The importance of random accumulation of small genetic changes is sufficient to explain evolution. Who proposed this concept?

Select the appropriate option for the given figure.

Which one of the following phenomena supports Darwin's concept of natural selection in organic evolution?

Which one of the following is $NOT$ the main postulate of Darwinism?

$XX$ is a type of selection process in evolution. $XX$ promotes population changes in one particular direction. $XX$ favours small or large-sized individuals,and the mean size of the population changes in $XX$. Identify $XX$.

Darwin,in his 'Natural Selection Theory',did not believe in any role of which one of the following in organic evolution?