Emigration.
The movement of new individuals into a population is called migration. In biology, it can refer to the movement of ions between electrodes during electrolysis.
Moving out of a population is called emigration. (Moving into a population is called immigration.)
Immigration
Immigration, as opposed to emigration, which is the movement of individuals out of an area.
Population Shift
The movement of humans into a population is called migration.
The movement of humans into a population is called migration.
The number of individuals in the population is the population's size. If a population is small enough you will be able to determine the size by counting the individuals.
immigration
The group of individuals used to represent a population is called the sample. It should have the same statistics as the population, though be of a smaller size.
Over population.
genetic variation