Gene flow occurs when individuals move into or out of a population, and gene flow between populations is unidirectional. Given these facts, what is individuals moving into or out of a population among the following options:
- Greenhouse gases
 - rapid expansion
 - Burning fuel and air
 - permineralization
 - peachleaf willow
 - competition
 - unidirectional
 - food and shelter


 

       unidirectional  