Artificial Selection- Definition, Steps, Examples, Uses

Artificial Selection is also known as Selective Breeding.

Charles Darwin introduced the term Artificial Selection in his book ‘On the Origin of Species (1859). Darwin Artificial selection happened at HMS Beagle when he returned from England to Galapagos Island. He studied finches on the island, then for explaining his ”theory of evolution” he used artificial selection as proof. He bred pigeons in his garden to experiment and observe different traits passed from one to another by selecting a desirable trait; he bred the two pigeons with that same trait and enhanced their chances of being passed on to their offspring.

What is Artificial Selection?

Artificial Selection or Selective Breeding is a process in which humans select the desired trait to pass in next-generation offspring of plants or animals.

  • The selection process by humans.
  • A long and planned steps.
  • Genetic changes.
  • Allelic frequency increases.

Steps of Artificial Selection

  1. Choose a species.
  2. Choose a trait of interest.
  3. Breed them together.
  4. Identify which individual shows the desired trait strongly.
  5. Breed that trait for the next generation.
  6. Repeat 4 & 5 steps for many generations.
  • Choosing of a trait- Humans select favorable traits in plants and animals. The selection of specific traits is required-   For better nutritional value, for seedless fruits, for higher yield; for disease resistance; for production of better milk, for better taste, to have different breeds of animals, etc. 
  • Selective-breeding- Choose the favorable trait. Select individuals with that trait and breed them together. Observe the individuals and breed them over a generation; select those which demonstrate the desired trait very strongly. Repeat it for generations to form a population with the desired trait.
  • Culling- Removing individuals that don’t have the desirable traits in the breeding population.

Examples of Artificial Selection

Artificial selection in animals

Artificial selection in animals such as dogs, the gray wolf is a pure form; this common ancestor bred to produce different types of dogs like Dane, chihuahua, slowest bulldog, greyhound for hunting. Dog hybrids are popular, such as Labrador retriever and poodle makes labradoodle, and breeding between pug and beagle makes puggle. Dog evolution showed a variety of breeds due to selective pressure; many traits disappeared because of selective breeding, but feral dogs don’t become wolves again. A change was in their behavior and physical appearance. An example of Moscow dogs as- the loss of traits like spots on their body, a wagging tail, friendly nature that contrasts domestic dogs from wolves. The stray dog’s living was becoming difficult, so selective breeding made them evolve into four types- according to one biologist, Andrei Poyarkov; he studied dogs for 30 years and observed the four types 1) guard dogs are for security. 2) Scavengers evolved to roam around the city looking for garbage. 3) Wild-wolf-like dogs are for hunting. 4) Beggar dogs have different behavior; they communicate with people and eat street food. They can travel in subways, remember stations, that’s why they’re ‘metro dogs. The example of dogs showed how evolution happened and, selective breeding brings out new breeds of dogs.

Artificial Selection or Selective Breeding
Image- Examples of Artificial Selection or Selective Breeding. Image Source: John Doebley and USDA. Created with biorender.

Artificial Selection in plants

Artificial selection of wild mustard plant (Brassica oleracea) leads to evolving of cabbage, cauliflower, and broccoli. The cabbage came into existence by selecting a short petiole. Selection of arrested flower developed in wild cabbage forms broccoli. By selecting sterile flowers, cauliflower formation happened. Swollen parts of wild cabbage developed into a variety called kohlrabi and kale by large leaves selection.

Artificial selection in corn

The wild ancestor of corn is teosinte. In ancient times, farmers selectively bred corn kernels according to their needs to improve the corn plants. Farmers picked specific characteristics like the ability to grow in different climate conditions, based on soil type, and high amount of kernels production, increase in yield and, seeds used to save for next season. The ability of corn to grow in different varieties was skilled breeding and diverse genetics. By improvement and climatic condition adaptation, flint corn developed as it holds large seeds. Another variety that exists is Pueblo corn, which can grow in a cold and wet climate; the specialty of this corn is- easy to grind and highly productive. So, in 1930 George Beadle observed the relationship between the teosinte and maize. He showed there was high compatibility between the chromosomes of teosinte and maize. He produced hybrids of them and observed their characteristics in offspring. Five genes were responsible for differences in the teosinte and maize strains. Application of inbreeding and hybridization artificial corn was introduced in 2014 and is available in 5 colors white, yellow, dark red, deep purple, blue-black. The offspring of artificially bred corn have the same genes, traits, and DNA as their bred parents. So, either homozygous dominant or homozygous recessive crossed to have purebred offspring.

Read Also- Natural vs Artificial Selection- Definition, 17 Differences, Examples

Artificial selection in cows

Artificial selection in cows led to high yields of milk and meat. Due to selective breeding, new breeds that came into existence could tolerate climatic conditions. An example is the Holstein cow that produces 72,000 pounds of milk. Artificial insemination:- A process in which sperm cells are collected from a male cow and inserted into the female reproductive tract manually. By this technique, males produced better offspring, and a semen dilution makes it easy to transport it in different countries to different female cattle. Many doses are prepared in one ejaculation and easily stored for future use. 

Selective breeding is for the following-

  • Increase in milk and meat production.
  • Increase in muscle and size.
  • Increase in udder size.
  • Increase the content of fat and protein.

Artificial insemination also reduced disease transmission; screening was performed for pathogen availability and semen analysis for quality. Female offspring (calves) produced by insemination have a longer life and good udder quality. Milk production is good in quantity and quality, but selective breeding affects fertility in herds.

Approaches to Selective Breeding

1) Outcrossing

Two animals mating in unrelated 4-6 generations back results in high genetic variation in traits. Outcrossing hides undesirable traits by keeping them recessive; this works best for desirable dominant genes. Outcrossing improves milk production, longer life.

2) Linebreeding

This involves the mating of related species having a common ancestor; it shows uniformity than outcrossing and has low genetic defects.

3) Inbreeding

The mating occurs between directly related species for genetically improved plants and animals. Recessive genes have a higher role in genetic flaws than dominant genes, so there is a higher chance of having trouble in children. Inbreeding depletes the gene pool and, extinct some lines; fitness of plants or animals is at higher risk.

Ethics of Artificial Selection

Artificial selection is used for better health and to improve well-being. In the agriculture system, plants and crops with pest resistance use fewer pesticides. Artificially selected trees can repopulate the forest at a faster rate; there is also a chance to eliminate Dengue and Malaria by artificial selection of sterile mosquitoes becoming less fictional. The artificial selection also reduced variation in the gene pool.

Advantages of Artificial Selection (selective breeding)

  1. Anyone can work in artificial selection by gaining knowledge about the specific characteristics of plants and animals. This method can work in every industry related to crops and livestock improvement.
  2. Improvement in plants and animals like- high productive animals for high-quality milk, beef. In plants for better taste, high yield of crops, seedless fruits, variety of vegetables, corn cobs to have more seeds per year.
  3. It can replicate the GMO work- selective breeding in plants led crops to be pest resistant and disease resistant. GMOs alter DNA and genes for quick results, but selective breeding does it on a safer and danger-free potential.
  4. The human food chain gets stabilized by selective breeding via eliminating waste and increasing production when plants and animals have desirable traits.
  5. Increase the yield of animal products- by selective breeding animals, produce more meat and milk. Cows are selectively bred for high content fat milk, high protein, and more milk production. Eggs can be produced by selective breeding in chickens, so hens lay eggs in the earlier stage.
  6. Low-cost management for artificial selection- In comparison to GMOs, selective breeding shows an affordable range and method to create animals and plants with desired traits minimize the genetic disease in plants and animals.
  7. It also enables the growth of crops in different climatic conditions and soils.

Disadvantages in Artificial Selection

  1. Lack of plants and animals variety- By artificial selection,a variety of species are created, and extinction of them also occurs, which causes inbreeding. There is compromisation in species variety and higher production of the desired trait product.
  2. Selective breeding allows the transfer of the desired trait from parent to offspring. Poor traits are also passed on to offspring and, there are chances of having a genetic mutation that can stop the process. Still, there’s no research examination on this.
  3. Selective breeding has been done so far, and although a desired trait or characteristic is present, other weaknesses occur in species. It also reduces the life span of animals or plants.
  4. It can cause evolutionary changes in species like the selection of specific traits in plants or animals, that lead to lower adaptation ability in new environments because they lack that ability due to selective breeding.

References

  1. https://agritech.tnau.ac.in/animal_husbandry/animhus_cattle_AI.html
  2. https://silverlakefarms.com/how-can-cattle-be-selectively-bred/
  3. https://www.ctc-n.org/technologies/selective-breeding-controlled-mating
  4. https://vittana.org/16-advantages-and-disadvantages-of-selective-breeding
  5. https://www.nzqa.govt.nz/assets/qualifications-and-standards/qualifications/ncea/NCEA-subject-resources/Biology/91607/91607-EXP-student3-001.pdf
  6. https://www.allaboutcorn.umn.edu/lessons/corn-breeding
  7. https://learn.genetics.utah.edu/content/evolution/corn
  8. https://biologydictionary.net/artificial-selection/
  9. https://blogs.scientificamerican.com/science-sushi/observations-evolution-the-curious-case-of-dogs/
  10. https://www.thoughtco.com/artificial-selection-in-animals-1224592
  11. https://lisbdnet.com/what-are-some-examples-of-artificial-selection/
  12. https://www.topperlearning.com/answer/wild-cabbage-artificial-selection/x6k55tuu
  13. https://www.thoughtco.com/artificial-selection-in-plants-1224593
  14. https://sciencing.com/adaptations-sheep-8454980.html
  15. https://bio.libretexts.org/Courses/Lumen_Learning/Book-_Biology_for_Non_Majors_II_(Lumen)/1.4.06%3A_Module_2-_History_of_Life/1.4.6.22%3A_Artificial_Selection
  16. https://en.ppt-online.org/380023

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