Varieties of purebred dogs are maintain by?

Varieties of purebred dogs are maintained by selective breeding.

Selective breeding is the process of breeding animals with specific traits in order to produce offspring with those same traits. In the case of purebred dogs, breeders select for specific physical characteristics, such as size, coat color, and temperament.

Selective breeding is also used to maintain and improve the health of purebred dogs. By selecting for dogs with good health and reproductive fitness, breeders can help to eliminate genetic diseases and disorders.

The process of selective breeding for purebred dogs has been going on for centuries, and it has resulted in the development of many different breeds, each with its own unique characteristics. Today, there are hundreds of recognized breeds of purebred dogs, and each breed has its own club or organization that sets standards for the breed and promotes its responsible breeding.