Clouded leopards are a medium-sized, endangered species of cat, living in the very wet cloud forests of Central America. Assume that the normal spots (XN) are a dominant, sex-linked trait and that dark spots are the recessive counterpart.
Suppose, as a Conservation Biologist, you are involved in a clouded leopard breeding program. One year you cross a male with dark spots and a female with normal spots. She has four cubs and, conveniently, two are male and two female. One male and one female cub have normal spots and one each have dark spots.
What is the genotype of the mother for this sex-linked trait?
a
homozygous
b
impossible to determine with given information
c
heterozygous
d
purebred for normal spots
In this scenario, the male cub with dark spots must have inherited the recessive allele (Xn) from the mother since the trait is sex-linked and the mother is female. Since one of the female cubs also has dark spots, it must have inherited the recessive allele from the mother as well. However, the other female cub and one of the male cubs have normal spots, indicating that they inherited the dominant allele (XN) from the mother.
Based on this information, we can conclude that the mother is heterozygous for this sex-linked trait (XN Xn). Therefore, the correct answer is c) heterozygous.