In an isolated population of 90 desert bighorn sheep, a mutant recessive allele
ID: 32249 • Letter: I
Question
In an isolated population of 90 desert bighorn sheep, a mutant recessive allele c has been found to cause curled coats in both males and females. The normal dominant allele C produces straight coats. A biologist studying these sheep counts 3 with curled coats and takes blood samples for DNA marker analysis, which reveals that 13 of the straight-coated sheep are carriers of the c allele.
To calculate inbreeding coefficient from population data, use the following equation:
F = (He - Ho)/He
He is the number of heterozygotes expected in the population--determined by the calculation 2pq
Explanation / Answer
Answer) Here we have mutant recessive c allele for curled coats and dominant C allele for the straight coat.
there are total 90 sheep, out of which 3 sheep are having curled coat (genotype cc) and 13 career sheep of c are having the straight coat (genotype Cc). therefore, rest 74 sheep are having the straight coat (genotype CC).
observed number of heterozygotes would be (Ho) = 13x2/90x2 = 0.144
now, the frequency of recessive c allele would be (q)= 6+13/180 = 0.105
where 6 alleles are added from the curled coat sheep and 13 alleles are added from the career sheep.
as we know p+q = 1, so p = 1-q
or p = 1-0.105 = 0.895
now, expected number of heterozygotes would be (He) = 2pq = 2x0.105x0.895 = 0.187
using the following equation for calculation of inbreeding coefficient;
F = (He - Ho)/He
F = (0.187-0.144)/0.187 = 0.229 (~0.23)
therefore, the inbreeding coefficient in the given population would be 0.23.
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