Natural selection does not always result in an increase in genetic diversity.

True.

Explanation:

Natural selection is one of the driving mechanisms of the evolutionary process, which, in turn, is the change of populations over time. It consists of the process by which individuals in a population that are better adapted to a given condition of the environment are favored because they are more likely to survive and reproduce than those less adapted.

Although natural selection is a driving mechanism of evolution and provides an increase in genetic diversity, this is not always the case. This is because genetic diversity and evolution depend on other factors. However, natural selection is the only one that explains the forms of adaptation that we find in nature in a consistent way.