Figure 22.2
The distribution of pocket- mouse coat colours in several Arizona populations is associated with substrate colour Some populations live on light- coloured granite substrate, and others live on dark volcanic rock. In Figure 22.2, 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- coloured 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 coloured. 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 both the melanic phenotype and the presence of dark substrate colour.
B) Frequency of the D allele is closely associated with the melanic phenotype, but is unrelated to the presence of dark substrate colour.
C) Frequency of the D allele is not associated with the melanic phenotype, but is associated with the presence of dark substrate colour.
D) Frequency of the D allele is associated neither with the melanic phenotype nor with the presence of dark substrate colour.
E) Frequency of the D allele does not vary.

Question

Figure 22.2
The distribution of pocket- mouse coat colours in several Arizona populations is associated with substrate colour Some populations live on light- coloured granite substrate, and others live on dark volcanic rock. In Figure 22.2, 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- coloured 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 coloured. 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 both the melanic phenotype and the presence of dark substrate colour. 
B) Frequency of the D allele is closely associated with the melanic phenotype, but is unrelated to the presence of dark substrate colour. 
C) Frequency of the D allele is not associated with the melanic phenotype, but is associated with the presence of dark substrate colour. 
D) Frequency of the D allele is associated neither with the melanic phenotype nor with the presence of dark substrate colour. 
E) Frequency of the D allele does not vary.

Quizplus · Accepted Answer

Chart A shows that populations living on dark substrate have a higher frequency of the melanic phenotype compared to populations living on light substrate. Chart B shows that the D allele, which is associated with the melanic phenotype, is also more frequent in populations living on dark substrate. Therefore, the frequency of the D allele is closely associated with both the melanic phenotype and the presence of dark substrate colour.

Figure 22.2 The Distribution of Pocket- Mouse Coat Colours in Several Arizona