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.
Types of Natural Selection. Directional selectionDirectional Selection:A type of selection that removes individuals from one end of a phenotypic distribution and thus causes a shift in the distribution. occurs when natural selection favors one extreme of continuous variation.ver time, the intermediate states become more common and each extreme variation will become less common or lost. Natural selection can occur with or without environmental change. 1  In a constant environment, natural selection will keep a population stable and essentially maintain the status quo.