Question

Briefly describe Charles Darwin’s theory of evolution by natural selection.

Answer 1

Answer -

Theory of natural selection was given by Charles Darwin . He proposed a scientific theory that all species evolve over a time period from one or few common ancestors through a process of natural selection .

Darwin started his journey on his ship H.M.S. Beagle. During his journey he was reached at some group of island in south america . This island was full of different kind of tortoise. So Darwin called group of island as Galapagos island . Here ,he saw different types of fiches.After that these finches known as Darwin's finches. Basically these are a group of 14 species of small birds.All finches are different only in their beak and corelated with feeding habit.

Natural selection - when selection process is done without involvement of human choice.

In evolution, natural selection is a process by which organism having favourable variation survive and reproduce at high rate.

Postulates of Darwin's theory-

1. Overproduction -Every species having reproductive potential and give birth to their progeny according to reproductive potential.

Some species having high reproductive power while other species have low .

2. Struggle for existance - Regular increase in number of species there also increase in struggle among organism .

Inter-species competition - when competition occur between same food resources in different species.

Intra-species competition- when competition between same species for same food resources.

Environmental struggle - when change in climate may be adversely affect result in extinction of species. Thunderstorm .

3. Variation - According to Darwin , there is some difference in population in their characterstics.These differences known as variation.

4. Arrival of new species - Those variation which enable some individual of a species to survive better in adverse natural condition. Favourable variations accumulate over generation to form a complete new species.

5. Survival of fittest - In the whole process , only those individuals survive which possess the best useful variations.

Darwin called it Natural selection.