The most likely genetic model for these results is that of a

The most likely genetic model for these results is that of a single gene locus with two codominant alleles.
Under such a model, we would expect a 1:2:1 ratio in F2.
Do the data support a codominance model of inheritance for this feather phenotype? Follow the four-step process in your answer.

The Frizzle fowl is a striking variety of chicken with curled feathers. In a 1930 experiment, Launder and Dunn crossed Frizzle fowls with a Leghorn variety exhibiting straight feathers. The first generation (F1) produced all slightly frizzled chicks. When the F1 was interbred, the following characteristics were observed in F2: The most likely genetic model for these results is that of a single gene locus with two codominant alleles. Under such a model, we would expect a 1:2:1 ratio in F2. Do the data support a codominance model of inheritance for this feather phenotype? Follow the four-step process in your answer. Step 1: STATE: Do the data support a codominant alleles genetic model with a 1:2:1 ratio? FORMULATE: What are the null and alternative hypotheses? Use p1 for pfrizzled, p2 for pslight friz and p3 for pstraight. A H 0: p1 = 0.247, p2 = 0.538, p3 = 0.215, vs. Ha: H0 is not true. B H 0: p1 = 1/4, p2 = 2/4, p3 = 1/4, vs. Ha: H0 is not true. C H 0: p1 = 1/4, p2 = 2/4, p3 = 1/4, vs. Ha: p1 = p2 =, p3. D H 0: p1 = 1/4, p2 = 2/4, p3 = 1/4, vs. Ha: p1 ? 1/4 p2 ? 2/4 p3 ? 1/4. Step 2: SOLVE: Are the conditions for a chi-square test satisfied? No Yes Step 3: SOLVE (continued): Give the chi-square statistic and use Table D to find the P-value. A ? 2 = 0.776, P > 0.25. B ? 2 = 0.776, P > 0.5. C ? 2 = 0.720, P > 0.25. D ? 2 = 0.720, P > 0.5.

Solution

D H 0: p1 = 1/4, p2 = 2/4, p3 = 1/4, vs. Ha: p1 1/4 p2 2/4 p3 1/4.

Yes