The Coefficient of Relatedness (r) measures the genetic relationship between two individuals. It is commonly used in genetics, anthropology, and evolutionary biology to determine the probability of sharing alleles due to common ancestry. This concept helps in understanding kinship, inheritance, and even altruistic behaviors in social species.
Formula
The formula to calculate the coefficient of relatedness is:
r = Σ(0.5ⁿ)
Where:
- n = Number of generations separating two individuals
- Σ = Summation over all common ancestors
How to Use
- Enter the number of generations (n) separating the individuals.
- Click “Calculate” to get the coefficient of relatedness (r).
- The result will display the probability of shared genetic material.
Example
If two individuals are separated by 3 generations, then:
r = (0.5³) = 0.125
This means they share 12.5% of their genetic material.
FAQs
1. What is the coefficient of relatedness?
It is a measure of how genetically related two individuals are, based on shared ancestry.
2. Why is the coefficient of relatedness important?
It helps in genetics, evolutionary studies, and understanding inheritance patterns.
3. How is relatedness between siblings calculated?
Full siblings have r = 0.5 since they share 50% of their genes from each parent.
4. What is the coefficient of relatedness between parent and child?
It is 0.5 because a child inherits half of their genes from each parent.
5. How related are first cousins?
First cousins have an r = 0.125 (12.5%), as they share one common grandparent.
6. What is the coefficient for identical twins?
Identical twins have r = 1, as they share 100% of their genetic material.
7. Can the coefficient of relatedness be greater than 1?
No, it ranges between 0 (no relation) and 1 (identical genetic makeup).
8. How is r used in evolutionary biology?
It helps explain altruistic behavior, as organisms may help relatives to ensure genetic survival.
9. What is the relatedness between uncle and niece/nephew?
It is r = 0.25 (25%), as they share genes through a common parent.
10. How is relatedness calculated in pedigree analysis?
Pedigree charts help track ancestry, applying the formula r = Σ(0.5ⁿ) for each ancestor.
11. How does inbreeding affect relatedness?
Inbreeding increases relatedness, leading to a higher probability of genetic disorders.
12. What is the coefficient between grandparent and grandchild?
It is r = 0.25 (25%), since one generation separates them.
13. Is relatedness always symmetric?
Yes, if person A is related to person B by r, then B is equally related to A.
14. How does relatedness impact kin selection?
Higher relatedness encourages altruistic behavior to support the survival of shared genes.
15. How is relatedness affected in large populations?
As populations grow, relatedness decreases among distant individuals.
16. Can relatedness be calculated for non-humans?
Yes, the same formula applies to animals, plants, and even microbial populations.
17. How does adoption affect genetic relatedness?
Adopted individuals have r = 0 with their adoptive family but may still share social bonds.
18. Can r be used in forensic analysis?
Yes, relatedness calculations help in identifying biological relationships in legal cases.
19. How does mutation impact relatedness?
Mutations introduce genetic variations but do not significantly alter r in close relatives.
20. Is there a difference between genetic and social relatedness?
Yes, genetic relatedness is based on DNA, while social relatedness is based on upbringing and relationships.
Conclusion
The Coefficient of Relatedness Calculator provides an easy way to determine genetic connections between individuals. Whether in genetics, anthropology, or social sciences, understanding relatedness helps in studying inheritance, kinship, and evolutionary behavior. Use this tool for quick and accurate calculations.