Volcanic eruptions is a good example of a primary succession because lava from the volcanic eruptions incinerate everything in it's path and form new land that is composed of organic materials. These organic materials is rich in minerals which can support the colonization of algae.
Primary succession occur in an area where their is not existence of life before and absence of soil. Series of events like volcanic eruptions, flooding, erosions, oil spills e.t.c lead to primary succession. It begins with the appearance of pioneer species like lichen, misses and fungi.
Genetic drift is the dramatic almost sped up process of natural selection due to the untouched habitat the species I lives in. Genetic drift is characterized by the changing in alleles, whether more or less, natural selection could care less as long as they're creating diverse populations.
