Coefficient of relationship

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Coefficient of relationship

The coefficient of relationship is a measure used in genetics to quantify the degree of genetic relatedness or kinship between two individuals. It is defined as the probability that a randomly selected allele from one individual is identical by descent to a randomly selected allele from another individual. This concept is crucial in the study of population genetics, evolutionary biology, and conservation biology.

Calculation

The coefficient of relationship is calculated based on the pedigree of the individuals. It is often denoted by the symbol r. The value of r ranges from 0 to 1, where 0 indicates no genetic relationship and 1 indicates that the individuals are genetically identical.

The coefficient of relationship can be calculated using the following formula:

<math> r = \sum (0.5)^n </math>

where n is the number of generations between the individuals through their most recent common ancestor.

Common Relationships

Here are some common relationships and their corresponding coefficients of relationship:

• Parent and offspring: 0.5
• Full siblings: 0.5
• Half siblings: 0.25
• Grandparent and grandchild: 0.25
• First cousins: 0.125

Applications

The coefficient of relationship is used in various fields:

• In genetic counseling, to assess the risk of inherited disorders.
• In animal breeding, to manage inbreeding and maintain genetic diversity.
• In conservation biology, to design breeding programs for endangered species.
• In evolutionary biology, to study the evolution of social behaviors such as altruism.

Related Concepts

• Inbreeding coefficient: A measure of the probability that an individual has two identical alleles for a given gene due to inheritance from common ancestors.
• Kin selection: A form of natural selection that favors the reproductive success of an organism's relatives, even at a cost to the organism's own survival and reproduction.

See Also

• Genetic distance
• Pedigree chart
• Population genetics
• Heritability