Question

In rabbits, an allelic series helps to determine coat color: C (full color), ch (chinchilla, gray color), ch (Himalayan, white with black extremities), and c (albino, all white). The C allele is dominant over all others, cch is dominant over ch and c, ch is dominant over c, and c is recessive to all the other alleles. This dominance hierarchy can be summarized as C>cchchc The rabbits in the following list are crossed and produce the progeny shown. Give the genotypes of the parents for each cross.

(a) full color x albinoe full color, % albino
(b) himalayan x albino himalayan, V2 albino
(c) full color × albino ½ full color, ½ chinchilla
(d) full color x himalayan full color, '4 himalayan, '4 albino
(e) full color x full color full color, ' albino

Answer 1

(a)

Since the full color rabbit is crossed with an albino rabbit, we can determine that the full color rabbit has a genotype of Cc (since it produces 50% C and 50% c gametes), and the albino rabbit has a genotype of cc (since it can only produce c gametes).

Therefore, the genotypes of the parents are Cc x cc.

(b)

Since the Himalayan rabbit is crossed with an albino rabbit, we can determine that the Himalayan rabbit has a genotype of cchc (since it can only produce cch and c gametes), and the albino rabbit has a genotype of cc (since it can only produce c gametes).

Therefore, the genotypes of the parents are cchc x cc.

(c)

Since the full color rabbit is crossed with an albino rabbit, we can determine that the full color rabbit has a genotype of Cc (since it produces 50% C and 50% c gametes), and the albino rabbit has a genotype of cc (since it can only produce c gametes).

The resulting progeny are 50% full color (C_) and 50% chinchilla (cch_).

Therefore, the genotypes of the parents are Cc x cc.

(d)

Since the full color rabbit is crossed with a Himalayan rabbit, we can determine that the full color rabbit has a genotype of Cc (since it produces 50% C and 50% c gametes), and the Himalayan rabbit has a genotype of cchc (since it can only produce cch and c gametes).

The resulting progeny are 50% full color (C_) and 50% Himalayan (cchc).

Therefore, the genotypes of the parents are Cc x cchc.

(e)

Since both parents are full color rabbits, they must both have a genotype of Cc (since they produce 25% CC, 50% Cc, and 25% cc gametes).

Therefore, the genotypes of the parents are Cc x Cc.