Segregating distortion is a phenomenon in which heterozygous genotypes do not pr
ID: 207451 • Letter: S
Question
Segregating distortion is a phenomenon in which heterozygous genotypes do not produce the equal frequencies of complementary functional gametes expected from Mendelian segregation. A random-mating population has genotype frequencies of A1A1, A1A2, and A2A2 given by p2, 2pq, and q2, respectively. A1 is a segregation distorter such that A1A2 heterozygotes produce a ratio k:(1-k) of functional A1-bearing and A2-bearing gametes (k>0.5).
A.What are the expected allele frequencies among gametes?
B.What are the expected genotype frequencies among zygotes in the next generation?
Explanation / Answer
The following formula can be used to calculate the allele frequency
For three alleles (A, B, and C) with frequencies p, q, and
r: (p + q + r)2 = p2(AA) + 2pq(AB) + q2(BB) + 2pr(AC) +
2qr(BC) + r2(CC)
For four alleles (A, B, C, and D) with frequencies p, q, r,
and s: (p + q + r + s)2 = p2(AA) + 2pq(AB) + q2 (BB) + 2pr(AC) +
2qr(BC) + r2 (CC) + 2ps(AD) + 2qs(BD) + 2rs(CD) + s2
(DD)