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Wright's Inbreeding Coefficient Formula:
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Wright's inbreeding coefficient (F) measures the probability that two alleles at any locus in an individual are identical by descent. It quantifies the degree of inbreeding in a population or pedigree, ranging from 0 (no inbreeding) to 1 (complete inbreeding).
The calculator uses Wright's formula:
Where:
Explanation: The formula calculates the probability that two alleles are identical by descent based on the path through a common ancestor, with the (1/2)^(n+1) term representing the genetic contribution decreasing with each generation.
Details: Calculating inbreeding coefficients is crucial in population genetics, animal breeding, and conservation biology to manage genetic diversity, avoid inbreeding depression, and maintain healthy populations.
Tips: Enter the number of generations to the common ancestor (must be ≥1) and the inbreeding coefficient of that ancestor (between 0-1). For multiple paths, calculate each path separately and sum the results.
Q1: What does an inbreeding coefficient of 0 mean?
A: An F value of 0 indicates no inbreeding - the individual has no ancestors in common on both sides of their pedigree.
Q2: What is considered a high inbreeding coefficient?
A: Values above 0.1 are generally considered high, with F > 0.25 indicating close inbreeding (e.g., sibling mating or parent-offspring mating).
Q3: How do I calculate F for multiple paths?
A: Calculate F for each path to each common ancestor separately using the formula, then sum all the values to get the total inbreeding coefficient.
Q4: Why do we add 1 to FA in the formula?
A: The (1 + FA) term accounts for the possibility that the common ancestor itself may be inbred, which increases the probability of identical alleles.
Q5: Who developed this coefficient?
A: Sewall Wright, an American geneticist, developed this coefficient in the early 20th century as part of his work on population genetics and evolutionary theory.