and plant breeding, conservation genetics, and human population studies. Elevated Inzuchtgrade are associated with inbreeding depression, a reduction in fitness-related traits (e.g., fertility, survival, disease resistance) caused by increased expression of deleterious recessive alleles and loss of heterozygote advantage. Management strategies to control Inzuchtgrade include maintaining effective population size, introducing unrelated individuals (outcrossing or genetic rescue), and monitoring genetic diversity over time.

Limitations of the measure include dependence on pedigree completeness for pedigree-based estimates and sensitivity to marker density and population structure for genomic estimates. Interpreting Inzuchtgrade requires context about population history, selection pressures, and breeding objectives.