Usually, Populations have a genetic variation among individuals, which is important to the population's ability to survive in different situations that have an effect on the natural selection. There are different factors which can increase or decrease the genetic diversity, and influencing natural selection.
These factors include an environmental factor, one of the major factors, which may cause changes in the genetic variation of a population and influence the natural selection. A famous and important example of environmental factors affecting natural selection was during the Industrial Revolution, when many more grey moths made up the moth population.
This was so that they could blend in with the soot from factories to avoid predators.
Some living organisms need a lot of sunlight to survive and cannot stand living in the shade, as is the case with some plants. In this case, the availability of sunlight presents itself as an environmental factor that will influence natural selection, because with less availability of sunlight, the less adapted organisms will die and the more adapted organisms will resist and pass this trait to their descendants.
Natural selection tends to decrease genetic variability because only a few genotypes will be selected. In addition, it also contributes to the permanence of a certain characteristic in the population.
