Figure 24.2
The distribution of pocket-mouse coat colors in several Arizona populations is associated with substrate color. Some populations live on light-colored granite substrate, and others live on dark volcanic rock. In Figure 24.2, chart A shows the frequency of the melanic (dark) coat phenotype across six populations. Populations C, D, and E live on dark volcanic rock; populations A, B, and F live on light-colored granite. Chart B shows the frequency of the Melanocortin-1 receptor (Mc1r) allele across these populations. The Mc1r alleles, D and d, differ by four amino acids; mice with DD and Dd genotypes have dark coats, whereas mice with dd genotype are light colored. Which of the following statements best interprets the results shown in charts A and B?
A) Frequency of the D allele is closely associated with the melanic phenotype, but is unrelated to the presence of dark substrate color.
B) Frequency of the D allele is not associated with the melanic phenotype, but is associated with the presence of dark substrate color.
C) Frequency of the D allele is closely associated with both the melanic phenotype and the presence of dark substrate color.
D) Frequency of the D allele is associated neither with the melanic phenotype nor with the presence of dark substrate color.
E) Frequency of the D allele does not vary.
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