J A Moore investigated the inheritance of spotting patterns

J. A. Moore investigated the inheritance of spotting patterns in leopard frogs (J. A. Moore. 1943. Journal of Heredity 34:3-7). The pipiens phenotype had the normal spots that give leopard frogs their name. In contrast, the burnsi phenotype lacked spots on its back. Moore earned out the following crosses, producing the progeny indicated. Parent phenotypes Progeny phenotypes burnsi X burnsi 42 burnsi, 8 pipiens burnsi X pipiens 25 burnsi, 34 pipiens burnsi X pipiens 194 bumsi, 208 pipiens On the basis of these results, what is the most likely mode of inheritance of the burnsi phenotype? Give the most likely genotypes of the parent in each cross. Use a chi-square test to evaluate the fit of the observed numbers of progeny to the number expected on the basis of your proposed genotypes for each of the three matings shown.

Solution

a. On the basis of the above crosses, the mode of inheritance of burnsi phenotype is
DOMINANT PHENOTYPE.

b. The Genotypes of the parents

Burnsi X Burnsi = Bb X Bb

Burnsi X pipiens = Bb X bb

Burnsi X pipiens = Bb X bb

C.

1.

Null hypothesis: The observed values are not deviating from 3:1 ratio.

Chisquare test:

Category

Burnsi

pipiens

Total

Observed values

42

8

50

Exptected Ratio

3

1

4

Exprected Values

37.5

12.5

Deviation

4.5

-4.5

D^2

20.25

20.25

D^2/E

0.54

1.62

2.16

X^2

2.16

Degrees of freedom

-

1

Inference: The calculated chisquare values is less than the table i.e. 3.84 at 1 DF and 0.05 probability, hence null hypothesis accepted.

2.

Null hypothesis: The observed values are not deviating from 1:1 ratio.

Chisquare test:

Category

Burnsi

pipiens

Total

Observed values

28

34

62

Exptected Ratio

1

1

2

Exprected Values

31

31

Deviation

-3

3

D^2

9

9

D^2/E

0.290323

0.290323

0.580645

X^2

0.580645

Degrees of freedom

-

1

Inference: The calculated chisquare values is less than the table i.e. 3.84 at 1 DF and 0.05 probability, hence null hypothesis accepted.

3.

Null hypothesis: The observed values are not deviating from 1:1 ratio.

Chisquare test:

Category

Burnsi

pipiens

Total

Observed values

194

208

402

Exptected Ratio

1

1

2

Exprected Values

201

201

Deviation

-7

7

D^2

49

49

D^2/E

0.243781

0.243781

0.487562

X^2

0.487562

Degrees of freedom

-

1

Inference: The calculated chisquare values is less than the table i.e. 3.84 at 1 DF and 0.05 probability, hence null hypothesis accepted.

Category	Burnsi	pipiens	Total
Observed values	42	8	50
Exptected Ratio	3	1	4
Exprected Values	37.5	12.5
Deviation	4.5	-4.5
D^2	20.25	20.25
D^2/E	0.54	1.62	2.16
X^2	2.16
Degrees of freedom		-	1