Which one of the following phenomena supports Darwin’s concept of natural selection in organic evolution? A) Development of transgenic animals B) Production of ‘Dolly’, the sheep by cloning C) Prevalence of pesticide resistant insects D) Development of organs from ‘stem cells’ for organ transplantation
Hint: Natural selection is the process by which an individual or an organism adapts to its environment by bringing about various changes. It is the key mechanism to evolution.
Complete Answer: We know that Charles Darwin is known as the ‘Father of evolution.’ He had written many books out of which “The origin of species” and “The voyage of Beagle” are few remarkable ones. He also introduced the term “Natural selection” in the year 1859.
Option a: Transgenic animals were created by Rudolf Jaenisch in the year 1974. This has nothing to do with natural selection. Therefore, this is the incorrect option.
Option b: Dolly the sheep was the first mammal to be cloned in the year 1996. This is not related to natural selection. Therefore, this is the incorrect option.
Option c: The theory of natural selection can be explained by prevalence of pesticide resistant insects. This can be explained by the example, in the year 1945 DDT was an effective insecticide against mosquitoes. It was so efficient that it would kill nearly all the mosquitoes, but after 2-4 years of introduction of DDT, it was seen that mosquitoes were not getting killed as effectively as they used to be. This happened because new strains of mosquitoes appeared which were DDT resistant. As these could survive even in the presence of DDT, they soon replaced the DDT sensitive mosquitoes. Therefore, this is the correct option.
Option d: It was in the year 1981, stem cells were discovered. This is not related to natural selection. Therefore, this is the incorrect option.
Thus, the correct option is c) prevalence of pesticide resistant insects.
Note: Another way of looking at this question is that, all the options except option c are man made, thus not naturally existing.
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