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North American wolves can have gray fur or black fur, determined by a single gene with two alleles. The information below shows the fur color of parents and offspring in four wolf families:

[tex]
\[
\begin{array}{|c|c|c|}
\hline
\text{Family} & \text{Parent Phenotype Cross} & \text{Phenotype Ratio in Offspring} \\
\hline
1 & \text{gray fur} \times \text{black fur} & 3 \text{ gray fur} : 2 \text{ black fur} \\
\hline
2 & \text{gray fur} \times \text{black fur} & 0 \text{ gray fur} : 5 \text{ black fur} \\
\hline
3 & \text{black fur} \times \text{black fur} & 1 \text{ gray fur} : 3 \text{ black fur} \\
\hline
4 & \text{gray fur} \times \text{gray fur} & 4 \text{ gray fur} : 0 \text{ black fur} \\
\hline
\end{array}
\]
[/tex]

a. Identify the most likely inheritance pattern (dominant-recessive, incomplete dominance, codominance, sex-linked, polygenic, multiple alleles) for fur color in wolves.

b. Explain how the information about family 3 supports the inheritance pattern you identified in part (a).

In both family 1 and family 2, one parent wolf has gray fur and one parent wolf has black fur. The phenotype ratio in the offspring is very different in the two families, however.

c. Using the allele symbols [tex]$N$[/tex] and [tex]$n$[/tex], identify the most likely genotypes of the parent wolves in family 1 and the most likely genotypes of the parent wolves in family 2. Be sure to identify which genotype is for the parent with gray fur and which genotype is for the parent with black fur in each family.

d. Draw two Punnett squares to support your answer to part (c).

Answer :

Sure, let's go through the solution step-by-step:

a. Identify the most likely inheritance pattern:
The phenotypic ratios suggest a dominant-recessive inheritance pattern. In such patterns, one allele is dominant over the other. Here, gray fur is likely to be the dominant trait over black fur.

b. How the information about family 3 supports the inheritance pattern:
In family 3, two black fur parents produce offspring with a 1 gray fur to 3 black fur ratio. This indicates that both black-fur parents could be carriers (heterozygous) for the gray fur allele, suggesting a recessive expression of the black fur trait. The appearance of a gray offspring implies that each parent carries one recessive and one dominant allele.

c. Genotypes for family 1 and family 2 using allele symbols (N for gray, n for black):
- Family 1: The cross between a gray fur and a black fur wolf results in a 3 gray to 2 black fur ratio.
- Gray parent genotype: Nn (heterozygous), as it produces both gray and black offspring.
- Black parent genotype: nn (homozygous recessive), since it can only pass on the recessive black allele.

- Family 2: The cross between a gray fur and a black fur wolf results in all black offspring (0 gray, 5 black).
- Gray parent genotype: nn (homozygous recessive), indicating that it actually has black fur since black is recessive.
- Black parent genotype: nn (homozygous recessive), as they also produce all black offspring.

d. Punnett squares to support the answers:

- Punnett Square for Family 1:
```
| | n | n |
|-------|-----|-----|
| N | Nn | Nn |
| n | nn | nn |
```
The gray parent (Nn) can give either N or n, while the black parent (nn) can only give n alleles. The possible offspring genotypes are Nn (gray) and nn (black), which align with the observed 3:2 phenotype ratio.

- Punnett Square for Family 2:
```
| | n | n |
|-------|-----|-----|
| n | nn | nn |
| n | nn | nn |
```
Here, both parents are nn (homozygous recessive), so all offspring will be nn (black), explaining the 0 gray to 5 black ratio.

These Punnett squares show the possible genetic combinations from the parental genotypes and help visualize why each family displays the phenotypic ratios observed.

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Rewritten by : Barada