Robert Bakewell was a very successful breeder of commercial livestock in the 18th century.
His work was based on the traditional method of visual appraisal of the animals that he selected.
Two or more genes may be associated with a specific locus and therefore with a specific trait.
Typically, one of the alleles will be expressed to the exclusion of the other allele, in which case the two alleles are referred to as dominant and recessive, respectively.
Complicating the implementation of a breeding program is the number of generations needed to reach the initial goals.
Ultimately, breeding goals are dictated by market demand; however, it is not easy to predict what consumers will want several years in advance.
Genetic variation is necessary in order to make progress in breeding successive generations.
Each gene, which is the basic unit of heredity, occupies a specific location, or locus, on a chromosome.