Gene flow occurs when individuals move into or out of a population.
Gene flow tends to decrease differentiation.
Decreased differentiation tends to occur when individuals move into or out of a population.
What tends to occur when individuals move into or out of a population?
Options:
  * competing for resources
  * extinction
  * matter is destroyed
  * metabolic reaction
  * rapid exponential growth
  * seed dispersal
  * decreased differentiation
  * permineralization