Directional selection is exemplified by the black bears' size changes in response to environmental shifts.
Directional Selection is the process where environmental changes lead to the selection of phenotypes at one end of the variation spectrum. An example is the evolution of the peppered moth during the Industrial Revolution, where darker moths had a higher survival rate due to polluted environments.
Black bears transitioning from larger sizes in glacial periods to smaller sizes in warmer periods is a clear example of directional selection. The shift in size based on environmental changes showcases how this evolutionary process works.
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