A selective pressure is any reason for organisms with certain phenotypes to have either a survival benefit or disadvantage. In the example above, strong sunlight is a selective pressure that favors darker-skinned people; lighter skin would be a disadvantage in these regions.

What is an example of a selection pressure?

Individuals produce more offspring than their environment can support, and some die because of factors such as predation, food shortage or disease. ... Predation, competition and disease are examples of selection pressures.

What is the selection pressure in this process?

Selection pressure means factors that contribute to selection which variations will provide the individual with an increase chance of surviving over others. Because of selective pressures, organisms with certain phenotypes have an advantage when it comes to survival and reproduction. Over time, this leads to evolution.