A poplulation of mice lives near a stream the larger mice tend to live longer and over many generations the avarge mouse size gets larger what type of selection is this?

This is an example of directional selection. In this scenario, the larger mice have a survival advantage, leading to increased reproductive success and a gradual increase in average mouse size over generations. As a result, the population evolves to favor the larger phenotype, demonstrating how environmental pressures can shape species characteristics.