The chances of a mutant gene spreading in a population increase when it is .......

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

Genetic drift operates in

Speciation is caused by

Given below are the two statements.
Statement $I$: Directional isolation favours the intermediate forms and eliminates both phenotypic extremes.
Statement $II$: In directional isolation,more individuals acquire a value other than the mean character value.
In the light of the above statements,choose the correct answer from the options given below:

Artificial selection to obtain cows yielding higher milk output represents: