Evo-Ed: Integrative Cases in Evolution Education

Cases for Evolution Education

Mouse Fur Color

The beach mouse, (Peromyscus polionotus) is a small rodent found in southeastern United States. It lives primarily in old fields and on white sand beaches. There are several sub-species, each having a somewhat unique fur color ranging from dark brown to very light brown, approaching white.

The geography of fur colors is not random. The darkest colored subspecies tend to live inland while the lighter subspecies live on light sand beaches. This case will examine the evolution of light fur in beach mice from the molecular level up to the population genetics level.

Photograph of an oldfield mouse, Peromyscus polionotus
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Question Guide


In beach mice, lighter fur correlates with lighter surroundings. Research suggests that this camouflage has evolved as a result of selective predation.

Cell Biology

Why do some individuals have dark fur while others have light fur? The MC1R protein can stimulate eumelanin synthesis – if it is working properly that is.

Molecular Genetics

A single nucleotide substitution in the melanocortin 1 receptor gene (MC1R) changes the physical properties of the MC1R transmembrane protein. This impacts on fur color.

Population Genetics

There are strong connections between the MC1R genotypes and coat color phenotypes among beach micepopulations.