Different alleles of the MC1R gene have been associated with hair/coat color variation in many different mammals, including mice, jaguars, cows, and humans. In humans, specific mutations of the MC1R gene are associated with red hair. Using the concept of homology, explain why the same gene would affect similar traits in multiple organisms.

• A. Because the MC1R gene affects hair/fur color variation, you can expect that the gene will change often as organisms adapt to different environments.
• B. Since hair color is not a trait that confers a survival or reproductive advantage in humans, the MC1R gene can be considered an example of a vestigial trait.
• C. The MC1R gene was likely involved in coat color determination in the common ancestor of these organisms and maintains that role in each of these lineages.
• D. It is likely that the MC1R gene evolved to control hair/fur color separately in each lineage, as the presence of hair/fur is a homologous trait in mammals.

Answer: (C)