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Artificial Selection  

Aug 22, 2022
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Introduction: 

Natural selection: It is a method of adaptation by an organism to the changing environmental conditions, by making selective changes to its genotype or genetic structure. 

Natural selection is one of the four main mechanisms of evolution, along with mutation, genetic drift, and migration. 

Natural selection is one of the major mechanisms of evolutionary change and is the process responsible for the evolution of adaptive features in various species. It is a force that causes groups of organisms to change over time and it leads to evolution.  

In natural selection organisms with traits that are best suited to their environment are more likely to survive and reproduce. These favourable traits are passed on to the next generation. 

Artificial selection: It is the process in which humans select the traits useful for improving the qualities of domesticated plants and animals. Humans select the organism with desired traits and separate them and then selected organisms are interbred. 

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For example, cows that give high yield milk are desired and breeders monitor the milk of a large number of cows and select cows which produce a large quantity of milk.  

Explanation: 

Artificial selection – Artificial selection is also known as selective breeding, Charles Darwin introduced the term artificial selection in his book On the Origin of Species. He studied Finches to explain his theory of evolution.  

Artificial selection  

Steps of artificial selection  

  1. Choose a species 
  1. Choose a trait of interest 
  1. Breed them together 
  1. Identify which individual shows the desired trait strongly 
  1. Breed that trait for the next generation 
  1. Repeat 4 and 5 steps for many generations 

Selecting a trait– Humans choose favorable characteristics in plants and animals. The selection of specific traits (characteristics) is necessary for good quality nutritional value, for seedless fruits, greater yield, disease resistance, the manufacture of better milk, improved taste, to have various breeds of animals, etc.  

Selective-breeding– Select the favorable trait. Choose individuals with that trait(characteristics) and breed them together. Observe the individuals and breed them over a generation; choose those traits which show the desired trait very strongly. Repeat this process for generations to create a population with the preferred trait. 

Culling– Eliminating individuals that do not show the desirable traits in the breeding population. 

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Types of artificial selection  

  • Selective breeding  
  • Hybridization
  • Inbreeding    

Selective breeding  

Selective breeding is also known as artificial selection, Humans select the breeding of species to produce desired traits in offspring, and selective breeding is observed in animals and plants.  

Selective breeding of plant crops has allowed the generation of new types of food from the same ancestral plant source.  

Examples of Selective breeding: 

  • Plants like brassica breed produce different foods by modifying plants by artificial selection.  
  • For example – broccoli, cabbage, and kale  
  • Selective breeding in animals results in the generation of different breeds of offspring  
  • Examples are horses, cows, and dogs. 
Selective breeding  

Examples – Cow Breeding 

  • Cows have selected bred of many generations to produce offspring with good milk production 
  • Farmers also targeted the breeding of cows resulting in increased muscle mass 
  • The resulting stock of cattle has produced more edible lean meat 
cow
Cow Breeding 

Dog Breeding 

  • Dog breeds show the amount of targeted selection of traits by man. 
  • Hunting dogs (e.g., beagles) are bred to be small as they enter fox holes. 
  • Racing dogs (e.g., greyhounds) were specially bred as sleek and fast.  
  • Toy dogs (e.g., chihuahuas) were selected and bred for their size. 
 Dog Breeding 

Hybridization

Hybridization is also a method of selective breeding. In hybridization breeding occurs between two parents who are genetically similar, hybridization can occur both in plants and animals resulting in a hybrid variety.  

For example, hybrid plants may produce more flowers, seeds, and less disease resistant, less insect and pests resistant or tolerate more herbicides. 

Example Mules are produced by mating horses and donkeys. 

Hybridization 

 Example: Luther Burbank created a disease-resistant potato called the Burbank potato. 

  • Luther Burbank crossed a disease-resistant plant with another plant that had a large food-producing capacity. 
  • Result: a disease-resistant plant that makes a lot of potatoes, liger, and grapple  
Luther Burbank    
 Burbank potato 

Inbreeding: 

In this method, the mating takes place between directly related species for genetically improved plants and animals. Recessive genes have a higher role in genetic defects than dominant genes, thus there is a greater chance of having problems in children. Inbreeding reduces the gene pool and, extinct some lines; health of plants or animals is at higher risk. 

Inbreeding is the other selective breeding the main purpose of inbreeding maintains desired characteristics of parents in the offspring.  

  • Dog breeds are kept pure by inbreeding and it’s how a Doberman remains a Doberman.  
  • It keeps each breed unique from the others. 
In breeding 

Outcrossing: 

In this method, two animals mating in unrelated 4-6 generations shows results in high genetic variation in their traits. Outcrossing hides undesirable traits or characteristics by keeping them recessive (suppressed); this works best for desirable dominant genes. Outcrossing enhances milk production and longer life. 

Linebreeding 

This method includes the mating of related species having a common ancestor. It shows consistency than outcrossing and has minimal genetic defects. 

Ethics of Artificial Selection 

Artificial selection is used for improved health and to enhance well-being. In the farming system, plants and crops with pest resistance use fewer pesticides. Artificially selected trees can grow the forest at a very faster rate; there is also a possibility to eradicate Dengue and Malaria by artificial selection of sterile mosquitoes developing less fictional. Artificial selection also helps in the decreased variation in the gene pool. 

Advantages of Artificial Selection (selective breeding): 

  • Anyone who can work on artificial selection will gain knowledge about the characteristics of plants and animals.  
  • Improvement in plants and animals like- productive animals for high-quality milk, beef, plants with a high yield of crops, seedless fruits, and different variety of vegetables.  
  • Replicate the GMO work- selective breeding in plants lead crops to be pest resistant and disease resistant.  
  • The human food chain stabilizes by selective breeding and also increasing production when plants and animals have desirable traits. 
  • Increase the yield of animal products- by selective breeding animals, produces more meat and milk. Cows are selected breed with content fat milk. Eggs are produced by selective breeding in chickens. 
  • Low-cost management for artificial selection- selective breeding shows an affordable range and methods that create animals and plants with desired traits to reduce the genetic disease in plants and animals. 
  • It enables the growth of crops in different climatic conditions and soils. 

Disadvantages in Artificial Selection: 

  • Lack of plants and animals’ variety- In artificial selection, the varieties of species are created and extinction of them also arises, which produces inbreeding. There is a compromise in species variety and higher production of the preferred trait product. 
  • Selective breeding allows transferring the desired trait from parent to offspring. Poor traits are passed to the offspring and, there are chances of having a genetic mutation. 
  • Selective breeding lowers the life span of plants and animals. 
  • It causes evolutionary changes in species like the selection of specific traits in plants or animals that lead to lower adaptation capability in new environments as they do not have that capability due to selective breeding. 

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