Natural Selection vs Artificial Selection
What is Natural Selection?
Individuals in a population have a high reproductive potential and produce a large number of offsprings. The number produced is greater than the number survive. This is known as over production. Individuals in a population differ in structure or morphology, activity or function or behavior. These differences are known as variations. Variations occur at random. Some variations are favourable, some variations are passed on to the next generation and others not. These variations, which are passed on to the next generation, are useful to the next generation. There is competition for limited resources such as food, habitat, breeding places and mates within the species or with other species. Individuals with favourable variations have a better advantage in the competition and utilize the environmental resources better than the others. They survive in the environment. This is known as the survival of the fittest. They reproduce, and those who do not possess favourable variation mostly die before reproduction or do not reproduce. The number of individuals in a population does not change much because of this. Thus, favourable variations undergo natural selection and are retained in the environment. The natural selection occurs from generation to generation resulting in individuals better adapted to the environment. When this group of individuals of a population differs so much due to the gradual accumulation of favourable variations so that they cannot naturally interbreed with mother population, a new species arise.
What is Artificial Selection?
Humans practice artificial selection for domestication of animals and plants. The basis of artificial selection is isolating natural populations and selective breeding of organisms with traits that are useful to humans. This can be practiced in order to increase the quantity of meat, milk yield etc. Humans exert a directional selection pressure in artificial selection. This may lead to a change in the genotype of a population. Artificial selection can be carried out by inbreeding and outbreeding. Inbreeding involves selective reproduction between closely related organisms. This can be between offsprings of the same parents. This is commonly carried out by livestock breeders to produce cattle, pigs, poultry and sheep with high yields of meat, milk, eggs etc. However, inbreeding may lead to a reduction in fertility. Intensive breeding may cause a reduction of genetic variability as the homozygous genotypes start to dominate. In order to avoid this problem, a breeder may switch to outbreeding after several generations are produced by inbreeding. Outbreeding is useful in plant breeding. It is now also being used to increase the commercial production of meat, eggs etc. It involves breeding between genetically distinct populations. Usually it is carried out between members of different strains and in some plants between closely related species. The progeny are called hybrids. The phenotypic characters expressed are superior to the parents. Recent advances in human knowledge on genetics have made it possible to eliminate or select certain characters in humans too.
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What is the difference between Artificial Selection and Natural Selection? • There is no difference between the artificial and natural selection in the genetic mechanism involved. • However, the difference is that, in artificial selection, the evolution process is being influenced by humans.
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