The frequency of an allele in an isolated population may change due to

Genetic drift does not apply to:

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

Given below are two statements regarding evolution.
Statement-$I$: Natural selection is the establishment of a phenotypic trait in changing environmental conditions.
Statement-$II$: Natural selection encourages those genes or traits that ensure highest degree of adaptive efficiency between population and its environment.
In the light of above statements, choose the most appropriate answer from the options given below.

Which of the following revolutionary concepts in biology is associated with Charles Darwin's 'The Origin of Species'?

Genetic drift operates in which of the following?