If two populations of a species exist in isolation from each other, and one population experiences genetic drift while the other does not, what is the most likely outcome?
The two populations will experience allopatric speciation.
The population that experiences genetic drift will go extinct.
The two populations, because they are the same species, will stay in Hardy-Weinberg equilibrium with each other.
Evolution will occur, since the gene frequencies in the gene pools of the two populations will change.