Question

A breed of dog (Mexican hairless) is completely hairless. There hairless dogs have heterozygous genotype "Hh". In contrast, normal, hairy dogs have the homozygous recessive genotype "hh". Puppy offspring that have the "HH" phenotype are aborted in utero, and still born. Matings between hairless dogs typically produce 10 offsprings. Given this information, how many hairless vs. hairy puppies would you expect in a typical mating between two hairless dogs.

Answer 1

Answer: Genotype: Hh;   phenotype: Hairless dogs

Genotype: hh ; Phenotype: Hairy dogs.

Genotype: HH; aborted in utero, still born.

If the cross is between two hairless dogs then the cross would be depicted as follows

gamates	H	h
H	HH Will not survive	Hh Hairless dogs
h	Hh Hairless dogs	hh hairy dogs

The percentage of hairless dogs would be 50 %

The percentage of hairy dogs would be 25%

And 25 % of dogs with the genotype HH will not survive.

As given in the question, the matings between two hairless dogs will produce 10 offspring; in that case the percentage of different phenotypes will remain the same. The number of hairless dogs would be approximately 5 (considering the percentage) and the number of hairy dogs would be 2/3 out of 10

(Note: 2/3 dogs with HH genotype will not survive)