Question

Write a note on "struggle for existence".

Answer 1

Darwin has already shown his reader the power of artificial selection and the exquisite variation that exists in nature. In Chapter III he asks how varieties can become full species. Crucial to this is what he calls "the struggle for existence". That may be a conflict for food or a battle against the elements. Part of the evidence for this struggle is the immense potential that animal and plant populations have to increase in size. Even the elephant, one of the slowest breeders in the animal kingdom, could take over the planet if it were allowed to reproduce unhindered for long enough. After 500 years, one pair would leave 15 million descendants, Darwin tells us. Populations are kept in check because there are not enough resources to go around, and that leads to intense competition for survival.

Answer 2

Struggle for existence ↓↓↓↓

➡According to the theories of Darwin , individuals multiply in geometric progression.

Example : 2 , 4 , 8 , 10 .....

➡However food multiplies in arithmetic progression .

Example : 2 , 4 , 6 , 8 ........

➡ Space for accommodation of organisms is constant and does not increase .

➡This leads to intense struggle between living organisms for food , shelter, climate , breeding places , food supply and mate .

➡ Intense competition arises and the competition is of different levels such as :

(i) interspecific ( different species ) and

(ii) intraspecific ( same species ) .

➡During this process of struggle for existence , only the strongest individuals who are fit for the environment survive.

➡The ones who are strong is only selected by nature and the rest die . This is called Natural Selection.

➡The process of struggle for existence while facing competitions within or between other species is called Struggle for existence .

Explanation with example :

➡Oysters lay 60 to 80 million eggs every spawn . If all would have survived,  then the oysters would have filled up the entire Earth.

➡Same with bacteria and paramecium .

➡Elephants who are the slowest breeder breeds once in 15 years average.

If all survived , the there would have been trillions of elephants up to date.

Thus natural selection and struggle for existence leads to variation and evolution of mankind !

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