ANATOMY

Detailed explanation-1: -Why did the MCr1 gene mutation become prevalent in the rock pocket mouse populations? The mutation produced dark colored mice who were better able to survive and reproduce in basalt environments.

Detailed explanation-2: -The mutated version of the Mc1r gene results in an increase in the production of eumelanin by melanocytes, resulting in the dark coat-color phenotype.

Detailed explanation-3: -The dark coloration in the rock pocket mouse did not arise because there was a lava flow. Rather, a random mutation proved adaptive to the mice living in areas of dark-colored volcanic rock.

Detailed explanation-4: -Why do dark-colored rock pocket mice on dark lava flows have white bellies? There is no selection for dark bellies by visual predators. There is a reproductive advantage to having a dark belly. White bellies are an important part of camouflage.

Detailed explanation-5: -Since the four missense mutations in the Mc1r gene change the amino acid sequence of the MC1R protein, the protein will not function properly, as a protein’s function is determined by its structure.