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.
In order for natural selection to operate on a trait, the trait must possess heritable variation and must confer an advantage in the competition for resources. If one of these requirements does not occur, then the trait does not experience natural selection. (We now know that such traits may change by other evolutionary mechanisms that have been discovered since Darwinâs time.) Natural selection operates by comparative advantage, not an absolute standard of design.