Identify the phenomenon in which the members of a species do not interbreed with the members of other species or the same species.

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:

Given below are two statements.
Statement-$I$: Elimination of particular alleles from a population due to natural disasters is called genetic drift.
Statement-$II$: Sudden temporary heritable change in the gene is called point mutation.
In the light of above statements,choose the most appropriate answer from the options given below:

The presence of deleterious alleles in a heterozygous genotype in a population is called......

Evolution is a process or the result of a process. Explain this statement.

As per the modern synthetic theory,organic evolution depends upon: