Pictured: Rupert Grint's tears at funeral for murdered teenage Harry Potter actor. Harry Potter star Rupert Grint was unable to contain his emotions at the funeral for his fellow Hogwarts' actor, Robert Knox who was stabbed to death last month.
Why is variation needed in order for natural selection to occur? If there were no differences in an organisms ability to survive and reproduce what would there be to select from? Variation in populations is key to the naturally selective pr â¦ ocess and these variations that are reproductively successful are passed on to progeny which leads to the change in populations over time called evolution.
A source of new variability is necessary for continued evolution to occur. Sources of genetic diversity External. Much of variation in populations, species, is retained due to changes in the environment (adaptive traits are only good in some environments, and not in others).or any evolutionary change to occur there must be some genetic variation in the population; the greater the amount of variability, the greater the possibilities for change. Natural selection decreases variability in populations: in a uniform environment, better adapted types should completely replace unfit types.