Genetic drift is also known as ........

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:

In a random mating population in equilibrium,which of the following brings about a change in gene frequency in a non-directional manner?

Which of the following scientists believed in the concept of natural selection like Darwin?

Natural selection operates at