Question

how a genetic drift proves to be profitable for a species ?

Answer 1

Genetic drift occurs in small population where the variations (mutations) that occur are random, sudden and non directional. Genetic drift results in speciation. If few individuals of a species are isolated from the rest of population due to some catastrophic event then genetic drift will occur in these few members making them adaptable for the new environmental conditions. Few mutations will be fixed and others will be lost resulting in a new species.