Coefficient of inbreeding
The coefficient of inbreeding (COI) is a number measuring how
Calculation
An individual is said to be inbred if there is a loop in its
and is the coefficient of inbreeding of the common ancestor of X's parents.
To give an example, consider the following pedigree.
In this pedigree chart, G is the progeny of C and F, and C is the biological
Because the common ancestors of the parents (A and B) are not inbred themselves, . Therefore the coefficient of inbreeding of individual G is .
If the parents of an individual are not inbred themselves, the coefficient of inbreeding of the individual is one-half the coefficient of relationship between the parents. This can be verified in the previous example, as 12.5% is one-half of 25%, the coefficient of relationship between an uncle and a niece.
Table of coefficients of inbreeding
Generations | Coefficient of inbreeding (f) |
---|---|
1 | 25% |
2 | 37.5% |
3 | 50% |
4 | 59.375% |
5 | 67.1875% |
6 | 73.4375% |
7 | 78.5156% |
8 | 82.6172% |
9 | 85.9375% |
10 | 88.623% |
11 | 90.7959% |
12 | 92.5537% |
13 | 93.9758% |
14 | 95.1263% |
15 | 96.0571% |
16 | 96.8102% |
17 | 97.4194% |
18 | 97.9122% |
19 | 98.3109% |
20 | 98.6335%A |
^A At this point the individuals are considered to be part of an inbred strain, and each individual can effectively be considered to be clones.
References
- ^ doi:10.1086/279872
- ^ Redei, George P. (2004), Encyclopedic Dictionary of Genetics, Genomics and Proteomics, John Wiley and Sons, Inc.
- ^ Charlesworth, Deborah (2005), "Inbreeding", Encyclopedia of Life Sciences, John Wiley and Sons, Inc.
- ^ Falconer, D.S.; Mackay, T.F.C. (1996), Introduction to Quantitative Genetics (4 ed.), Longman
- ^ Carol Beuchat (June 4, 2015). "COI FAQS: Understanding the Coefficient of Inbreeding". The Institute of Canine Biology. Retrieved Feb 5, 2024.
- ^ Schonewald-Cox, C.M., S.M. Chambers, B. MacBryde, and L. Thomas (eds.). 1983. Genetics and Conservation. Benjamin/Cummings, Menlo Park, Calif.