Table 2

Genotype–phenotype associations between Mclr alleles and coat color in C. intermedius from the Pinacate site

GenotypeMouse phenotype
  • The dark Mclr allele, D, has the following amino acids: Arg-18, Arg-109, Arg-160, and Gln-233. The light allele, d, has the following amino acids: Cys-18, Trp-109, Trp-160, and His-233. A Fisher's exact test comparing light homozygotes with dark homozygotes and heterozygotes is highly significant (i.e., 2 × 2 table with row entries 12 and 0, 0 and 17; P < 0.0001). Observed numbers of heterozygotes are slightly lower than expected under Hardy–Weinberg equilibrium (χ2 = 4.89, P = 0.087), consistent with disruptive selection across the two habitats.