To constitute natural selection, the difference in survival and/or reproduction cannot be due to chance, and it must have the potential consequence of altering the proportions of the different ...

Note that this change was not due to pollution making the moths darker. The dark variety had always existed in small numbers, but only had a selective advantage when the selection pressure changed.

Natural selection is the process by which some organisms in a population survive and reproduce, while others do not, based on their bodies and behaviour. It is one of the processes by which ...

The proportion of well-adapted organisms in a population can increase over the generations by the process of evolution by natural selection.