Describe how the effects of directional selection can be off

Describe how the effects of directional selection can be offset by gene flow.

Solution

Lets just understand by an example:

A tribe of subterrestrial people has the ability to glow in the dark but if they keep marrying other non-luminescent people then they will never become truly unique. So, the population undergoes selection pressure from other population otherwise the gene from outside will impact or dilute the impact of the origin gene this will lead to directional selection.