Coat color variation in mammals has long served as one of most fruitful examples

Question

Coat color variation in mammals has long served as one of most fruitful examples of genetics, with over 120 loci and 800 alleles affecting coat color described in mice alone. For this question, we will consider the W adaptive transition from dark to light coat coloration that accompanied the movement of mice from the B forest to the beach among two species of mouse. The ancestral species was darkly colored while the derived | species was more lightly colored, consistent with the selective pressures that come when you arc a dark mouse living on lightly Colored sand. The phenotypes of the two parental species. along with a representative Fl individual and representatives from the F2 generation arc shown below. Assume that you only had the data shown above tor the parental lines (ancestral and derived species) and the Fl. What inferences would you make about the mode of inheritance for the overall (whole body) coat color? Support your inferences clearly (do not just write the mode of inheritance, explain why you arrived at that answer). 2.2 (10) With the added data from the F2, what inferences might you make about the mode of inheritance for the overall (whole body) coat color? Support your inferences clearly (do not just write the mode of inheritance, explain why you arrived at that answer).

Explanation / Answer

ANSWER:

1) Considering only the above data given we could say that the mode of inheritance would be Mendelian Inheritance. The condition over here is recognized by the F1 individual who is a dominant dark colored individual but a heterozygote. When this F1 heterozygote is again crossed with itself to yield F2 generation, we get a distribution in which most of the individuals are lighter than the ancestral dark with a single progeny as light as the derived species, i.e. 9:3:3:1, though all the 16 phenotypes are not shown here.

2) With the added data from F2 we can say that the species have incomplete dominance . This condition can be recognised with the heterozygotes having an intermediate color as compared to the parental phenotypes , also with the presence of the derived light colored body , showing that none of the phenotypes are completely dominant over the other.

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