Selective Breeding vs Genetic Engineering
Gene manipulation techniques are often used in these days in order to produce certain organisms with specific genetic combinations. These techniques are being improved by scientists, and they have produced animals and plants with higher reproductive capacities, high disease resistance abilities, and other desirable characteristics. Cloning, selective breeding, and genetic engineering are the techniques that can be used to develop or produce such specialized genetically manipulated organisms.
Selective Breeding
The process of selective breeding of animals and plants to obtain offspring with certain specific characteristic or characteristics is referred to as selective breeding. George Mendel’s studies of Monohybrid and Dihybrid crossings and Charles Darwin’s study of evolution and natural selection showed the possibilities of actively manipulating phenotypes of parents or offspring by the process of selective breeding. Inbreeding, linebreeding, and outcrossings are well known breeding techniques.
In the process of selective breeding, first the individuals with specified desirable characteristics should be carefully selected. Then the controlled mating should be done in order to obtain a population with the desired characteristics. This is very effective if the two verities have homozygous genotypes. Hybrid between two separate species is known as interspecific hybrids while hybrid between separate varieties of the same species is known as intraspecific hybrids.
The selective breeding can be used to improve growth rates of animals and plants, survival rates, meat quality of animals etc.
Genetic Engineering
The process of producing an organism with particular and valuable characteristics by manipulating the DNA pieces and transferring them into that organism is known as genetic engineering.
First, endonuclease enzyme is used to split a particular gene that controls the interested characteristic from the rest of the chromosome. The removed gene is next placed in another organism and then it can be sealed into the DNA chain using the enzyme ligase. Here, the resulting DNA is called recombinant DNA, and the organism with the recombinant DNA is called genetically modified (GM) or transgenic organism. Such organisms or their offspring contain genes from at least one unrelated organism, which can be a bacterium, a fungus, a plant or an animal.
Using genetic engineering, it is possible to produce many medically important products such as human insulin, interferon, growth hormones etc. Also, this method enables cells to produce specific, valuable molecules that they would not normally make.
Genetic Engineering vs Selective Breeding
• The species used in selective breeding have common evolutionary origin, especially in interspecific breeding. In genetic engineering techniques, the genes can be taken from any species. Evolutionary origin or varieties of species are not considered here.
• Natural breeding takes place in selective breeding while artificial breeding takes place in genetic engineering. In the selective breeding, it only selects the parents considering their traits that allow them to breed on their own, but in genetic engineering, the genes are being transferred.
• To make GM plants or animals, the genes must be isolated from different organisms. This step does not take place in selective breeding.
• Endonuclease and ligase enzymes are used to make GM organisms. In selective breeding, no such enzyme is used.
• The traits are only being considered in selective breeding while the genes with a specific DNA sequence are being considered in genetic engineering.
• Unlike selective breeding, highly trained technicians are needed for genetic engineering.
• Expensive machineries with modern laboratories are needed to carry out genetic engineering process steps. Compared to genetic engineering, selective breeding is a less expensive method.
• The techniques of genetic engineering are difficult more than the techniques of selective breeding.
• Large output can be obtained from GM modified organisms (example: large crop from a certain plant species) more than from selectively bred organisms.
• Wide range of characteristics can be produced by genetic engineering techniques more than it can be by selective breeding.
• Genetically modified genes may have side effects unlike in selective breeding.