Question

Tail length in salamanders is controlled by a sex-linked gene. The heterozygous condition gives tails intermediate in length, whereas long and short tailed individuals are homozygous.

a. What phenotypic ratio is expected from a cross of a long-tailed male and an intermediate-tailed female?

b. In addition to sex-linked inheritance, what kind of inheritance is illustrated here? Is it incomplete dominance or codominance? Explain.

Answer 1

Let XL encodes long tail. And Xl encodes short tail.

A) Parents: XL Y ( long tailed male) × XL Xl ( intermediate tail female)

Punnet square:

Gametes	XL	Xl
XL	XL XL ( long tailed daughter)	XL Xl ( intermediate tailed daughter)
Y	XL Y ( Long tailed son)	Xl Y ( short tailed son)

Phenotypic ratio: Long tailed (2): Intermediate tailed (1) : short tailed (1)

-----

B) This is the case of incomplet type inheritance. Because there are found incomplete dominance of XL allele over Xl allele. Because the XL Xl genotype encodes intermediate tailed inheritance.

----.

Please rate high.