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| Modern Genetic Analysis Chapter 6. Gene Interaction Gene Interaction Leads to Modified Dihybrid Ratios Figure 6-15. Temperature-sensitive alleles of the C gene result in similar phenotypes in several different mammals. These alleles result in very much reduced or no synthesis of the dark pigment melanin in the skin covering warmer parts of the body. At lower temperatures, such as those found at the body extremities, melanin is synthesized, producing darker snout, ears, tail, and feet. (a) Himalayan mouse. (b) Siamese cat. Furthermore, Himalayan rabbits (not shown) are often sold as pets. All three are of genotype ch/ch. (Part a, Anthony Griffiths; part b, Walter Chandoha.)

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