March 09, 2005

Phenotype & Genotype

The dog’s genetic makeup is manifested by its appearance (phenotype) and its genome (genotype). The phenotype is visible or measurable: a dog’s color, coat type, bone structure, height, head shape, etc. all comprise the phenotype. The genotype is hidden.

Because some genes are dominant and others are recessive, the genotype is not necessarily represented by the phenotype. In other words, even though you can see a black coat, the dog may be carrying the gene for a red coat, and may produce red puppies.

In assessing a dog’s potential as a parent, a breeder takes account of how they look, the phenotype – whether they are true to type.

To assess the genotype it is necessary to look at the dog’s family. Knowledge of pedigrees including the dogs’ titles, show ratings, and hip ratings, along with littermates, parents, grandparents, offspring and their ratings, allows the breeder to make an informed guess at the genotype. Software like Breed Mate and Breeders Assistant makes this more manageable.

The Dog Genome Project aims to produce a map of all the chromosomes in dogs, which can be used to locate the genes causing disease and those controlling appearance and behavior. Having the map will make assessing genotype a more reliable process.

NorthWest K9 Reading Room has an excellent reading list on canine genetics.

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