Читать книгу Horse Genetics - Ernest Bailey - Страница 72

The genotype of a red horse will always be e/e. Because the black allele is dominant to the red allele, the genotype for a black horse is not readily apparent from the phenotype. Genotypes E/E and E/e will both have a black phenotype (although horses may actually be bay, black, or buckskin depending on the alleles present at other loci). We know that one allele is E because black is present. Unless we have further genetic information, we cannot know whether the second allele is E or e. By convention, we list the unknown allele as a “–”. A black horse of unknown parentage would be identified by the genotype as “E/–.” When both alleles in a pair are the same (E/E or e/e), the horse is said to be homozygous; when the pair has unlike alleles (E/e), the horse is said to be heterozygous.