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.
Selection is the process that increases the frequencies of plant resistance alleles in natural ecosystems through coevolution, and it is the process that increases the frequencies of virulence alleles in agricultural ecosystems during boom and bust cycles.