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.
Describe the theory of evolution by natural selection. Natural selection occurs when environmental conditions select for certain advantageous traits. Because traits are heritable, the traits of those who successfully reproduced are more common in the next generation. And in this way, nature selects for these traits. Evolution by natural selection is thus the change in the frequency of different alleles for a trait through time. Over time, natural selection can allow species to adapt to changing environmental conditions and diverge from one another, leading to the great diversity of form and function of organisms we observe today.