Gene flow occurs when individuals move into or out of a population.
Gene flow between populations is unidirectional.
Individuals moving into or out of a population is unidirectional.
what is individuals moving into or out of a population?

a. Greenhouse gases
b. rapid expansion
c. Burning fuel and air
d. permineralization
e. peachleaf willow
f. competition
g. unidirectional
h. food and shelter