What is selective breeding (artificial selection)?
One of the earliest forms of biotechnology is the origin of many of the plants and animals we know today. Selective breeding, also known as artificial selection, is a process used by humans to develop new organisms with desirable characteristics. Breeders select two parents who have advantages phenotypic traits reproduce, giving offspring with the desired traits.
Selective breeding can be used to produce tastier fruits and vegetables, more pest resistant crops, and larger animals that can be used for meat. The term “artificial selection” was coined by Charles Darwin in his famous book on evolution, About the origin of species, but the practice itself predates Darwin by thousands of years. As some of the earliest forms of biotechnology, plant and animal breeding has been a common practice since the birth of civilization.
Domestication of dogs
Perhaps the first example of selective breeding is the domestic dog (Canis familiaris). It is not known exactly when and where dogs were first domesticated, but humans have been raising dogs for at least 14,000 years.Scientists believe that the domestic dog evolved from the wild gray wolf (Canis lupus), and through artificial selection, humans have been able to create hundreds of different dog breeds.As people domesticated and raised dogs, they favored specific traits, such as size or intelligence, for certain tasks, such as hunting, herding, or companionship. As a result, many breeds of dogs differ considerably in appearance, a phenomenon unique to the animal world, as different breeds of the same species generally resemble each other. The Chihuahua and the Dalmatian, for example, are both dogs, but they share few physical attributes.
Examples in agriculture
Selective breeding has also been practiced in agriculture for thousands of years.Almost all the fruits and vegetables consumed today are made from artificial selection. Cabbage, broccoli, cauliflower, Brussels sprouts, and kale are all vegetables derived from the same plant, Brassica oleracea, also known as wild cabbage.By isolating wild cabbage plants with specific characteristics, farmers were able to create a variety of vegetables from a single source, each with different flavors and textures. Broccoli, for example, was developed from wild cabbage plants that suppressed flower development while kale was derived from Brassica oleracea with larger leaves.
Maize, or maize, is an unusual product of selective breeding. Unlike rice, wheat, and cabbage, which have clear ancestors, there is no wild plant that resembles corn.The earliest records of corn indicate that the plant was developed in southern Mexico 6,000-10,000 years ago from an herb called teosinte. Scientists believe that early Mexican farmers selected only the largest, tastiest teosinte grains for planting, rejecting the more punitive grains. This process allowed Mexicans to develop corn very quickly, as small changes in the genetic makeup of the plant had dramatic effects on the taste and size of the grain. Despite their physical dissimilarities, teosinte and corn differ in only about five genes. Today, corn is a staple in diets around the world. On average over the years 2012 to 2017, 986 million tonnes of corn were produced each year worldwide, mainly in the United States, China and Brazil.
Without selective breeding, many plants and animals on earth today would not exist. However, artificial selection has certain drawbacks, especially in the case of inbreeding. Through inbreeding, two closely related organisms reproduce to result in a purebred with the desired traits. However, these organisms can also have unwanted traits due to recessive genes found in both parents.So, purebred dogs are sometimes born with health issues like hip dysplasia and have a shorter lifespan than other mixed breed dogs. Since artificial selection reduces variation in a population, breeders need to be careful that their selectively selected organisms do not become overly susceptible to disease or environmental changes.