Which of the following concepts is attributed to Charles Darwin?

The modern theory of organic evolution,also known as the Synthetic Theory of Evolution,is based on which of the following factors?

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.

The frequency of traits increases when they are ........

Which of the following is related to reproductive isolation?

In the diagrammatic representation of the operation of natural selection,two peaks are formed. This condition shows the effect of . . . . . . .