How would one explain a testcross involving f1 dihybrid flies in which more parental-type offspring than recombinant-type offspring are produced?

The two genes are linked.

Explanation:

In the given case, the parental offspring are more and the production of recombinant type offspring is less, shows that recombination is not or less witnessed. The mentioned case is only possible when the two genes are linked. That is, the two genes are positioned very close to each other on a chromosome that they get inherited together at the time of meiosis.

the darker peppered moth species were favored due to the fact that the industrial revolution had made all the nearby trees a darker color instead of white.

answerscaffolding proteins;