breed

A breed is a population within a species that has been shaped by human selection for particular heritable traits and that shows a relatively uniform set of characteristics across individuals. In animals, a breed is defined by a recognized combination of appearance, behavior, and lineage, often tracing back through documented pedigrees. In horticulture, breeders likewise select for stable traits, though the term is used less formally than in animal breeding.

Breeds arise through selective breeding, pairing individuals with desirable traits to increase their frequency in future generations. Over many generations, a breed becomes well standardized. Breeders manage genetic diversity to avoid inbreeding depression, balancing purity with health and vigor. Certain populations may develop distinct regional variants that are later recognized as separate breeds.

Breed identity is typically codified by breed standards and pedigrees maintained by registries or associations. These standards describe the ideal specimen for a breed, including size, coat, color, structure, and temperament, and provide criteria for judging and registration. Examples of well-known dog breeds include the Labrador Retriever and German Shepherd, while cattle may include the Holstein and Angus, and sheep the Merino and Suffolk.

Distinctions exist between breed and related terms. A purebred is produced from parents of the same breed; crossbreeding yields mixed traits. In plants, the analogous concepts are cultivars or varieties. Ongoing breeding programs aim to improve productivity, health, adaptability, or appearance while maintaining genetic health and diversity.