Final answer:
The four factors that govern changes in population size are birth rate, death rate, and migration.
Step-by-step explanation:
The four factors that govern changes in population size are birth rate, death rate, and migration.
If the birth rate is larger than the death rate, the population grows. Conversely, if the death rate is larger than the birth rate, the population decreases. If the birth and death rates are equal, the population size remains unchanged.
Migration, which refers to the movement of individuals from one place to another, can also impact population size. Immigration, which is the movement of individuals into a population, increases population size. Emigration, which is the movement of individuals out of a population, decreases population size.