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. 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) BB+ - burnsi

b⁺b⁺ - pipiens

(c) With one degree of freedom, the chi-square value is greater than 2.706 for a probability value of less than 0.1, so the deviation between observed and expected was not likely to occur by chance