In a polar owl, feathered legs dominate bare. This trait is controlled by autosomal genes. Long claws are a dominant trait that is determined by a gene localized in the Z chromosome.
A female with feathered legs was crossed with a male with long claws and feathered legs. As a result, offspring with a different combination of all phenotypic characters were obtained. What is the probability (%) of the appearance among the offspring of a male with bare legs and short claws?
We introduce the notation of genes:
A – feathered legs;
a – bare legs;
B – long claws;
b – short claws.
– In birds, the heterogametic sex is female, therefore, for a female with feathered legs, the A – Z – W phenotypic radical can be recorded, and for a male with feathered legs and long claws: A – ZBZ–.
In the offspring, various combinations of phenotypic characters were observed. This means that the descendants had feathered (A–) and bare legs (aa), long (ZBW for females, ZBZ for males) and short claws (ZbW for females, ZbZb for males).
Based on this, we supplement the genotypes of the parental individuals with the missing recessive genes. Thus, the female genotype is AaZbW, the male is AaZBzb.
So, the probability of occurrence among the offspring of a male with bare legs and short claws is 1/16 × 100% = 6.25%.
Answer: the probability of a male with bare legs and short claws is 6.25%.
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