The development of herbicide resistance in populations of weeds over several generations is an example

Evolution

Explanation:

Evolution can be defined as the  change in the characteristics of the species over a period of time which basically relies on the process of the natural selection.

The characters that allows the survival of the organism is favored and is known as the survival of fittest which is a natural selection.

This is known as evolution in which the herbicide resistant plant is favored more and has developed over a period of time.

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