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According to Darwin the organic evolution is due to intraspecific competition. Individuals of same species have variation in characteristics. Those characteristics which enable some to survive better in natural conditions (climate, food, physical factors etc.) would outbreed others that are less-endowed to survive under such natural conditions. There, therefore, will survive more and hence are selected by nature. He called it natural selection and implied it as a mechanism of evolution.

1. Genetic drift is variation in gene frequencies within populations can occur by chance rather than by natural selection, sometimes the change in allele frequency is so different in the new sample of population that they become a different species. The original drifted population becomes founders and the effect is called founder effect.
2. According to Darwin the organic evolution is due to intraspecific competition. Individuals of same species have variation in characteristics. Those characteristics which enable some to survive better in natural conditions (climate, food, physical factors etc.) would outbreed others that are less-endowed to survive under such natural conditions. There, therefore, will survive more and hence are selected by nature. He called it natural selection and implied it as a mechanism of evolution.
3. Genetic drift is random change in allele number and frequency in a gene pool due to chance (e.g., small size of population). It is caused by sampling error or error in gene pool sample that is to form the next generation. The sampling gene pool is generally small in size. Variability is also limited.
4. Darwin observed an amazing diversity of creatures on galapagos islands. He realised that there were many varieties of finches in the same island like seed-eating, with altered beaks insectivorous and vegetarian finches. Carrion are dead bodies. No finches feed on carrion.

Correct answer: According to Darwin the organic evolution is due to intraspecific competition. Individuals of same species have variation in characteristics. Those characteristics which enable some to survive better in natural conditions (climate, food, physical factors etc.) would outbreed others that are less-endowed to survive under such natural conditions. There, therefore, will survive more and hence are selected by nature. He called it natural selection and implied it as a mechanism of evolution.

Solution

The correct choice is the one that describes Darwin’s mechanism of evolution: individuals vary, those with advantageous traits survive and reproduce more, and nature “selects” them. The other options either define genetic drift or discuss unrelated observations.

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