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Selective breeding

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Selective breeding is the process in which a specific trait is selected to become more prevalent, and then plants or animals displaying this characteristic are bred so that their offspring will also possess this trait. The breeding process usually spans multiple generations, with the trait in question becoming more and more pronounced with each generation. Selective breeding has many applications. However, like every technique, there are benefits and drawbacks. Each individual needs to assess the pros and cons if they wish to use selective breeding in their animals or plants. Selective breeding is used quite often today, from individuals breeding within their own plants and animals to entire breeds of organisms.

What is Selective Breeding? / Applications

Dogs of all kinds are selectively bred for one or more desirable traits.

Selective breeding is a relatively complicated process in which man selects desirable traits in animals or plants, and breeds the organisms in question to make this trait more prominent. People agree that selective breeding is both practical and easy to put into effect. [1] Selective breeding augments the prevalence of hereditary traits in the offspring. This is usually achieved through breeding animals that possess the trait desired.[2] Selective breeding is important for multiple reasons. One reason is that enhancing crops and increasing yield, agriculturalists must breed their crops for this.[1]

Selective breeding is used in many forms, and for many reasons. Larger amounts of crops can be produced and harvested, and the offspring of the crops will begin to develop higher resistance to pests and disease.[1] Selective breeding also allows living organisms to be bred for their best features and characteristics from parent to offspring. Plants bred will grow larger, animals will become thinner, and simply overall better products. Sustainable food is a major opportunity available through selective breeding. by the year 2050, the world population is projected to reach nearly 10 billion. Sustainable food will be a major necessity for the food chain to be able to support so many diets, if hunger was to be eliminated. In theory, selective breeding in humans could possibly lead to living longer and eliminating genetic diseases.[3]

Pros and Cons

The Belgian cow has been breed specifically for a higher meat yield.

Negatives

Selective breeding faces negative issues:

-Selective breeding eradicates the variety amongst organisms as they are bred. Much like selective breeding can eliminate a disease, entire traits can be lost. The goal is to created an enhanced version of the organism, meaning that at some point down the line, the diversity will give way to productivity.[3]

-Organisms that have already been bred through selective breeding face the risk, even a minor one, of diseases and certain environmental changes because they may lack the trait to help them adjust.[1]

-Genetic mutations are able to occur without any hope of control. Selective breeding speeds up the development of good traits but has no power over the negative traits. When genetic mutations occur, the effectiveness of the crops being developed will drop.[3]

-It cannot stop the forming of genes inherited by the offspring, meaning that errors in the process for selective breeding would be obvious.[1]

-A genetic depression could occur. A genetic depression is when organisms being selectively bred are so genetically similar that they enter into a depression of genetic diversity able to lead to many negative mutations. [3]

-Selective breeding, can cause entire traits within organisms to be lost entirely.[1]

-Offspring are vulnerable. Because of the extensive inbreeding (breeding the same group of organisms’ for multiple generations) within the group, the offspring become very vulnerable to certain pathogens. This means that constant and diligent monitoring and analysis are required to figure out if the selective breeding process or the organism's population itself is causing the spike in risk against the pathogens.[2]

-Discomfort for animals. When a breeder wants to develop a particular trait, they might unintentionally produce traits that are harmful to the animal. As an example, cows require large udders if they are to produce large amounts of milk. Selective breeding usually results with the udder being large, almost certainly causeing the cow to live in discomfort. [2]


-Within dogs alone there are many cons to selective breeding: skin problems, immune system disease, blood disorders, neurological, behavioral, and sensory, Hearing and vision, and heart disease, other organs and systems, cancer, and orthopedic[4]

Positives

There are also many pros to selective breeding:

-The entire process of selective breeding is free, if you hvae the animals, and can involve any plant or animal with a desired trait. If one wanted to develop a specific trait, they only need to understand the process.[1]

-No company has a patent on selective breeding, allowing anyone to participate in it. Farmers can increase profits annually by specifically breeding plants and animals to be more and more productive.[3]

-There is no danger to a person in selective breeding. This is because there are no safety malfunctions that can occur, so a person faces no danger in selective breeding.[1]

-Selective breeding allows characteristics to be developed that are beneficial to the specific farmer.[2]

-Unlike GMO, people are comfortable with products that are selectively bred. Selective breeding offers higher quality product, without any of the objections of GMOs.[1]

-There is no danger in selective breeding like in GMO crops. Selective breeding is a natural process, with the DNA sequences never being modified as in GMO.[3]

-Elimination of disease. There is an opportunity to eradicate a disease from a group of organisms by screening and identifying a disease will help in controlling it. Once the disease has been identified, only those organisms without it will be bred, and eventually, the disease should disappear from the posterity.[2]

Modern Examples

Corn has been selectively bred for years.

Plants

Practically all principal crops that we produce have been dramatically changed from their original wild forms. Grains, such as wheat, now have larger seeds than the smaller ones that grow in the wild. The domestic corn that farmers now grow was developed from the wild grass teosinte, that produces grains that resemble a centipede or some other such insect.

People have also discovered a way to graft two different types of trees to develop hybrid fruit without needing to breed the trees together. One example, the navel orange, is only able to be grown through cuttings. This means that the navel oranges in stores today are clones of the navel oranges from decades ago.

In the 1930’s, scientists started blasting seeds with gamma rays and X-rays, effectively adding mutations and creating new plant hybrids. The mutations caused by the radiation could mean an altered growth rate, flesh color, and chemical composition of the plants, which then alters their productivity, as well as their flavor and appearance. These hybrids also have a different response to various diseases.[5]

Animals

There are many modern examples of selective breeding within the animal kingdom:

In 1959, a Russian geneticist became curious of how dogs were domesticated. In his hypothesis, he assumed that because there was such a wide variety of dog breeds, each one must have been selectively bred for the trait of tamability (able to be tamed), and then a trait that was found desirable. To test his theory, the geneticist created a program to domesticate the silver fox, a species similar to dogs, but one that had never before been domesticated. To start, silver foxes were acquired from where they were bred on pelt farms. Selecting foxes to breed based on tamability, like his hypothesis suggested, meant that the foxes’ offspring would experience appearance changes, as well as behavioral variations. In the next 52 years, the silver fox was bred for the trait of tamability, and the silver fox has undergone appearance changes. The domesticated silver fox can now be found with many traits, including: white patches, short legs and tails, floppy ears, rolled tails, and brown mottling. The trait of tamability also gives these domesticated silver foxes a much quicker response to socialization techniques rapidly in comparison to wild silver foxes bred at pelt farms.[6]

The Belgian Blue cow, a hulking creature compared to an average cow, possess mutations that suppress myostatin production for the animal. Myostatin is a protein that helps to keep muscle growth under control. When people began breeding the cows that lacked this protein, the offspring would display this trait essentially from birth.The mutation in question naturally occurred in a few cows in the Belgian Blue breed, but after extensive selective breeding in the 1950’s, the mutation is now permanent within the breed’s offspring. Every Belgian Blue cow today presents myostatin deficiency, which allows breeders to produce cows with a much higher meat yield. Because the amount of muscle is so large, even as babies, C-sections are often performed on the females. The mutation has become so extreme that there are some European countries that have debated whether or not to eradicate the breed permanently.[5]

The Musk Ox has been selectively bred for 62 years for their domesticated livestock temperament. At one point, the Musk Ox faced extinction because of excessive hunting. In the late 1800’s, they actually went extinct in Alaska and had to be reintroduced by the U.S. Fish and Wildlife in small herds in 1935. In past years, the Musk Ox has revived its populations and is no longer considered endangered. In the 1950’s, anthropologist John Teal attempted to prove that the Musk Ox could be tamed and domesticated. After researching for around a year, he began the Musk Ox Farm Project in Alaska. The W.K.Kellogg Foundation offered their help, as well as the University of Alaska, and the project grew, and now produces domesticated Musk Oxen. A unique Native Alaskan industry has developed as a result of this project, that low-income native residents can participate in. The project in still running, overseen by the Musk Ox Farm, which is a non-profit organization dedicated to preserving the Native Alaskan industry.[6]

Chesty La Rue birds, are the form of turkey now sold and eaten. The Broad Brested White, the standard turkey used for food, is the turkey that was bed into the Chesty La Rue, and was bred to accentuated their pectoral muscles. The selective breeding process for this particular breed of fowl began in the 1950’s, because it fulfilled the necessities for farmers and consumers. Large amounts of breast meat is able to be produced rapidly, and if the farmer kills it while it is young, the bird will fit easily into a refrigerator. However, if the bird is allowed to mature, the male Broad Breasted turkeys’ chest is so large that it is unable to breed with the females without crushing his partner, so breeding is required to occur through artificial insemination. Because of the high percentage muscle presence on these turkeys, some reaching up to 50 lbs., the turkeys face much shorter lifespans. This is because carrying so much weight causes heart failure, respiratory illness and joint issues. Breeders, hoping to avoid this, have sought to increase the percentage of eggs produced through parthenogenesis, the creation of an embryo without fertilization, to create clones of the turkey.[5]

The American Alsatian undergoes the selective breeding process for temperament. In the past, medium to large dogs were bred because they were able to assist in various tasks, including herding, hunting and protection. Today, there is a much smaller call for such work dogs, but rather a desire for companionship. Because of this, the Dire Wolf Project, for their first 24 years, bred American Alsatians for quiet temperaments alone. However, as the generations of offspring progressed, the appearance of the breed began to change. Because the dogs with larger bone structure and skull size, as well as heavier bodies, have the softest temperaments, these traits became accentuated within the breed.[6]

Video

A short explanation of selective breeding.

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Pros and Cons of Selective Breeding HealthResearchFunding.org. Web. Published May 21, 2014. Unknown Author.
  2. 2.0 2.1 2.2 2.3 2.4 Advantages and Disadvantages of Selective Breeding Occupy Theory. Web. Published September 10, 2014. Unknown Author.
  3. 3.0 3.1 3.2 3.3 3.4 3.5 Selective Breeding Pros and Cons Asia-Pacific Economic Blog. Web. Published January 23, 2015. Unknown Author.
  4. Selective Breeding Problems PBS. Web. Published September 16, 2010. Author Unknown. .
  5. 5.0 5.1 5.2 Mitchell, Rachel. Genetic Manipulation: the First 50,000 Years io9'. Web. Published May 23, 2014.
  6. 6.0 6.1 6.2 Selective Breeding The Dire Wolf Project. Web. Accessed May 29, 2015.Unknown Author.